Title of Invention	PROCESS FOR PRODUCTION OF LIGHT OLEFINS FROM HYDROCARBON FEEDSTOCK
Abstract	Disclosed is a process for producing light olefins from hydrocarbon idstock. The process is characterized in that a porous molecular sieve catalyst isisting of a product obtained by evaporating water from a raw material mixture uprising a molecular sieve with a framework of Si-OH-Al- groups, a water-oluble metal salt, and a phosphate compound, is used to produce light olefins, rticularly ethylene and propylene, from hydrocarbon, while maintaining rtiellent selectivity to light olefins. According to the process, by the use of a icific catalyst with hydrothermal stability, light olefins can be selectively educed in high yield with high selectivity from hydrocarbon feedstock, rticularly full-range naphtha In particular, the process can maintain higher icking activity than the reaction temperature required in the prior thermal icking process for the production of light olefins, and thus, can produce light jfins with high selectivity and conversion from hydrocarbon feedstock.

Title of Invention

PROCESS FOR PRODUCTION OF LIGHT OLEFINS FROM HYDROCARBON FEEDSTOCK

Abstract

Disclosed is a process for producing light olefins from hydrocarbon idstock. The process is characterized in that a porous molecular sieve catalyst isisting of a product obtained by evaporating water from a raw material mixture uprising a molecular sieve with a framework of Si-OH-Al- groups, a water-oluble metal salt, and a phosphate compound, is used to produce light olefins, rticularly ethylene and propylene, from hydrocarbon, while maintaining rtiellent selectivity to light olefins. According to the process, by the use of a icific catalyst with hydrothermal stability, light olefins can be selectively educed in high yield with high selectivity from hydrocarbon feedstock, rticularly full-range naphtha In particular, the process can maintain higher icking activity than the reaction temperature required in the prior thermal icking process for the production of light olefins, and thus, can produce light jfins with high selectivity and conversion from hydrocarbon feedstock.

Full Text	[DESCRPTION l [Invention Title] Process for Production of Light Olefins fix)m Hydrocarbon Feedstock [Technical Fieldl The present invention relates to a process for producing light olefins firom hydrocarbon feedstock, and more particularly to a process for producing light olefins at high yield with high selectivity fiom hydrocarbon feedstock using a catafyst which, even in an atmosphere of high temperature and humidity, has a relatively stable structure, thereby maintaining its catalytic activity over a long period of time, and shows hydroftermal stability. [Background Art] Olefibs, particularly light olefins, sudi as ediylene and propylene, are widely used in the petroleum chemical industry. These light olefins are generally produced by the thermal racking (steam cracking) of naphtha in the presence of steam. The steam cracking technology is being improved in many fields in order to cope with high process temperature and a reduction in residence time and to optimize enery efficiency. However, it is not easy to inaprove energy efficiency merely by simple improvements in engineering technology, and the steam cracking process currently accounts for about 40% of the total energy required in the petroleum chemical industry. Accordingly, to reduce environmental pollution and incrase econcHnic efficiency, there is a need for improved process technologies for the optimization of energy, flie reduction of feedstock use, the minimization of carbon dioxide discharge, eto. Also, light n^htha is typically used as feedstock, but is expulsive compared to fiill-range naphtiia as desoibed later, and thus, will necessarily act as a limitation in increasing economic efficiency. Particularly, in the steam cracking technology, that is currently applied, not only it is not easy to control the composition of olefins but also the reaction temperature is a level of 800-900 C, indicating a requirement for a large amount of thermal energy. Thus, a need for improvement in steam crackii^ tedmology has suggested. Also, light olefin compounds can be produced by a fluid catalytic aacking (FCC) process. This FCC process is widely known in the art as catalytic craddng technology using a catalyst having the form of fine particles, which behaves like fluid wiien treated with steam. Particularly, deep catalytic cracking PCC) technology is known which is a process developed by modifying the FCC process in order to increase the yield of olefins (mainly, propylene) other than gasoline. In the FCC process, a heavier firacdon than fiill-rai^e nqjhtha used m the present invention, such as vacuum residue, atmospheric residue, or gaseous oil, is used as feedstock. Regarding the production of olefins, in addition to the above-desoibed steam cracking and FCC processes, olefin conv^sion processes using catalytic aaddng have been proposed. In most of these processes, the HZSM-5 catalyst as a solid acid catalyst is widely used. However, in the conventional catalytic cracking processes using the solid acid catalyst, the reaction temperature is typically at least 650 C, and at least 30% of the reaction feed is steam. The porous solid add catalyst (e.g., zeolite) used in these catalytic cracking processes has problems in that, when it is placed in a steam atmosphere of more than 500 "C, tiie dealumination of its tetrahedral fiamework will occur to cause structural Iweakdown thereof and at tiie same time, tiie acid sites of the solid acid catalyst will be reduced, resulting in a Tdpid reduction in catalytic activity and reactivity. Accordii^y, in the above-described conventional light olefin production processes including the catalytic cracking process, studies are actively performed to decrease tiie instability of the catalyst, and thus, a reduction in process performance, which occur when the catalyst is placed in a severe process atmosphere of high temperature and humidity. Regarding these studies, US patent No. 6,867341 discloses a naphtha craddng catalyst obtained by controlling the distribution of aluminum atoms and crystal size of zeolite, as well as a process for acacking n£q)htim usii^ tiiis catalyst According to tiie disclosure of said patent, the catalyst is designed so that the production of aromatic compounds on tiie pore surfece can be minimized by chemically neutralizing aluminum present outside the pores, whereas efliylene and propylene, havir^ small sizes, can be more selectively produced by increasing the concentration of aluminum ions inside ^ pores to increase tiie numbo: of add sites. Meam^iiile, as disclosed in said patent, vAyen a ferrierite zeolite catalyst obtained by this teclmology is used in catalytic cracking, the reactivity of the catalyst will become excellent even in a relatively severe process environment, such as maiitiainirjg the catalyst in an atmosphere of 50% steam at 690 C for 2 hours. Regarding the hydrothermal stability of the catalyst, however, it is expected that the structural stability and reactivity of the catalyst cannot be secured when it is treated with 100% steam at 750 C for 24 hours. US patent No. 6,835,863 discloses a process for producing light olefins by catalytically cracking n£^htha (boilfa^ point: 27-221 Xl) using a pelledzed catalyst containing 5--75% by weight of ZSM-5 and/or ZSM-11,25-95% by weight of silica or kaolin and 0.5-10% by weight of phosphorus. However, there is no mention of hydrothermal stability in a severe environment of high temperature and humidity. Japanese patent laid-open publication No. Hei 6-192135 discloses a catalytic cracking process for producing ethylene and propylene fiom C2-12 parafBn-containing Ugjit nsphiha, (density: 0.683 g/cc; composition: 42.7 wt% n-paraffin, 36.1 wt% iso-paraffin, 0.1 wt% olefins, 14.0 wt% naphthene, and 7.1 wt% aromatics; and the distribution of the paraffin component: 0.1 wt% C3, 5.2 wt% C4, 18.7 wt% C5, 19.0 wt% C6> 15.2 wt% C7, 13.5 wt% Cg, 6.1 wt% C9, 0.1 wt% Cio and 0.1 wt% Cn) using HZSM-5 and HZSM-11 catalysts (molar ratio of Si02/Al203: 150-300) at a temperature of 620-750 13 and a WHSV of 1-200 h'. According to tiie disclosure of said patent, under reaction conditions of 680 t) and a WHSV of 25 h', a conversion rate of 93.6\vt% and efliylrae + px>pylene production of 44.9 \vt% are showa However, the HZSM-5 or HZSM-11 catalyst is used in the catalytic craddng reaction in an impelletized state, and steam or inert gas is not fed during the reaction. Thus, flie catalyst has excellent initial activity, but there is a possibility for the catalyst to be easily inactivated. For this reason, it is expected fliat the reactivity of the catalyst in a seva« environment of high ten^)erature and humidity will be nanarkably reduced. Meanwhile, Jq)anese patent laid-open publication No. 6-199707 reports that, in a catalytic cracking process for producirig ethylene and px>pylene as main products fix>m light naphtha contaming C2.12 paraffin, the use of a proton-zeolite (SiO2/Al2O3=20-500) catalyst loaded with 100 ppm iron (Fe) allows light olefins to be produced with good selectivity. The catalyst has excellrat initial activity since steam or inert gas is not fed during the reaction, but there is a possibility for the catalyst to be easily deactivated in a high-temperature reaction involving steam. For this reason, it is expected that the reactivity of the catalyst in a severe environment of high temperature and humidity will be remarkably reduced. AccordiQgly, there is an urgent need for the developmrat of a process wiiere reaction activity is maintained even in a severe process environment of high tempCTature and humidity so that light olefins, such as ethylene and propylene, can be selectively produced with hi^ conversion and selectivity icom reaction feedstock, particularly fidl-range naphtha. [Disclosure] [Technical Problem] Accordingly, title present inventors have conducted extensive studies to solve tiie above problems occurring in the prior art and as a result, found that v^en a specific catalyst with excellent hydrothennal stability was used, light olefins could be produced at high yield with high selectivity ftom hydrocarbon feedstock without a reduction in the reactivity of the catalyst even in a severe process environment On tfxe basis of this feet, ttie present invention has been completed. Therefore, it is an object of the present invention to provide a process capable of selectively producing light olefins, such as ediylene and propylene, in high yield with hi^ selectivity fiom hydrocarbon feedstock, particularly fiill-range n^htiha, even in a severe environment of high traipwature and humidity. Anotho- olgect of the present invention is to provide a process vAere higji crackir^ activity is maintained even at a temperature lowar than the reaction tenqjerature required in iht prior thermal cracking process for the production of light olefins, so tiiat light olefins can be produced with high selectivity arid conversion fix>m hydrocarbon feedstock, [Technical Solution] To achieve the above objects, the present invention provides a process for producing light olefins fiom hydrocarbon feedstock, comprising tiie steps of; (a) providing a hydrocarbon frmMion as feedstodq (b) feeding the feedstock into at least one fixed-bed or fluidized-bed reactor where it is allowed to react in ttie presence of a catalyst; and (c) separating and recovering light olefins fi?om the eflEluent of the reaction zone; in vsdiich the catalyst consists of a product obtained by the water evaporation of a raw matoial mfarture comprising 100 parts by weight of a molecule sieve with a fiamewoik of-Si-OH-Al- groups, 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0.05-17,0 parts by weight of aphosphate conqKJund. La the inventive process, the feedstock is preferably fiill-range n^htha or kerosene, and more preferably naphtha containing C 2-15 hydrocarbons. Preferably, tiie total content of parafBn components (n-parafi5n and iso-paraJBfin) in the full-range n^htha is 60-90% by weight, and the content of olefins in the n^tha is less than 20% by weight. Also, the inventive process may furtho comprise the steps of mbdng C4-5 hydrocarbons remaining after the separation and recovery of light olefins in the step (c) wifli naphtiia and providing the C 4.5 hydrocarbon/n^htha mixture as feedstock. Meanwhile, if the reactor is a fixed-bed reactor, the reaction will preferably be carried out at a temperature of 500-750 t;, a hydrocaibon/steam weight ratio of 0.01-10, and a space velocity of 0.1-20 h'^ If the reactor is a fluidized-bed reactor, the reaction will preferably be carried out at a temperature of 500-750 tJ, a hydrocaibon/steam weight ratio of 0.01-10, a catalyst/hydrocarbon weight ratio of 1-50, and a hydrocarbon residaice time of 0.1-600 seconds. Meanwhile, if the catalyst is used after steam treatment m an atmo^here of 100% steam at 750 t) for 24 hours, the total content of efhyloie and propylaie in ttie effluent of the reaction zone will be more than 30% by weight, and the ethylene^sropylene weight ratio will be 0.25-1.5. [Advantageous Effects! According to the present invention, the use of a certain catalyst with hydrothomal stability shows excellent reaction perfonnance in selectively producing light olefins in hi^ yield with high selectivity fix)m hydrocarbon, particularly fidl-range naphtha, even in a severe process environment of high temperature and humidity. Particularly, tiie invrative iMxx:ess is highly usefial in tibat it can maintain high cracking activity even at a lower temperature that reaction temperature required in the prior tiiermal cracking for flie production of light olefins, and thxis, can produce light olefins with high selectivity and conversion fix)m hydrocarbon feedstock. [Description of Drawir^] FIG. 1 schematically shov^ a system for measuring tiie reaction activity of a catalyst during the production of light olefins according to Examples of the present invention and Comparative Exan:q)les. [Best Model Hereinafter the present invention will be described in more detail. As described above, according to the present invention, the use of fte porous molecular sieve catalyst with hydrothemial stability allows light olefins to be selectively produced at hi^ yield with high selectivity fit>m hydrocarbon feedstock, particularly full-range naphtha. The porous molecular sieve catalyst used in tiie inventive process for ttie production of light olefins consists of a product obtained by tiie water ev25X)ration of a mw material mbcture comprising 100 parts by weight of a molecule sieve with a firamework of -Si-OH-Al- groiflps, 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0-05-17.0 parts by weight of a phosphate compound When this product is used as a calalyst for the production of light olefins, it can diow excellent hydrothermal stability, reaction activity and selectivity ^^4ule increasmg economic e£Sciency. The porous molecular sieve catalyst can be prepared to have the desired physical and chemical properties by suitably selecting and adjusting the kind of starting material for a modifier, the composition ratio of each component, the loading amount, the pH and temp^ature of the solution during loading, etc. During the catalyst preparation process, the following technical particulars are considered: (1) technology of selectively modifying only the surface pores of a molecular sieve with a phosphate compound vMch is present in the form of an ion selected fix>m a monohydrogen phosphate ion, a dihydrogen jrfiosphate ion, and a phosphate ion; (2) technology of using a water-insoluble metal salt to prevent the ion exchange of protons in the molecular sieve with a large amount of dissolved metal ions and at the same time, to stabilize a phosphate compound of modifying the molecular sieve; and (3) technology of stabili^ng a molecular sieve modified witii a phosphate compourKi and a metal by water evaporation. With this technical background, any support for the catalyst may be used if it is a molecular sieve containing a ftamework of-Si-OH-Al- groups. It is preferable to use any one selected fiom mesoporous molecular aeves with a pore size of 10-100 A and an Si/Al molar ratio of 1-300 and preferably about 25-80, including zeolites with a pore size of 4-10 A. Among them, more prefened are ZSM-5, Ferrioite, ZSM-11, Mordenite, Beta-zeolite, MCM-22, L-zeolile, MCM-41, SBA-15 and/or Y-zeolite, the general properties of which are already widely known in the art. As used herein, the term water-insoluble metal salt means a metal salt with a solubility product (Ksp) of less than 10", i.e., a pKsp of more than 4. An example of this metal salt may be an oxide, hydroxide, carbonate or oxalate of a metal with an oxidation state of more than +2. Prefoiably, the metal salt is an oxide, hydroxide, carbonate or oxalate of at least one metal selected fiom tiie groiq) consisting of alkaline earth metals, transition metals and heavy metals with an oxidation state of+3 to +5. Preferably, ^ alkaline earth metals may include M^ Ca, Sr and Ba, the transition metals may include Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and the heavy metals may include B, Al, Ga,hi, Ti, Sn,Pb, SbandBi. Mean^^4lile, the i^osphate compound is not specifically limited if it is one known in the art However, because the use of phosphoric acid as ttie phosphate compound has a disadvantage in that the ciystaUinity of a porous material is reduced, alkyl phosphine derivatives in place of phosphoric acid may also be used but have a problem in that they are not suitable for use in mass production because they are xineconomical and not easy to handle. For this reason, it is preferable to use phosphoric acid, ammonium phosphate [(NH4)3P04, (NH4)2HP04, (NH4)H2P04], or aUcyl phosphate as the phosphate compound. It is generally known that the acid dissociation constants pKa(l), pKa(2) and pKa(3) of phosphoric acid (H3PO4) are 2.2,12 and 12.3, respectively, and the phosphoric acid is present as a monohydrogen phosphate ion ([HP04]^, a dihydrogen phosphate ion ([H2PO4]0 and a phosphate ion ([P04]^ at pHs 22, 7.2 and 12.3, respectively. Thus, it will be obvious that tiie desired chanical species of phosphate ions can be selectively formed by suitably adjusting tiie pH of an aqueous solution containing the phosphate compound. The porous molecular sieve catalyst formed fixon the above-described composition is modified with one compound selected fix)m compounds represented by the following fcmiulas 1 to 3: [Formula 1] Mx(H2P04)y, vAerein M is a metal, X is 1, and y is an inte^ fiom 2 to 6; [Formula 2] Mx(HP04)y, vsdierein M is a metal, x is 2, and y is an integer of fi^om 2 to 6; and [Formula 3] Mx(P04)y, wherein M is a metal, x is 3, and y is an integer fix)m 2 to 6. Accordingly, e3qx)sed acid sites outside the pores of the porous molecular sieve are selectively modified with a modifier having physical and chemical stabilities in an atmosphere of high temperature and humidity, so that the surface of zeolite can be protected fix>m dealunfunation. Althoi^ the description for the preparation of tiie molecular sieve catalyst is not restricted to a certain theory, it is believed that ttie -Si-OH-Al- groups forming the molecular sieve are modified with the phosphate compound/metal composite structure as shovm in the following reaction schmies 1 and 2 so as to be condensed wifli the proton of zeolite so that a =P=OgK)iq) stabilizes unstable Al while two -OH groi5)s are stabilized with the metal, whereby the fi:amework structure is relatively stably maintained even in an atmosphere of high temperature and humidity: [Reacdon scheme 1] A meflKxi for prq)ariDg the porous molecular sieve catalyst can be broadly divided into two methods and involve the step of removing water contained in the above-desaibed raw material mixture by a selective evaporation process so as to recover a solid product Hereinafter^ the preparation method of the catalyst according to one preferred embodiment of the present invention will be described. (1) The phosphate compound is added to and mixed with an aqueous slurry containii^ the water-insoluble metal salt. The nuxture is adjusted to a suitable pH using a convrational alkaline or acidic aqueous solution, such as NaOH, KOH, NH4OH, HCl or HNO3, and stirred at a tempaature of about 20-60 "C, and preferably about 40-50 C, for about 30 minutes to 3 hours, and preferably about 1-3 hours, so that the phosphate compound is present in the form of an ion selected ftom a monohydrogen phosphate ion, a dihydrogm phosphate ion and a phosphate ion, in the aqueous solution. Particularly, it is preferable that the mixture is adjusted to a desired pH range so &at only one chemical spedes of phosphate ion that ^dsts at this pH range will be formed in tiie aqueous solution. Namely, if a specific pH range is not met, one or more species of phosphate ions will coexist in the aqueous solution so that a diemical species of modifying the pore surfece of the molecular sieve will not be uniform, thus making it difficult to secure the durability of the modified catalyst (2) To the mixture of tiie part (1), a molecular sieve witii a fi:amework of-Si-OH-Al-groiq>s is added The resdting mixture is stirred at a teinperature of preferably about 10-9^ C, and more preferably about 50-70 "C, ia a specific pH range corresponding to purpose, until water in the aqueous slurry is completely evs^rated Thus, fee phosphate ion spares modifying the molecular sieve is stabilized with metal ions vMe water present in title sluny is removed. Then, vacuum filtration is perfonned to recover the solid pxxJuct. In this way, the molecular sieve catalyst having the -Si-OH-Al- frameworic modified with the phosphate^n^tal salt is prepared. Meanwhile, the composition of the raw material mixture used in the preparation of the catalyst is as follows: 100 parts by weight of the molecular sieve having fee -Si-OH-Al-fi-amework; 0.01-5.0 parts by weight of fee water-insoluble metal salt; and 0.05-17.0 parts by weight of fee phosphate compound. The preparation mefeod of fee catalyst according to anofeer embodiment of fee present invention will now be described. (1) A phosphate compound is added to and mixed wife an aqueous slurry containing fee water-inrx)luble metal salt The mixture is adjusted to a suitable pH using a conventional alkaline or acidic aqueous solution, such as NaOH, KOH, NH4OH, HCl or HNO3, and stirred at a temperature of about 20-60 C, and preferably about 40-50 1C, for about 30 minutes to 3 hours, and preferably about 1-3 hours, so that fee phosphate compound exists in fee form of an ion selected fiom a monohydrogen phosphate ion, a dihydrogen {diosphate ion and a phosphate ion, in fee aqueous slurry. Then, fee aqueous slurry is subjected to water evaporation at a teiiq)erature of preferably 10-90 "C, and more preferably 50-70 t;, in a specific pH range suitable for fee purpose, until water in fee aqueoifiS\|Mrry completely evaporates. Then, fee solid product is vacuum filtered and washed to separate a first solid product In this way, ttie water-insoluble phosphate-metal salt is prepared. (2) The first solid product of the part (1) is added to and rruxedwift an aqueous solution containing a molecular sieve with a fi:amework of-Si-OH-Al- groups. The resulting mixture is stirred at a temperature of preferably about 20-60 TC, and more preferably about 40-50 V, for about 30 minutes to 7 hours, and preferably about 1-5 hours, until water in the mixture conipletely evaporates. Th^ ^ remaining solid product is vacuum filtered to separate a second solid product In this way, the molecular sieve catalyst having the -Si-OH-Al- fi:ameworic modified vsdth the phosphate-metal salt is prepared. Meanwiiile, the raw material mixture used in tibe preparation of the catalyst is used in such a coribx>Ued maimer that the con:qx)sition of the raw niaterialriiixtu^ 100 parts by weight of the molecular sieve having the -Si-OH-Al- fiamework; 0.01-5.0 parts by weight of the water-insoluble metal salt; and 0.05-17.0 parts by weight of the phosphate compound. Particularly, it is preferable in temis of tiie desired effect feat fee first solid product should be used in an amount of 0.01-20.0 parts by weight based on 100 parts by weight of fee molecular sieve. In fee above-described mefeods of preparing fee catalyst, it is necessary to find conditions v^ere fee metal ions formed by fee dissolution of some of fee metal salt in the aqueous solution can stabilize only the modified phosphate ion species without ion exchange wife fee proton of fee molecular sieve. Ofeerwise fee dissolved metal ions will be ion-exchanged wife fee proton of fee molecular sieve to reduce fee number of add sites, resulting in a reduction in reactivity of modified catalysts. Accordingly, as described above, by fee use of a water-msoluble metal salt having a solubility product of less than 10"^ in aqueous solution, and preferably, an oxide, hydroxide, carbonate or oxalate of at least one metal selected fix)m fee group consisting of alkaline earth metals, transition metals, and heavy metals wife an oxidation state of +3 to +5, it is possible to substantially prevent tiie phenomenon of ion exchange with &e proton of the molecular sieve by the presence of a large amount of metal ions, vMcb is a problem in the case of using water-soluble metal salts, and at the same time, it is possible to maximize tiie effect of stabilizing the modified phosphate ions with the desired metal ions. Meanwhile, the raw material mixture in the aqueous slurry for the preparation of the catalyst must be maintained at the following composition: 100 parts by weight of the molecular sieve; 0.01-5.0 parts by weight of the water-insoluble metal salt; and 0.05-17.0 parts by weight of the phosphate compound. If the composition of the raw material mixture is out of flie specified composition range, the sur&ce pores of the molecular sieve will not be selectively modified with the iiiodifier, and the number of acid sites wiU be rath^ reduced, leadirig to a reduction in ^^ activity. Particularly, the molar ratio of the water-insoluble metal salt to the phosphate compound is 1.0 : 0.3-10.0, and preferably 1.0 : 0.7-5.0. If the molar ratio of the phosphate compound to tiie waler-insoluble metal salt is less than 0.3, there will be a problem in that unnecessary metal ions are present in excess so that the number of acid sites in the molecular sieve is reduced, leading to a reduction in the reactivity of the modified catalyst. On the other hand, if the ratio of the phos[diate compound to the v^^ter-insoluble metal salt is less more than 10.0, there will be a problem in that the molecular sieve fiamework is not sufficiently modified so that the hydrothermal stability of the modified molecular sieve becomes poor. Hereinafter, the inventive process for producing light olefins fix)m hydrocarbon feedstock using the above-described porous molecular sieve catalyst, where the hydrothermal stability of the catalyst in a sever environment of high temperature and humidity is necessarily required, will be described. As the hydrocarbon feedstock, fidl-range naphtha or kerosene may be used. More preferably, full-range naphtha havii^ C2.15 hydrocarbons may be used. The most suitable process inaction for this hydrocarbon feedstock may be catalytic cracking reacdcm but is not specifically limited thereto. Examples of Ihe feedstock v^ch can be used in the present invention include, in addition to full-range wphiha, ejq)ensive light n£q)htha used in a steam a:acking process for the production of light olefins, and olefin-containing feedstock typically used in a plurality of catalytic cracldng processes, and C20-30 heavy fiactions wiiidi have been used in the prior FCC process. Among &CT1, the fidl-range n^htha is a fiaction containing C2-12 hydrocarbons produced directiy in crude oil refining processes and contains paraffins (n-parafBn and iso-parafSn), n^hthene, aromatic conqxtunds, etc., and may sometimes contain olefin compounds. Generally, Ihe hi^ier the content of paraffin components in m^htha, the slighter n^htha becomes, and on tiie other hand, the lower the content of parafBn conqx)nents, flie heavier naphtha becomes. According to the present invention, the feedstock is selected by considering yield, economic efficiency, etc. Under this consideration, fiill-range n^htha may be used where the total content of paraffin components (n-paraffin and iso-parafBn) is 60-90 wt%, more preferably 60-80 wt%, and most preferably 60-70 wt%. Also, the selected rmphtha may contain olefins in an amount of less than 20 wt%, preferably less tiian 10 wt%, and most preferably less tiian 5 wt%. Table 1 below shows an illustrative feedstock composition (unit: wt%) which can be used in the present invention. Moreov^, in the present invention, the naphtha feedstock may also be used in a mixture with C4-5 hydrocarbons remaining after tiie separation and recovery of light olefins and heavy products fix)m the effluent of a reaction zone containing the catalyst In the pres«it invention, ttie reaction zone may comprise at least one reactor, and preferably a fixed-bed or fluidized-bed reactor. In the reactor, the feedstock is converted to a large amount of li^ olefirK by a conversion reaction (e.g., a catalytic cracking reaction) with the invQitive catalyst Generally, catalytic activity greatly depends on reaction tenq)erature, space velocity, the naphtiia/steam wei^ ratio, etc. In this case, reaction conditions detemiined with the following considerations must be presented: flie lowest possible temperature to minimize aiergy consumption, the optimal conversion, the optimal olefin production, the nninimization of catalyst deactivation caused by coke production, etc. According to a preferred embodiment of the present invention, the reaction temperature is about 500-750 t;, preferably about 600-700 V, and more preferably about 610-680 t). Also, the hydrocarbon/steam weight ratio is about 0.01-10, preferably about 0.1 -2.0, and more pref^ably about 0.3-1.0. If the fixed-bed reactor is used, the space velocity will be about 0.1-20 h'^ preferably about 0.3-10 h"^ and more preferably about 0.5-4 h'^ Furthomore, if the fluidized-bed reactor is used, the catalyst/hydrocarbon weight ratio will be about 1-50, preferably about 5-30, and more preferably about 10-20, and the residence time of hydrocarbons will be about 0.1-600 seconds, preferably alx)ut 0.5-120 seconds, and more preferably about 1-20 seconds. Meanwhile, in order to examine if the molecular sieve catalyst according to the present invention can maintain its catalytic activity to some extent even in a severe environment or is deactivated in this aivironment, the inventive catalyst was steamed in an atmosphere of 100% steam at 750 t) for 24 hours. Namely, if the inventive catalyst is used after steaming in the above-described atmosphere, the content of light olefins ^.e., ethylaie and propylene) in the eflQuent of said reaction zone will preferably be more than about 30 wt%, more preferably more than about 35 wt%, and most preferably more than about 40 wt%. In this case, the ethylene/propylene weight ratio is i^faably about 0.25-1.5, more preferably 0.5-L4, and most pref^ably 0,7-1.3, indicating that propylene is produced in a relatively large amount [Mode for InvCTtionl Hereinafter, the present invention will be desoibed in more detail by exan:q>les. It is to be understood, however, that these examples are not construed to limit the scope of the present invention. Example 1 A^ Preparation of catal\^ To 100 mL of distiUed water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.55 g of concentrated phosphoric acid (85% H3PO4), were added and stirred for 20 minutes. To the stirred solution, 0.36 g of Mg(0H)2 was added and the mixture was adjusted to a pH of 7-8 using ariimoiiia water, followed by stirring at a temperature of about 45 C for about 20 minutes. Next, ttie mixture was stirred at about 50 C until the water completely evaporated, and then, vacuum filtration was used to separate the solid product. The separated solid product was calcined in air at a traiperature of 500 t) for 5 hours, thus preparing an Mg-HP04-HZSM-5 catalyst. B) Steaming step for evaluation of hvdrotfaermal stability To evaluate the hydro&ermal stability of the catalyst, the catalyst was maintained in an atmosphere of 100% steam at 750 "C for 24 hours. C) Production of light olefins As shown in FIG. 1, a system for measuring the activity of tiie catalyst during the production of light olefins comprises a n^h^ feed device 4, a water feed device 3, fixed-bed reactors 5 and 5', and an activity evaluation device, which are integrally connected with each other. In this case, n^htha specified in Table 1 above was used as feedstock. Naphtha and water fed by a liquid injection pump were mixed with each other in a preheats* (not shown) at 3000, and mixed with 6 ml/min of He and 3 mlAnin of Na fed by helium feed device 2 and 2 and nitrogen feed devices 1 and \\ respectively, and the mixture was fed into tiie fixed-bed reactors 5 and 5'. At tbis time, tiie amount and rate of eadi gas were controlled with a flow controller (not shown). The fixed-bed reactors are divided into an inner reactor and an out^ reactor, in which the outer reactor, an Inconel reactor, was manufactured to a size of 38 cm in length and 4.6 cm in outer diameter, and the inner reactor made of stainless steel was manufactured to a size of 20 cm in lengtih and 0.5 indies in outo diameter. The temperature within the reactors was indicated by tempCTature ou^ut devices 7 and 7, and reaction conditions were controlled by PE) controllers (8 and 8' NP200; Han Young Electronics Co., Ltd, Korea). The gas fed into the reactors was passed through ^ inner reactor and then passed through the outer reactor, tiirough which 40 ml/min of He flowed. The bottom of the inner reactor was filled with the catalyst The mixed gas was catalytically cracked through the catalyst layers 6 and 6', and after the reaction, vapor phase product 12 was quantified online by gas chromatography 11 (Model: HP 6890N). The remainii^ liquid phase prcxiuct 13 passed through condensers 9 and 9' were recova:ed into storage tanks 10 and 10* and quantified by gas chromatography (Model: DS 6200; not shown). The amount of catalyst used in the catalytic cracking reaction was 0.5 g, tfie feed amount of each of naphtha and water was 0.5 g/h, and the reaction was carried out at 675 "C. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene wei^ ratio, are shown in Table 3 below. Example 2 A) Preparation of catalyst To 100 mL of distilled water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.26 g of concentrated phosphoric acid (85% H3PO4), were added and stirred for about 20 minutes. To tiie stirred solution, 0.08 g of Mg(0H)2 was added, and the mbrture was adjusted to a pH of 2-3 using an aqueous nitric acid solution, followed by stirring at about 45 C for about 20 minutes. After stirring tiie mixture at about 50 "C until water completely evaporated, vacuum filtration was performed to separate tte solid product The sq)arated solid product was calcined in air at a temperature of 500 "C for 5 hoinrs, thus prq)aring a Mg-H2P04-HZSM-5 catalyst. B) Steanung step for evaluation of hvdrotiiermal stability Steaming was carried out in tiie same manner as in Example 1. Q Production of light olefins The production of light olefins was carried out in tiie same maimer as in Example 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the etiiylene/propylene weight ratio are shown in Table 3 below. Examples A^ Preparation of catalyst Slurry comprising 6.6 kg of the Mg-HaPOa-HZSM-S prepared in the part (A) of Exanple 2, 0.7 kg of Y zeolite and 3 kg of an alumina binder was stirred, followed by spray drying, thus preparing a pelletized catalyst with an average particle size of 80 //m B) Steaming for evaluation of hvdrothermal stability Steaming was carried out in the same manner as in Example 1. O Production of light olefins In this Example, a fluidized-bed reaction system was used to measure the activity of the catalyst during the production of light olefins. The fluidized-bed reaction system conpises a riser reactor, a regenerator, a striper and a stabilizer. Tbe riser reactor is 2.5 m in height and 1 cm in diameter, flie regenerator is 1.5 m in height and 12 cm in diameter, the strii^)er is 2 m in height and 10 cm in diameter, and the stabilizer is 1.7 m in height and 15 cm in diameter. As feedstock, naphtha specified in Table 1 above was used. At the riser inlet, flie feedstock, steam and the catalyst are fed and mixed vwth each other, such that the feedstock is fed in 133 g/hr at 400 t:, the steam is fed in 45 g/hr at 400 V, and the catalyst is fed in 5320 g/hr at 725 C. During the passage of the mixture through the riser, a fluidized-bed catalytic cracking reaction occurs, and the riser ouflet has a temperature of 675 X^, The rnixture passed tiirough the riser is sq)arated into the catalyst and a fi^^ stripper at 500 "C. The separated catalyst is recycled to the regeneratcff, and fl)e ftaction flows into the stabilizer. The catalyst mtroduced into the r^enerator is regenerated in contact with air at 725 "C, and the regenerated catalyst is fed again into flie riser. Ibe fiaction fed into the stEdDilizer is separated into a gas component arid a liqirid component at-10 ^C. Ibe analysis of the gas component and liquid component factions produced by the reaction was performed in the same manner as in Example 1. The obtained results for converaon, selectivity to light olefins (ediylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below. Example 4 A) Preparation of catalyst To 100 mL of distilled water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.18 g of concentrated pho^horic acid (85% H3PO4), were added and stirred for about 20 minutes. To the stirred soliition, 0.146 g of MgCOHfe was added, and the mbcture was adjusted to a pH of 12-13 using ammonia water, followed by stirring at about 45 C for about 20 minutes. Ailer stirring the mixture at about 50 "C until the water completely evqx)raled, vacuum filtration was performed to separate the solid product The sq)arated solid product was calcined in air at a traiperature of about 500 TC for 5 hours, thus preparing a Mg-P04-HZSM-5 catalyst B. Steaming for evaluation of hvdrothermal stability Steaming was carried out in the same manner as in Example 1. Q Production of licht olefins This was carried out intiie same manner as in Example 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the efliylene/piopylaie weight ratio are shown in Table 3 below. Examples 5 to 10 A) Preparation of catalysts Catalysts were prepared in fte same manner as in Example 1 excq that the composition of the raw material mixture was changed as shown in Table 2 below. B) Steaming for evaluation of hvdrotiiCTnal stability Steaming was carried out in tiie same manner as in Example 1. Q Production of lisht olefins This was carried out in the same manner as in Exanf^le 1. The obtained results for converaon, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below. Comparative Example 1 A) Preparation of catalyst An HZSM-5 catalyst was prepared by calcining 10 g of HZSM-5 (Si/Al=25; Zeolyst) inairataternperatureofaboutSOO C for 5 hours. B) Steaming for evaluation of hvdrotfaermal stability Steaming was not carried out C) Production of light olefins Ibis was carried out in the same manner as in Example 1. The obtained results for conversion, selectivity to light olefins (ethyl^e and propylwie) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below. Comparative Example 2 A) Preparation of catalyst An HZSM-5 catalyst was prepared by calcining 10 g of HZSM-5 (Si/Al=25; Zeolyst) inairatatemp^atureofaboiit500 "C for5hours. R) Steaminpr for evaluation of hvdrotbermal stability Steaming was carried out in the same manner as in Example L C) Production of light olefins This was carried out in the same manner as mBcample 1. n^e obtained results for conversion, selectivity to light olefins (eftiyl«ie and propylene) in the reaction product, and the ethylene/propylene wei^t ratio are shown in Table 3 below. Comparative Example 3 A) Preparation of catalyst To 100 mL of distilled water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.15 g of concentrated phosphoric add (85% H3PO4) woe added. The mixture was adjusted to a pH of 7-8 using ammonia water, and then stirred at about 50 V until water completely evaporated. Then, vacuum filtration was performed to separate the solid product The separated solid jM-oduct was calcined in air at a temperature of about 500 C for 5 hours, thus preparing an HPO4-HZSM-5 catalyst B) Steaming for evaluation of hvdrottienmal stability Steaming was carried out in the same manner as in Example 1. C) Production of light olefins ^lis was carried out in the same manner as in Example 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below. Comparative Example 4 A) Preparation of catalyst To 100 mL of distilled water, 10 g of HZSM-S (Si/Al=25; Zeolyst) and 1.4 g of La(N03)3 • xHaO were added The mixture was stined at about 50 t; until the water completdy evqx)rated The remaining material was vacuum filtaied to separate a solid product The sq)arated solid product was caldned in air at a temp^ature of 500 Xl for 5 hours, thus preparing a La-HZSM-5 catalyst B^ Steaming for evaluation of hvdrothermal stability Steaming was carried out in the same manner as in Example 1. C) Production of light olefins this was carried out in the same manner as in Example 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below. Comparative Example 5 A^ Preparation of catalyst To 100 mL of distilled water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.74 g of concentrated phosphoric acid (85% H3PO4) were added and stirred for about 20 minutes. To Ae solution, 1.40 g of La(N03)3 ' XH2O was added, and the mixture was adjusted to a pH of 7-8, followed by stirring at a temperature of about 45 C for20minutKL After stirrir^ the mixture at about 50 V. until water completely evqxjrated, the remaining inaterial was vacuum filtered to separate tiie solid product. The separated solid product was caldned in air at a temperature of about 500 V for 5 hours, thus preparing a La-H3P04-HZSM-5 catalyst B) Steaming for evaluation of hvdrothermal stability Steaming was carried out in the same manner as in Example 1. O Production of light olefins This was performed in the same manner as in Example 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylrae) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below. Comparative Example 6 A^ Preparation of catalyst To 100 mL of distiUed water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.55 g of concentrated phosphoric acid (85% H3PO4) were added, followed l^ stirring for 20 minutes. To tiie stirred solution, 1.58 g of Mg(N03)2 • 6H2O was added, and the mfacture was adjusted to apH of 7-8 using ammonia water, and then stirred at a temperature of about 45 "C for about 20 minutes. After stirring the mixture at about 50 t; until the water completely evaporated, vacuum filtration was used to separate the solid product The separated solid product was calcined in air at a traiperature of about 500 C for 5 hours, thus preparing a Mg-H3P04-HZSM-5 catalyst B) Steaming for evaluation of hvdrothermal stability Steaming was carried out in the same manner as in Example 1. Q Production of light olefins This was carried out in the same manner as in ]&cample 1. The obtained results for converaon, selectivity to light olefins (efliylene and propylene) in the reaction product, and flie efliylene/propylme weight ratio, are shown in Table 3 below. Comparative Example 7 A) Preparation of catalyst A catalyst was prepared according to a method disclosed in US patent No. 6,211,104 Bl. Hie catalyst was prepared in the following specific manna:. To 40 gofa solution of 85% phosphoric acid and MgCfe ' 6H2O in distilled water, 20 g of NH4-ZSM-5 was added and loaded with the metal ions, followed by stirring. Then, the loaded molecular sieve was dried in an oven atl20 t, and finally, calcined at 550 X: for2hour. B^ Steaming for evaluation of hvdrotfaemial stability The catalyst was steamed in the same manner as in Example 1. Q Production of light olefins This was carried out in the same manner as in Exanq)le 1. The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propyloie weight ratio are shown in Table 3 below. in the case of Examples 1-10 according to the present invention, even ttie use of the catalyst steamed in an atmosphere of high temperature and humidity (maintained at 750 t) m 100% steam for 24 hours) showed a high conversion of about 76-80 wt%, and at tiie same time, high selectivity corresponding to the sum of ethylene + propjiene of about 33-37 wt% (ethylene/propylene weight ratio = about 0.8-1.0). On the other hand, it could be observed that the unsteamed HZSM-5 used in Comparative Example 1 showed a conv^on of 77.7 wt% aiKi a sum of ethylene + propylene of 40.5 wt%, but tfie use of HZSM-5 steamed in a severe hydrothermal atmosphere as in Comparative Bcample 2 showed rapid reductions in convorsion and the sum of ettiylene + propylene to 67.7 wt% and 24.5 wt%, respectively. In Conqjarative Examples 2,3,4 and 6, the conversion was about 58-75 wt% and the sum of ethylene + propylaie was 20-30 wt%, indicating that these Comparative Examples excludii^ Conqjatative Example 5 showed very low conversion and olefin production as compared to the inventive production process. Meanwhile, Comparative Example 5 showed a conversion of about 75.4 wt% and a sum of ettiylene + propylene of 30.5 wt%. These results can be seen to be inferior to those of Examples 1-9, and this is believed to be because ttie use of nitric acid salt, ^^ilich is a water-soluble metal salt, not a water-insoluble salt, led to a reduction in hydrothermal stability. Also, evaluated reactivity of the catalyst prepared according to tiie method described in US patent No. 6,211,104 Bl was inferior to tiiat of the inventive process. As described above, in the inventive process, even tiie use of a catalyst that has been hydrofliermally treated in an atmosphere of 100% steam at 750 *C for 24 hours, showed C2'-+C3"= 33-37%, whereas the use of HZSM-5, P-HZSM-5 and La.HZSM-5 catalysts showed C2"+C3" = 23-24%, and the use of La-P-HZSM-5 showed C2"'-K:3" = about 30%, Also, adjusting the component and composition ratio of a chemical q)ecies of modifying the catalyst used in the olefin production process according to the present invention shows a characteristic in that the hydrothermal stability of the catalyst can be ^isured and at ttie same time, the conversion and C27C3" ratio in the olefin production process can be controlled. In addition, tiie inventive catalyst is excellent in reaction activity required m producing light olefins fix)m nsphiha containing C2-12 hydrocarbons. [Industrial Applicability] As described above, according to the jnesent invention, the use of a certain catalyst having l^drothermal stability shows excellent reaction performance in selectively produdng light olefins at hd^ yield with higji selectivity from hydrocarbon feedstock, particularly full-range naphtha, even in a severe process environment of high temperatotc and humidity. Particularly, the inventive process 'is highly useful in Ifaat it can maintain high cracking activity even at a temperature lower tiian reaction temperature requited in the prior thermal cracking tatiperature for the production of light olefiiis, and thus, can produce light olefins with high selectivity and conversion fix)m hydrocarbon feedstocL Although the preferred embodiments of the present invention have been described for illustrative purposes, tiiose skilled in the art will appreciate that simple modifications, additions, and substitutions are possible, witiiout departing fix>m the scope and ^irit of the invention as disclosed in the accompanyir^ claims. [CLAIMS] [Claim 1] A process for producing light olefins fix)m hydrocarbon feedstock, comprising the steps of: (a) \|MX)vidii a hydrocarbon flection as feedstock; (b) feeding tiie feedstock into at least one fixed-bed or fluidized-bed reactor where it is allowed to react in the presence of a cat and (c) separating and recovering light olefins fix)m tiie effluent of the reaction zone; in vAich the catalyst consists of a product obtained by the wat- evqxration of a raw material mixture comprising 100 parts by weight of a molecule sieve with a fi:amework of -Si-OH-Al- groi^ 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0,05-17.0 parts by weight of a phosphate compound. [Claim 2] The process of Claim 1, wherein the feedstock is fiali-rare n htha or kerosene. [Claims] The process of Claim 1, wherein the feed stock is n^htha containing C MS hydrocarbons. [Claim 4] The process of Claim 2, \^4^erein the total content of parafiSn components (n-paraflBn and iso-paraffin) in the feedstock is 60-90% by weight, and the content of olefins in the feedstock is less than 20% by weight [Claim 5] The process of Claim 3, which further comprising the steps of mixing C 4-5 hydrocarbons ranaining after the separation and recovery of light olefins in the step (c) wifli ng^htha and providing the C 4-5 hydrocarbon/naphtha mixture as feedstock. [Claim 6] The process of Claim 1, wherein, if the reactor is a fluidized-bed reactor, the reaction is then carried out at a temperature of 500-750 C, a hydrocarbon/steam weight ratio of 0.01-10, a catalyst/hydrocarbon wdgjit ratio of 1-50, arid a hydrocarbon residence time of 0 1-600 [Claim 71 The process of Claim 1, wherein, if the reactor is a fixed-bed reactor, the reaction is then carried out at a temperature of 500-750 "C, a hydrocarbon/steam weight ratio of 0.01-10, and a space velocity of 0.1-20 h-1 [Claim 8] The process of Claim 1, v^erein, if the catalyst is used after steam treatment in an atmosphere of 100% steam at 750 "C for 24 hours, the total content of ethylene and propylotie in the effluent of the reaction zone will be more than 30% by weight, and the ethylene/propylene weight ratio will be 0.25-1.5.

Full Text

[DESCRPTION l
[Invention Title]
Process for Production of Light Olefins fix)m Hydrocarbon Feedstock
[Technical Fieldl
The present invention relates to a process for producing light olefins firom hydrocarbon feedstock, and more particularly to a process for producing light olefins at high yield with high selectivity fiom hydrocarbon feedstock using a catafyst which, even in an atmosphere of high temperature and humidity, has a relatively stable structure, thereby maintaining its catalytic activity over a long period of time, and shows hydroftermal stability.
[Background Art]
Olefibs, particularly light olefins, sudi as ediylene and propylene, are widely used in the petroleum chemical industry.
These light olefins are generally produced by the thermal racking (steam cracking) of naphtha in the presence of steam. The steam cracking technology is being improved in many fields in order to cope with high process temperature and a reduction in residence time and to optimize enery efficiency. However, it is not easy to inaprove energy efficiency merely by simple improvements in engineering technology, and the steam cracking process currently accounts for about 40% of the total energy required in the petroleum chemical industry. Accordingly, to reduce environmental pollution and incrase econcHnic efficiency, there is a need for improved process technologies for the optimization of energy, flie reduction of feedstock use, the minimization of carbon dioxide discharge, eto. Also, light n^htha is typically used as feedstock, but is expulsive compared to fiill-range naphtiia as desoibed later, and thus, will necessarily act as a limitation in increasing economic efficiency. Particularly, in the steam cracking technology, that is currently applied, not only it is not easy to control the composition of olefins but also the reaction temperature is a level of 800-900 C, indicating a requirement for a

large amount of thermal energy. Thus, a need for improvement in steam crackii^ tedmology has suggested.
Also, light olefin compounds can be produced by a fluid catalytic aacking (FCC) process. This FCC process is widely known in the art as catalytic craddng technology using a catalyst having the form of fine particles, which behaves like fluid wiien treated with steam. Particularly, deep catalytic cracking PCC) technology is known which is a process developed by modifying the FCC process in order to increase the yield of olefins (mainly, propylene) other than gasoline. In the FCC process, a heavier firacdon than fiill-rai^e nqjhtha used m the present invention, such as vacuum residue, atmospheric residue, or gaseous oil, is used as feedstock.
Regarding the production of olefins, in addition to the above-desoibed steam cracking and FCC processes, olefin conv^sion processes using catalytic aaddng have been proposed. In most of these processes, the HZSM-5 catalyst as a solid acid catalyst is widely used. However, in the conventional catalytic cracking processes using the solid acid catalyst, the reaction temperature is typically at least 650 *C, and at least 30% of the reaction feed is steam. The porous solid add catalyst (e.g., zeolite) used in these catalytic cracking processes has problems in that, when it is placed in a steam atmosphere of more than 500 "C, tiie dealumination of its tetrahedral fiamework will occur to cause structural Iweakdown thereof and at tiie same time, tiie acid sites of the solid acid catalyst will be reduced, resulting in a Tdpid reduction in catalytic activity and reactivity.
Accordii^y, in the above-described conventional light olefin production processes
including the catalytic cracking process, studies are actively performed to decrease tiie instability of the catalyst, and thus, a reduction in process performance, which occur when the catalyst is placed in a severe process atmosphere of high temperature and humidity.

Regarding these studies, US patent No. 6,867341 discloses a naphtha craddng catalyst obtained by controlling the distribution of aluminum atoms and crystal size of zeolite, as well as a process for acacking n£q)htim usii^ tiiis catalyst According to tiie disclosure of said patent, the catalyst is designed so that the production of aromatic compounds on tiie pore surfece can be minimized by chemically neutralizing aluminum present outside the pores, whereas efliylene and propylene, havir^ small sizes, can be more selectively produced by increasing the concentration of aluminum ions inside ^ pores to increase tiie numbo: of add sites. Meam^iiile, as disclosed in said patent, vAyen a ferrierite zeolite catalyst obtained by this teclmology is used in catalytic cracking, the reactivity of the catalyst will become excellent even in a relatively severe process environment, such as maiitiainirjg the catalyst in an atmosphere of 50% steam at 690 *C for 2 hours. Regarding the hydrothermal stability of the catalyst, however, it is expected that the structural stability and reactivity of the catalyst cannot be secured when it is treated with 100% steam at 750 *C for 24 hours.
US patent No. 6,835,863 discloses a process for producing light olefins by catalytically cracking n£^htha (boilfa^ point: 27-221 Xl) using a pelledzed catalyst containing 5--75% by weight of ZSM-5 and/or ZSM-11,25-95% by weight of silica or kaolin and 0.5-10% by weight of phosphorus. However, there is no mention of hydrothermal stability in a severe environment of high temperature and humidity.
Japanese patent laid-open publication No. Hei 6-192135 discloses a catalytic cracking process for producing ethylene and propylene fiom C2-12 parafBn-containing Ugjit nsphiha, (density: 0.683 g/cc; composition: 42.7 wt% n-paraffin, 36.1 wt% iso-paraffin, 0.1 wt% olefins, 14.0 wt% naphthene, and 7.1 wt% aromatics; and the distribution of the paraffin component: 0.1 wt% C3, 5.2 wt% C4, 18.7 wt% C5, 19.0 wt% C6> 15.2 wt% C7, 13.5 wt% Cg, 6.1 wt% C9, 0.1 wt% Cio and 0.1 wt% Cn) using HZSM-5 and HZSM-11 catalysts (molar ratio of Si02/Al203: 150-300) at a temperature of 620-750 13 and a WHSV of 1-200 h'. According to tiie

disclosure of said patent, under reaction conditions of 680 t) and a WHSV of 25 h', a conversion rate of 93.6\vt% and efliylrae + px>pylene production of 44.9 \vt% are showa However, the HZSM-5 or HZSM-11 catalyst is used in the catalytic craddng reaction in an impelletized state, and steam or inert gas is not fed during the reaction. Thus, flie catalyst has excellent initial activity, but there is a possibility for the catalyst to be easily inactivated. For this reason, it is expected fliat the reactivity of the catalyst in a seva« environment of high ten^)erature and humidity will be nanarkably reduced.
Meanwhile, Jq)anese patent laid-open publication No. 6-199707 reports that, in a catalytic cracking process for producirig ethylene and px>pylene as main products fix>m light naphtha contaming C2.12 paraffin, the use of a proton-zeolite (SiO2/Al2O3=20-500) catalyst loaded with 100 ppm iron (Fe) allows light olefins to be produced with good selectivity. The catalyst has excellrat initial activity since steam or inert gas is not fed during the reaction, but there is a possibility for the catalyst to be easily deactivated in a high-temperature reaction involving steam. For this reason, it is expected that the reactivity of the catalyst in a severe environment of high temperature and humidity will be remarkably reduced.
AccordiQgly, there is an urgent need for the developmrat of a process wiiere reaction activity is maintained even in a severe process environment of high tempCTature and humidity so that light olefins, such as ethylene and propylene, can be selectively produced with hi^ conversion and selectivity icom reaction feedstock, particularly fidl-range naphtha. [Disclosure] [Technical Problem]
Accordingly, title present inventors have conducted extensive studies to solve tiie above problems occurring in the prior art and as a result, found that v^en a specific catalyst with excellent hydrothennal stability was used, light olefins could be produced at high yield with high selectivity ftom hydrocarbon feedstock without a reduction in the reactivity of the catalyst even in

a severe process environment On tfxe basis of this feet, ttie present invention has been completed.
Therefore, it is an object of the present invention to provide a process capable of selectively producing light olefins, such as ediylene and propylene, in high yield with hi^ selectivity fiom hydrocarbon feedstock, particularly fiill-range n^htiha, even in a severe environment of high traipwature and humidity.
Anotho- olgect of the present invention is to provide a process vAere higji crackir^ activity is maintained even at a temperature lowar than the reaction tenqjerature required in iht prior thermal cracking process for the production of light olefins, so tiiat light olefins can be produced with high selectivity arid conversion fix>m hydrocarbon feedstock, [Technical Solution]
To achieve the above objects, the present invention provides a process for producing light olefins fiom hydrocarbon feedstock, comprising tiie steps of; (a) providing a hydrocarbon frmMion as feedstodq (b) feeding the feedstock into at least one fixed-bed or fluidized-bed reactor where it is allowed to react in ttie presence of a catalyst; and (c) separating and recovering light olefins fi?om the eflEluent of the reaction zone; in vsdiich the catalyst consists of a product obtained by the water evaporation of a raw matoial mfarture comprising 100 parts by weight of a molecule sieve with a fiamewoik of-Si-OH-Al- groups, 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0.05-17,0 parts by weight of aphosphate conqKJund.
La the inventive process, the feedstock is preferably fiill-range n^htha or kerosene, and more preferably naphtha containing C 2-15 hydrocarbons.
Preferably, tiie total content of parafBn components (n-parafi5n and iso-paraJBfin) in the full-range n^htha is 60-90% by weight, and the content of olefins in the n^tha is less than 20% by weight.

Also, the inventive process may furtho* comprise the steps of mbdng C4-5 hydrocarbons remaining after the separation and recovery of light olefins in the step (c) wifli naphtiia and providing the C 4.5 hydrocarbon/n^htha mixture as feedstock.
Meanwhile, if the reactor is a fixed-bed reactor, the reaction will preferably be carried out at a temperature of 500-750 t;, a hydrocaibon/steam weight ratio of 0.01-10, and a space velocity of 0.1-20 h'^
If the reactor is a fluidized-bed reactor, the reaction will preferably be carried out at a temperature of 500-750 tJ, a hydrocaibon/steam weight ratio of 0.01-10, a catalyst/hydrocarbon weight ratio of 1-50, and a hydrocarbon residaice time of 0.1-600 seconds.
Meanwhile, if the catalyst is used after steam treatment m an atmo^here of 100% steam at 750 t) for 24 hours, the total content of efhyloie and propylaie in ttie effluent of the reaction zone will be more than 30% by weight, and the ethylene^sropylene weight ratio will be 0.25-1.5. [Advantageous Effects!
According to the present invention, the use of a certain catalyst with hydrothomal stability shows excellent reaction perfonnance in selectively producing light olefins in hi^ yield with high selectivity fix)m hydrocarbon, particularly fidl-range naphtha, even in a severe process environment of high temperature and humidity. Particularly, tiie invrative iMxx:ess is highly usefial in tibat it can maintain high cracking activity even at a lower temperature that reaction temperature required in the prior tiiermal cracking for flie production of light olefins, and thxis, can produce light olefins with high selectivity and conversion fix)m hydrocarbon feedstock. [Description of Drawir^]
FIG. 1 schematically shov^ a system for measuring tiie reaction activity of a catalyst during the production of light olefins according to Examples of the present invention and Comparative Exan:q)les.

[Best Model
Hereinafter the present invention will be described in more detail.
As described above, according to the present invention, the use of fte porous molecular sieve catalyst with hydrothemial stability allows light olefins to be selectively produced at hi^ yield with high selectivity fit>m hydrocarbon feedstock, particularly full-range naphtha.
The porous molecular sieve catalyst used in tiie inventive process for ttie production of light olefins consists of a product obtained by tiie water ev25X)ration of a mw material mbcture comprising 100 parts by weight of a molecule sieve with a firamework of -Si-OH-Al- groiflps, 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0-05-17.0 parts by weight of a phosphate compound When this product is used as a calalyst for the production of light olefins, it can diow excellent hydrothermal stability, reaction activity and selectivity ^^4ule increasmg economic e£Sciency. The porous molecular sieve catalyst can be prepared to have the desired physical and chemical properties by suitably selecting and adjusting the kind of starting material for a modifier, the composition ratio of each component, the loading amount, the pH and temp^ature of the solution during loading, etc. During the catalyst preparation process, the following technical particulars are considered:
(1) technology of selectively modifying only the surface pores of a molecular sieve with a phosphate compound vMch is present in the form of an ion selected fix>m a monohydrogen phosphate ion, a dihydrogen jrfiosphate ion, and a phosphate ion;
(2) technology of using a water-insoluble metal salt to prevent the ion exchange of protons in the molecular sieve with a large amount of dissolved metal ions and at the same time, to stabilize a phosphate compound of modifying the molecular sieve; and
(3) technology of stabili^ng a molecular sieve modified witii a phosphate compourKi and a metal by water evaporation.

With this technical background, any support for the catalyst may be used if it is a molecular sieve containing a ftamework of-Si-OH-Al- groups.
It is preferable to use any one selected fiom mesoporous molecular aeves with a pore size of 10-100 A and an Si/Al molar ratio of 1-300 and preferably about 25-80, including zeolites with a pore size of 4-10 A.
Among them, more prefened are ZSM-5, Ferrioite, ZSM-11, Mordenite, Beta-zeolite, MCM-22, L-zeolile, MCM-41, SBA-15 and/or Y-zeolite, the general properties of which are already widely known in the art.
As used herein, the term water-insoluble metal salt means a metal salt with a solubility product (Ksp) of less than 10"*, i.e., a pKsp of more than 4. An example of this metal salt may be an oxide, hydroxide, carbonate or oxalate of a metal with an oxidation state of more than +2. Prefoiably, the metal salt is an oxide, hydroxide, carbonate or oxalate of at least one metal selected fiom tiie groiq) consisting of alkaline earth metals, transition metals and heavy metals with an oxidation state of+3 to +5.
Preferably, ^ alkaline earth metals may include M^ Ca, Sr and Ba, the transition metals may include Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and the heavy metals may include B, Al, Ga,hi, Ti, Sn,Pb, SbandBi.
Mean^^4lile, the i^osphate compound is not specifically limited if it is one known in the art However, because the use of phosphoric acid as ttie phosphate compound has a disadvantage in that the ciystaUinity of a porous material is reduced, alkyl phosphine derivatives in place of phosphoric acid may also be used but have a problem in that they are not suitable for use in mass production because they are xineconomical and not easy to handle. For this reason, it is preferable to use phosphoric acid, ammonium phosphate [(NH4)3P04, (NH4)2HP04, (NH4)H2P04], or aUcyl phosphate as the phosphate compound.

It is generally known that the acid dissociation constants pKa(l), pKa(2) and pKa(3) of phosphoric acid (H3PO4) are 2.2,12 and 12.3, respectively, and the phosphoric acid is present as a monohydrogen phosphate ion ([HP04]^, a dihydrogen phosphate ion ([H2PO4]0 and a phosphate ion ([P04]^ at pHs 22, 7.2 and 12.3, respectively. Thus, it will be obvious that tiie desired chanical species of phosphate ions can be selectively formed by suitably adjusting tiie pH of an aqueous solution containing the phosphate compound.
The porous molecular sieve catalyst formed fixon the above-described composition is modified with one compound selected fix)m compounds represented by the following fcmiulas 1 to 3:
[Formula 1]
Mx(H2P04)y, vAerein M is a metal, X is 1, and y is an inte^ fiom 2 to 6;
[Formula 2]
Mx(HP04)y, vsdierein M is a metal, x is 2, and y is an integer of fi^om 2 to 6; and
[Formula 3]
Mx(P04)y, wherein M is a metal, x is 3, and y is an integer fix)m 2 to 6.
Accordingly, e3qx)sed acid sites outside the pores of the porous molecular sieve are selectively modified with a modifier having physical and chemical stabilities in an atmosphere of high temperature and humidity, so that the surface of zeolite can be protected fix>m dealunfunation.
Althoi^ the description for the preparation of tiie molecular sieve catalyst is not restricted to a certain theory, it is believed that ttie -Si-OH-Al- groups forming the molecular sieve are modified with the phosphate compound/metal composite structure as shovm in the following reaction schmies 1 and 2 so as to be condensed wifli the proton of zeolite so that a =P=OgK)iq) stabilizes unstable Al while two -OH groi5)s are stabilized with the metal, whereby the fi:amework structure is relatively stably maintained even in an atmosphere of high temperature and humidity:
[Reacdon scheme 1]

A meflKxi for prq)ariDg the porous molecular sieve catalyst can be broadly divided into two methods and involve the step of removing water contained in the above-desaibed raw material mixture by a selective evaporation process so as to recover a solid product
Hereinafter^ the preparation method of the catalyst according to one preferred embodiment of the present invention will be described.
(1) The phosphate compound is added to and mixed with an aqueous slurry containii^ the water-insoluble metal salt. The nuxture is adjusted to a suitable pH using a convrational alkaline or acidic aqueous solution, such as NaOH, KOH, NH4OH, HCl or HNO3, and stirred at a tempaature of about 20-60 "C, and preferably about 40-50 *C, for about 30 minutes to 3 hours, and preferably about 1-3 hours, so that the phosphate compound is present in the form of an ion selected ftom a monohydrogen phosphate ion, a dihydrogm phosphate ion and a phosphate ion, in the aqueous solution.
Particularly, it is preferable that the mixture is adjusted to a desired pH range so &at only one chemical spedes of phosphate ion that ^dsts at this pH range will be formed in tiie aqueous solution. Namely, if a specific pH range is not met, one or more species of phosphate ions will coexist in the aqueous solution so that a diemical species of modifying the pore surfece

of the molecular sieve will not be uniform, thus making it difficult to secure the durability of the
modified catalyst
(2) To the mixture of tiie part (1), a molecular sieve witii a fi:amework of-Si-OH-Al-groiq>s is added The resdting mixture is stirred at a teinperature of preferably about 10-9^ *C, and more preferably about 50-70 "C, ia a specific pH range corresponding to purpose, until water in the aqueous slurry is completely evs^rated Thus, fee phosphate ion spares modifying the molecular sieve is stabilized with metal ions vMe water present in title sluny is removed. Then, vacuum filtration is perfonned to recover the solid pxxJuct. In this way, the molecular sieve catalyst having the -Si-OH-Al- frameworic modified with the phosphate^n^tal salt is prepared.
Meanwhile, the composition of the raw material mixture used in the preparation of the catalyst is as follows: 100 parts by weight of the molecular sieve having fee -Si-OH-Al-fi-amework; 0.01-5.0 parts by weight of fee water-insoluble metal salt; and 0.05-17.0 parts by weight of fee phosphate compound.
The preparation mefeod of fee catalyst according to anofeer embodiment of fee present invention will now be described.
(1) A phosphate compound is added to and mixed wife an aqueous slurry containing fee water-inrx)luble metal salt The mixture is adjusted to a suitable pH using a conventional alkaline or acidic aqueous solution, such as NaOH, KOH, NH4OH, HCl or HNO3, and stirred at a temperature of about 20-60 *C, and preferably about 40-50 1C, for about 30 minutes to 3 hours, and preferably about 1-3 hours, so that fee phosphate compound exists in fee form of an ion selected fiom a monohydrogen phosphate ion, a dihydrogen {diosphate ion and a phosphate ion, in fee aqueous slurry. Then, fee aqueous slurry is subjected to water evaporation at a teiiq)erature of preferably 10-90 "C, and more preferably 50-70 t;, in a specific pH range suitable for fee purpose, until water in fee aqueoifiS|Mrry completely evaporates. Then, fee solid

product is vacuum filtered and washed to separate a first solid product In this way, ttie water-insoluble phosphate-metal salt is prepared.
(2) The first solid product of the part (1) is added to and rruxedwift an aqueous solution containing a molecular sieve with a fi:amework of-Si-OH-Al- groups. The resulting mixture is stirred at a temperature of preferably about 20-60 TC, and more preferably about 40-50 V, for about 30 minutes to 7 hours, and preferably about 1-5 hours, until water in the mixture conipletely evaporates. Th^ ^ remaining solid product is vacuum filtered to separate a second solid product In this way, the molecular sieve catalyst having the -Si-OH-Al- fi:ameworic modified vsdth the phosphate-metal salt is prepared.
Meanwiiile, the raw material mixture used in tibe preparation of the catalyst is used in
such a coribx>Ued maimer that the con:qx)sition of the raw niaterialriiixtu^ 100 parts
by weight of the molecular sieve having the -Si-OH-Al- fiamework; 0.01-5.0 parts by weight of the water-insoluble metal salt; and 0.05-17.0 parts by weight of the phosphate compound. Particularly, it is preferable in temis of tiie desired effect feat fee first solid product should be used in an amount of 0.01-20.0 parts by weight based on 100 parts by weight of fee molecular sieve.
In fee above-described mefeods of preparing fee catalyst, it is necessary to find conditions v^ere fee metal ions formed by fee dissolution of some of fee metal salt in the aqueous solution can stabilize only the modified phosphate ion species without ion exchange wife fee proton of fee molecular sieve. Ofeerwise fee dissolved metal ions will be ion-exchanged wife fee proton of fee molecular sieve to reduce fee number of add sites, resulting in a reduction in reactivity of modified catalysts.
Accordingly, as described above, by fee use of a water-msoluble metal salt having a solubility product of less than 10"^ in aqueous solution, and preferably, an oxide, hydroxide, carbonate or oxalate of at least one metal selected fix)m fee group consisting of alkaline earth metals, transition metals, and heavy metals wife an oxidation state of +3 to +5, it is possible to

substantially prevent tiie phenomenon of ion exchange with &e proton of the molecular sieve by the presence of a large amount of metal ions, vMcb is a problem in the case of using water-soluble metal salts, and at the same time, it is possible to maximize tiie effect of stabilizing the modified phosphate ions with the desired metal ions.
Meanwhile, the raw material mixture in the aqueous slurry for the preparation of the catalyst must be maintained at the following composition: 100 parts by weight of the molecular sieve; 0.01-5.0 parts by weight of the water-insoluble metal salt; and 0.05-17.0 parts by weight of the phosphate compound. If the composition of the raw material mixture is out of flie specified composition range, the sur&ce pores of the molecular sieve will not be selectively modified with the iiiodifier, and the number of acid sites wiU be rath^ reduced, leadirig to a reduction in ^^ activity. Particularly, the molar ratio of the water-insoluble metal salt to the phosphate compound is 1.0 : 0.3-10.0, and preferably 1.0 : 0.7-5.0. If the molar ratio of the phosphate compound to tiie waler-insoluble metal salt is less than 0.3, there will be a problem in that unnecessary metal ions are present in excess so that the number of acid sites in the molecular sieve is reduced, leading to a reduction in the reactivity of the modified catalyst. On the other hand, if the ratio of the phos[diate compound to the v^^ter-insoluble metal salt is less more than 10.0, there will be a problem in that the molecular sieve fiamework is not sufficiently modified so that the hydrothermal stability of the modified molecular sieve becomes poor.
Hereinafter, the inventive process for producing light olefins fix)m hydrocarbon feedstock using the above-described porous molecular sieve catalyst, where the hydrothermal stability of the catalyst in a sever environment of high temperature and humidity is necessarily required, will be described.
As the hydrocarbon feedstock, fidl-range naphtha or kerosene may be used. More preferably, full-range naphtha havii^ C2.15 hydrocarbons may be used. The most suitable

process inaction for this hydrocarbon feedstock may be catalytic cracking reacdcm but is not
specifically limited thereto.
Examples of Ihe feedstock v^ch can be used in the present invention include, in addition to full-range wphiha, ejq)ensive light n£q)htha used in a steam a:acking process for the production of light olefins, and olefin-containing feedstock typically used in a plurality of catalytic cracldng processes, and C20-30 heavy fiactions wiiidi have been used in the prior FCC process.
Among &CT1, the fidl-range n^htha is a fiaction containing C2-12 hydrocarbons produced directiy in crude oil refining processes and contains paraffins (n-parafBn and iso-parafSn), n^hthene, aromatic conqxtunds, etc., and may sometimes contain olefin compounds. Generally, Ihe hi^ier the content of paraffin components in m^htha, the slighter n^htha becomes, and on tiie other hand, the lower the content of parafBn conqx)nents, flie heavier naphtha becomes.
According to the present invention, the feedstock is selected by considering yield, economic efficiency, etc. Under this consideration, fiill-range n^htha may be used where the total content of paraffin components (n-paraffin and iso-parafBn) is 60-90 wt%, more preferably 60-80 wt%, and most preferably 60-70 wt%. Also, the selected rmphtha may contain olefins in an amount of less than 20 wt%, preferably less tiian 10 wt%, and most preferably less tiian 5 wt%. Table 1 below shows an illustrative feedstock composition (unit: wt%) which can be used in the present invention.
Moreov^, in the present invention, the naphtha feedstock may also be used in a mixture with C4-5 hydrocarbons remaining after tiie separation and recovery of light olefins and heavy products fix)m the effluent of a reaction zone containing the catalyst

In the pres«it invention, ttie reaction zone may comprise at least one reactor, and preferably a fixed-bed or fluidized-bed reactor. In the reactor, the feedstock is converted to a large amount of li^ olefirK by a conversion reaction (e.g., a catalytic cracking reaction) with the
invQitive catalyst
Generally, catalytic activity greatly depends on reaction tenq)erature, space velocity, the naphtiia/steam wei^ ratio, etc. In this case, reaction conditions detemiined with the following considerations must be presented: flie lowest possible temperature to minimize aiergy consumption, the optimal conversion, the optimal olefin production, the nninimization of catalyst deactivation caused by coke production, etc. According to a preferred embodiment of the present invention, the reaction temperature is about 500-750 t;, preferably about 600-700 V, and more preferably about 610-680 t). Also, the hydrocarbon/steam weight ratio is about 0.01-10, preferably about 0.1 -2.0, and more pref^ably about 0.3-1.0.
If the fixed-bed reactor is used, the space velocity will be about 0.1-20 h'^ preferably about 0.3-10 h"^ and more preferably about 0.5-4 h'^ Furthomore, if the fluidized-bed reactor is used, the catalyst/hydrocarbon weight ratio will be about 1-50, preferably about 5-30, and more preferably about 10-20, and the residence time of hydrocarbons will be about 0.1-600 seconds, preferably alx)ut 0.5-120 seconds, and more preferably about 1-20 seconds.
Meanwhile, in order to examine if the molecular sieve catalyst according to the present invention can maintain its catalytic activity to some extent even in a severe environment or is deactivated in this aivironment, the inventive catalyst was steamed in an atmosphere of 100% steam at 750 t) for 24 hours. Namely, if the inventive catalyst is used after steaming in the above-described atmosphere, the content of light olefins ^.e., ethylaie and propylene) in the eflQuent of said reaction zone will preferably be more than about 30 wt%, more preferably more than about 35 wt%, and most preferably more than about 40 wt%. In this case, the

ethylene/propylene weight ratio is i^faably about 0.25-1.5, more preferably 0.5-L4, and most pref^ably 0,7-1.3, indicating that propylene is produced in a relatively large amount [Mode for InvCTtionl
Hereinafter, the present invention will be desoibed in more detail by exan:q>les. It is to be understood, however, that these examples are not construed to limit the scope of the present invention.
Example 1
A^ Preparation of catal\^
To 100 mL of distiUed water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.55 g of concentrated phosphoric acid (85% H3PO4), were added and stirred for 20 minutes. To the stirred solution, 0.36 g of Mg(0H)2 was added and the mixture was adjusted to a pH of 7-8 using ariimoiiia water, followed by stirring at a temperature of about 45 *C for about 20 minutes. Next, ttie mixture was stirred at about 50 *C until the water completely evaporated, and then, vacuum filtration was used to separate the solid product. The separated solid product was calcined in air at a traiperature of 500 t) for 5 hours, thus preparing an Mg-HP04-HZSM-5 catalyst.
B) Steaming step for evaluation of hvdrotfaermal stability
To evaluate the hydro&ermal stability of the catalyst, the catalyst was maintained in an atmosphere of 100% steam at 750 "C for 24 hours.
C) Production of light olefins
As shown in FIG. 1, a system for measuring the activity of tiie catalyst during the production of light olefins comprises a n^h^ feed device 4, a water feed device 3, fixed-bed reactors 5 and 5', and an activity evaluation device, which are integrally connected with each other. In this case, n^htha specified in Table 1 above was used as feedstock. Naphtha and water fed by a liquid injection pump were mixed with each other in a preheats* (not shown) at

300*0, and mixed with 6 ml/min of He and 3 mlAnin of Na fed by helium feed device 2 and 2 and nitrogen feed devices 1 and \\ respectively, and the mixture was fed into tiie fixed-bed reactors 5 and 5'. At tbis time, tiie amount and rate of eadi gas were controlled with a flow controller (not shown). The fixed-bed reactors are divided into an inner reactor and an out^ reactor, in which the outer reactor, an Inconel reactor, was manufactured to a size of 38 cm in length and 4.6 cm in outer diameter, and the inner reactor made of stainless steel was manufactured to a size of 20 cm in lengtih and 0.5 indies in outo* diameter. The temperature within the reactors was indicated by tempCTature ou^ut devices 7 and 7, and reaction conditions were controlled by PE) controllers (8 and 8' NP200; Han Young Electronics Co., Ltd, Korea).
The gas fed into the reactors was passed through ^ inner reactor and then passed through the outer reactor, tiirough which 40 ml/min of He flowed. The bottom of the inner reactor was filled with the catalyst The mixed gas was catalytically cracked through the catalyst layers 6 and 6', and after the reaction, vapor phase product 12 was quantified online by gas chromatography 11 (Model: HP 6890N). The remainii^ liquid phase prcxiuct 13 passed through condensers 9 and 9' were recova:ed into storage tanks 10 and 10* and quantified by gas chromatography (Model: DS 6200; not shown). The amount of catalyst used in the catalytic cracking reaction was 0.5 g, tfie feed amount of each of naphtha and water was 0.5 g/h, and the reaction was carried out at 675 "C.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene wei^ ratio, are shown in Table 3 below.
Example 2
A) Preparation of catalyst
To 100 mL of distilled water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.26 g of concentrated phosphoric acid (85% H3PO4), were added and stirred for about 20 minutes. To tiie stirred solution, 0.08 g of Mg(0H)2 was added, and the mbrture was adjusted to

a pH of 2-3 using an aqueous nitric acid solution, followed by stirring at about 45 *C for about 20 minutes. After stirring tiie mixture at about 50 "C until water completely evaporated, vacuum filtration was performed to separate tte solid product The sq)arated solid product was calcined in air at a temperature of 500 "C for 5 hoinrs, thus prq)aring a Mg-H2P04-HZSM-5 catalyst.
B) Steanung step for evaluation of hvdrotiiermal stability
Steaming was carried out in tiie same manner as in Example 1.
Q Production of light olefins
The production of light olefins was carried out in tiie same maimer as in Example 1.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the etiiylene/propylene weight ratio are shown in Table 3 below.
Examples
A^ Preparation of catalyst
Slurry comprising 6.6 kg of the Mg-HaPOa-HZSM-S prepared in the part (A) of Exanple 2, 0.7 kg of Y zeolite and 3 kg of an alumina binder was stirred, followed by spray drying, thus preparing a pelletized catalyst with an average particle size of 80 //m
B) Steaming for evaluation of hvdrothermal stability
Steaming was carried out in the same manner as in Example 1.
O Production of light olefins
In this Example, a fluidized-bed reaction system was used to measure the activity of the catalyst during the production of light olefins. The fluidized-bed reaction system conpises a riser reactor, a regenerator, a striper and a stabilizer. Tbe riser reactor is 2.5 m in height and 1 cm in diameter, flie regenerator is 1.5 m in height and 12 cm in diameter, the strii^)er is 2 m in height and 10 cm in diameter, and the stabilizer is 1.7 m in height and 15 cm in diameter.
As feedstock, naphtha specified in Table 1 above was used.

At the riser inlet, flie feedstock, steam and the catalyst are fed and mixed vwth each other, such that the feedstock is fed in 133 g/hr at 400 t:, the steam is fed in 45 g/hr at 400 V, and the catalyst is fed in 5320 g/hr at 725 *C. During the passage of the mixture through the riser, a fluidized-bed catalytic cracking reaction occurs, and the riser ouflet has a temperature of 675 X^, The rnixture passed tiirough the riser is sq)arated into the catalyst and a fi^^ stripper at 500 "C. The separated catalyst is recycled to the regeneratcff, and fl)e ftaction flows into the stabilizer. The catalyst mtroduced into the r^enerator is regenerated in contact with air at 725 "C, and the regenerated catalyst is fed again into flie riser. Ibe fiaction fed into the stEdDilizer is separated into a gas component arid a liqirid component at-10 ^C.
Ibe analysis of the gas component and liquid component factions produced by the reaction was performed in the same manner as in Example 1.
The obtained results for converaon, selectivity to light olefins (ediylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below.
Example 4
A) Preparation of catalyst
To 100 mL of distilled water, 10 g of HZSM-5 (Zeolyst) with a Si/Al molar ratio of 25, and 0.18 g of concentrated pho^horic acid (85% H3PO4), were added and stirred for about 20 minutes. To the stirred soliition, 0.146 g of MgCOHfe was added, and the mbcture was adjusted to a pH of 12-13 using ammonia water, followed by stirring at about 45 *C for about 20 minutes. Ailer stirring the mixture at about 50 "C until the water completely evqx)raled, vacuum filtration was performed to separate the solid product The sq)arated solid product was calcined in air at a
traiperature of about 500 TC for 5 hours, thus preparing a Mg-P04-HZSM-5 catalyst B. Steaming for evaluation of hvdrothermal stability
Steaming was carried out in the same manner as in Example 1. Q Production of licht olefins

This was carried out intiie same manner as in Example 1.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the efliylene/piopylaie weight ratio are shown in Table 3 below. Examples 5 to 10
A) Preparation of catalysts
Catalysts were prepared in fte same manner as in Example 1 excq* that the composition of the raw material mixture was changed as shown in Table 2 below.
B) Steaming for evaluation of hvdrotiiCTnal stability
Steaming was carried out in tiie same manner as in Example 1.
Q Production of lisht olefins
This was carried out in the same manner as in Exanf^le 1.
The obtained results for converaon, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below. Comparative Example 1
A) Preparation of catalyst
An HZSM-5 catalyst was prepared by calcining 10 g of HZSM-5 (Si/Al=25; Zeolyst) inairataternperatureofaboutSOO *C for 5 hours.
B) Steaming for evaluation of hvdrotfaermal stability Steaming was not carried out
C) Production of light olefins
Ibis was carried out in the same manner as in Example 1.
The obtained results for conversion, selectivity to light olefins (ethyl^e and propylwie) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below. Comparative Example 2 A) Preparation of catalyst

An HZSM-5 catalyst was prepared by calcining 10 g of HZSM-5 (Si/Al=25; Zeolyst) inairatatemp^atureofaboiit500 "C for5hours.
R) Steaminpr for evaluation of hvdrotbermal stability
Steaming was carried out in the same manner as in Example L
C) Production of light olefins
This was carried out in the same manner as mBcample 1.
n^e obtained results for conversion, selectivity to light olefins (eftiyl«ie and propylene) in the reaction product, and the ethylene/propylene wei^t ratio are shown in Table 3 below.
Comparative Example 3
A) Preparation of catalyst
To 100 mL of distilled water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.15 g of concentrated phosphoric add (85% H3PO4) woe added. The mixture was adjusted to a pH of 7-8 using ammonia water, and then stirred at about 50 V until water completely evaporated. Then, vacuum filtration was performed to separate the solid product The separated solid jM-oduct was calcined in air at a temperature of about 500 *C for 5 hours, thus preparing an HPO4-HZSM-5 catalyst
B) Steaming for evaluation of hvdrottienmal stability Steaming was carried out in the same manner as in Example 1.
C) Production of light olefins
^lis was carried out in the same manner as in Example 1.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below. Comparative Example 4 A) Preparation of catalyst

To 100 mL of distilled water, 10 g of HZSM-S (Si/Al=25; Zeolyst) and 1.4 g of La(N03)3 • xHaO were added The mixture was stined at about 50 t; until the water completdy evqx)rated The remaining material was vacuum filtaied to separate a solid product The sq)arated solid product was caldned in air at a temp^ature of 500 Xl for 5 hours, thus preparing a La-HZSM-5 catalyst
B^ Steaming for evaluation of hvdrothermal stability
Steaming was carried out in the same manner as in Example 1.
C) Production of light olefins
this was carried out in the same manner as in Example 1.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propylene weight ratio, are shown in Table 3 below.
Comparative Example 5
A^ Preparation of catalyst
To 100 mL of distilled water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.74 g of concentrated phosphoric acid (85% H3PO4) were added and stirred for about 20 minutes. To Ae solution, 1.40 g of La(N03)3 ' XH2O was added, and the mixture was adjusted to a pH of 7-8, followed by stirring at a temperature of about 45 *C for20minutKL After stirrir^ the mixture at about 50 V. until water completely evqxjrated, the remaining inaterial was vacuum filtered to separate tiie solid product. The separated solid product was caldned in air at a temperature of about 500 V for 5 hours, thus preparing a La-H3P04-HZSM-5 catalyst
B) Steaming for evaluation of hvdrothermal stability
Steaming was carried out in the same manner as in Example 1.
O Production of light olefins
This was performed in the same manner as in Example 1.

The obtained results for conversion, selectivity to light olefins (ethylene and propylrae) in the reaction product, and the ethylene/propylene weight ratio are shown in Table 3 below.
Comparative Example 6
A^ Preparation of catalyst
To 100 mL of distiUed water, 10 g of HZSM-5 (Si/Al=25; Zeolyst) and 0.55 g of concentrated phosphoric acid (85% H3PO4) were added, followed l^ stirring for 20 minutes. To tiie stirred solution, 1.58 g of Mg(N03)2 • 6H2O was added, and the mfacture was adjusted to apH of 7-8 using ammonia water, and then stirred at a temperature of about 45 "C for about 20 minutes. After stirring the mixture at about 50 t; until the water completely evaporated, vacuum filtration was used to separate the solid product The separated solid product was calcined in air at a traiperature of about 500 *C for 5 hours, thus preparing a Mg-H3P04-HZSM-5 catalyst
B) Steaming for evaluation of hvdrothermal stability
Steaming was carried out in the same manner as in Example 1.
Q Production of light olefins
This was carried out in the same manner as in ]&cample 1.
The obtained results for converaon, selectivity to light olefins (efliylene and propylene) in the reaction product, and flie efliylene/propylme weight ratio, are shown in Table 3 below.
Comparative Example 7
A) Preparation of catalyst
A catalyst was prepared according to a method disclosed in US patent No. 6,211,104 Bl. Hie catalyst was prepared in the following specific manna:. To 40 gofa solution of 85% phosphoric acid and MgCfe ' 6H2O in distilled water, 20 g of NH4-ZSM-5 was added and loaded with the metal ions, followed by stirring. Then, the loaded molecular sieve was dried in an oven atl20 t, and finally, calcined at 550 X: for2hour.

B^ Steaming for evaluation of hvdrotfaemial stability The catalyst was steamed in the same manner as in Example 1. Q Production of light olefins
This was carried out in the same manner as in Exanq)le 1.
The obtained results for conversion, selectivity to light olefins (ethylene and propylene) in the reaction product, and the ethylene/propyloie weight ratio are shown in Table 3 below.

in the case of Examples 1-10 according to the present invention, even ttie use of the catalyst steamed in an atmosphere of high temperature and humidity (maintained at 750 t) m 100% steam for 24 hours) showed a high conversion of about 76-80 wt%, and at tiie same time, high selectivity corresponding to the sum of ethylene + propjiene of about 33-37 wt% (ethylene/propylene weight ratio = about 0.8-1.0).
On the other hand, it could be observed that the unsteamed HZSM-5 used in Comparative Example 1 showed a conv^on of 77.7 wt% aiKi a sum of ethylene + propylene of 40.5 wt%, but tfie use of HZSM-5 steamed in a severe hydrothermal atmosphere as in Comparative Bcample 2 showed rapid reductions in convorsion and the sum of ettiylene + propylene to 67.7 wt% and 24.5 wt%, respectively. In Conqjarative Examples 2,3,4 and 6, the conversion was about 58-75 wt% and the sum of ethylene + propylaie was 20-30 wt%, indicating that these Comparative Examples excludii^ Conqjatative Example 5 showed very low conversion and olefin production as compared to the inventive production process.
Meanwhile, Comparative Example 5 showed a conversion of about 75.4 wt% and a sum of ettiylene + propylene of 30.5 wt%. These results can be seen to be inferior to those of Examples 1-9, and this is believed to be because ttie use of nitric acid salt, ^^ilich is a water-soluble metal salt, not a water-insoluble salt, led to a reduction in hydrothermal stability.
Also, evaluated reactivity of the catalyst prepared according to tiie method described in US patent No. 6,211,104 Bl was inferior to tiiat of the inventive process.
As described above, in the inventive process, even tiie use of a catalyst that has been hydrofliermally treated in an atmosphere of 100% steam at 750 *C for 24 hours, showed C2'-+C3"= 33-37%, whereas the use of HZSM-5, P-HZSM-5 and La.HZSM-5 catalysts showed C2"+C3" = 23-24%, and the use of La-P-HZSM-5 showed C2"'-K:3" = about 30%, Also, adjusting the component and composition ratio of a chemical q)ecies of modifying the catalyst used in the olefin production process according to the present invention shows a characteristic in

that the hydrothermal stability of the catalyst can be ^isured and at ttie same time, the conversion and C27C3" ratio in the olefin production process can be controlled. In addition, tiie inventive catalyst is excellent in reaction activity required m producing light olefins fix)m nsphiha containing C2-12 hydrocarbons. [Industrial Applicability]
As described above, according to the jnesent invention, the use of a certain catalyst having l^drothermal stability shows excellent reaction performance in selectively produdng light olefins at hd^ yield with higji selectivity from hydrocarbon feedstock, particularly full-range naphtha, even in a severe process environment of high temperatotc and humidity. Particularly, the inventive process 'is highly useful in Ifaat it can maintain high cracking activity even at a temperature lower tiian reaction temperature requited in the prior thermal cracking tatiperature for the production of light olefiiis, and thus, can produce light olefins with high selectivity and conversion fix)m hydrocarbon feedstocL
Although the preferred embodiments of the present invention have been described for illustrative purposes, tiiose skilled in the art will appreciate that simple modifications, additions, and substitutions are possible, witiiout departing fix>m the scope and ^irit of the invention as disclosed in the accompanyir^ claims.

[CLAIMS] [Claim 1]
A process for producing light olefins fix)m hydrocarbon feedstock, comprising the steps
of:
(a) |MX)vidii a hydrocarbon flection as feedstock;
(b) feeding tiie feedstock into at least one fixed-bed or fluidized-bed reactor where it is allowed to react in the presence of a cat and
(c) separating and recovering light olefins fix)m tiie effluent of the reaction zone;
in vAich the catalyst consists of a product obtained by the wat- evqxration of a raw material mixture comprising 100 parts by weight of a molecule sieve with a fi:amework of -Si-OH-Al- groi^ 0.01-5.0 parts by weight of a water-insoluble metal salt, and 0,05-17.0 parts by weight of a phosphate compound. [Claim 2]
The process of Claim 1, wherein the feedstock is fiali-rare n htha or kerosene. [Claims]
The process of Claim 1, wherein the feed stock is n^htha containing C MS hydrocarbons. [Claim 4]
The process of Claim 2, \^4^erein the total content of parafiSn components (n-paraflBn and iso-paraffin) in the feedstock is 60-90% by weight, and the content of olefins in the feedstock is less than 20% by weight [Claim 5]
The process of Claim 3, which further comprising the steps of mixing C 4-5 hydrocarbons ranaining after the separation and recovery of light olefins in the step (c) wifli ng^htha and providing the C 4-5 hydrocarbon/naphtha mixture as feedstock.

[Claim 6]
The process of Claim 1, wherein, if the reactor is a fluidized-bed reactor, the reaction is then carried out at a temperature of 500-750 C, a hydrocarbon/steam weight ratio of 0.01-10, a catalyst/hydrocarbon wdgjit ratio of 1-50, arid a hydrocarbon residence time of 0 1-600 [Claim 71
The process of Claim 1, wherein, if the reactor is a fixed-bed reactor, the reaction is then carried out at a temperature of 500-750 "C, a hydrocarbon/steam weight ratio of 0.01-10, and a space velocity of 0.1-20 h-1 [Claim 8]
The process of Claim 1, v^erein, if the catalyst is used after steam treatment in an atmosphere of 100% steam at 750 "C for 24 hours, the total content of ethylene and propylotie in the effluent of the reaction zone will be more than 30% by weight, and the ethylene/propylene weight ratio will be 0.25-1.5.

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Patent Number

268470

Indian Patent Application Number

525/CHENP/2008

PG Journal Number

36/2015

Publication Date

04-Sep-2015

Grant Date

31-Aug-2015

Date of Filing

31-Jan-2008

Name of Patentee

SK INNOVATION CO., LTD

Applicant Address

99 SEORIN-DONG, JONGRO-GU, SEOUL 110-110, KOREA.

Inventors:

#	Inventor's Name	Inventor's Address
1	CHOI, SUN	103-1709, EXPO APT, JEONMIN-DONG, YUSEONG-GU, DAEJEON 305-761, KOREA.
2	KIM, YONG SEUNG	206-1302, EXPO APT, JEONMIN-DONG, YUSEONG-GU, DAEJEON 305-761, KOREA.
3	PARK, DEUK, SOO	807-1004, HUGOK MAEUL, ILSAN 3-DONG, ILSAN-GU, GOYANG-SI, GYEONGGI-DO 411-313, KOREA.
4	KIM, SUK, JOON	204-1002, MUGUNGHWA APT, WOLPYEONG 2-DONG, SEO-GU, DAEJEON 302-747, KOREA.
5	YANG, II, MO	1011-1804 HYUNDAI 10-CHA APT, GWANGJANG-DONG, GWANGJIN-GU, SEOUL 143-769, KOREA.
6	KIM, HEE, YOUNG	101-203, HANBIT APT, EOEUN-DONG-YUSEONG-GU, DAEJEON 305-755, KOREA
7	PARK, YONG, KI	119-302, HANBIT APT, EOEUN-DONG, YUSEONG-GU, DAEJEON 305-755, KOREA
8	LEE, CHUL, WEE	107-603 HANA APT, SINSEONG-DONG,YUSEONG-GU, DAEJEON 305-345, KOREA
9	CHOI, WON, CHOON	120-1306, HANBIT APT, EOEUN-DONG, YUSEONG-GU, DAEJEON 305-755, KOREA
10	KO, KWANG-AN	22-73, YANGLIM-DONG, NAM-GU, GWANGJU 503-821, KOREA.
11	KANG, NA, YOUNG	33-1 3-GU, DAECHEON-RI, GODEOK-MYEON, YESAN-GUN CHUNGCHEONGNAM -DO 340-932, KOREA.

PCT International Classification Number

C10G11/05

PCT International Application Number

PCT/KR2006/002276

PCT International Filing date

2006-06-14

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2006-0053069	2006-06-13	Republic of Korea
2	10-2005-0094468	2005-10-07	Republic of Korea