Title of Invention	A PROCESS FOR THE PREPARATION OF CATALYST FOR CONVERSION OF C5 HYDROCARBONS INTO BUTANE
Abstract	The present invention provides a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. In particular, the present process is useful for the preparation of valuable butane from low value iso-pentane with high yield and selectivity, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of value added low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks.

Title of Invention

A PROCESS FOR THE PREPARATION OF CATALYST FOR CONVERSION OF C5 HYDROCARBONS INTO BUTANE

Abstract

The present invention provides a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. In particular, the present process is useful for the preparation of valuable butane from low value iso-pentane with high yield and selectivity, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of value added low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks.

Full Text	Field of the invention The present invention relates to a process for the conversion of C5 hydrocarbons into butane. More specifically, the present invention relates to a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. Hence, in particular, the present process is useful for the preparation of valuable butane from low value iso-pentane, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks. Background and prior art of the invention Increasing reformer severity and introducing FCC olefins in motor gasoline did compensate the octane loss due to lead phase out programmes all over the world. However, the restrictions have already been imposed on aromatics and olefins due to their high photochemical activities. Now the attention is to reduce the vapour pressure of motor gasoline, which has already restricted C4 hydrocarbons from gasoline pool, and C5 hydrocarbons are under close observation due to their higher Reid Vapor Pressure(RVP) values. The advantage of increased octane with iso-pentane will be limited for its high vapour pressure while amylens will be restricted for high photochemical activities. Therefore blending of iso pentane into gasoline pool beyond a certain limit is not acceptable due to its high RVP. Light naphtha and natural gas liquids (NGL) are of the least viable petroleum feed stocks treated today. These feedstocks primarily consist of C5-C6 paraffins rich of normal and iso-pentanes. The projected production of NGL (1996-97) indicates that India produces 2.25 MMTA from various gas fields (Sharma, R.L. et al, Chem. Eng. World 1994, 29(10) 171. These feedstocks are filing up in refineries and the situation calls an immediate need for the valorization of these into butane and propane is an attractive proposition. The co-product, high-octane gasoline can be used as a gasoline volume builder. Thus, the this process stands relevant by addressing the light paraffin utilization on one hand and the production of butane along with high-octane low-benzene content gasoline on the other. In addition to this, the demand for LPG is also growing much faster in India at growth rate of 14 percent per year and there will be continuous shortage of LPG in India. The production of LPG in the year 1999-2000 was 2.487 MMT with consumption of 8.029 MMT with a corresponding deficit of 5.542 MMT (Ministry of Petroleum and Natural gas "Report on basic statistics in Petroleum Products in India 2001). This disparity between LPG production and consumption patterns may expect to increase further by 2010-11due to increase in use of LPG in domestic and automobile sector. Therefore the major concern of Indian refinery would be to have secondary refinery process to increase the production of butanes, propane. C4 streams generally come from a number of sources, but they are mainly found as co-product from steam cracking processes that produce ethylene. And as a co-product stream from FCC, distillation units and from the NGL as well. The availability of butane from the said sources is very less in compared to propane. One of the major uses for the butane stream is in rubber production. In Asia petrochemical companies are planning new complexes and developing new C4 strategies, to take the advantage of the need for synthetic rubber feedstocks. This comes in light of an increased demand for rubber in Asia as the automotive and allied industries continue to expand. On the other hand, butane production either from refineries or from gas fields is not enough to meet the demands. The import situation is also not encouraging, as only a few private entrepreneurs have actually created facilities for import market. Thus, there is a considerable incentive for conversion of these low value feed stocks to high value products such as butane and aromatics. Similarly, conversion of other unconventional feedstocks such as natural gas liquids and raffinates into butane, propane and gasoline and LPG also gains significant importance in this scenario. It is proposed here that the surplus light naphtha or NGL can send to depentanizer column and the obtained C5 hydrocarbons led to disproportionation reactor to yield value added butane product. Disproportionation of paraffins is a well-known reaction step in the isomerization of n-paraffins to i-paraffins during petroleum refining. The general object of this invention is to provide process for production of butanes from pentane feedstocks. As mentioned by way of introduction, isoparaffins including isopentane are presently preferred components in high-octane gasoline products. However, recent requirements to lower vapour pressure of gasoline, makes it necessary to substitute isoparaffins having a high vapour pressure of gasoline with components of low vapour pressure in gasoline. There is an incentive to convert isopentanes to higher isoparaffins, such as, isohexanes which is a low vapour pressure motor fuel component and to butanes, which is a preferred feedstock for alkylation processes for the production of high octane alkylate gasoline and methyl tertiary-butyl ether(MTBE); hence it is desirable to obtain the above substitution of isopentane in gasoline. It has now been found that a strong acid catalyzes conversion of isopentane, and the reaction is further promoted by the presence of olefins or higher paraffins, which crack to olefins by influence of a strong acid. Zeolite catalysts have become widely used in the processing of petroleum and in the production of various petrochemicals. Reactions such as cracking, alkyaltion, polymerization, isomerization, trans alkylation, addition, dewaxing, disproportionation and other acid catalyzed reactions may be performed with use of these catalysts. Zeolites are porous crystalline aluminosilicates having definite crystalline structure as determined by X-ray diffraction studies whose preparation was first described in U.S. Pat.No. 3, 702, 886. Such zeolites have pores of uniform size that are uniquely determined by unit structure of the crystal. The zeolites are referred as "molecular sieves" because interconnecting channel systems created by pores of uniform size allow a zeolite to selectively absorb molecules of certain dimensions and shapes. Zeolites may be classified by pore size, ZSM-5 is a member of class of zeolites some times referred as medium pore zeolites and its pore size ranges from 5 to 7 angstroms. Because of its high protonic acidity and unique shape selective behavior, ZSM-5 zeolite has been proved to be a highly active and stable catalyst for hydrocarbon conversion processes e.g. oligomerization at low temperature and high pressures and aromatization at higher temperatures and lower pressures of light olefins. ZSM-5 zeolites modified with zinc or gallium have been reported as catalysts for the conversion of lower paraffins into BTX (Ref: E. E. Davis and A.J. Kolombos, Br. Pat., 1 561 590, 1976). Various modifications and pretreatments of zeolite catalyst have resulted in improvement in light hydrocarbon conversion and aromatic selectivity, though often one has been achieved to the slight detriment of the other. Gallium containing zeolites for catalysis particularly for catalysis of light paraffin aromatization, have received great attention recently. Different formulations of such catalysts have included catalysts prepared by ion exchange, by impregnation of ZSM-5 with gallium salts. The zeolites described in this patent is ZSM-5 promoted with Group IIIA metal such as Ga, In, Tl for conversion of iso-pentane to butane and low aromatic content high-octane gasoline. There are reports in the literature on the conversion of C5 paraffins into butanes and aromatics utilizing zeolites and metal-modified zeolites as catalyst but all of them suffer from disadvantages in some or more ways. Reference may be made to a process developed by Atlantic Richfield Company researchers (U.S. Pat. 3,953,537) wherein a process for disproportionating a paraffinic hydrocarbon containing 2 to 6 carbon atoms to produce compounds containing one more and one less carbon fragments over calcium exchanged Y zeolite catalyst containing sodium aluminosilicate. Another reference may be made to (U.S.Pat. 4,686,316) wherein method of producing butanes from propane by contacting with ZSM-5 type zeolite catalyst having silica-to-alumina ratio of at least 12. Another reference may be made to (Hydrocarbon Processing Sept., 1989 p 72) wherein a process developed jointly by UOP Inc. and British Petroleum, based on gallium doped zeolite catalyst has been reported. In this process LPG was converted into BTX aromatics and the process has been demonstrated in a large-scale pilot plant of the British Petroleum Grangemouth refinery in Scotland. Another reference may be made to (U. S. Pat. 5, 763, 727) wherein a process developed by Mobil Oil Company, based on fluidized bed reactor to produce propane from CA normal and iso paraffins on Pt-Sn /ZSM-5 catalyst. Yet another reference may be made to (US patent 5,026,938 dated 25th June' 1991) wherein a process for converting a gaseous feed stock containing C3-C5 paraffins into aromatics hydrocarbons by contacting the feed with gallosilicate molecular sieve catalyst has been described. The draw back of all these processes is that these are mainly related to the production of propane from C4 paraffins and aromatics from C3 - C5 range paraffins which are in high demand as LPG in India. Still another reference may be made to Chevron U.S.A Inc. (U.S. Pat No. 6, 566, 569), wherein the combination of dehydrogenation/hydrogenation catalyst (Pt/Alumina) and olefin metathesis catalyst (WO3/Silica) used for conversion of C5 paraffins into C4 and C6 paraffins. The limitation of the above process is it utilizes mixture of two catalyst formulations and homogeneity of active sites may not be achieved and it produces only 12% butanes form iso-pentane as feedstock. Still another reference may be made to (US patent No. 4,861,934 dated Aug, 29, 1989) wherein a process for the conversion of light hydrocarbon containing C2-C7 paraffins and C2-C7 olifins to high-octane gasoline using aluminogallosilicate has been reported. The disadvantage of above process is that it operates at high severity of operating conditions i.e., Temperature: 540°C, LHSV: 1hr'1. Still another reference may be made to (US patent No. 4, 579, 987 dated Apr. 1, 1986) wherein a process for the preparation of conversion of C2+ olefins, C2-C7 paraffins or a mixture thereof to C5+ hydrocarbons over high silica zeolite has been reported. The limitation of this process is that it utilizes the treatment of AIF3 on zeolite in catalyst preparation steps. Still another reference may be made to Haldor Topse A/S (US patent No. 5, 900, 522 dated May 4, 1999) wherein a process for the preparation of an isobutene/isohexane containing product from disproportionating the iso-pentane over an acid catalyst with the acidity H0 > 8. has been reported. The limitation of this process is that it utilizes the treatment of AIF3 on zeolite in catalyst preparation steps. Still another reference may be made to (US patent No. 6, 423, 880 dated July, 2002 and US Pat. No. 6, 573, 416 dated June 3, 2003) wherein a processes for disproportionating isoparaffins and paraffins in the presence of at least one initiator was disclosed. The product from the disproportionation contains a gasoline range material having high-octane rating than the isoparaffins and paraffins in the feed. The major disadvantage of this process is that it utilizes hydrofluoric acid/polyfluoroalkane sulfonic acid as the catalyst. The above processes are mainly utilizing broad range hydrocarbons and for production of aromatics. In addition to this high quantity of dry gas yields are formed during the reaction, which will be a loss to the economy of the process. Further the added hydrogen gas is used in this process, which in turn increases the overall cost of the process. Objects of the invention The main object of the present invention is to provide a process for the conversion of C5 hydrocarbons into butane which obviates the drawbacks as detailed above. Another object of the present invention is to provide a process for conversion of isopentane into butane and high-octane low aromatic content C6+ hydrocarbons by using dehydrogenating metal ion doped zeolite catalyst. Still another object of the present invention is to provide a process for the conversion of n-pentane into butane, propane and high-octane low aromatic content C6+ hydrocarbons. Yet another object of present invention is to provide a process that produces butane, propane with low yields of low cost dry gas (C1+C2) from C5 paraffins. Yet another object of present invention is to provide s process, which is economical and environmentally acceptable. Summary of the invention Accordingly, the present invention provides a process for the conversion of C5 hydrocarbons into butane comprising the steps of: a) loading Group III metal ion supported HZSM-5 catalyst in a fix bed, b) reducing the above said catalyst at a temperature of about 400-550°C under H2 gas, at a flow rate of about 10 l/h for a period of 2-5 hrs in a reactor followed by cooling to a temperature of about 300°C, under nitrogen atmosphere, c) further increasing the temperature of the above said catalyst obtained in step (b) to a temperature in the range of 300-600°C, d) contacting the feed vapours of C5 paraffins with the above said catalyst bed obtained in step (c) in a reactor, at a weight hourly space velocity ranging from of 1 to 8 hrs"1, at a temperature ranging between 300- 600°C, at a pressure of 1 to 20 kg/Cm2, for a period of atleast 24 hours in the absence of hydrogen gas to obtain the desired butane and high octane C5+ liquid, e) separating the butane, C5+ liquid and other products of the resultant reaction mixture obtained in step (d) by known method to obtain the desired C4 butane. In an embodiment of the present invention, the group III metal ion used in step (a) is selected from Ga, In, and Tl. In another embodiment of the present invention, the amount of Group III metal present in the modified zeolite catalyst is in the range of 0.5 to 5% (w/w). In yet another embodiment of the present invention, the the feedstock used is C5 paraffins from light naphtha or NGL through depentanizer in the refinery. In yet another embodiment of the present invention, the feed of C5 paraffin used is selected from isopentane, n-pentane and a mixture thereof. In yet another embodiment the catalyst obtained in step (c) is regenerated in-situ by oxidative combustion, for atleast 14 hrs for further catalytical reactions. In yet another embodiment of the present invention, the weight hourly space velocity used in step (d) is in the range of 1.5 to 3 hr"1. In yet another embodiment of the present invention, the reactor temperature used in step (d) is in the range of 360-480°C. In yet another embodiment of the present invention, the reactor pressure used is in the range of 5-20kg/Cm2. In yet another embodiment of the present invention, the silica-to-alumina ratio of ZSM-5 catalyst used is in the range of 10-100 preferably 20-50. In yet another embodiment, the ZSM-5 zeolite used is incorporated into matrix material of synthetic or natural occurring substances such as clay, silica, alumina imparting extra strength to zeolite catalysts. In yet another embodiment, the relative proportion of ZSM-5 with matrix material used on anhydrous basis is ranging between 80-30% by weight. In yet another embodiment, the group III metal ion is incorporated into zeolite catalyst system by known incipient wetness impregnation or ion-exchange method. The present invention provides an improved process for the conversion of C5 hydrocarbon compounds to butane with high yield and selectivity using Ga doped zeolite catalyst. The comparative data of the production of butane from pentane with the prior art citation is herein described. Chen et al described in US patent No. 6,566,569 dated June, 23, 2000 wherein a process for the conversion of C5 paraffins into C4and C6+ product streams over two catalyst zones containing dehydrogenation/hydrogenation component and olefin metathesis components. Where as the present invention utilizes single catalyst component and doesn't require olefin metathesis catalyst. The disadvantage of above process is that it operates at high severity of operating conditions i.e., pressure 2000 psig, Temperature: 290°C, LHSV: 0.5hr~1. Where as in the said patent the process conditions are relatively low ie pressure 140 psig, WHSV: 3.0 hr"1. The yield of C4 obtained at 290°C is 17% where as in the present invention 25% butane yields are obtained at 425°C. The major advantage of this patent over the referred patent is that it operates at low severity of operating conditions and utilizes single catalyst system and yields are relatively high. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. EXAMPLE -1 20 g of MFI type zeolite powder with silica-alumina-ratio 30-40 is mixed with 13.4 g of alumina monohydrate binder (60:40 ratio) on dry weight basis and pugged with 60 ml of 3% Glacial acetic acid solution and left for peptization for 12 hours. Later this material is extruded to 1.2 mm diameter pellets and kept it for room temperature for 12 hours. Finally these extrudates were dried at 120°C for 16 hours. The extruded ZSM-5/Alumina composite is calcined at 540°C in air for about 4 hours to burn off the template molecules and to impart mechanical strength to the extrudates. EXAMPLE - 2 The ZSM-5 extrudates as prepared in example-1 is utilized for incorporation of group IMA metal particularly gallium by impregnation method. The 30 g zeolite extrudates are impregnated with 2.8237 g Gallium nitrate salt (Aldrich) solution ( 2.824 g of gallium nitrate in 15 ml of distilled water) by incipient wetness technique so as to have 2.5 wt-.% Ga loading on Zeolite extrudate. This material is kept it aside for 10 hours with occasional stirring. The above material is dried in oven at 110°C for 12 hours and taken for calcination later. The dried gallium incorporated catalyst is calcined at 500°C for 4 hours in presence of dry air to burnt off the nitrates. The final catalyst will be in the form of Ga2O3 supported on HZSM-5. EXAMPLE - 3 Unlike as discussed in earlier example-2, here Ga incorporation on ZSM-5 carried out by ion exchange method. 25 g of ZSM powder is added to gallium salt solution containing 2.3531 g of Gallium nitrate (Aldrich) in 300 ml distilled water. It is refluxed for 20 hours at 100°C and cool down to ambient temperature. Then it is filtered and washed with 100 ml distilled water and the material is dried at 110°C for 12 hours. 20 g of gallium exchanged HZSM-5 powder is mixed with 13.4 g of alumina monohydrate binder (60:40 ratio) on dry weight basis and pugged with 60 ml of 3% Glacial acetic acid solution and left for peptization for 12 hours. Later this material is extruded to 1.2 mm diameter pellets and kept it for room temperature for 12 hours. Finally these extrudates were dried at 120°C for 16 hours. The extruded ZSM-5/Alumina composite is calcined at 500°C in air. EXAMPLE - 4 Physico-chemical characteristics such as BET surface area, pore volume and pore size distribution of HZSM-5, Ga/HZSM-5 (imp) are determined by Micromeritcs Instruments using argon as adsorbing gas. The results are shown in table-1. Table-1: Physico-chemical characteristics of gallium free and gallium containing catalysts (Table Removed) Reduction in BET surface area, pore volume and pore size distribution is observed upon addition of binder alumina to zeolite. Incorporation of gallium on ZSM-5 zeolite extrudate by impregnation method did not affect its physico-chemical characteristics. EXAMPLE - 5 The number and strength of acid sites of catalyst plays a significant role in activity and product selectivities in paraffin conversion reactions. Very strong acid sites those are present in the catalyst leads to sever cracking and forms dry gas such as methane and ethane to an extent in paraffin conversion reactions, which makes the process economically unviable. Therefore in this patent, optimization of strength of acid sites of zeolites is carried out by incorporating dehydrogenating metal into zeolite composite in order to reduce the number of very strong acid sites in the catalyst. The number of total acid sites and acid strength distribution of HZSM-5, Ga/HZSM-5 (imp) are determined by microcalorimetric adsorption using ammonia as probe molecule at 175°C. Generally the acid sites are arbitrarily divided in to weak (AH100kJ/mol), depending upon energy of interaction of the base probe molecule with the acid sites. The acid sites of various catalyst formulations accounting the above classification are given in Table 2. Table-2: Total acidity and acid strength distribution of gallium free and gallium containing catalysts (Table Removed) mmol/g catalyst As can be seen that the density of strong and medium acid sites are significantly reduced in Zeolite extrudate due to introduction of gallium regardless of mode of incorporation. Gallium oxide addition by incipient wetness impregnation method on ZSM-5 support showed a significant reduction in number of total acid sites (from 0.83 to 0.63 mmol/g) and strong acid sites (from 0.40 to 0.20 mmol/g) as well with increase in number of medium acid sites. Where as exchange of protons of Zeolite with Ga ions carried out with 2.5-wt% Gallium metal salt solution shown decrease in number of strong and medium acid sites with remarkable increase in weak acid sites. The activities of these catalysts are carried out towards n- and i- pentane conversion reactions. EXAMPLE - 6 About 13 g of the catalyst in extruded form of 1.2 mm diameter, length 5-10 mm is loaded in a fixed bed, down flow, high-pressure SS 316 reactor, a-alumina is used as diluent to the catalyst with the ratio of 1: 2.5 by volume. Prior to the test runs, the catalyst is reduced at 500°C under H2 gas flow rate of 10 l/h for 4 hours. Later it is cooled down to 300°C in N2 flow and heated again to desired reaction temperature. Three independently regulated temperature controllers control the temperature of the reaction zone, pre and post heating zones. After attaining the desired process conditions, the nitrogen stream was replaced by pentane feed vapour fed by plunger type feed pump. Reactor effluents are cooled before being fed to high-pressure separator. The feed and C5+liquid product is analyzed using a gas Chromatograph fitted with OV-275, 30% packed column and a 25 mt DB-1 fused silica capillary column while the gaseous (C1-C5) fraction was analyzed by Hewlett Packard gas Chromatograph model 5730 A fitted with a squalene column. In the present invention, the aromatics C9 and above have been reported as C9+ aromatics. This example illustrates the product yields obtained over gallium modified ZSM-5 by impregnation and ion exchange method in iso-pentane reaction are shown in table-3. Table-3: Effect of mode of gallium loading on ZSM-5 catalyst in conversion of iso-pentane to butane Reaction Conditions: (Table Removed) Low yield of dry gas around 4% and remarkable higher yields (25%) of butanes were obtained on Ga incorporated on ZSM-5 by impregnation method along with high octane C5+ liquid yield 43% on feed basis. Where as Ga incorporation by ion exchange method yields very low butane yields with proportionate increase in propane yields and high yields of BTX aromatics in C5+ liquid in iso-pentane conversion reaction. The obtained C5+ liquid exhibits very high RONC 98, which can form an excellent gasoline blending pool. The activity of unpromoted ZSM-5 catalyst shown high yields of undesirable dry gas yields in iso pentane conversion reaction and deactivated very rapidly due to presence of very strong acid sites in the Ga free ZSM-5 catalyst. EXAMPLE - 7 About 13 g of the catalyst in extruded form of is charged in a fixed bed, down flow, high-pressure SS 316 reactor, a-alumina is used as diluent to the catalyst with the ratio of 1: 2.5 by volume. Prior to the test runs, the catalyst is reduced at 500°C under H2 gas flow rate of 10 l/h for 4 hours. Later it is cooled down to 300°C in N2 flow and heated again to desired reaction temperature. After attaining the desired process conditions, the nitrogen stream was replaced by pentane feed vapour fed by plunger type feed pump. The feed and C5+liquid product is analyzed using a gas Chromatograph as described in previous example-6. This example illustrates the product yields obtained over gallium modified ZSM-5 by impregnation and ion exchange method in n-pentane reaction which are shown in table-4. Table-4: Effect of mode of gallium loading on zeolite catalyst in conversion of n-pentane to butane Reaction Conditions: (Table Removed) Undesirable high yields of dry gas observed at 450°C temperature with low yields of butanes with high yields of BTX aromatics. The ex-reactor yields obtained in n-pentane reaction over Ga exchanged HZSM-5 catalyst exhibits 1:1 ratio of butane and aromatics (18% each) with very low dry gas yields (3wt%). EXAMPLE - 8 This example includes the results of the effect of reaction-regeneration cycle on catalytic activity of gallium incorporated ZSM-5 by impregnation method. Pure iso-pentane was used as feed for the study and reaction was carried out at optimized reaction conditions. The deactivated catalyst after three cycles of reaction-regeneration was regenerated by oxidative combustion method under controlled flows of air in inert atmosphere. Table-4: Regenerability of Ga/HZSM-5 zeolite catalyst in conversion of iso-pentane to butane Reaction Conditions: (Table Removed) Table-4 shows the similar yield patterns of butane and liquid products after the regeneration indicating the complete removal of coke lay down during the reaction and reproducibility of the product yield pattern in iso-pentane reaction. The main advantages of the present invention are: 1. The catalyst of the present invention provides most versatile process for the conversion of economically non-viable petroleum feedstocks into value added products 2. The catalyst used in this process is eco-friendly and it does not involve the acid leaching with hazardous mineral acids such as HCI during catalyst preparation. 3. The catalyst is not very sensitive to sulphur compounds and moisture 4. The process is expected to operate in swing mode of operation with multiple fixed bed reactors. 5. The process of the present invention converts surplus C5 paraffin rich feedstocks into butane and high-octane C5+ liquid products. 6. Butanes, can meet the industrial and domestic demands and also as a major component in fuel LPG. 7. High-octane C5+ liquid product a by-product obtained in this process can be used as gasoline blending stock to boost the octane number. 8. Light naphtha, which does not have potential use as conventional reformer feed stock, can be used as a feed in this process. 9. The catalyst used in this process reduces dry gas yields to 4-wt% with increase of high-octane liquid product and thereby improves the economics of this process. 10. The process does not require added hydrogen. 11. The process also does not require use of corrosive organic chloride additives. 12. The process maintains constant production of high-octane gasoline pool by utilization of light naphtha from reformate. 13. It provides as rich resource of reactive molecules, which form the backbone of the synthetic rubber industry and the production of unleaded gasoline. 14. If this process is integrated with a refinery light naphtha or NGL processing plant for butane and high-octane gasoline production, the process is further attractive with less capital investment. 15. In the present invention, preparation of the catalyst for the process does not involve the steps of steaming and acid leaching before the actual catalytic application. The mentioned and claimed catalyst is environmentally friendly as the preparation does not involve the use of hazardous mineral acids, viz., HCI, HNO3 etc. The present invention provides a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. In particular, the present process is useful for the preparation of valuable butane from low value iso-pentane with high yield and selectivity, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of value added low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks.

Full Text

Field of the invention
The present invention relates to a process for the conversion of C5 hydrocarbons into butane.
More specifically, the present invention relates to a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. Hence, in particular, the present process is useful for the preparation of valuable butane from low value iso-pentane, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks.
Background and prior art of the invention
Increasing reformer severity and introducing FCC olefins in motor gasoline did compensate the octane loss due to lead phase out programmes all over the world. However, the restrictions have already been imposed on aromatics and olefins due to their high photochemical activities. Now the attention is to reduce the vapour pressure of motor gasoline, which has already restricted C4 hydrocarbons from gasoline pool, and C5 hydrocarbons are under close observation due to their higher Reid Vapor Pressure(RVP) values. The advantage of increased octane with iso-pentane will be limited for its high vapour pressure while amylens will be restricted for high photochemical activities. Therefore blending of iso pentane into gasoline pool beyond a certain limit is not acceptable due to its high RVP.
Light naphtha and natural gas liquids (NGL) are of the least viable petroleum feed stocks treated today. These feedstocks primarily consist of C5-C6 paraffins rich of normal and iso-pentanes. The projected production of NGL (1996-97) indicates that India produces 2.25 MMTA from various gas fields (Sharma, R.L. et al, Chem. Eng. World 1994, 29(10) 171. These feedstocks are filing up in refineries and the situation calls an immediate need for the valorization of these into butane and propane is an attractive proposition. The co-product, high-octane gasoline can be used as a gasoline volume builder.

Thus, the this process stands relevant by addressing the light paraffin utilization on one hand and the production of butane along with high-octane low-benzene content gasoline on the other.
In addition to this, the demand for LPG is also growing much faster in India at growth rate of 14 percent per year and there will be continuous shortage of LPG in India. The production of LPG in the year 1999-2000 was 2.487 MMT with consumption of 8.029 MMT with a corresponding deficit of 5.542 MMT (Ministry of Petroleum and Natural gas "Report on basic statistics in Petroleum Products in India 2001). This disparity between LPG production and consumption patterns may expect to increase further by 2010-11due to increase in use of LPG in domestic and automobile sector. Therefore the major concern of Indian refinery would be to have secondary refinery process to increase the production of butanes, propane.
C4 streams generally come from a number of sources, but they are mainly found as co-product from steam cracking processes that produce ethylene. And as a co-product stream from FCC, distillation units and from the NGL as well. The availability of butane from the said sources is very less in compared to propane. One of the major uses for the butane stream is in rubber production. In Asia petrochemical companies are planning new complexes and developing new C4 strategies, to take the advantage of the need for synthetic rubber feedstocks. This comes in light of an increased demand for rubber in Asia as the automotive and allied industries continue to expand. On the other hand, butane production either from refineries or from gas fields is not enough to meet the demands. The import situation is also not encouraging, as only a few private entrepreneurs have actually created facilities for import market. Thus, there is a considerable incentive for conversion of these low value feed stocks to high value products such as butane and aromatics. Similarly, conversion of other unconventional feedstocks such as natural gas liquids and raffinates into butane, propane and gasoline and LPG also gains significant importance in this scenario.

It is proposed here that the surplus light naphtha or NGL can send to depentanizer column and the obtained C5 hydrocarbons led to disproportionation reactor to yield value added butane product. Disproportionation of paraffins is a well-known reaction step in the isomerization of n-paraffins to i-paraffins during petroleum refining. The general object of this invention is to provide process for production of butanes from pentane feedstocks. As mentioned by way of introduction, isoparaffins including isopentane are presently preferred components in high-octane gasoline products. However, recent requirements to lower vapour pressure of gasoline, makes it necessary to substitute isoparaffins having a high vapour pressure of gasoline with components of low vapour pressure in gasoline. There is an incentive to convert isopentanes to higher isoparaffins, such as, isohexanes which is a low vapour pressure motor fuel component and to butanes, which is a preferred feedstock for alkylation processes for the production of high octane alkylate gasoline and methyl tertiary-butyl ether(MTBE); hence it is desirable to obtain the above substitution of isopentane in gasoline.
It has now been found that a strong acid catalyzes conversion of isopentane, and the reaction is further promoted by the presence of olefins or higher paraffins, which crack to olefins by influence of a strong acid. Zeolite catalysts have become widely used in the processing of petroleum and in the production of various petrochemicals. Reactions such as cracking, alkyaltion, polymerization, isomerization, trans alkylation, addition, dewaxing, disproportionation and other acid catalyzed reactions may be performed with use of these catalysts. Zeolites are porous crystalline aluminosilicates having definite crystalline structure as determined by X-ray diffraction studies whose preparation was first described in U.S. Pat.No. 3, 702, 886. Such zeolites have pores of uniform size that are uniquely determined by unit structure of the crystal. The zeolites are referred as "molecular sieves" because interconnecting channel systems created by pores of uniform size allow a zeolite to selectively absorb molecules of certain dimensions and shapes.

Zeolites may be classified by pore size, ZSM-5 is a member of class of zeolites some times referred as medium pore zeolites and its pore size ranges from 5 to 7 angstroms. Because of its high protonic acidity and unique shape selective behavior, ZSM-5 zeolite has been proved to be a highly active and stable catalyst for hydrocarbon conversion processes e.g. oligomerization at low temperature and high pressures and aromatization at higher temperatures and lower pressures of light olefins. ZSM-5 zeolites modified with zinc or gallium have been reported as catalysts for the conversion of lower paraffins into BTX (Ref: E. E. Davis and A.J. Kolombos, Br. Pat., 1 561 590, 1976).
Various modifications and pretreatments of zeolite catalyst have resulted in improvement in light hydrocarbon conversion and aromatic selectivity, though often one has been achieved to the slight detriment of the other. Gallium containing zeolites for catalysis particularly for catalysis of light paraffin aromatization, have received great attention recently. Different formulations of such catalysts have included catalysts prepared by ion exchange, by impregnation of ZSM-5 with gallium salts. The zeolites described in this patent is ZSM-5 promoted with Group IIIA metal such as Ga, In, Tl for conversion of iso-pentane to butane and low aromatic content high-octane gasoline.
There are reports in the literature on the conversion of C5 paraffins into butanes and aromatics utilizing zeolites and metal-modified zeolites as catalyst but all of them suffer from disadvantages in some or more ways.
Reference may be made to a process developed by Atlantic Richfield Company researchers (U.S. Pat. 3,953,537) wherein a process for disproportionating a paraffinic hydrocarbon containing 2 to 6 carbon atoms to produce compounds containing one more and one less carbon fragments over calcium exchanged Y zeolite catalyst containing sodium aluminosilicate.
Another reference may be made to (U.S.Pat. 4,686,316) wherein method of producing butanes from propane by contacting with ZSM-5 type zeolite catalyst having silica-to-alumina ratio of at least 12.

Another reference may be made to (Hydrocarbon Processing Sept., 1989 p 72) wherein a process developed jointly by UOP Inc. and British Petroleum, based on gallium doped zeolite catalyst has been reported. In this process LPG was converted into BTX aromatics and the process has been demonstrated in a large-scale pilot plant of the British Petroleum Grangemouth refinery in Scotland.
Another reference may be made to (U. S. Pat. 5, 763, 727) wherein a process developed by Mobil Oil Company, based on fluidized bed reactor to produce propane from CA normal and iso paraffins on Pt-Sn /ZSM-5 catalyst.
Yet another reference may be made to (US patent 5,026,938 dated 25th June' 1991) wherein a process for converting a gaseous feed stock containing C3-C5 paraffins into aromatics hydrocarbons by contacting the feed with gallosilicate molecular sieve catalyst has been described.
The draw back of all these processes is that these are mainly related to the production of propane from C4 paraffins and aromatics from C3 - C5 range paraffins which are in high demand as LPG in India.
Still another reference may be made to Chevron U.S.A Inc. (U.S. Pat No. 6, 566, 569), wherein the combination of dehydrogenation/hydrogenation catalyst (Pt/Alumina) and olefin metathesis catalyst (WO3/Silica) used for conversion of C5 paraffins into C4 and C6 paraffins. The limitation of the above process is it utilizes mixture of two catalyst formulations and homogeneity of active sites may not be achieved and it produces only 12% butanes form iso-pentane as feedstock.
Still another reference may be made to (US patent No. 4,861,934 dated Aug, 29, 1989) wherein a process for the conversion of light hydrocarbon containing C2-C7 paraffins and C2-C7 olifins to high-octane gasoline using aluminogallosilicate has been reported. The disadvantage of above process is

that it operates at high severity of operating conditions i.e., Temperature: 540°C, LHSV: 1hr'1.
Still another reference may be made to (US patent No. 4, 579, 987 dated Apr. 1, 1986) wherein a process for the preparation of conversion of C2+ olefins, C2-C7 paraffins or a mixture thereof to C5+ hydrocarbons over high silica zeolite has been reported. The limitation of this process is that it utilizes the treatment of AIF3 on zeolite in catalyst preparation steps.
Still another reference may be made to Haldor Topse A/S (US patent No. 5, 900, 522 dated May 4, 1999) wherein a process for the preparation of an isobutene/isohexane containing product from disproportionating the iso-pentane over an acid catalyst with the acidity H0 > 8. has been reported. The limitation of this process is that it utilizes the treatment of AIF3 on zeolite in catalyst preparation steps.
Still another reference may be made to (US patent No. 6, 423, 880 dated July, 2002 and US Pat. No. 6, 573, 416 dated June 3, 2003) wherein a processes for disproportionating isoparaffins and paraffins in the presence of at least one initiator was disclosed. The product from the disproportionation contains a gasoline range material having high-octane rating than the isoparaffins and paraffins in the feed. The major disadvantage of this process is that it utilizes hydrofluoric acid/polyfluoroalkane sulfonic acid as the catalyst.
The above processes are mainly utilizing broad range hydrocarbons and for production of aromatics. In addition to this high quantity of dry gas yields are formed during the reaction, which will be a loss to the economy of the process. Further the added hydrogen gas is used in this process, which in turn increases the overall cost of the process. Objects of the invention
The main object of the present invention is to provide a process for the conversion of C5 hydrocarbons into butane which obviates the drawbacks as detailed above.

Another object of the present invention is to provide a process for conversion of isopentane into butane and high-octane low aromatic content C6+ hydrocarbons by using dehydrogenating metal ion doped zeolite catalyst.
Still another object of the present invention is to provide a process for the conversion of n-pentane into butane, propane and high-octane low aromatic content C6+ hydrocarbons.
Yet another object of present invention is to provide a process that produces butane, propane with low yields of low cost dry gas (C1+C2) from C5 paraffins.
Yet another object of present invention is to provide s process, which is economical and environmentally acceptable.
Summary of the invention
Accordingly, the present invention provides a process for the conversion of C5 hydrocarbons into butane comprising the steps of:
a) loading Group III metal ion supported HZSM-5 catalyst in a fix bed,
b) reducing the above said catalyst at a temperature of about 400-550°C
under H2 gas, at a flow rate of about 10 l/h for a period of 2-5 hrs in a
reactor followed by cooling to a temperature of about 300°C, under
nitrogen atmosphere,
c) further increasing the temperature of the above said catalyst obtained in
step (b) to a temperature in the range of 300-600°C,
d) contacting the feed vapours of C5 paraffins with the above said catalyst
bed obtained in step (c) in a reactor, at a weight hourly space velocity
ranging from of 1 to 8 hrs"1, at a temperature ranging between 300-
600°C, at a pressure of 1 to 20 kg/Cm2, for a period of atleast 24 hours
in the absence of hydrogen gas to obtain the desired butane and high
octane C5+ liquid,
e) separating the butane, C5+ liquid and other products of the resultant
reaction mixture obtained in step (d) by known method to obtain the
desired C4 butane.
In an embodiment of the present invention, the group III metal ion used in step (a) is selected from Ga, In, and Tl.

In another embodiment of the present invention, the amount of Group III metal present in the modified zeolite catalyst is in the range of 0.5 to 5% (w/w).
In yet another embodiment of the present invention, the the feedstock used is C5 paraffins from light naphtha or NGL through depentanizer in the refinery.
In yet another embodiment of the present invention, the feed of C5 paraffin used is selected from isopentane, n-pentane and a mixture thereof.
In yet another embodiment the catalyst obtained in step (c) is regenerated in-situ by oxidative combustion, for atleast 14 hrs for further catalytical reactions.
In yet another embodiment of the present invention, the weight hourly space velocity used in step (d) is in the range of 1.5 to 3 hr"1.
In yet another embodiment of the present invention, the reactor temperature used in step (d) is in the range of 360-480°C.
In yet another embodiment of the present invention, the reactor pressure used is in the range of 5-20kg/Cm2.
In yet another embodiment of the present invention, the silica-to-alumina ratio of ZSM-5 catalyst used is in the range of 10-100 preferably 20-50.
In yet another embodiment, the ZSM-5 zeolite used is incorporated into matrix material of synthetic or natural occurring substances such as clay, silica, alumina imparting extra strength to zeolite catalysts.
In yet another embodiment, the relative proportion of ZSM-5 with matrix material used on anhydrous basis is ranging between 80-30% by weight.
In yet another embodiment, the group III metal ion is incorporated into zeolite catalyst system by known incipient wetness impregnation or ion-exchange method.
The present invention provides an improved process for the conversion of C5 hydrocarbon compounds to butane with high yield and selectivity using Ga doped zeolite catalyst. The comparative data of the production of butane from pentane with the prior art citation is herein described.
Chen et al described in US patent No. 6,566,569 dated June, 23, 2000 wherein a process for the conversion of C5 paraffins into C4and C6+ product

streams over two catalyst zones containing dehydrogenation/hydrogenation component and olefin metathesis components. Where as the present invention utilizes single catalyst component and doesn't require olefin metathesis catalyst. The disadvantage of above process is that it operates at high severity of operating conditions i.e., pressure 2000 psig, Temperature: 290°C, LHSV: 0.5hr~1. Where as in the said patent the process conditions are relatively low ie pressure 140 psig, WHSV: 3.0 hr"1. The yield of C4 obtained at 290°C is 17% where as in the present invention 25% butane yields are obtained at 425°C. The major advantage of this patent over the referred patent is that it operates at low severity of operating conditions and utilizes single catalyst system and yields are relatively high.
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
EXAMPLE -1
20 g of MFI type zeolite powder with silica-alumina-ratio 30-40 is mixed with 13.4 g of alumina monohydrate binder (60:40 ratio) on dry weight basis and pugged with 60 ml of 3% Glacial acetic acid solution and left for peptization for 12 hours. Later this material is extruded to 1.2 mm diameter pellets and kept it for room temperature for 12 hours. Finally these extrudates were dried at 120°C for 16 hours. The extruded ZSM-5/Alumina composite is calcined at 540°C in air for about 4 hours to burn off the template molecules and to impart mechanical strength to the extrudates.
EXAMPLE - 2
The ZSM-5 extrudates as prepared in example-1 is utilized for incorporation of group IMA metal particularly gallium by impregnation method. The 30 g zeolite extrudates are impregnated with 2.8237 g Gallium nitrate salt (Aldrich) solution ( 2.824 g of gallium nitrate in 15 ml of distilled water) by incipient wetness technique so as to have 2.5 wt-.% Ga loading on Zeolite extrudate. This material is kept it aside for 10 hours with occasional stirring. The above material is dried in oven at 110°C for 12 hours and taken for calcination later.

The dried gallium incorporated catalyst is calcined at 500°C for 4 hours in presence of dry air to burnt off the nitrates. The final catalyst will be in the form of Ga2O3 supported on HZSM-5.
EXAMPLE - 3
Unlike as discussed in earlier example-2, here Ga incorporation on ZSM-5 carried out by ion exchange method. 25 g of ZSM powder is added to gallium salt solution containing 2.3531 g of Gallium nitrate (Aldrich) in 300 ml distilled water. It is refluxed for 20 hours at 100°C and cool down to ambient temperature. Then it is filtered and washed with 100 ml distilled water and the material is dried at 110°C for 12 hours.
20 g of gallium exchanged HZSM-5 powder is mixed with 13.4 g of alumina monohydrate binder (60:40 ratio) on dry weight basis and pugged with 60 ml of 3% Glacial acetic acid solution and left for peptization for 12 hours. Later this material is extruded to 1.2 mm diameter pellets and kept it for room temperature for 12 hours. Finally these extrudates were dried at 120°C for 16 hours. The extruded ZSM-5/Alumina composite is calcined at 500°C in air.
EXAMPLE - 4
Physico-chemical characteristics such as BET surface area, pore volume and pore size distribution of HZSM-5, Ga/HZSM-5 (imp) are determined by Micromeritcs Instruments using argon as adsorbing gas. The results are shown in table-1.
Table-1: Physico-chemical characteristics of gallium free and gallium containing catalysts

(Table Removed)
Reduction in BET surface area, pore volume and pore size distribution is observed upon addition of binder alumina to zeolite. Incorporation of gallium on ZSM-5 zeolite extrudate by impregnation method did not affect its physico-chemical characteristics.
EXAMPLE - 5
The number and strength of acid sites of catalyst plays a significant role in activity and product selectivities in paraffin conversion reactions. Very strong acid sites those are present in the catalyst leads to sever cracking and forms dry gas such as methane and ethane to an extent in paraffin conversion reactions, which makes the process economically unviable. Therefore in this patent, optimization of strength of acid sites of zeolites is carried out by incorporating dehydrogenating metal into zeolite composite in order to reduce the number of very strong acid sites in the catalyst. The number of total acid sites and acid strength distribution of HZSM-5, Ga/HZSM-5 (imp) are determined by microcalorimetric adsorption using ammonia as probe molecule at 175°C. Generally the acid sites are arbitrarily divided in to weak (AH100kJ/mol),
depending upon energy of interaction of the base probe molecule with the acid sites. The acid sites of various catalyst formulations accounting the above classification are given in Table 2.
Table-2: Total acidity and acid strength distribution of gallium free and gallium containing catalysts

(Table Removed)

mmol/g catalyst
As can be seen that the density of strong and medium acid sites are significantly reduced in Zeolite extrudate due to introduction of gallium regardless of mode of incorporation. Gallium oxide addition by incipient wetness impregnation method on ZSM-5 support showed a significant reduction in number of total acid sites (from 0.83 to 0.63 mmol/g) and strong acid sites (from 0.40 to 0.20 mmol/g) as well with increase in number of medium acid sites. Where as exchange of protons of Zeolite with Ga ions carried out with 2.5-wt% Gallium metal salt solution shown decrease in number of strong and medium acid sites with remarkable increase in weak acid sites. The activities of these catalysts are carried out towards n- and i- pentane conversion reactions.
EXAMPLE - 6
About 13 g of the catalyst in extruded form of 1.2 mm diameter, length 5-10 mm is loaded in a fixed bed, down flow, high-pressure SS 316 reactor, a-alumina is used as diluent to the catalyst with the ratio of 1: 2.5 by volume. Prior to the test runs, the catalyst is reduced at 500°C under H2 gas flow rate of 10 l/h for 4 hours. Later it is cooled down to 300°C in N2 flow and heated again to desired reaction temperature. Three independently regulated temperature controllers control the temperature of the reaction zone, pre and post heating zones. After attaining the desired process conditions, the nitrogen stream was
replaced by pentane feed vapour fed by plunger type feed pump. Reactor effluents are cooled before being fed to high-pressure separator. The feed and C5+liquid product is analyzed using a gas Chromatograph fitted with OV-275, 30% packed column and a 25 mt DB-1 fused silica capillary column while the gaseous (C1-C5) fraction was analyzed by Hewlett Packard gas Chromatograph model 5730 A fitted with a squalene column. In the present invention, the aromatics C9 and above have been reported as C9+ aromatics. This example illustrates the product yields obtained over gallium modified ZSM-5 by impregnation and ion exchange method in iso-pentane reaction are shown in table-3.
Table-3: Effect of mode of gallium loading on ZSM-5 catalyst in conversion of iso-pentane to butane Reaction Conditions:
(Table Removed)
Low yield of dry gas around 4% and remarkable higher yields (25%) of butanes were obtained on Ga incorporated on ZSM-5 by impregnation method along with high octane C5+ liquid yield 43% on feed basis. Where as Ga incorporation by ion exchange method yields very low butane yields with proportionate increase in propane yields and high yields of BTX aromatics in C5+ liquid in iso-pentane conversion reaction. The obtained C5+ liquid exhibits very high RONC 98, which can form an excellent gasoline blending pool. The activity of unpromoted ZSM-5 catalyst shown high yields of undesirable dry gas yields in iso pentane conversion reaction and deactivated very rapidly due to presence of very strong acid sites in the Ga free ZSM-5 catalyst.
EXAMPLE - 7
About 13 g of the catalyst in extruded form of is charged in a fixed bed, down flow, high-pressure SS 316 reactor, a-alumina is used as diluent to the catalyst with the ratio of 1: 2.5 by volume. Prior to the test runs, the catalyst is reduced at 500°C under H2 gas flow rate of 10 l/h for 4 hours. Later it is cooled down to 300°C in N2 flow and heated again to desired reaction temperature. After attaining the desired process conditions, the nitrogen stream was replaced by pentane feed vapour fed by plunger type feed pump. The feed and C5+liquid product is analyzed using a gas Chromatograph as described in previous example-6. This example illustrates the product yields obtained over gallium modified ZSM-5 by impregnation and ion exchange method in n-pentane reaction which are shown in table-4.
Table-4: Effect of mode of gallium loading on zeolite catalyst in conversion of n-pentane to butane Reaction Conditions:
(Table Removed)
Undesirable high yields of dry gas observed at 450°C temperature with low yields of butanes with high yields of BTX aromatics. The ex-reactor yields obtained in n-pentane reaction over Ga exchanged HZSM-5 catalyst exhibits 1:1 ratio of butane and aromatics (18% each) with very low dry gas yields (3wt%).
EXAMPLE - 8
This example includes the results of the effect of reaction-regeneration cycle
on catalytic activity of gallium incorporated ZSM-5 by impregnation method.
Pure iso-pentane was used as feed for the study and reaction was carried out
at optimized reaction conditions. The deactivated catalyst after three cycles of
reaction-regeneration was regenerated by oxidative combustion method under
controlled flows of air in inert atmosphere.
Table-4: Regenerability of Ga/HZSM-5 zeolite catalyst in conversion of
iso-pentane to butane
Reaction Conditions:
(Table Removed)
Table-4 shows the similar yield patterns of butane and liquid products after the regeneration indicating the complete removal of coke lay down during the reaction and reproducibility of the product yield pattern in iso-pentane reaction.
The main advantages of the present invention are:
1. The catalyst of the present invention provides most versatile process for the
conversion of economically non-viable petroleum feedstocks into value
added products
2. The catalyst used in this process is eco-friendly and it does not involve the
acid leaching with hazardous mineral acids such as HCI during catalyst
preparation.
3. The catalyst is not very sensitive to sulphur compounds and moisture
4. The process is expected to operate in swing mode of operation with
multiple fixed bed reactors.
5. The process of the present invention converts surplus C5 paraffin rich
feedstocks into butane and high-octane C5+ liquid products.
6. Butanes, can meet the industrial and domestic demands and also as a
major component in fuel LPG.
7. High-octane C5+ liquid product a by-product obtained in this process can be
used as gasoline blending stock to boost the octane number.
8. Light naphtha, which does not have potential use as conventional reformer
feed stock, can be used as a feed in this process.
9. The catalyst used in this process reduces dry gas yields to 4-wt% with
increase of high-octane liquid product and thereby improves the economics
of this process.

10. The process does not require added hydrogen.
11. The process also does not require use of corrosive organic chloride
additives.
12. The process maintains constant production of high-octane gasoline pool
by utilization of light naphtha from reformate.
13. It provides as rich resource of reactive molecules, which form the
backbone of the synthetic rubber industry and the production of unleaded
gasoline.
14. If this process is integrated with a refinery light naphtha or NGL processing
plant for butane and high-octane gasoline production, the process is further
attractive with less capital investment.
15. In the present invention, preparation of the catalyst for the process does not
involve the steps of steaming and acid leaching before the actual catalytic
application. The mentioned and claimed catalyst is environmentally friendly
as the preparation does not involve the use of hazardous mineral acids,
viz., HCI, HNO3 etc.

The present invention provides a process for the conversion of C5 hydrocarbons into butane by using a catalyst consisting of a porous crystalline synthetic material constituted by silicon, gallium and aluminium oxides. The said material is given the name gallium-aluminosilicate or Ga-HZSM-5 molecular sieve catalyst. In particular, the present process is useful for the preparation of valuable butane from low value iso-pentane with high yield and selectivity, which can be used as petrochemical feed stocks or domestic fuel (LPG). In addition to butane, some amount of value added low benzene content C5+ liquid by-product are also obtained which can be used as gasoline blending stocks.

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Patent Number

279528

Indian Patent Application Number

853/DEL/2006

PG Journal Number

04/2017

Publication Date

27-Jan-2017

Grant Date

24-Jan-2017

Date of Filing

28-Mar-2006

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	PERUPOGU VIJAYANAND	INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR, DEHRADUN 248005, UTTRANCHAL, INDIA.
2	GUPTA JAI KRISHAN	INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR, DEHRADUN 248005, UTTRANCHAL, INDIA.
3	GARG MADHUKAR ONKARNATH	INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR, DEHRADUN 248005, UTTRANCHAL, INDIA.
4	MANOJ KUMAR	INDIAN INSTITUTE OF PETROLEUM, MOHKAMPUR, DEHRADUN 248005, UTTRANCHAL, INDIA.

PCT International Classification Number

B01J 29/87

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA