Title of Invention

AN IMPROVED PROCESS FOR PREPARATION OF CRYSTALLINE SAPO -11 TYPE NON-ZEOLITIC MOLECULAR SIEVE

Abstract

This invention relates to an improved process for preparation of crystalline SAPO-II type Non-Zeolitic Molecular Sieve comprising in the step of subjecting a reaction mixture wherein reaction mixture is prepared by adding phosphoric acid to an organic templating agent .containing carbon & nitrogen and aluminium isopr9poxide having an H<SUB>2</SUB>0/ AI<SUB>2</SUB>0<SUB>3</SUB> molar ratio of greater than 20, a reactive silicon dioxide having an average particle size of 10 to 30 nanometers, a sodium content of less than 0.03 wt% and bulk density of less than 0.1 g/ cc, said reaction mixture having a composition expressed in terms of mole ratios of (0.5-1.5) R : AI<SUB>2</SUB>0<SUB>3</SUB>: (0.1-1.0) SiO<SUB>2</SUB> : (0.9-1.2) P<SUB>2</SUB>0<SUB>5</SUB> : 20-100 H<SUB>2</SUB>O to under crystallisation condition until crystals of non-zeolitic sieve are formed.

Full Text

FIELD OF INVENTION This invention relates to an improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve. It is more particularly relates to a method of producing non-Zeolitic molecular sieves (NZMS) at reduced crystallization time and temperatures. The non-zeolitic molecular sieves of the present invention are highly crystalline, three dimensional microporous framework structures of tetrahedrally bound AI02 (-) and P02 (+) oxide units and optionally one or more metals in tetrahedral co-ordination with oxygen atoms. The crystalline aluminophosphate-type materials, which are prepared by the present process, are useful, inter alia, for a number of catalytic conversion processes, including dewaxing, isomerization, hydroisomerization, hydrocracking and hydrogenation etc. BACKGROUND OF THE INVENTION Molecular sieves belong to a commercially important class of frameworks with ordered pore structures, which are demonstrated by distinct x-ray diffraction patterns. The crystal structure defines cavities and pores which are characteristic of the different specifies. Natural and synthetic molecular sieves are useful as adsorbents and catalyst. The adsorptive and catalytic properties of each molecular sieve are determined in part by the dimentions of its pores and cavities. Thus, the utility of a particular application depends at least partly on its crystal structure. In the prior art the conventional preparation of the non-Zeolite molecular sieves essentially involve high reaction-temperatures upto about 190° -225°C (Patent WO 97/17291, 1977; U.S. Patent 4 943 424, 1990; WO 91/13132, 1991-etc.) and thereby causing to develop higher operating autogenous pressure of the order of 25 kg/cm2 and above, during the crystallization process. In order to overcome these operational problems the present invention is directed to an improved low temperature synthesis process involving cheaper raw material sources. OBJECTS OF THE INVENTION It is therefore, an object of the present invention to provide an improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve which is prepared at lower operational temperatures and pressures using reagents which are less expensive than those used in the conventional preparation methods. A further object of the present invention to provide an improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve using particulate silica such as Si02. XH2O as the silica source. Yet a further object of the present invention to provide an improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve at reduced manufacturing cost and with simplified operation. DETAILED DESCRIPTION OF THE INVENTION According to this invention there is provided an improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve comprising in the step of subjecting a reaction mixture wherein reaction mixture is prepared by adding phosphoric acid to an organic templating agent containing carbon & nitrogen and aluminium isopropoxide having an H2O/AI2O3 molar ratio of greater than 20, a reactive silicon dioxide having an average particle size of 10 to 30 nanometers, a sodium content of less than 0.03 wt% and bulk density of less than 0.1 g/cc, said reaction mixture having a composition expressed in terms of mole ratios of (0.5-1.5) R: AI2O3: (0.1-1.0) SiO2 : (0.9-1.2) P2O5 : 20-100 H2O to under crystallisation condition until crystals of non-zeolitic molecular sieve are formed, Non-zeolite molecular sieves include aluminophosphates (AIPO4) silicoaluminophosphate (SAPO), Metaloaluminophosphates (MeAPO) and nonmetal-substituted aluminophosphates (EIAPO). The preferred non-Zeolite molecular sieve prepared as described herein is an intermediate pore silicoaluminophosphate or SAPO. More preferred SAPO's include SAPO-11, SAPO-31, SAPO-41. A still more preferred intermediated pore isomerization silicoaluminophossphate molecular sieve prepared in the present process is SAPO-11, which has a crystalline structure falling within that of SAPO-11 molecular sieves. As used herein, the term "non-zeolite molecular sieve^ and its abbreviation "NZMS" will be used interchangeably. By "intermediate pore size" as used herein, is meant an effective pore aperature in the range of about 5.3 to about 6.5 Angstroms when the molecular sieve is in the calcined form. The effective pore size can be measured using standard adsorption techniques and hydrocarbon compounds of known kinetic diameters (see Breck D.W.,Zeolite Molecular Sieves 1974 Ch.8) Intermediate pore size molecular sieves will typically admit molecules having kinetic diameters of 5.3 to 6.5 Angstroms with little hindrance. Examples of such compounds (and their Kinetic diameters in Angstroms) are :n-hexene (4.3), 3-methylpentane (5.5), Benzene (5.85), and Toluene (5.8). Compounds having kinetic diameters of about 6.0 to 6.5 Angstroms can be admitted into the pore depending on the particular sieve, but do not penetrate as quickly and in some cases are effectively excluded. Compounds having kinetic diameters in the range 6.0 to 6.5 Angstroms include: Cyclohexane (6.0), 2-3 dimethylbutane (6.1), and m-xylene (6.1). Generally, compounds having kintetic diameters of greater than 6.5 Angstroms do not penetrate and thus are not absorbed into the interior of the molecular sieve lattice. Examples of such larger compounds include: O-xylene (6.8) hexamethylbenzene (7.1), and tributylamine (8.1). The preferred effective pore size range is from about 5.5 to about 6.2 Angstroms. The non-zeolitic molecular sieve (NZMS) prepared using process of this invention is characterized by a three dimensional microporous framework structure of AIO2 and PO2 tetrahedral oxide units with a unit empirical formula on anhydrous basis of (Mx Aly Pz) O2 Wherein: "M" represents atleast one element, other than aluminium and phosphorous, which is capable of forming an oxide in tetrahedral coordination with AI02 and P02 Oxide structural units in the crystalline molecular sieve; and "x" "y" and 'z" represent the mole fractions, respectively, of elements "M", aluminium and phosphours, wherein "x" has a value equal to or greater than zero (O), and "y and "z" each have a value of at least 0.01. In preferred embodiment, metallic elements "M" is selected from the group of arsenic, boron, chromium, gallium, germanium, iron, nickel. Zinc, more preferably selected from the group consisting of Silicon, magnesium. Zinc and Cobalt, and still more preferably Silicon dioxide (SiO2/silicon). While the unit emphirical formula represented above is on an anhydrous basis, the non-zeolitic molecular sieve as prepared herein may exist in any state or degree of hydration. It will be clear to one skilled in the art from the present disclosure that the non-zeolitic molecular sieve formed in the reaction mixture may be hydrated to some degree depending on the synthesis materials used and on the amount of heat treatment applied to the crystalline molecular sieve. Both hydrated as well as anhydrous non-zeolitic molecular sieve are within the scope of the present invention. In preparing the non-zeolitic molecular sieve according to the present invention, an organic templating agent, also known as a structure-directing agent, is generally added to the reaction mixture to facilitate crystallization of the molecular sieve. Organic templating agents can be selected from those known to be effective in the synthesis of crystalline molecular sieve and crystalline zeolites. Some of the Patent data discloses examples of templating agents include U.S.PatentNos.4,710, 485; 4,310, 440;4, 686, 093 etc. In general, the templating agents useful in the present invention contain elements of group VA of periodic table of elements, particularly nitrogen, phosphorous, preferably nitrogen or phosphorous and most preferably nitrogen. Particularly preferred nitrogen - containing compounds for use as templating agents are the amines and quaternary ammonium compounds, the latter being represented by the formula R4 N+ wherein R is an alkyl or aryl group containing from 1 to 8 carbon atoms. Both mono-di-and triamines are advantageously utilized, either alone or in combination with a quaternary compound or other templating compound. Mixtures of two or more templating agents can either produce mixtures of desired non-zeolitic molecular sieves or the more strongly directing templating species may control the course of the reaction with the other templating species serving primarily to establish the pH conditions of the reaction gel. Representative templating agents include tetramethylammonium, tetraethylammonium, tripropylamine, trithylamine, triethanolamine, di-n-butylamine, di-n-propylamine, diisopropylmine neopentylamine, di-n-pentylamine, ethylenediamine etc. Not every templating agent will direct the formation of every species of non-zeolitic molecular sieve i.e., a single templating agent can, with proper manipulation of the reaction conditions, direct the formation of several non-zeolitic molecular sieve compositions, and a given non-zeolitic molecular sieve composition can be produced using several different templating agents. In the preparation of the non-zeolitic molecular sieve, phosphoric acid is the preferred source of phosphorous. Organic phosphates and a crystalline aluminophosphate can also be employed as a source of phosphorous. Silica sol or fummed silica, silica gel, silicon dioxide or reactive solid amorphous silica are also suitable sources of silica. A more preferred method for according to the instant process comprises. (A) Preparing an aqueous reaction mixture containing phosphoric acid, a reactive source of alumina alkoxide, an organic templating agent and a particulate hydrated silica having an average particle size of less than 15 manometers, a particle bulk density of about 0.05 g/cc and alkali content of less than 0.03 wt%, said reaction mixture having a composition express in terms of mole ratios of (0.5-1.5) R: AI2O3 : (0.9-1.2) P2O5: (0.1-0.9) SiO2 : 20-100 H2O. said reaction mixture having being formed by combining the alumina and phosphorous sources in the substantial absence of the silicon source and thereafter combining the resulting mixture with silicon source and the organic templating agents to form the complete reaction mixture; (b) Heating the complete reaction mixture under mile agitation at autogenous pressure to a temperature in the range of form 80°C to 120°C for at least 24 hours. (c) Continue heating the same reaction mixture further to a temperature in stepwise mode in the range of form 120°C to 170° C until crystals of the non-zeolitic molecular sieve are formed; and (d) Recovering solid crystals. In the preparation of the reaction mixture in which the NZMS in formed, a chilled water (4° -5°C) is added under ice-bath to alumina alkoxide powder to facilitate suppressing an exothermicity of the mixture. In one embodiment, the molar ratio of water to alumina in the above mixture is in the range of from about 20 to about 30, preferably from about 25 to 28. In this embodiment, sufficient water is added so that the reaction mixture may be formed into self-supporting particles. In a separate emodiment, an aqueous reaction mixture is prepared containing active sources of the NZMS, including sources of alumina, phosphorous and silica to be incorporated into the crystalline molecular sieve. Frequently, a templating agent will also be present. The amount of water added to the reaction mixture in this emodiment is generally less than about 200 moles of water per mole of alumina, preferably from about 20 to about 120, more preferably from about 30 to about 50, moles of water per mole of alumina. Adding the Silicon (as Silicon dioxide) component after mixing well the aluminium and phosphorus components results in high purity NZMS type material. The NZMS - Silicoaluminophosphate is prepared at low pH, in the range of from about 4.0 to about 8.5 and preferably from 5.0-6.8, and an H2O/AI2O3 mole ratio of about 20 to 100 and preferably 30 to 50. Under these conditions, SiO2 depolymerization is slow and nucleaction is rapid. Crystallisation under the reaction conditions of this invention is generally completed in less than 30 to 40 hours. While not intending to be limited to theory, it appears SiO2 does not enter the structure until late in crystallization such that under the conditions of the process of this invention, in the early phases of the reaction, there is produced a near aluminophosphate phase surrounded by SiO2 -rich amorphous phase. As P04-3 is depleted by reaction with Al3+Species, the pH of the mixture rises to about 9.0 to about 9.5. This increases the dissolution of SiO2 permitting Silica Incorporation into the structure such that a silicoalumophosphat shell forms around the aluminophosphate core. From a microscopic point of view, the sieve could almost be considered a crystalline aluminophosphate, since the P2O5 to AI2O3 mole ration within the bulk of the NZMS is 0.8 or greater and preferably 0.8 to 1.2. By controlling the pH and the H2O/AI2O3 ratio of the mix, the thickness of NZMS shell can be adjusted. One way to reduce thickness, for example, is by adding additional H3P04to mix. This will hold down the final pH i.e., control the acidity, so that Si is not incorporated until the very end of the crystallization step. If necessary, the pH can be lowered into the proper region using mineral acids such as HCI or H3PO4. The latter may be preferred, since having a slight excess of P04-3 will help ensure that the P04-3 concentration is never so low that the alumina and silica components have nothing to react with but each other. An excess of water over the described range tend to lead to rapid introduction of silica into the ■a NZMS product. Excess water also tend to increase crystallite size which may diminish activity due to diffusion constraints. In the present invention, a crystallite size of less than 1.0 micron is produced with an average size of 0.5 micron. At the start of the reaction the pH of the reaction mixture may be adjusted as required for the synthesis of the desired molecular sieve. As an example, the reaction mixture from which non-Zeolitic molecular sieve (NZMS) are prepared will typically have an initial pH in the range of about 4.0 to about 8.5.Crystallization of the non-zeolitic molecular sieve is conducted at hydrothermal conditions under pressure and usually in an autoclave so that the reaction mixture is subject to autogenous pressure and preferably with stirring. The autogenous pressures generally remains in the range from about 7.0 to 12.0 Kg/cm which are typically, reasonably lower in order than that used for the conventional preparation methods. Following crystallization, the reaction mixture containing the crystallized non-zeolitic molecular sieve is fittered and recovered crystals are washed with water, and then dried, such as by heating at from 25°C to 120 C at atmospheric pressure. Preferably any supernatant liquid above the crystals is removed prior to the initial filtering process. The NZMS prepared by the present method is beneficially subjected to thermal treatment to remove the occluded organic templating species. This thermal treatment is generally performed by heating at a temperature of 300" C to 650°C for at least one hour and generally not longer than 50 hrs. While atmospheric pressure can be employed for the thermal treatment, atmospheric pressure is desired for reasons of convenience. The thermally treated product is particularly useful in the catalysis of certain hydrocarbon conversion reactions. The non-zeolitic molecular sieve can be used in intimate combination with hydrogenating components, such as nickel, cobalt, chromium, palladium, rhodium, platinum or mixtures thereof, for those applications in which a hydrogenation dehydrogenation functions is desired. The techniques of introducing catalytically active metals to a molecular sieve are disclosed in the literature using standard methods known to the art. The metal incorporation techniques and treatment of molecular sieve to form an active catalyst such as ion exchange, impregnation or occlusion during sieve preparation are suitable for use in the present process. The term "metal" or "active metal" means one more metals in the elemental state or in some form such as sulfide, oxide, or salts such as nitrate, ammonium amines and mixtures thereof Regardless of the state in which the metallic component actually exists, the concentrations are computed as if they existed in the elemental state. Following addition of metals, the molecular sieve may be calcined in air or inert gas at temperatures ranging from about 200 C to 650 C, for periods of time ranging from 1 to 48 hours, or more, to produce catalytically active product especially useful in hydrocarbon conversion processes. The molecular sieve can be composited with one or more of materials resistant to the temperatures and other conditions employed in organic conversion processes, using techniques such as spray drying, extrusion, and the like. Such matrix materials include active and inactive materials and synthetic or naturally occurring inorganic materials such as silica, clays and metal oxides such as alumina, magnesia and titania. The inorganic materials may occur naturally or may be in the form of gelatinous precipitates, sols, or gels, including mixtures of silica and metal oxides. Use of an active material in conjunction with the synthetic molecular sieve, i.e., combined with it, tends to improve the conversion and selectivity of the catalyst in certain organic conversion processes. Inactive materials can suitably serve as diluents to control the amount of conversion in a given process so that products can be obtained economically without using other means for controlling the rate of reaction. Frequently, molecular sieve materials have been incorporated into naturally occurring clays, e.g., bentonite and kaolin. These materials, i.e., clays, oxides etc., function, in part, as binders for the catalyst. It is desirable to provide a catalyst having good crush strengths, because in petroleum refining the catalyst is often subjected to rough handling. This tends to break the catalyst down into powders, which cause problem in processing. In addition to the foregoing materials, the NZMS produced can be composited with a porous matrix material such as aluminium, alumina and silica-alumina. The relative proportions of finely divided crystalline NZMS material and inorganic oxide gel matrix very windely, with the crystal containing 10 to 90% by weight, and more particularly when the composite is prepared in the form of extrudates 1/8" or 1/16" dia, in the range of 20 to 80 % by weight of the composite. The NZMS prepared in the present process can be used in a process to dewax hydrocarbonaceous feeds. The NZMS catalyst may be used to isomerize a waxy feedstock. The NZMS also can be used in a process to prepare lubricating oils, comprising in process steps as, (a) Hydrocracking of hydrocarbonaceous feedstock to obtain an effluent hydrocracked oil, (b) Catalytic dewaxing the hydrocracked oil of stap (a) with a Catalyst comprising NZMS and active metal, preferably platinum or palladium. The improved process of the preparation of non-zeolitic molecular sieves of this invention will now be illustrated by examples which are not to be construed as limiting the invention as described in this specification including the attached claims. Ebcamples Example 1, Non-zeolitic molecular sieve (NZMS) was prepared as follows: a reaction mixture was made by combining 34 g of 85% orthophosphoric acid (H3PO4) with 18g of cold (40-50C) deionized water in a Teflon beaker under ice-bath. This mixture was then added alongwith 75 g of cold water to 60 g of alkoxide of alumina [Al(OC3H7)3] (98 + % Forum, India) placed in an another Teflon beaker under ice-bath; while simultaneously mixing and stining. 40 g of dionized water + 4.0 g of very fine powder silica (Sio2.xH20) were then mixed separately and then added to above mixture under constant stirring till forms a homogeneous slurry. Fine silica powder S 001, Sio2.xH20 supplied by Forum, India had an average particle size of 14 manometers (by laser Particle analyzer), the sodium content of Sio2.xH20 was 80 ppm and particle density 0.05 g/cc. 15 g of di-n-propylamine (Prs NH, DPA) were then added to the above mixture with vigorous stirring. silica (Si02 : XH2O, S 001, Forum India) in a separate vessel and then added to the above mixture under stirring till it forms homogeneous slurry. Si02 : xHaO supplied by Forum, India had an average particles of 15 nanometer size with sodium as NasO of 180 ppm and particle density of 50 g/litre. 0.465 litres of di-n-propylamine (DPA) were then quickly added to the above mix while continuously stirring. The final mixture had pH 5.4 + 0.2 and the following composition expressed in terms of molar ratio of oxides: 850 grams of 85% orthophosphoric acid were placed in a stainless steel vessel in an ice bath. To this vessel were added 90 grams of deionized ice and 360 grams of cold deionized water. To this were slowly added 1500 grams of aluminium isopropoxide (98-99% Forum, India) alongwith 1875 grams of cold DM water while simultaneously mixing with stirrer. 150 gms of fine powdered SiO2.xH20 (Forum, India) having average particle size between 10 to 30 nanometers and sodium content of 200 ppm was then added in dry state under rigorous stirring speed till it forms a homogeneous slurry. Then 188 grams of di-n-propylamine followed by 187 grams of di-isopropylamine were added to the homogenized slurry. The maximum viscosity during the mix was 500-600 CPS (at 25°C which was also the final viscosity). The mixture had pH 5.3 and the following composition expressed in terms of molar ratio of oxides 1.0 iPrjNH : 0.68 SiO2: AI2O3: P2 O5: 35 H2O The slurry mix was charged to stainless steel crystallizer (Cap. 5 gallon) and aged at lOO^^C for one day. The temperature of the crystallizer was then raised to 170°C in stepwise mode at which the autogenous pressure was registered to be 11.5 kg/cm , The Crystallization conditions were maintained for another 48-50 hours and thereafter rapidly cooled down to 50°C. The supernatant liquid was removed and the crystallized NZMS filtered, washed with water and dried at 120°C overnight. The dried product weighed about 980 gms at 25°C. The part of the dried product was subjected to stepwise programmed calcinations at 550°C in a dynamic air flow current for 12 hours. X-ray diffraction analysis identified the product as silicoluminophosphate SAPO-11 type pure phase as characterized in Fig. 1. The Sodium content estimated as Na2O in NZMS was about 120 ppm. Example 5 The preparation in this example demonstrate the use of relatively expensive raw materials other than that of mentioned in examples 1 to 4. 231 grams of 35% H3PO4 were added to 118 g of cold distilled water in a Teflon beaker under ice bath. 408 g of aluminium isopropoxide (Al(OC3H7)3 98%, 22,041-8, Aldrich) were slowly added with mixing and then mixed until homogeneous. Then 38 g of fumed silica (Cabosil M-5, Aldrich, USA) in 168 g of distilled water were added with mixing. 91.2 g of di-n-propylamine (99+ % Aldrich 24, 008-7) were finally added with mixing. The mixture had a pH of 6.0 ±0.2 and the following composition, expressed in molar ratios of oxides. 0.9 Pr2NH : 0.6 SiO2: AI2O3: P2O5: 18 H2O The mixture was placed in a stainless steel pressure vessel and initially aged at 100**C for one day, after which was raised to 170°C in stepwise mode and hold therefore 2-3 days. The sample of crysrallised material was withdrawn at this stage to verify the x-ray crystallinity and phase purity. X-ray diffraction analysis revealed the product to be partly crystalline with large quantity of silica remaining unreacted over the crystallization period. Based on this, the crystallization temperature was further raised to 200°C and hold there for another 2 days to complete the crystallization. The sample withdrawn at this stage showed improved crystallinity in the product. The example 5, clearly indicated the advantage of the process of this invention (example 1 to 4) in terms of raw materials selection, crystallization temperatures and period to obtain highly crystalline NZMS at reasonably lower synthesis temperature with shorter period for crystallization. Example 6 A NZMS sieve was prepared as in example 1, but enough distilled water was added to the orthophosphoric acid to bring the mixture H2O/AI3O3 molar ratio upto 102 and outside the range of the invention. The reaction mixture pH (7.5) was lowered to 5.5 + 0.2 by the addition of mineral acid. The product obtained from this composition exhibited non-uniform particle size distribution (laser particle analyzer) having average larger particle size range. Example 7 A reaction mixture was prepared combining 58 grams of 85% orthophosphoric acid (H3PO4) and 30 grams of deionized water. This mixture was allowed to cool under ice bath and then added to 102 grams of alkoxide of alumina (98% Forum India) and the mixture stirred will. 30 grams of an aquenous silica sol containing 30 wt% SiO2 was then added to above alongwith 4 grams of deionized water and stirred until homogeneous. 21 grams of di-n-propylamine were finally added to this mixture and stirred until homogeneous. The reaction mixture had a pH 7.9, was lowered to 6.0 ± 0.2 by the addition of concentrated H3PO4 before charging to a reaction vessel. The reaction mixture was sealed in a stainless steel vessel and heated to 155°C for 3 days at autogenous pressure of 9-10 Kg./cm2 under stirring. The Solid crystalline product was recovered by centrifugation, washed with water repeatedly to ensure complete washing of free excess alkali from the product, X-ray analysis and chemical analysis after calcinations at 550°C established the product to be silicoaluminophosphate - SAPO family. The product powder X-ray pattern was essentially identical to that in Fig. 1. Example 8 A reaction mixture was prepared from 23 grams of 85% O-phosphoric acid (H3PO4) and 60 grams of deionized water which was added to 41 grams of alumina-alkoxide-Al(OC3H7)3 and 5.0 grams of DM Water and Stirred well. To this mixture 1.85 grams of powdered SiO2 - XH2O (Forum, India) and 5 grams of DM Water and stirred until homogeneous. To this miture was added 10 grams of diisopropylamine (I-Pr2NH) and 5 grams of DM Water and stirred well to get good homogenized slurry the reaction mixture had pH 5,5 ± 0.2 and the composition interms of molar oxide ratios: 1.0I-Pr2NH : AI2O3: P2O5 : 3,0SiO2: 50 H2O The entire mixture was transferred into the stainless steel vessel and healed to 150° C at autogenous pressure of 8-9 Kg/cm for 5 days. The solid reaction product was filter, water washed and dried. The calcined product NZMS was found to be crystalline SAPO phase. Example 9 The NZMS of Example 1 was mixed with 20 wt% (volatiles free, dry basis) ppetized alumina (pural S.B. equvalent to calapal B grade) and extruded through a 1/16 inch die. The extrudates were dried initially in atmosphere for 2 hours, and then in air over at 90°C for one hour and 120°C for three hours. The dried extrudates were subjected to calcination in muffle furnace at 480°C for 5 hours. The exturdates had 8.0 Kg. Crush Strength (Versa Test, Mac Machine) and BD (Bulk density) of about 0.6 g/cc Example 10 A NZMS sieve was prepared as in example 1, except the quantities of di-n-propylamine and diisopropylamine were reduced to half to bring the mixture iPr2NH+Pr2NH/Al203 molar ratio upto 0.5. The reaction mixture pH 8.9 was lowered to 5.4 ± 0.1 by the addition of concentrated HCI. The reaction mixture was initially aged at 100°C for 24 hours and than allowed to crystallized at 150°C for 7 days at autogeneous pressure of 7-8 Kg./cm . The product NZMS obtained from this composition after calcination at 550°C had an X-ray diffraction pattern essentially identical to that of example I (Sapo-11 phase) and had the following anhydrous molar composition. 0.3 SiO2: AI2O3: 0.7 P2O5 The sodium content of NZMS product was about 95 PPM. Example 11 A NZMS sieve was prepared as in example 1, except the quantities of di-n-propylamine and diisopropylamine were doubled to bring the mixture iPr2NH+Pr2NH/Al203 molar ratio upto 2.0. The reaction mixture had a pH 10.2 which was lowered to 5.3 + 0.1 by the addition of concentrated H3P04(85%) acid. The reaction mixture was treated hydrothermally at 140°C for 12 days at autogeneous pressure of 6-7 Kg./cm . The product NZMS obtained from this Following example illustrates the effect of using a different silica having a particle size and particle density outside the range of reactive Silica (SiO2X H2O) source of the present invention. Comparative Example 1. The NZMS was prepared similar to example 1 & 2 except that Silica. XH2O was substituted by Silicon dioxide (National Chem-India) containing 91 wt% SiOa and 500 ppm sodium. The average particle diameter of Silicon dioxide was 130 mincrons and the particle density of about 1.2 g/cc. The x-ray diffration pattern of the calcined product of this example showed substaintial amount of other impure phases co-crystallized along with NZMS. Comparative Example 2. The NZMS was prepared similar to example 1 & 2 of this invention except that aluminium alkoxide was substituted by 51 grams (for example 1), 1275 grams (for example 2) hydrated aluminium oxide, (psendo-boehmitc, 70 wt% AI2O3 & 30 wt% H2O) containing 100 ppm sodium. The calcined product obtained from this example was found to contain substantial amount of undecomposed hard mater and X-ray analysis showed uncharacterized impure phases associated with NZMS product. WE CLAIM: 1. An improved process for preparation of crystalline SAPO-11 type Non- Zeolitic Molecular Sieve comprising in the step of subjecting a reaction mixture wherein reaction mixture is prepared by adding phosphoric acid to an organic templating agent containing carbon 86 nitrogen and aluminium isopropoxide having an H2O/AI2O3 molar ratio of greater than 20, a reactive silicon dioxide having an average particle size of 10 to 30 nanometers, a sodium content of less than 0.03 wt% and bulk density of less than 0.1 g/cc, said reaction mixture having a composition expressed in terms of mole ratios of : 2. An improved process as claimed in claim 1 wherein said reaction mixture contains an active source of phosphours, a particulate aluminium alkoxide, a templating agent and active source of one or more additional elements capable of forming oxides in tetrahedral coordination with AIO2 and PO2 units, under hydrothermal conditions at lower temperatures until crystals of non-zeolitic molecular sieve form, the particulate hydrated Silica, Si02.xH20 having an average particle size of less than 20 nanometers. 3. An improved process as claimed in claim 2 wherein additional element is selected from Silicon, cobalt, zinc and magnesium. 4. An improved process as claimed in claim 3 wherein additional element is silicon-dioxide. 5. An improved process as claimed in claim 4 wherein the molecular sieve is silicoaluminophosphate SAPO-II structure type phase. 6. An improved process as claimed in claim 2 wherein the templating agent is selected from di-n-proplamine, di-iso-propylamine. 7. An improved process as claimed in claim 2 wherein the pH value of the reaction mixture is in the range of 4 to 9. 8. An improved process as claimed in claim 2 wherein the reaction mixture comprises at least one reaction source of SiO2 as hydrated silicon dioxide, the reaction mixture having a composition expressed in terms of mole ratios of aR: AI2O3: (0.9-1.2) P2O5: (0.1-1.0) SiO2 : bH20 where "R" is an organic templating agent, "a" has value within the range of from greater than Zero (O) to about 2.0; "b" has a value of from 30 to 50. 9. An improved process as claimed in claim 8 wherein the sodium content of the particulate hydrated silica is in the range from about 0.01 wt% to about 0.03 wt%. 10. An improved process as claimed in claim 1 wherein the reaction gel-mixture is heated under hydrothermal conditions at autogenous pressure at temperature in the range from 80° to 120°C for at least 24 hours. 11. An improved process as claimed in claim 1 wherein the step of heating the reaction contents is in the temperature range in step-wise mode from 120° to 1700°C until the crystals of NZMS are formed. 12. An improved process as claimed in claim 1 wherein the steps of recovering the crystalline NZMS product, filtering washing with water till free from alkali, drying at 110° - 120°C to recover hydrated NZMS, calcining NZMS at elevated temperature in the range from 300° to 650°C in air atmosphere for not more than 50 hours, having anhydrous composition. 13. An improved process as claimed in claim 1 wherein said NZMS has inorganic matrix in the range of 20 to 80 wt% of the composite. 14. An improved process for preparing of crystalline non-zeolitic molecular sieves prepared by the process as claimed in claims 1-13 substantially as described herein. 15. An improved process for preparation of crystalline SAPO-11 type Non-Zeolitic Molecular Sieve substantially as herein described and exemplified in the examples.

Documents:

937-mas-2000 abstract duplicate.pdf

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937-mas-2000 description (complete) duplicate.pdf

937-mas-2000 drawing duplicate.pdf

937-mas-2000-abstract.pdf

937-mas-2000-assignement.pdf

937-mas-2000-claims.pdf

937-mas-2000-correspondnece-others.pdf

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937-mas-2000-form 1.pdf

937-mas-2000-form 13.pdf

937-mas-2000-form 19.pdf

937-mas-2000-form 26.pdf

937-mas-2000-form 6.pdf

937-mas-2000-other documents.pdf