Title of Invention

"PROCESS FOR PREPARATION OF LPG SELECTIVE CRACKING CATALYST"

Abstract

The present invention relates to a process for preparing a cracking catalyst composition for cracking heavy hydrocarbon, said process comprising of treating zeolite with sodium free basic compound with or without phosphate; treating an alumina with a dilute acid; acidifiying a colloidal silica; preparing a fine slurry of clay with a source of phosphate; adding alumina slurry and/or acidified colloidal silica to clay phosphate slurry; adding treated zeolite and spray-drying the slurry and calcining the same to obtain a cracking catalyst having adequate ABD and attrition resistance property and suitable for enhancing yield of C3 to C4 hydrocarbons. These hydrocarbons are major constituents of liquefied petroleum gas (LPG). The invention particularly relates to a catalyst composition comprising alumina, silica, silica-alumina with clay phosphate binder for cracking heavy residual hydrocarbon feed.

Full Text

PROCESS FOR PREPARATION OF LPG SELECTIVE CRACKING CATALYST FIELD OF INVENTION The present invention relates to a process for the preparation of a cracking catalyst suitable for enhancing yield of C3 to C4 hydrocarbons, which are major constituents of liquefied petroleum gas (LPG). The invention particularly relates to a catalyst composition comprising alumina, silica, silica-alumina with clay phosphate binder for cracking heavy residual hydrocarbon feed. In addition, the present invention relates to preparation of said catalyst composition. BACKGROUND AND PRIOR ART OF THE INVENTION Catalytic cracking today constitutes several refining processes in which heavier hydrocarbons are cracked into lighter useful products. They are fluid catalytic cracking (FCC), hydrocracking, reforming, etc. FCC process is simple and highly flexible, as required product slate can be obtained independent of feed and hardware through tailoring of catalyst. The earliest catalysts used for fixed bed cracking were based on acid reacted clays. The exigencies imposed during the Second World War provided required acceleration to the concept and growth of moving bed catalytic cracking process. This process demanded more rugged catalysts than activated clays. Demand for this was met by more active silica alumina gel based synthetic catalysts, which provided an improved physical stability, and greater selectivity. Grinding and screening methods were used to produce catalyst particles of required size. Later, spray-drying technique produced catalyst particles of required size and with improved attrition resistance suitable for fluid bed reactor systems. Introduction of silica-magnesia based matrix provided greater selectivity towards the production of middle distillates than silica-alumina based catalysts. One of the most significant developments in the area of cracking catalyst was the introduction of crystalline inorganic synthetic products called "Y zeolites". The "Y zeolites" have discrete pores in the range 6.5 to 13.5°A, higher surface area and higher acidity as compared to the amorphous silica-alumina based catalysts thereby generating higher catalytic activity and much more selectivity towards gasoline. Later on, by employing rare earth exchanged Y zeolites and ultra stable Y zeolites, many active and stable catalysts were developed. Along with the introduction of highly stable cracking components like zeolites in different forms, in the past, there have been gradual improvements in binder system used for binding these crystalline materials into attrition resistant microspheres. Discovery of medium pore high silica zeolite and it's application in cracking catalyst process offers required impetus in shifting product selectivity from gasoline and middle distillate to C3-C4 hydrocarbons with increased octane number has been described in US Pat. Nos. 3,702,886, 4,828,679 and 5,389,232. Binding of low soda Y zeolite with gel alumina and polysilicate has been described in US Pat. Nos. 4,333,857 and 4,326,993. US Pat, No. 4,309,280 describes a process for maximizing yield of LPG by adding very small amounts of powdered, neat ZSM-5 catalyst, characterized by a particle size below 5 microns to the FCC catalyst inventory. US Pat. No. 5,997,728 refers to a process for catalytically cracking of a heavy feed in a FCC unit, with large amounts of shape selective cracking additive. The catalyst inventory preferably contains at least 10 wt % additives, of 12-40% ZSM-5 on an amorphous support, equivalent to more than 3.0 wt % ZSM-5 crystals circulating with equilibrium catalyst. This process yields large amount of light olefins, without excessive production of aromatics, or loss of gasoline yield. US Pat. No. 6,137,022 discloses a process of making an olefin product from an oxygenated feedstock by contacting the feedstock in a reaction zone containing 15 volume percent or less of a catalyst, preferably a catalyst comprising a silica-alumina-phosphate molecular sieve. A process for jointly producing butene-1 and ether in a catalytic distillation column, which comprises an upper catalytic zone for etherification and a lower catalytic zone for isomerisation of C3 to C4olefins and conversion of butadiene has been described in US Pat. No. 6,156,947. US Pat. No. 6,258,257 refers to a process for producing polypropylene from C3 olefins by a two-stage fluid catalytic cracking process having two types of catalysts made from zeolites of large pore and medium pore.] US Pat. No. 5,286,369 describes a phosphate based binder composition suitable for binding high silica zeolites. Here, reaction between aluminium nitrate and phosphoric acid forms aluminium phosphate binder. However, during the reaction, along with the formation of aluminium phosphate binder, nitric acid is also formed as a by-product as per following reaction. Al (NO3)3 + H3PO4 -------------> A1PO4+ 3HNO3 Presence of nitric acid is detrimental to the activity of any type of zeolite. Nevertheless, additives prepared by this process exhibit higher ABD and excellent attrition resistance. US Pat. 6,858,556 relates to a process for preparing a hydrocarbon conversion catalyst comprising stabilized ZSM-5 type zeolite and a Y zeolite bonded with a common silica alumina binder. This is due to the fact, ZSM-5 type high silica zeolite and low silica Y zeolite cannot be bonded with a common binder at the same time maintaining catalytic activity. From US Patent Nos. 5,190,902 and 5,286,369, it can be concluded that attrition resistant catalysts based on ZSM-5 zeolite can be prepared with an acidic clay-phosphate binders but with loss of catalytic activity. Further improvement in activity is possible by preparing similar catalyst at higher pH by sacrificing attrition resistance properties. From prior art processes, it can be concluded that ZSM-5 type high silica zeolites based microspheroidal catalyst particles can easily be prepared by employing several types of binders. Retaining catalytic activity with adequate physical properties is tedious. ZSM-5 type zeolites are sensitive to extreme pH conditions. While the use of basic or semibasic phosphate source does improve catalytic activity of the particles, however, attrition resistance has to be sacrificed. Hence, there is a need to develop a process for the restoration of catalytic activity of high silica zeolites without sacrificing attrition resistance and ABD of resulting catalyst particles. OBJECTS OF THE INVENTION The primary object of the present invention is to provide a process for the preparation of LPG selective catalyst. Another object of the invention is to provide a catalyst composition for cracking heavy residual hydrocarbon feed. Another object of the invention is to explore the potential of ZSM-5 crystals by stabilisation to retain catalytic activity and LPG selectivity. Yet another object of the present invention is to provide a process for the preparation of catalyst additive having adequate ABD and attrition resistance property to obtain LPG. Yet another object of the present invention is to reduce undesired hydrocarbons such as C1, C2 and boiling fraction above 360°C when used in cracking process. Yet another object of the present invention is to develop a process for simultaneously enhancing catalytic activity with enhanced yield of LPG and higher attrition resistance and ABD of resulting catalyst particles and suppressing dry gas and heavy fraction. SUMMARY OF THE INVENTION The present invention provides a process for the preparation of LPG selective catalyst particles comprising medium pore zeolite bonded with clay-phosphate-silica-alumina binder, suitable for cracking heavy residual hydrocarbon feeds. The present invention relates to a process for preparing a cracking catalyst composition for cracking heavy hydrocarbon, the process comprising of treating zeolite with sodium free basic compound with or without phosphate; treating an alumina with a dilute acid; acidifiying a colloidal silica ; preparing a fine slurry of clay with a source of phosphate; adding free flowing alumina slurry to clay phosphate slurry; adding treated zeolite and spray-drying the slurry and calcining the same to obtain a cracking catalyst having adequate ABD and attrition resistance property and suitable for enhancing yield of C3 to C4 hydrocarbons. These hydrocarbons are major constituents of liquefied petroleum gas (LPG). The invention particularly relates to a catalyst composition comprising alumina, silica, silica-alumina with clay phosphate binder for cracking heavy residual hydrocarbon feed. DETAILED DESCRIPTION OF THE PRESENT INVENTION Accordingly, the present invention provides a cracking catalyst having adequate ABD, attrition index, enhanced catalytic activity and LPG selectivity, which is suitable for cracking heavy hydrocarbon feeds and said catalyst comprising: (a) treated high silica medium pore zeolite in the range of 1 wt% to 50 wt%; (b) silica in the range of 1 wt% to 30 wt%; (c) alumina in the range of 1 wt% to 30 wt%; (d) clay in the range of 10 wt% to 50 wt%; and (e) phosphate in the range 1 wt% to 20 wt%. The said catalyst may be prepared by first treating the high silica zeolite with alkaline component with or without phosphate source to a pH in the range 5-9 and thus resulting product having phosphate in the range of 1 wt% to 20 wt%, prior to introduction to acidic binder. The stabilised zeolite is then treated with an acidic clay-phosphate / clay-phosphate-silica-alumina / clay-phosphate-silica / clay-phosphate-alumina slurry and subsequently spray dried. The clay is selected from a group consisting of kaolin and halloysite and mixtures thereof. The phosphate source is selected from a group consisting of phosphoric acid, ammonium di hydrogen phosphate, ammonium monohydrogen phosphate, triammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium dihydrogen ortho-phosphate, ammonium monohydrogen ortho-phosphate, ammonium hypophosphite, ammonium dihydrogen ortho-phosphite and mixtures thereof. The alumina is selected from the group consisting of amorphous gel alumina, aluminium trihydrate, pseudoboehmite alumina, bayrite alumina, gamma alumina and mixtures thereof. The silica is in colloidal form of particles having a mean diameter ranging from 4 nm to 90 nm and the product having lowest residual soda below 0.3 wt%. In an embodiment, the binder used in preparing the catalyst is slurry of clay with a phosphate source and in addition, it may contain silica, alumina, or both in varying proportion. The acid used for acidifying colloidal silica is selected from the group consisting of nitric acid, hydrochloric acid, formic acid and acetic acid or a mixture thereof. The dilute acid used for treating alumina is selected from a group consisting of nitric acid, hydrochloric acid, formic acid and acetic acid and mixtures thereof. The catalyst of the present is having particle size in the range of from about 20-about 150 microns, preferably about 30-about 100 microns. One more embodiment of the present invention relates to process for preparing a cracking catalyst composition for cracking heavy hydrocarbon, said process comprising of: a. treating zeolite with sodium free basic compound with or without phosphate resulting zeolite slurry having pH between 5 and 9; b. treating an alumina with a dilute acid and to obtain alumina binder; c. acidifiying colloidal silica d. preparing a fine slurry of clay with a source of phosphate; e. adding free flowing alumina slurry to clay phosphate slurry; f. optionally adding acidified colloidal silca to the alurnina-clay- phosphate slurry; g. adding treated zeolite of step (a) to the contents of step (f); and h. spray-drying the slurry and calcining the same to obtain a cracking catalyst. The treated zeolite has silica to alumina ratio in the range of 5 to 300. The high silica zeolite is selected from a group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, Zeolite beta, mordenite and preferably ZSM-5. The zeolite used has silica to alumina ratio from about 10 to about 1000. The colloidal silica consisting of silica particles having a mean diameter ranging from about 4 nm to 30 nm. The colloidal silica containing soda in the range of 0.01 to 0.5wt%. The colloidal silica having a pH between 7.0 and 11.5, acidified to pH range of 0.5-5. The ammonium polysilicate is acidified to a pH between 0.5 and 3.5 before use. The zeolite slurry of having phosphate content in the range of 0 to 20 wt percent calculated on a volatile-free basis. The phosphate source used for preparing clay slurry and the phosphate source is phosphoric acid preferably ortho-phosphoric acid. The colloidal silica is acidified using an acid selected from a group consisting of nitric acid, hydrochloric acid, formic acid and acetic acid. The alumina is selected from a group consisting of pseudoboehmite, gel alumina and bayrite. The alumina has residual soda content ranging between 0.001 and 0.1 wt%. The alumina is acidified using acids selected from a group consisting of acetic acid, formic acid, nitric acid, hydrochloric acid and mixtures thereof. The present invention is further explained in the form of following preferred embodiments Clays Clays are commonly used as major component of cracking catalysts. They are favoured due to their low cost and used as diluents and density modifier. Clays are used in finely divided form with a size below 3 microns. The most common varieties of clays used in cracking catalyst formulations are kaolinite and halloysite. Clays have a two-layer structure, consisting of alternating sheets of silica in tetrahedral configuration and alumina in octahedral configuration. These sheets are separated with a gap of 7.13 °A. Dry atmosphere equilibrated clay has moisture content of about 15wt%. Clays are good sources for silica and alumina as they contain about 45 wt% of silica and 38 wt% of alumina. It is preferable to use clays having particle size below 3 microns. It has been shown that use of delaminated clays in catalyst formulations enhances ABD and attrition resistance. Medium pore high silica zeolites Zeolites are synthetic or naturally occurring crystalline inorganic material characterized by properties such as ion exchange and molecular sieving. The most important and industrially exploited members of zeolite family are ZSM-5, ZSM-11, beta and mordenite a few to mention. These zeolites are synthesized with SiOj to Al2O3 ratio in the range 10 to infinity and 0.1 to 4 wt %Na2O. To make them suitable for catalytic application, soda present inside for balancing electrovalence is required to be exchanged with a proton, via ammonium exchange followed by calcination. Higher silica to alumina ratio zeolite may be further prepared by modification of synthetic forms by steaming, chemical treatment or replacement of framework aluminium with silica. These modification steps for ultra-stabilization drastically reduce the catalytic activity of the zeolite. Most commonly used medium pore zeolite in cracking catalyst is ZSM-5 zeolite. This material has pores in the range 5.4 to 5.5°A. This zeolite is known for dewaxing and isomerisation abilities of hydrocarbons. In cracking processes, these zeolites lead to the production of higher LPG and high-octane gasoline. ZSM-5 zeolite cannot be employed for cracking catalyst with conventional silica alumina binders, as it cannot sustain LPG selectivity due to the requirement of stabilization of acid sites and pores with phosphate radicals. The present invention shows how to enhance catalytic activity of zeolite materials. Step of zeolite activation involves reacting of medium pore high silica zeolite with required amount of sodium free basic components with or without phosphate. Once these zeolite materials are treated with a basic phosphate compound, it can be incorporated to an acidic catalyst binder containing clay, phosphate, silica and/or alumina. The phosphate source could be ammonium di-hydrogen phosphate, ammonium mono hydrogen phosphate, tri-ammonium phosphate, ammonium hypo phosphate, ammonium ortho-phosphate, ammonium di-hydrogen ortho-phosphate, ammonium mono hydrogen ortho-phosphate, ammonium hypophosphite, ammonium di-hydrogen ortho-phosphite, and mixtures thereof. Colloidal silica Colloidal silica is aqueous colloidal dispersions of silica particles, stabilized by the use of small quantities of soda or ammonium. These products having soda less than 0.2 wt % can be readily used for matrix or catalyst binding purpose. These are stable between pH of 8.5 and 11. These products are commercially available in varying particle size ranging from 7 to 22 nm. However, pH of these colloidal silica materials may be lowered between 1-3 employing mineral and/or organic acids for enhancing binding property. Alumina Pseudoboehmite alumina with soda, less than 0.1 wt % are ideal binders for different zeolite based catalysts as they can be converted to a glue by reacting with acids like nitric acid, formic acid or acetic acid. Glue alumina can be mixed with a zeolite, clay-phosphate and colloidal silica and spray dried. Once spray dried product is calcined, alumina gets transformed into gamma phase, a hard material, which holds clay, zeolite and other catalyst ingredients together to form attrition resistant mass. Varieties of pseudoboehmite alumina are commercially available in different crystallite sizes and surface area. Besides this other species of alumina such as aluminium trihydrate, bayrite, gamma alumina can also be used for enhancing binding and catalytic activity with respect to cracking of heavier hydrocarbons. Cracking catalyst In a preferred method for preparing cracking catalyst of present invention, (a) a conditioned medium pore high silica zeolite is prepared by reacting dry zeolite with loss on ignition below 3 wt%, with a basic phosphate compound, (b) preparing silica-alumina-clay-phosphate binder by homogenising acidified colloidal silica and/or, alumina with a clay phosphate binder, (c) adding finely ground slurry of conditioned zeolite to silica-alumina clay phosphate obtained under (b) to obtain a slurry ready for spray drying having composition, 1 to 50 wt% conditioned low soda zeolite, 1 to 20 wt% alumina, 1 to 20 wt% silica , 10 to 50 wt% kaolin clay and 1 to 20 wt% phosphoric acid, (d) drying the slurry and (e) calcination. The present invention is further explained in the form of following examples. However, these examples should not be construed as limiting the scope of the invention. EXAMPLES Example 1 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 425 gm of DM water. The slurry was peptized with 21.52 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of DM water and milled to a fine paste to produce a zeolite slurry having pH of 7.0. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 218.45 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina gel and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 1.8 was spray dried in a counter current spray drier having two fluid nozzles. Spray dried product was calcined at 500 °C. Calcined catalyst showed ABD of 0.8 g/cc and attrition index of 2. Calcined catalyst was impregnated with 400 ppm Nickel and 7500 ppm Vanadium and steam deactivated at 750 °C for three hours. Steam deactivated catalyst was evaluated in an ACE micro reactor employing a resid FCC feed having physical properties, shown in Table 1. For performance evaluation, 5% ZSM-5 additive was mixed with 95% equilibrated RFCC catalysts. Results of performance are shown in a Table 2. Example 2 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 425 gm of DM water. The slurry was peptized with 21.52 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of 5% ammonical solution to produce a zeolite slurry having pH of 8.2. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 219.25 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina gel and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 2.53 was spray dried similar to slurry of example 1 and the product was processed further. Spray dried product showed ABD of 0.79 with attrition index of 2.2. (Table Removed) Example 3 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 425 gm of DM water. The slurry was peptised with 21.52 gm of formic acid (85% concentration).. 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of DM water and milled to produce a fine slurry of pH 7. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 163.83 gm of orthophosphoric acid (concentration 85 wt% ) was added. To clay-phosphate slurry, alumina gel and zeolite slurry were added one after another under vigorous stirring. This was followed by the addition of 130 gm of basic phosphate solution containing 62.56 gm of diammonium hydrogen phosphate. Final slurry having pH: 2.53 was spray dried similar to slurry of example 1 and the product was processed further. Spray dried product showed ABD of 0.77 with attrition index of 3. Example 4 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) wasslurried with slurried with 425 gm of DM water. The slurry was peptized with 21.52 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%), having silica to alumina molar ratio of 30, was slurried with 490 gm of DM water and milled to a fine paste to produce a zeolite slurry having pH of 7.0. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 218.45 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina gel and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 1.8 was vigorously stirred under addition of ammonical water (25%) and pH was raised to 8. This slurry was spray dried similar to slurry of example 1 and the product was processed further. Spray dried product showed ABD of 0.69 with attrition index of 15. Example 5 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 425 gm of DM water. The slurry was peptized with 21.52 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of diluted ortho-phosphoric acid containing 54.61 gm acid and milled to a fine paste to produce a zeolite slurry having pH of 1. 1022.45 grn of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 163.83 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina gel and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 1.8 was spray dried. Spray dried product was calcined. This product showed an ABD of 0.78 g/cc with attrition index of 2. Calcined product was impregnated with metals content similar to that of example 1, processed and evaluated for performance. Example 6 243.48 gm of Ammonium Poly Silicate (having solid content 31 wt%) was mixed with 279.5 gm of DM water and the resultant solution was acidified with 10.75 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of diluted ortho-phosphoric acid containing 54.61 gm acid and milled to a fine paste to produce a zeolite slurry having pH of 1. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 163.83 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina gel and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 1.8 was spray dried. Spray dried product was calcined. This product showed an ABD of 0.8 g/cc with attrition index of 1.8. Calcined product was impregnated with metals content similar to that of example 1, processed and evaluated for performance. Example 7 98.63 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 425 gm of DM water. The slurry was peptised with 21.52 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of 10% ammonical solution followed by addition of 27.7g phosphoric acid (85%) to produce a zeolite slurry having pH of 7.5. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 191.53 gm of orthophosphoric acid (concentration 85 wt%) was added. To clay-phosphate slurry earlier prepared alumina sol and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 2.53 was spray dried similar to slurry of example 1 and the product was processed further. Spray dried product showed ABD of 0.79 with attrition index of 2.2. This catalyst has shown LPG yield of 18.2 wt% with a conversion of 60.2%. Example 8 49.32 gm of Pural SB grade alumina (having loss on ignition of 23.96 wt %) was slurried with 213 gm of DM water. The the slurry was peptised with 10.75 gm of formic acid (85 % concentration). 121.75 gm of Ammonium Poly Silicate (having solid content 31 wt%) was added to 140 gm of DM water and acidified with 5.38 gm of formic acid (85 % concentration). 426.7 gm of ZSM-5 zeolite (loss on ignition 12.12 wt%) having silica to alumina molar ratio of 30 was slurried with 490 gm of 5% ammonical solution to produce a zeolite slurry having pH of 8.2. 1022.45 gm of kaolin clay (having loss on ignition 14.91 wt%) was slurried with 1107 gm DM water and kept under vigorous stirring while 219.25 gm of orthophosphoric acid (concentration 85 wt% ) was added. To clay-phosphate, slurry earlier prepared alumina sol, silica sol and zeolite slurry were added one after another under vigorous stirring. Final slurry having pH of 2.45 was spray dried similar to slurry of example 1 and the product was processed further. Spray dried product showed ABD of 0.8 with attrition index of 2. This catalyst has shown LPG yield of 18.3 wt%, DG 2.8 wt%, with a conversion of 60.8%. (Table Removed) I / We claim 1. A process for preparing a cracking catalyst composition for cracking heavy hydrocarbon, said process comprising of: i. treating zeolite with sodium free basic compound with or without phosphate resulting zeolite slurry having pH between 5 and 9; j. treating an alumina with a dilute acid to obtain alumina binder; k. acidiflying colloidal silica; 1. preparing a fine slurry of clay with a source of phosphate; m. adding free flowing alumina slurry to clay phosphate slurry; n. optionally adding acidified collidal silica to the alumina-clay-phosphate slurry; o. adding treated zeolite of step (a) to the contents of step (f); and p. spray-drying the slurry and calcining the same to obtain a cracking catalyst. 2. The process as claimed in claim 1, wherein the sodium free basic compound is ammonium hydroxide. 3. The process as claimed in claim 1, wherein the zeolite is selected from a group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, Zeolite beta, mordenite and matures thereof. 4. The process as claimed in claim 1, wherein the phosphate compound is selected from a group consisting of ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, triammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium dihydrogen ortho- phosphate, ammonium monohydrogen ortho-phosphate, ammonium hypophosphite, ammonium dihydrogen ortho-phosphite, ortho phosphoric acid and mixtures thereof. 5. The process as claimed in claim 1, wherein the alumina is selected from a group consisting of pseudoboehmite alumina, boehmite, aluminium trihydrate, bayrite alumina, gamma alumina and mixtures thereof 6. The process as claimed in claim 1, wherein the dilute acid for treating alumina is selected from a group consisting of nitric acid, hydrochloric acid, formic acid and acetic acid and mixtures thereof. 7. The process according to claim 1, wherein the colloidal silica is sodium and/or ammonium stabilized poly silicate. 8. The process according to claim 1, wherein the colloidal silica having a pH between 7.0 and 11.5. 9. The process according to claim 1, wherein colloidal silica is acidified to a pH between 0.5 and 3.5 before use. 10. The process according to claim 1, wherein the acid used for acidifying colloidal silica is selected from a group consisting of nitric acid, hydrochloric acid, formic acid, acetic acid and mixtures thereof. 11. The process according to claim 7, wherein the colloidal silica consists of silica particles having a mean diameter ranging between 4 to 30 nm. 12. The process according to claim 7, wherein the colloidal silica has soda or ammonia in the range between 0.1 to 0.8 wt %. 13. The process as claimed in claim 1, wherein the zeolite slurry of step (a)has phosphate content in the range of 0 to 20 wt % calculated on a volatile-free basis. 14. The process as claimed in claim 1, wherein said alumina has soda content in the range of between 0.001 and 0.1 wt %. 15. The process as claimed in claim 1, wherein the clay is selected from a group consisting of kaolin and halloysite and mixtures thereof. 16. The process according to claim 1, wherein phosphate source used for preparing clay slurry is phosphoric acid preferably ortho-phosphoric acid. 17. The process as claimed in claim 1, wherein the alumina used is pseudoboehmite. 18. The process as claimed in claim 1, wherein the zeolite is ZSM-5. 19. The process as claimed in claim 1, wherein the acid used for acidifying collidal silica is formic acid. 20. A catalyst composition for cracking heavy residual hydrocarbon feed, said catalyst comprising of: a. treated high silica medium pore zeolite in the range of 1 wt% to 50 wt%; b. silica in the range of 1 wt% to 30 wt%; c. alumina in the range of 1 wt% to 30 wt%; d. clay in the range of 10 wt% to 50 wt%; and e. phosphate in the range 1 wt% to 20wt%. 21 .The catalyst as claimed in claim 20, wherein Zeolite is selected from a group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, Zeolite beta, mordenite, and mixtures thereof which is further treated with silica. 22. The catalyst as claimed in claim 20, wherein the silica is colloidal silica is ammonium and/or sodium stabilized poly silicate. 23. The catalyst as claimed in claim 20, wherein the particle size of silica is in the range of from 4 nm to 10 nm. 24. The catalyst as claimed in claim 20, wherein the alumina is selected from a group consisting of pseudoboehmite, boehmite, aluminium trihydrate, bayrite alumina, gamma alumina and mixtures thereof. 25. The catalyst as claimed in claim 20, wherein the clay is selected from kaolin, holloysite and mixtures thereof. 26. The catalyst as claimed in claim 20, wherein said phosphate of step (e) is selected from a group consisting of ortho phosphoric acid, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, triammonium phosphate, ammonium hypophosphate, ammonium ortho-phosphate, ammonium dihydrogen ortho-phosphate, ammonium monohydrogen ortho- phosphate, ammonium hypophosphite, ammonium dihydrogen ortho- phosphite and mixtures thereof. 27. The catalyst as claimed in claim 19, wherein the particle size of the catalyst is in the range of 20-150 microns. 28. The catalyst as claimed in claim 19, wherein the particle size of the catalyst is in the range of 30-100 microns. 29. A catalyst composition for cracking heavy hydrocarbon feed, the catalyst comprising of: a. treated high silica medium pore zeolite in the range of 1 wt% to 40 wt%; b. silica in the range of 1 wt% to 30 wt%; c. alumina in the range of 1 wt% to 30 wt%; d. clay in the range of 10 wt% to 50 wt%; and e. phosphate in the range 1 wt% to 20 wt%.

Documents:

516-del-2006-abstract.pdf

516-del-2006-claims.pdf

516-del-2006-Correspondence Others-(26-03-2013).pdf

516-del-2006-correspondence-others.pdf

516-del-2006-description (complete).pdf

516-del-2006-form-1.pdf

516-del-2006-form-2.pdf

516-del-2006-form-26.pdf

516-del-2006-form-3.pdf

516-del-2006-form-5.pdf

516-del-2006-GPA-(26-03-2013).pdf

Amended Claims_Clear.pdf

FER Reply.pdf

Others.pdf

Petition.pdf