COMPOSITION AND PROCESS FOR PREPARATION OF CRACKING CATALYST SUITABLE FOR ENHANCING YIELDS OF LIGHT OLEFINS

Abstract

The present invention relates to a fluid catalytic cracking additive composition for cracking of heavy hydrocarbon feed stocks and process for preparing the additive. The additive is suitable for enhancing yields of light olefins such as propylene, isobutylene, LPG and reduces the bottom yields. The invention specifically relates to a fluid catalytic cracking additive composition comprising a pentasil zeolite, zeolites having pore size in a range of 5.4-7.7 , alumina, colloidal silica, kaolin clay, and phosphate, wherein the zeolites having pore size in the range of 5.4-7.7 is present in an amount of 1 to 10 wt % with respect to the total amount of the pentasil zeolite and zeolite having the pore size in the range of 5.4-7.7 .

Claims

1. A fluid catalytic cracking additive composition comprising: 1-50 wt % pentasil zeolite; 0.01-5 wt % of zeolite having the pore size in a range of 5.4-7.7 ; 0-15 wt % alumina; 5-20 wt % colloidal silica; 10-60 wt % kaolin clay; and 5-15 wt % phosphate, each based on the total amount of the fluid catalytic cracking additive composition.

2. The fluid catalytic cracking additive composition of claim 1, wherein the pentasil zeolite and zeolite having the pore size in the range of 5.4-7.7 having the silica alumina ratio ranging from 8 to 500.

3. The fluid catalytic cracking additive composition of claim 1 wherein the zeolites having pore size in the range of 5.4-7.7 is present in an amount of 1 to 10 wt % with respect to the total amount of the pentasil zeolite and zeolite having the pore size in the range of 5.4-7.7 .

4. The fluid catalytic cracking additive composition of claim 1 wherein the pentasil zeolite is selected from the group consisting of ZSM-5 Zeolite, ZSM-11 Zeolite, ZSM-12 Zeolite, ZSM-22 Zeolite, ZSM-23 Zeolite, and ZSM-35 Zeolite.

5. The fluid catalytic cracking additive composition of claim 1 wherein the zeolite having pore size in the range of 5.4-7.7 is selected from the group consisting of beta zeolite, mordenite zeolite, and ferrirete zeolite.

6. The fluid catalytic cracking composition of claim 1 wherein the fluid catalytic cracking additive composition preferably comprises ZSM-5 Zeolite and beta zeolite.

7. The fluid catalytic cracking additive composition of claim 1, wherein the fluid catalytic cracking additive composition is in the form of micro-spheroidal particles with an average particle size of 80-100 micron having an ABD above 0.75 g/cm.sup.3, and having an attrition index below 5.

8. The fluid catalytic cracking additive composition of claim 1 wherein the additive has propylene selectivity up to 12 wt %, LPG selectivity up to 28 wt %, and isobutylene selectivity up to 5 wt % when used at 5 wt % concentration in a base catalyst.

9. The fluid catalytic cracking additive composition of claim 1 having an isobutylene selectivity in total C4 is in the range of 35-40%.

10. A process for preparing a fluid catalytic cracking additive composition comprising the steps of: a) preparing a slurry of an alumina and peptizing the slurry to form an alumina gel; b) preparing a phosphated pentasil zeolite slurry; c) dispersing a zeolite having pore size in the range of 5.4-7.7 in water to form a zeolite slurry; d) preparing a clay-phosphate slurry by adding a slurry of kaolin clay with a source of phosphate; e) adding the alumina gel of step (a) with the phosphated pentasil zeolite slurry of step (b) and the zeolite slurry of step (c) to the clay-phosphate slurry of step (d) to form an alumina-phosphated zeolite-clay-phosphate slurry; f) adding colloidal silica to the alumina-phosphated zeolite-clay-phosphate slurry of step (e) to form a catalyst precursor slurry; and g) spray drying and calcining the catalyst precursor slurry to obtain the fluid catalytic cracking additive composition.

11. The process as claimed in claim 10, wherein the pentasil zeolite is used in an amount of 1 to 50 wt. % and zeolites having pore size in the range of 5.4-7.7 is used in an amount of 0.01 to 5 wt %, with respect to the total amount of ingredients used in preparing the fluid catalytic cracking additive composition.

12. The process as claimed in claim 10, wherein the zeolites having pore size in a range of 5.4-7.7 is present in an amount of 1 to 10 wt % with respect to the total amount of the pentasil zeolite and zeolite having the pore size in the range of 5.4-7.7 .

13. The process as claimed in claim 10, wherein the pentasil zeolite is selected from the group consisting of ZSM-5 Zeolite, ZSM-11 Zeolite, ZSM-12 Zeolite, ZSM-22 Zeolite, ZSM-23 Zeolite, and ZSM-35 Zeolite.

14. The process as claimed in claim 10, wherein the zeolite having pore size in the range of 5.4-7.7 is selected from the group consisting of beta zeolite, mordenite zeolite and ferrirete zeolite.

15. The process as claimed in claim 10, wherein the zeolite used to prepare the fluid catalytic cracking additive composition preferably comprises ZSM-5 Zeolite and beta zeolite.

16. The process as claimed in claim 10, wherein the fluid catalytic cracking additive composition is in the form of micro-spheroidal particles having an average particle size of 80-100 micron, having an ABD above 0.75 g/cm.sup.3, and having an attrition index below 5.

17. The process as claimed in claim 10, wherein the additive has propylene selectivity up to 12 wt %, LPG selectivity up to 28 wt %, and isobutylene selectivity up to 5 wt % when used at 5 wt % concentration in a base catalyst.

18. The process as claimed in claim 10, wherein the isobutylene selectivity in total C4 is in the range of 35-40%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0046] The catalyst composition of present invention is mainly used for enhancing olefin yield i.e. ethylene, propylene, isobutylene & LPG from heavy hydrocarbon feed stock. The catalyst composition is used to enhance olefin yield during fluid catalytic cracking (FCC). The feedstock includes Coker gasoline, Coker Fuel Oil (CFO), hydro cracker bottom, Vacuum Gas Oil (VGO), Heavy Vacuum Gas Oil (HVGO), Vacuum Residue, Residue Coker Oil (RCO), Once Through Hydrocracker Unit Bottom (OHCUB) and mixtures thereof.

[0047] According to the main objective of the invention is to develop a catalyst where the cracking function is modified through the inclusion of additives for cracking function that ultimately converts gasoline range hydrocarbons to light olefins, e.g., propylene, isobutylene and LPG. Unless expressly indicated otherwise, light olefins is meant to refer to C.sub.3 and C.sub.4 olefins.

[0048] More specifically, the formulation of this additive composition according to the invention comprises: [0049] 1-50 wt % pentasil zeolite, [0050] 0.01-5 wt % of zeolites having pore size in the range of 5.4-7.7 like beta, mordenite, ferrirete zeolite etc., [0051] 0-15 wt % alumina, [0052] 5-20 wt % colloidal silica, [0053] 10-60 wt % clay and [0054] 5-15 wt % phosphate.

[0055] According to the other embodiments of the invention is to develop a process for the preparation of isobutylene selective catalyst particles comprising a medium pore pentasil zeolite in combination with zeolite having pore size in the range of 5.4-7.7 like beta, mordenite, ferrirete zeolite etc., which are bonded with clay-phosphate-silica-alumina binder.

[0056] In an embodiment of the present invention, the pentasil zeolite selected from a group comprising of ZSM-5 Zeolite, ZSM-11 Zeolite, ZSM-12 Zeolite, ZSM-22 Zeolite, ZSM-23 Zeolite, and ZSM-35 Zeolite.

[0057] Further, another objective of the present invention is modification of acid sites of pentasil zeolite prior to incorporation in clay-phosphate binder as well as incorporation of zeolite having pore size in the range of 5.4-7.7 in such a way that it can produce predominantly propylene, LPG and iso-butylene.

[0058] Thus developed product has ABD above 0.75 g/cm.sup.3 & Attrition Index below 5. This additive can be used from 1-20 wt % concentration in the main FCC catalyst. The additive is suitable for enhancing yields of light olefins such as propylene, LPG, iso-butylene and reduces the bottom yields.

[0059] Typical methodology to prepare the additive formulation is summarized in Table 2B. The quantities of the raw materials are varied in line with the additive compositions as mentioned in Table 2B.

[0060] Pural SB grade alumina (SASOL, Germany) (having loss on ignition of 24 wt %) was made into a slurry with of Demineralised (DM) water. The slurry was peptized with formic acid (85% concentration) to form alumina gel. The required amount of ZSM-5 zeolite (loss on ignition 12 wt %) having silica to alumina molar ratio of 30 was stabilized with Di-ammonium hydrogen phosphate (DAHP). The pH of phosphated zeolite slurry was found to be in the range of 7-8. The beta zeolite (loss on ignition 10 wt %) having silica to alumina molar ratio of 20 was dispersed in to DM water to form a beta zeolite slurry. Further, kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with DM water and kept under vigorous stirring while ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel, phosphated zeolite slurry and beta zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally, ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 h to produce final catalyst precursor slurry. The final slurry having a pH of about 2.5 to 3.5 was spray dried in a counter current spray drier having two fluid nozzle. Spray dried product was calcined at 500 C.

[0061] Calcined catalyst was impregnated with 3500 ppm of Nickel and 6500 ppm of Vanadium and steam deactivated at 750 C. for 3 h.

[0062] Steam deactivated additives were evaluated in an ACE micro reactor employing a resid FCC feed having physical properties shown in Table 1. For performance evaluation, 5 wt % of ZSM-5 additive was mixed with 95 wt % equilibrated RFCC catalysts and conducted reaction at a temperature of 510 C. in ACE MAT unit.

Example-1

[0063] 65.79 gm of Pural SB grade alumina (having loss on ignition of 24 wt %) was made into a slurry with 198 gm of Demineralised (DM) water. The slurry was peptized with 6 gm of formic acid (85% concentration) to form an alumina gel. 83.41 gm of DAHP was dissolved in 512 gm of DM water after that further 284.09 gm of ZSM-5 zeolite (loss on ignition 12 wt %) having silica to alumina molar ratio of 30 was slurred to form phosphated zeolite slurry having pH of 7.8. 552.36 gm of kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with 662 gm DM water and kept under vigorous stirring while 84.95 gm of ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel and phosphated zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally 333.33 gm of ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 hr to produce final catalyst precursor slurry. The final slurry having a pH of about 2.6 was spray dried in a counter current spray drier having two fluid nozzle. Spray dried product was calcined at 500 C.

[0064] Calcined catalyst showed ABD of 0.76 g/cc and attrition index of 4.3. Calcined catalyst was impregnated with 3500 ppm of Nickel and 6500 ppm of Vanadium and steam deactivated at 750 C. for 3 hours.

[0065] 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 wt % of ZSM-5 additive was mixed with 95 wt % equilibrated RFCC catalysts and conducted reaction at a temperature of 510 C. in ACE MAT unit. Physical properties along with performance results are shown in a Table 2A & 2B.

Example-2

[0066] 65.79 gm of Pural SB grade alumina (having loss on ignition of 24 wt %) was made into a slurry with 198 gm of Demineralised (DM) water. The slurry was peptized with 6 gm of formic acid (85% concentration) to form an alumina gel. 83.41 gm of DAHP was dissolved in 300 gm of DM water and gradually added 170.45 gm of ZSM-5 zeolite (loss on ignition 12 wt %) having silica to alumina molar ratio of 30 under stirring to form phosphated zeolite slurry having pH of 7.0. Dispersed 111.12 gm of beta zeolite (loss on ignition 10 wt %) having silica to alumina molar ratio of 20 in 212 gm of DM water to form beta zeolite slurry. 552.36 gm of kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with 662 gm DM water and kept under vigorous stirring while 84.95 gm of ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel, phosphated zeolite slurry and beta zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally 333.33 gm of ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 hr to produce final catalyst precursor slurry. The final slurry having a pH of about 3.0 was spray dried in a counter current spray drier having two fluid nozzle. Spray dried product was calcined at 500 C.

[0067] Calcined catalyst showed ABD of 0.77 g/cc and attrition index of 4.5. The catalyst was then deactivated and evaluated in ACE MAT unit as mentioned in Example-1. Physical properties along with performance results are shown in a Table 2A & 2B.

Example 3

[0068] 65.79 gm of Pural SB grade alumina (having loss on ignition of 24 wt %) was made into a slurry with 198 gm of Demineralised (DM) water. The slurry was peptized with 6 gm of formic acid (85% concentration) to form an alumina gel. 83.41 gm of DAHP was dissolved in 300 gm of DM water and gradually added 255.68 gm of ZSM-5 zeolite (loss on ignition 12 wt %) having silica to alumina molar ratio of 30 under stirring to form phosphated zeolite slurry having pH of 7.2. Dispersed 27.78 gm of beta zeolite (loss on ignition 10 wt %) having silica to alumina molar ratio of 20 in 100 gm of DM water to form beta zeolite slurry. 552.36 gm of kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with 662 gm DM water and kept under vigorous stirring while 84.95 gm of ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel, phosphated zeolite slurry and beta zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally 333.33 gm of ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 hr to produce final catalyst precursor slurry. The final slurry having a pH of about 3.0 was spray dried in a counter current spray drier having two fluid nozzles. Spray dried product was calcined at 500 C.

[0069] Calcined catalyst showed ABD of 0.78 g/cc and attrition index of 4.2. The catalyst was then deactivated and evaluated in ACE MAT unit as mentioned in Example-1. Physical properties along with performance results are shown in a Table 2A & 2B.

Example-4

[0070] 65.79 gm of Pural SB grade alumina (having loss on ignition of 24 wt %) was made into a slurry with 198 gm of Demineralised (DM) water. The slurry was peptized with 6 gm of formic acid (85% concentration) to form an alumina gel. 83.41 gm of DAHP was dissolved in 300 gm of DM water and gradually added 269.89 gm of ZSM-5 zeolite (loss on ignition 12 wt %) having silica to alumina molar ratio of 30 under stirring to form phosphated zeolite slurry having pH of 7.0. Dispersed 13.89 gm of beta zeolite (loss on ignition 10 wt %) having silica to alumina molar ratio of 20 in 100 gm of DM water to form beta zeolite slurry. 552.36 gm of kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with 662 gm DM water and kept under vigorous stirring while 84.95 gm of ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel, phosphated zeolite slurry and beta zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally 333.33 gm of ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 hr to produce final catalyst precursor slurry. The final slurry having a pH of about 3.1 was spray dried in a counter current spray drier having two fluid nozzles. Spray dried product was calcined at 500 C.

[0071] Calcined catalyst showed ABD of 0.77 g/cc and attrition index of 4.1. The catalyst was then deactivated and evaluated in ACE MAT unit as mentioned in Example-1. Physical properties along with performance results are shown in a Table 2A & 2B.

Example-5

[0072] 65.79 gm of Pural SB grade alumina (having loss on ignition of 24 wt %) was made into a slurry with 198 gm of Demineralised (DM) water. The slurry was peptized with 6 gm of formic acid (85% concentration) to form an alumina gel. 83.41 gm of DAHP was dissolved in 512 gm of DM water after that further 277.77 gm of beta zeolite (loss on ignition 10 wt %) having silica to alumina molar ratio of 20 was slurred in it to form phosphated zeolite slurry having pH of 7.0. 552.36 gm of kaolin clay (having loss on ignition 14.91 wt %) was made into a slurry with 662 gm DM water and kept under vigorous stirring while 84.95 gm of ortho-phosphoric acid (concentration 85 wt %) was added. Earlier prepared alumina gel and phosphated zeolite slurry were added to the clay-phosphate slurry one after another under vigorous stirring. Finally 333.33 gm of ammonium polysilicate was added to this alumina-phosphated zeolite-clay-phosphate slurry and was kept under stirring for 1 hr to produce final catalyst precursor slurry. The final slurry having a pH of about 3.1 was spray dried in a counter current spray drier having two fluid nozzles. Spray dried product was calcined at 500 C.

[0073] Calcined catalyst showed ABD of 0.71 g/cc and attrition index of 5.1. The catalyst was then deactivated and evaluated in ACE MAT unit as mentioned in Example-1. Physical properties along with performance results are shown in a Table 2A & 2B.

Properties of Feed Employed for Performance Evaluation of Catalyst Prepared Under Examples-1 to 5 is Given Below Table-1:

[0074]

TABLE-US-00001 TABLE 1 Feed properties Sr No Attributes Unit Value 1 Density @ 15 C. g/cc 0.887 2 Kinematic Viscosity @ Cst 7.4 100 C. 3 Distillation, D-1160 4 IBP C. 162 5 5% C. 267 6 30% C. 370 7 50% C. 409 8 70% C. 457 9 Sulphur wt % 1.72 10 Total N2 ppm 860 11 CCR wt % 3.3 12 V ppm 23 13 Ni ppm 9 14 Na ppm 1.8 15 Fe ppm 2.4

Physicochemical Properties & Performance Data of Additive Prepared as Per Examples 1 to 5 are Given in Table-2 & 2B

[0075]

TABLE-US-00002 TABLE 2A Performance results of additive prepared as per examples 1 to 5 Base catalyst + 5 wt % Base Base Base Base catalyst + Additive catalyst + 5 wt % catalyst + 5 wt % catalyst + 5 wt % 5 wt % of Additive of Additive of Additive of Additive of Example-1 Example-2 Example-3 Example-4 Example-5 Cat/oil 4.51 4.51 4.51 4.51 4.51 Conversion, 62.32 62.72 64.61 65.7 63.32 216 Coke 4.5 4.49 4.44 4.92 4.47 DG 1.94 1.74 2.01 2.33 1.43 LPG 24.23 22.42 26.78 27.65 19.7 Propylene 9.55 8.48 10.31 11.10 8.84 iso-butylene 3.49 3.44 4.38 4.29 3.36 Total C4 9.57 9.27 11.13 10.83 8.83 olefins Gasoline (C5-150) 22.06 23.88 21.78 22.15 26.6 HN (150-220) 11.10 11.10 9.60 8.61 11.13 LCO (220-370) 16.72 17.32 16.6 16.44 18.22 Bottom (370+) 19.45 19.05 18.79 17.90 18.45 iso-butylenes/ 36.47 37.11 39.35 39.61 38.05 C4 olefins

TABLE-US-00003 TABLE 2B Additive composition and their physical properties Additive Additive Additive Additive Additive Example-1 Example-2 Example-3 Example-4 Example-5 Additive composition PSB, wt % 5 5 5 5 5 ZSM-5 25 15 22.5 23.75 0 Zeolite, wt % Beta 0 10 2.5 1.25 25 Zeolite, wt % Clay, wt % 47 47 47 47 47 DAHP as 6 6 6 6 6 PO4 H3PO4 (as 7 7 7 7 7 PO4), wt % APS, as 10 10 10 10 10 SiO2 Additive Physical properties ABD, gm/cc 0.76 0.77 0.78 0.77 0.71 Attrition 4.3 4.5 4.2 4.1 5.1 Index
The examples 3 & 4 are prepared based on present invention. Performance of the additive prepared under these examples (3 & 4) showed higher selectivity towards light olefins such as LPG, propylene and iso-butylene.