ZSM-5 additive activity enhancement by improved zeolite and phosphorus interaction

Abstract

A catalytic additive comprising an intermediate pore zeolite, such as ZSM-5 is treated so as to improve propylene yields when the additive is included in a FCC catalytic inventory by first treating the zeolite with a phosphorus compound to incorporate the phosphorus in the zeolite, and mixing the P-treated zeolite with a matrix component comprising kaolin and another phosphorus-containing compound.

Claims

1. A process for producing a first attrition resistant catalyst, the process comprising: i) mixing a first ZSM-5 zeolite with a first aqueous phosphorus-containing solution so as to form a phosphorus-treated ZSM-5 zeolite having from 2 wt. % to 6 wt. % P.sub.2O.sub.5 incorporated therein; ii) spray-drying the phosphorus-treated ZSM-5 zeolite to form a spray-dried, phosphorus-treated ZSM-5 zeolite; iii) calcining the spray-dried, phosphorus-treated ZSM-5 zeolite at a first temperature below 650 C. to form a calcined, phosphorus-treated ZSM-5 zeolite; iv) mixing a first aqueous slurry of the calcined, phosphorus-treated ZSM-5 zeolite with a second aqueous slurry comprising alumina and kaolin to form a slurry mixture, wherein the first aqueous slurry has a first solids content of 30-45 wt. %, the first aqueous slurry having been milled until at least 90% of particles of the first aqueous slurry are less than 3 microns; v) spray-drying the slurry mixture with a second aqueous phosphorus-containing solution into microspheres having a size of from about 20 to 200 microns, wherein the second aqueous phosphorus-containing solution is added to the slurry mixture prior to entering a spray dryer such that a contact time of the second aqueous phosphorus-containing solution and the slurry mixture is less than 20 seconds; vi) calcining the microspheres at a second temperature from 150 C. to 815 C., wherein the microspheres contain about 10-25 wt. % P.sub.2O.sub.5; and vii) combining between about 0.1 wt % and 30 wt % of the microspheres, based on total weight of the first attrition resistant catalyst, with a FCC base catalyst to form the first attrition resistant catalyst, wherein the FCC base catalyst comprises pore openings of greater than about 7 angstroms, wherein a first propylene yield, at 75% conversion, of the first attrition resistant catalyst prepared according to i) through vii) is greater than a second propylene yield of a second attrition resistant catalyst prepared according to iv) through vii) with iv) referring to a second ZSM-5 zeolite that was not subjected to i) through iii).

2. The process of claim 1, wherein the iii) calcining of the spray-dried, phosphorus-treated ZSM-5 zeolite is at the first temperature from 350 C. to 650 C. in presence of 15-25% steam to form the calcined, phosphorus-treated ZSM-5 zeolite, and wherein the second temperature is from 150 C. to 680 C.

3. The process of claim 1, wherein the microspheres contain at least 25 wt. % of the first ZSM-5 zeolite.

4. The process of claim 1, wherein the i) mixing of the first ZSM-5 zeolite with the first aqueous phosphorus-containing solution is to incorporate from 4 wt. % to 6 wt. % P.sub.2O.sub.5 therein, and wherein the microspheres contain 10-15 wt. % P.sub.2O.sub.5.

5. The process of claim 2, wherein the slurry mixture is further formed by adding, a high density component to the first aqueous slurry, the high density component having a density greater than 2.8 g/cc.

6. The process of claim 5, wherein the high density component has a first BET surface area of less than 50 m.sup.2/g.

7. The process of claim 5, wherein the slurry mixture is further formed by adding a reactive alumina species to the first aqueous slurry, the reactive alumina species having a second BET surface area of greater than 50 m.sup.2/g.

8. The process of claim 7, wherein the second BET surface area is from about 140 to 400 m.sup.2/g.

9. The process of claim 7, wherein the reactive alumina species is a transitional alumina.

10. The process of claim 1, wherein at least one of the first aqueous phosphorus-containing solution or the second aqueous phosphorus-containing solution is phosphoric acid or ammonium phosphate.

11. The process of claim 7, wherein each of the microspheres has a composition comprising 25 to 50 wt. % ZSM-5, 10 to 15 wt. % P.sub.2O.sub.5, 12 to 25 wt. % alumina, and 20 to 35 wt. % kaolin.

12. The process of claim 1, wherein the first ZSM-5 zeolite is an organic-templated ZSM-5 zeolite.

13. The process of claim 1, wherein the first ZSM-5 zeolite has a SiO.sub.2/Al.sub.2O.sub.3 molar ratio from 25 to 28.

14. The process of claim 1, wherein the slurry mixture is further formed by adding a mixture of aluminas comprising alpha alumina and dispersed boehmite to the first aqueous slurry.

15. The process of claim 1, wherein the second aqueous slurry has a second solids content of 60-75 wt. %.

16. The process of claim 1, wherein the first attrition resistant catalyst comprises 5 to 23.5 wt. % of the microspheres and up to 10 wt. % inert kaolin microspheres.

17. A process for producing a first attrition resistant catalyst additive in form of first microspheres having a size of from about 20 to 200 microns, wherein the first microspheres contain at least 25 wt. % of a first ZSM-5 zeolite and from 10 to 15 wt. % P.sub.2O.sub.5, the process comprising: i) mixing the first ZSM-5 zeolite with a first aqueous phosphorus-containing solution to form a phosphorus-treated ZSM-5 zeolite having from 4 wt. % to 6 wt. % P.sub.2O.sub.5 incorporated therein; ii) spray-drying the phosphorus-treated ZSM-5 zeolite to form a spray-dried, phosphorus-treated ZSM-5 zeolite; iii) calcining the spray-dried, phosphorus-treated ZSM-5 zeolite at a first temperature below 650 C. to form a calcined, phosphorus-treated ZSM-5 zeolite; iv) combining a first aqueous slurry of the calcined, phosphorus-treated ZSM-5 zeolite, a second aqueous slurry of kaolin, a high density component of greater than 2.8 g/cc, and a reactive alumina species having a BET surface area of greater than 50 m.sup.2/g to form a slurry mixture, wherein the first aqueous slurry has a first solids content of 30-45 wt. %, the first aqueous slurry having been milled until at least 90% of particles of the first aqueous slurry are less than 3 microns; v) spray-drying the slurry mixture with a second aqueous phosphorus-containing solution to form a spray-dried mixture, wherein the second aqueous phosphorus-containing solution is added to the slurry mixture prior to entering a spray dryer such that a contact time of the second aqueous phosphorus-containing solution and the slurry mixture is less than 20 seconds; and vi) calcining the spray-dried mixture at a second temperature from 150 C. to 680 C., wherein a greater propylene yield is exhibited by a first attrition resistant catalyst comprising the first microspheres prepared according to i) through vi) as compared to a propylene yield exhibited by a second attrition resistant catalyst comprising second microspheres prepared according to iv) through vi) with iv) referring to a second ZSM-5 zeolite that was not subjected to i) through iii), the first attrition resistant catalyst being a combination of between about 0.1 wt % and 30 wt % of the first microspheres and a FCC base catalyst having pore opening of greater than about 7 angstroms, wherein the wt % is based on total weight of the first attrition resistant catalyst.

18. A process for producing a first attrition resistant catalyst additive in form of first microspheres having a size of from about 20 to 200 microns, the process comprising: i) treating an organic-templated ZSM-5 zeolite with a first aqueous phosphorus-containing solution to form a phosphorus-treated ZSM-5 zeolite having from 2 wt. % to 6 wt. % P.sub.2O.sub.5 incorporated therein; ii) spray-drying the phosphorus-treated ZSM-5 zeolite to form a spray-dried, phosphorus-treated ZSM-5 zeolite; iii) calcining the spray-dried, phosphorus-treated ZSM-5 zeolite at a first temperature below 650 C. to form a calcined, phosphorus-treated ZSM-5 zeolite; iv) mixing a first aqueous slurry of the calcined, phosphorus-treated ZSM-5 zeolite, a second aqueous slurry of kaolin, and alumina to form a mixture, wherein the first aqueous slurry has a first solids content of 30-45 wt. %, the first aqueous slurry having been milled until at least 90% of particles of the first aqueous slurry are less than 3 microns; v) spray-drying the mixture into the first microspheres, wherein a second aqueous phosphorus-containing solution is added to the mixture prior to entering a spray dryer such that a contact time of the second aqueous phosphorus-containing solution and the mixture is less than 20 seconds; and vi) calcining the first microspheres at a temperature from 150 C. to 815 C., wherein the first microspheres contain about 10-25 wt. % P.sub.2O.sub.5, wherein a greater propylene yield is exhibited by a first attrition resistant catalyst comprising the first microspheres prepared according to i) through vi) as compared to a propylene yield exhibited by a second attrition resistant catalyst comprising second microspheres prepared according to iv) through vi) with iv) referring to a second ZSM-5 zeolite that was not subjected to i) through iii), the first attrition resistant catalyst being a combination of between about 0.1 wt % and 30 wt % of the first microspheres and a FCC base catalyst having pore opening of greater than about 7 angstroms, wherein the wt % is based on total weight of the first attrition resistant catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) FCC catalysts are often blends of microspheres containing a catalytically active component (microspheres containing zeolite Y) and additives (microspheres composed of highly calcined kaolin with low surface area, with and without zeolite, such as ZSM-5). During the process of fluid cracking, the catalyst components attrit forming fines. While formation of fines generally is considered undesirable, formation of particles less than 2.6 microns (microfines) is considered particularly undesirable as these can lead to operational problems in some FCC units while fines less than 2 microns can be important contributors to stack opacity problems. The formation of attrition resistant active components and additives is, thus, important in reducing fines formation. The addition of active zeolites, such as zeolite Y or ZSM-5 into an attrition-resistant kaolin-containing microspheres is accordingly desirable.

(2) An active catalytic zeolite such as ZSM-5 can be incorporated into the kaolin slurry by mixing therewith an aqueous slurry of the zeolite catalyst. While ZSM-5 is preferred, other known shape-selective zeolites useful for FCC are known and are characterized by an intermediate pore size (e.g., pore size of from about 4 to about 7 angstroms). Besides ZSM-5, ZSM-11 can also be used. Methods for preparing the intermediate pore ZSM zeolite catalysts are well known in the art. Both organic templated and untemplated ZSM-5 are useful in this invention. Organic templated ZSM-5 treated in accordance with this invention has been found to improve propylene yield. The ZSM-5 catalyst is preferably prepared in an aqueous slurry containing from 10-40% by weight solids. Sufficient ZSM-5 is provided to yield a microsphere that contains at least 25 wt. % of the catalytic active component. Amounts of at least 30 wt. % are preferred.

(3) In accordance with the invention, prior to incorporation with a kaolin slurry, the ZSM-5 zeolite is treated with a phosphorus containing compound (phosphoric acid or ammonium phosphate). For example, 2 to 10 weight %, preferably 4 to 6 weight % P.sub.2O.sub.5 on ZSM-5 is prepared by mixing ZSM-5 with a solution of a phosphorus compound. The mixture is then spray dried, followed by a mild calcination below 650 C., preferably in the presence of steam. The P treated ZSM-5 is made into a 30 to 45 weight % aqueous slurry, passed through a media mill until 90% of the particles are less than 3 microns. The attrition resistant ZSM-5 additive is prepared by mixing the P treated ZSM-5 slurry with a hydrous kaolin slurry having a solids content of 60-75%, and preferably, a mixture of aluminas, including alpha alumina and dispersed boehmite. This slurry mixture can then be spray dried with the addition of phosphoric acid or ammonium phosphate solution (20-30 wt. % concentration) via an in-line mixer just prior to entering the spray dryer with a contact time of the phosphoric acid and kaolin/P-ZSM-5 zeolite/aluminas of less than 20 seconds. Likewise, the kaolin-containing slurry can be mixed thoroughly with the slurry of ZSM-5, alumina and phosphorus compounds prior to spray drying for several minutes or more. The final ZSM-5 additive has a typical composition of 25 to 50 weight % ZSM-5; 10-15 weight % P.sub.2O.sub.5; 12-25 weight % alumina; 20-35 weight % kaolin.

(4) Prior to mixing the P-treated ZSM-5 slurry with the kaolin slurry, it is preferred to add the reactive alumina and other high density inorganic components into the P-ZSM-5 slurry. The high density component can be characterized as an inactive component and have a low BET surface area and high density. Typically, the inorganic component which is added to the catalytic slurry will have a BET surface area of less than 50 m.sup.2/g and a density greater than 2.8 g/cc. Preferably the high density unreactive component will have a BET surface area less than 25 m.sup.2/g and a density greater than 3.0 g/cc. Most preferably the high density unreactive component will have a BET surface area less than 25 m.sup.2/g and a density greater than 3.5 g/cc. By density it is meant the solid or crystal density of the solid material excluding pores having a diameter of greater than 20 angstroms. Examples of the inactive components include alpha-alumina and inorganic oxides or silicates such as zirconia, titania, zirconium silicate, mullite, metal carbides such as silicon carbide, metal nitrides such as silicon nitride, and other inorganic materials which have the desired low surface area and high density. Typically these materials can be added in solid form into the P-ZSM-5-containing slurry. Levels of the inactive component are such as to provide a final level of unreactive alumina or other unreactive component in the microsphere in amounts ranging from 3-25 weight %, more typically from about 4-10% by weight.

(5) Also added to the microspheres of the present invention are reactive alumina species. These reactive alumina species are added to the P-ZSM-5 slurry and are characterized as having a total surface area (BET) of greater than 50 m.sup.2/g. Preferably, reactive aluminas of much higher surface areas of from about 140 to 400 m.sup.2/g can be used. These reactive aluminas can typically include boehmite including dispersible boehmite (sometimes referred to as pseudoboehmite), gibbsite, and other transitional aluminas. Particularly useful is a dispersible boehmite which forms fine particles in acid such as formic acid or surfactants. Thus, the dispersible boehmite can be first dispersed in an aqueous solution of acid or surfactants and then added to the P-ZSM-5 catalyst slurry. Levels of the reactive high surface area alumina which can be added include levels that will provide from about 2-20 wt. % of the reactive alumina in the final microsphere. Typical amounts of the reactive alumina will range from 4-8 wt. %. The total weight of alumina, whether active or inactive, which can be added to and form part of the microsphere of this invention can range from at least 5 wt. % and typically will range from about 8-25 wt. %. A total alumina content, not including the alumina of the kaolin or the zeolite, in other words the amount of alumina in the form of added unreactive and reactive alumina, in amounts of greater than 10%, have been found most useful, including amounts from about 12-20 wt. %.

(6) The phosphoric acid is preferably added to the mixed slurry as an aqueous solution. Thus, the phosphoric acid concentration can be from 5 to 40% by weight; 20 to 30% concentrations are preferred. Satisfactory results have been attained using sufficient phosphoric acid to produce products analyzing 5-25% P.sub.2O.sub.5, expressed on a volatile free weight basis. Microsphere products containing 10-15% P.sub.2O.sub.5 are typical.

(7) Calcination can be carried out in a standard laboratory high temperature oven. Alternatively, the calcination can be carried out on a large scale in a rotary kiln or other commercial scale calciner.

(8) The material is calcined at temperatures of from about 150 C.-815 C., with a range of 150 C.-680 C. preferred. Time at temperature is important only insofar as sufficient time must be provided for the entire mass being calcined to reach the desired calcination temperature. Thus, adequate heating can be accomplished in relatively short times provided samples are small.

(9) An FCC catalyst (primary or additive) is added to an FCC process as a powder (20-200 microns) and generally is suspended in the feed and propelled upward in a reaction zone. A relatively heavy hydrocarbon feedstock, e.g., a gas oil, is admixed with a catalyst to provide a fluidized suspension and cracked in an elongated reactor, or riser, at elevated temperatures to provide a mixture of lighter hydrocarbon products. The gaseous reaction products and spent catalyst are discharged from the riser into a separator, e.g., a cyclone unit, located within the upper section of an enclosed stripping vessel, or stripper, with the reaction products being conveyed to a product recovery zone and the spent catalyst entering a dense catalyst bed within the lower section of the stripper. After stripping entrained hydrocarbons from the spent catalyst, the catalyst is conveyed to a catalyst regenerator unit. The fluidizable catalyst is continuously circulated between the riser and the regenerator and serves to transfer heat from the latter to the former thereby supplying the thermal needs of the cracking reaction which is endothermic.

(10) Gas from the FCC main-column overhead receiver is compressed and directed for further processing and separation to gasoline and light olefins, with C.sub.3 and C.sub.4 product olefins being directed to a petrochemical unit or to an alkylation unit to produce a high octane gasoline by the reaction of an isoparaffin (usually iso-butane) with one or more of the low molecular weight olefins (usually propylene and butylene). Ethylene would be recovered in a similar fashion and processed to additional petrochemical units.

(11) The FCC conversion conditions include a riser top temperature of from about 500 C. to about 595 C., preferably from about 520 C. to about 565 C., and most preferably from about 530 C. to about 550 C.; catalyst/oil weight ratio of from about 3 to about 12, preferably from about 4 to about 11, and most preferably from about 5 to about 10; and catalyst residence time of from about 0.5 to about 15 seconds, preferably from about 1 to about 10 seconds.

(12) The ZSM-5 catalyst of this invention is preferably used as an additive to the cracking processes which employ conventional large-pore molecular sieve component. The same applies for processes other than cracking processes. When used as an additive the catalyst of this invention is typically present in an amount between about 0.1% by weight and 30% by weight of the total catalyst inventory, and more typically in an amount between about 1% by weight and 15% by weight of the total. Cracking catalysts are large pore materials having pore openings of greater than about 7 Angstroms in effective diameter. Conventional large-pore molecular sieve include zeolite X (U.S. Pat. No. 2,882,442); REX; zeolite Y (U.S. Pat. No. 3,130,007); Ultrastable Y (USY) (U.S. Pat. No. 3,449,070); Rare Earth exchanged Y (REY) (U.S. Pat. No. 4,415,438); Rare Earth exchanged USY (REUSY); Dealuminated Y (DeAl Y) (U.S. Pat. Nos. 3,442,792 and 4,331,694); Ultrahydrophobic Y (UHPY) (U.S. Pat. No. 4,401,556); and/or dealuminated silicon-enriched zeolites, e.g., LZ-210 (U.S. Pat. No. 4,678,765). Preferred are higher silica forms of zeolite Y. ZSM-20 (U.S. Pat. No. 3,972,983); zeolite Beta (U.S. Pat. No. 3,308,069); zeolite L (U.S. Pat. Nos. 3,216,789 and 4,701,315); and naturally occurring zeolites such as faujasite, mordenite and the like may also be used (with all patents above in parentheses incorporated herein by reference). These materials may be subjected to conventional treatments, such as impregnation or ion exchange with rare earths to increase stability. In current commercial practice most cracking catalysts contain these large-pore molecular sieves. The preferred molecular sieve of those listed above is a zeolite Y, more preferably an REY, USY or REUSY. NaphthaMax catalyst from BASF Corp. is a particularly suitable large pore catalyst. Methods for making these zeolites are known in the art.

(13) Other large-pore crystalline molecular sieves include pillared silicates and/or clays; aluminophosphates, e.g., AlPO.sub.4-5, AlPO.sub.4-8, VPI-5; silicoaluminophosphates, e.g., SAPO-5, SAPO-37, SAPO-40, MCM-9; and other metal aluminophosphates. Mesoporous crystalline material for use as the molecular sieve includes MCM-41 and MCM-48. These are variously described in U.S. Pat. Nos. 4,310,440; 4,440,871; 4,554,143; 4,567,029; 4,666,875; 4,742,033; 4,880,611; 4,859,314; 4,791,083; 5,102,643; and 5,098,684, each incorporated herein by reference.

(14) The large-pore molecular sieve catalyst component may also include phosphorus or a phosphorus compound for any of the functions generally attributed thereto, such as, for example, attrition resistance, stability, metals passivation, and coke make reduction.

EXAMPLES

Comparative Example 1

(15) A ZSM-5 additive was prepared in a similar way as described in Example 1 of BASF patent U.S. Pat. No. 7,547,813. ZSM-5 having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 28 was slurried with water and milled to a particle size of 90% <3 micron to obtain 30 wt. % solids slurry. The ZSM-5 additive was prepared by mixing a 70 wt. % hydrous kaolin slurry with a 30 wt. % ZSM-5 slurry and a mixture of aluminas, including alpha alumina and dispersed boehmite. This mixture was then spray dried with addition of phosphoric acid (28 wt. %) via an in-line mixer just prior to entering the spray dryer. The contact time of the phosphoric acid and kaolin/ZSM-5 zeolite/aluminas is typically less than 20 seconds. The additive was then calcined at 677 C. for 2 hours. The spray dried and calcined additive had a composition as listed in Table 1.

Example 1

(16) The purpose of this example is to illustrate that the P treated ZSM-5 preparation provides a ZSM-5 additive with increased propylene yield for petrochemical FCC process.

(17) 5.5 wt. % P.sub.2O.sub.5 on ZSM-5 having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 28 was prepared by mixing ZSM-5 with an aqueous solution of phosphoric acid. The mixture was then spray dried, followed by a mild calcination at 593 C. for 40 min in the presence of 25% steam. The P treated ZSM-5 was made into a 30 wt. % aqueous slurry, passed through a media mill until 90% of the particles are less than 3 microns. The ZSM-5 additive was prepared by mixing the P treated ZSM-5 with hydrous kaolin and a mixture of aluminas, including alpha alumina and dispersed boehmite. This slurry mixture was then spray dried with addition of 28 wt. % phosphoric acid via an in-line mixer just prior to entering the spray dryer with a contact time of the phosphoric acid and kaolin/P-ZSM-5 zeolite/aluminas in less than 20 seconds. The additive was then calcined at 677 C. for 2 hours. The final ZSM-5 additive had a composition (wt. %) listed in Table 1.

(18) TABLE-US-00001 TABLE 1 Additive composition (wt. %) Comparative Example (1) Example (1) (wt. %) (wt. %) ZSM-5, 40 40 Total P.sub.2O.sub.5, 13.8 13.2 Reactive Al.sub.2O.sub.3 6.5 6.5 Alpha Al.sub.2O.sub.3 8.5 8.5 Hydrous kaolin 31.2 31.8

Example 2

(19) The catalytic testing of the spray dried ZSM-5 additives described above was performed on an ACE fluidized-bed hydrocarbon cracking reactor using a gas oil feed. The catalyst was comprised of 76.5 wt. % FCC base catalyst and 23.5 wt. % ZSM-5 additive. Both the base catalyst and the ZSM-5 additive were steamed separately at 816 C. for 15 hr in 100% steam prior to testing. The results at a constant conversion of 70 wt. % are presented in Table 2 as wt. %. The results indicated that the additional P treatment of ZSM-5 enhances the activity and propylene yield for the additive with similar composition.

(20) TABLE-US-00002 TABLE 2 Catalytic Data (wt. %) at 70% Conversion Comparative Example (1) Example (1) (wt. %) (wt. %) Ethylene 2.60 2.79 Propylene 13.5 14.2 Butenes 11.9 12.5 Total C2- 3.65 3.73 LPG 31.8 33.5 Gasoline 32.0 30.4 LCO 19.2 19.1 HCO 10.8 10.9 Coke 2.52 2.42 Cat/Oil 8.00 7.71

Comparative Example 2

(21) A ZSM-5 additive was prepared in a similar way as described in Comparative Example 1. The spray dried and calcined additive had a composition as listed in Table 3.

Example 3

(22) The purpose of this example is to illustrate that a small crystal organic template and P treated ZSM-5 preparation provides a ZSM-5 additive with increased propylene yield for petrochemical FCC process.

(23) 4.7 wt. % P.sub.2O.sub.5 on templated, small crystal ZSM-5 having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 25 was prepared by mixing an aqueous solution of diammonium phosphate with the ZSM-5 that still contained an organic template. The mixture was then spray dried, followed by calcination. The calcination included ramping from ambient temperature to 350 C. in 1 hr. followed by a 1 hr. soak at 350 C., then ramping to 550 C. in one hour followed by a 2 hr. soak at 550 C. The P treated ZSM-5 was made into a 30 wt. % aqueous slurry, passed through a media mill until 90% was less than 3 microns. The ZSM-5 additive was prepared by mixing the P treated ZSM-5 with hydrous kaolin and a mixture of aluminas, including alpha alumina and dispersed boehmite. This slurry mixture was then spray dried with addition of 28 wt. % phosphoric acid via an in-line mixer just prior to entering the spray dryer with a contact time of the phosphoric acid and kaolin/P-ZSM-5 zeolite/aluminas of less than 20 seconds. The additive was then calcined at 677 C. for 2 hours. The final ZSM-5 additive had a composition (wt. %) listed in Table 3.

(24) TABLE-US-00003 TABLE 3 Additive composition (wt. %) Comparative Example (2) Example (3) (wt. %) (wt. %) ZSM-5, 40 40 Total P.sub.2O.sub.5, 12.5 12.8 Reactive Al.sub.2O.sub.3 6.5 6.5 Alpha Al.sub.2O.sub.3 8.5 8.5 Hydrous kaolin 32.5 32.2

Example 4

(25) The catalytic testing of the spray dried ZSM-5 additives described above was performed on an ACE fluidized-bed hydrocarbon cracking reactor using a gas oil feed. The catalyst was comprised of 85 wt. % FCC base catalyst, 5 wt. % ZSM-5 additive and 10% inert kaolin microspheres. The base catalyst was steam deactivated for 24 hr. at 788 C. in 100% steam and the ZSM-5 additive at 816 C. for 15 hr in 100% steam prior to testing. The results at a constant conversion of 75 wt. % are presented in Table 4 as wt. %. The results indicated that the additional P treatment of ZSM-5 enhances the activity and propylene yield for the additive with similar composition.

(26) TABLE-US-00004 TABLE 4 Catalytic Data (wt. %) at 75% Conversion Comparative Example (2) Example (3) (wt. %) (wt. %) Ethylene 1.24 1.46 Propylene 11.8 13.1 Butenes 11.5 11.8 Total C2- 2.69 2.86 LPG 29.9 32.1 Gasoline 40.3 37.9 LCO 17.6 17.6 HCO 7.40 7.40 Coke 2.10 2.10 Cat/Oil 9.30 8.83

Comparative Example 3

(27) ZSM-5 having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 28 was slurried with water and milled to a particle size of 90% <3 micron to obtain 30 wt. % solids slurry. The ZSM-5 additive was prepared by mixing 70 wt. % hydrous kaolin slurry with a 30 wt. % ZSM-5 slurry and a mixture of aluminas, including alpha alumina and dispersed boehmite. This mixture was thoroughly mixed with phosphoric acid (28 wt. %) before spray drying. The contact time of the phosphoric acid and kaolin/ZSM-5 zeolite/aluminas varies from several minutes to an hour, depending on the mixing efficiency. The additive was then calcined at 677 C. for 2 hours. The spray dried and calcined additive had a composition as listed in Table 5.

Examples 5A and 5B

(28) The purpose of these examples are to illustrate that another P treated (with either phosphoric acid or diammonium phosphate) ZSM-5 preparation without in-line phosphoric acid injection provides a ZSM-5 additive with increased propylene yield for petrochemical FCC process.

(29) 4.8 and 4.4 wt. % P.sub.2O.sub.5 on ZSM-5 zeolite, having a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 28, were prepared by mixing with an aqueous solution of phosphoric acid or diammonium phosphate, respectively. The mixture was then spray dried, followed by a mild calcination at 500 C. for 2 hr. in the presence of 15% steam. The P treated ZSM-5 was made into a 30 wt. % aqueous slurry, passed through a media mill until 90% is less than 3 microns. The ZSM-5 additive was prepared by mixing the P treated ZSM-5 with hydrous kaolin and a mixture of aluminas, including alpha alumina and dispersed boehmite. This mixture was thoroughly mixed with phosphoric acid (28 wt. %) before spray drying. The contact time of the phosphoric acid and kaolin/P-ZSM-5 zeolite/aluminas varies from several minutes to an hour, depending on the mixing efficiency. The additive was then calcined at 677 C. for 2 hours. The final ZSM-5 additive had a composition (wt. %) listed in Table 5.

(30) TABLE-US-00005 TABLE 5 Additive composition (wt. %) Comparative Example Example Example (3) (5A) (5B) (wt. %) (wt. %) (wt. %) ZSM-5, 40 40 40 Total P.sub.2O.sub.5, 12.9 12.9 12.9 Reactive Al.sub.2O.sub.3 7.5 7.5 7.5 Alpha Al.sub.2O.sub.3 7.5 7.5 7.5 Hydrous kaolin 32.1 32.1 32.1

Example 6

(31) The catalytic testing of the spray dried ZSM-5 additives described above was performed on an ACE fluidized-bed hydrocarbon cracking reactor using a gas oil feed. The catalyst was comprised of 85 wt. % FCC base catalyst, 5 wt. % ZSM-5 additive and 10% inert kaolin microspheres. The base catalyst was steam deactivated for 24 hr. at 788 C. in 100% steam and the ZSM-5 additive at 816 C. for 15 hr in 100% steam prior to testing. The results at a constant conversion of 75 wt. % are presented in Table 6 as wt. %. The results indicated that the additional P treatment of ZSM-5 enhances the activity and propylene yield for the additive with similar composition.

(32) TABLE-US-00006 TABLE 6 Catalytic Data (wt. %) at 75% Conversion Comparative Example (3) Example (5A) Example (5B) (wt. %) (wt. %) (wt. %) Ethylene 1.07 1.23 1.18 Propylene 10.5 11.5 11.1 Butenes 10.9 11.0 11.1 Total C2- 2.46 2.61 2.59 LPG 28.0 29.3 29.0 Gasoline 42.0 40.6 40.9 LCO 17.8 17.7 17.8 HCO 7.20 7.30 7.20 Coke 2.55 2.55 2.53 Cat/Oil 8.34 8.22 8.27