A bifunctional Additive for More Low-Carbon Olefins and Less Slurry and Its Preparation Method and Application Thereof

Abstract

The invention discloses a bifunctional additive for increasing low-carbon olefins and reducing slurry in cracking product, wherein the dry-basis components of said additive is as follows: 40˜55 wt % of phosphorus-containing MFI zeolite, 0˜10 wt % of large pore type Y and Beta zeolites, 3˜20 wt % of inorganic binder, 8˜22 wt % of inorganic matrix composed of alumina and amorphous silica-alumina and 15˜40 wt % of clay. The bifunctional additive is mainly used to facilitate production rate of cracked LPG and increase concentration of propylene in LPG and octane number of produced the gasoline, and at the same time reduce the yield of slurry in the cracking products. The invention also discloses its preparation method and application of said additive.

Claims

1. A bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry, wherein the dry-basis components of said additive is as follows: 40˜55 wt % of phosphorus-containing MFI zeolite, 0˜10 wt % of large pore zeolites, 3˜20 wt % of inorganic binder, 8˜22 wt % of inorganic matrix composed of alumina and amorphous silica-alumina and 15˜40 wt % of clay.

2. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein the molar ratio of SiO.sub.2/Al.sub.2O.sub.3 of said phosphorus-containing MFI zeolite is 10˜50, and the content of P.sub.2O.sub.5 in the zeolite is 1˜5 wt %.

3. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein said large pore zeolite is of Y type and/or Beta type zeolites.

4. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 3, wherein said Y type zeolite is of rare earth-modified Y type zeolite, phosphorus-modified Y type zeolite, rare earth- and phosphorus-modified Y type zeolite, ultra-stable Y type zeolite and/or rare earth-modified ultra-stable Y type zeolite.

5. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein said inorganic binder is of alumina binder, silica binder and/or alumina-silica binder.

6. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein said inorganic matrix is of calcined alumina and/or amorphous alumina-silica, with a total specific surface area of more than 200 m.sup.2/g.

7. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein said clay is of kaolinite, montmorillonite, attapulgite, diatomite and/or sepiolite.

8. A method for making the bifunctional additive according to claim 1, wherein said method comprises the following steps of: spray-drying with phosphorus-containing MFI zeolite, large pore type Y and/or Beta zeolites, inorganic binder, inorganic matrix composed of alumina and/or amorphous alumina-silica and clay as raw materials, and calcining the spray-dried materials at 450° C.˜750° C. for 0.1˜10 h.

9. The bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 1, wherein said additive is applied to fluid catalytic cracking of atmospheric residue, vacuum residue, atmospheric gas oil, vacuum gas oil, straight-run gas oil and/or coker gas oil.

10. The application of the bifunctional additive of producing more low-carbon olefins and simultaneously reducing slurry according to claim 9, wherein the proportion of said additive to total catalyst mass in fluid catalytic cracking unit is 1˜30 wt %.

Description

MOST PREFERRED EMBODIMENTS OF THE INVENTION

[0026] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) with ammonium di-hydrogen phosphate, and then calcining the flash dried material at 500° C. for 2 h to obtain phosphorus-containing ZSM-5 zeolite, wherein P.sub.2O.sub.5 content in the zeolite is 2.7 wt %.

[0027] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) rare earth-modified ultra-stable Y type zeolite (SiO.sub.2/Al.sub.2O.sub.3 molar ratio is 9, and content of RE.sub.2O.sub.3 is 8 wt %) to 5.5 kg deionized water, and stir at high speed for 30 min to obtain phosphorus-containing MFI zeolite suspension.

[0028] Add 2.6 kg (dry-basis) kaolinite to 6 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) of pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. After stirring for 30 min, add 1.4 kg (dry-basis) silicon-alumina binder (with 30 wt % of SiO.sub.2 and 3 wt % of Al.sub.2O.sub.3). Stir for 30 min, and then add the said zeolite suspension. Keep blending for 30 min until the solid content of the final suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Bifunctional additive LOBC-5 for producing more low-carbon olefins and reducing slurry is then obtained.

[0029] The bifunctional additive LOBC-5 has an abrasion index of 1.2 wt %/h, a specific surface area of 213 m.sup.2/g and a P.sub.2O.sub.5 content of 1.08 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to a selected FCC equilibrium catalyst (FCC e-cat). Cracking performance testing result of the mixed catalyst is shown in Table 3.

Comparative Example and Embodiments

[0030] The followings further describe the claims of the invention in details by means of comparative examples and specific embodiments, but with no restrictions.

[0031] In the following embodiments and comparative examples, specific surface areas of catalysts are determined by using the BET low-temperature nitrogen adsorption method, elements and compositions of catalysts are measured with X-ray fluorescence spectrophotometer and abrasion index of catalysts are obtained with abrasion index analyzer.

Comparative Example 1

[0032] Add 3.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 5 kg deionized water while stirring, and continuously stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite (with a specific surface area of 240 m.sup.2/g, same below). Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min and then add a zeolite suspension prepared with 4 kg (dry-basis) H-ZSM-5 zeolite (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) and 4.5 kg deionized water. Keep blending for 30 min until the solid content of the suspension slurry obtained is 40 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Comparative additive C-1 is obtained.

[0033] The comparative additive C-1 has an abrasion index of 1.2 wt %/h, a specific surface area of 178 m.sup.2/g and a P.sub.2O.sub.5 content of 0 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Comparative Example 2

[0034] Disperse 0.75 kg (dry-basis) pseudo-boehmite in 1.2 kg deionized water while stirring, and then slowly add 4 kg concentrated phosphoric acid (containing 85 wt % of H.sub.3PO.sub.4); stir at 60° C. until the solution becomes transparent, phosphorus-alumina binder is obtained. Add 5.5 kg (dry-basis) kaolinite to 20 kg deionized water, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 0.75 kg (dry-basis) alumina sol binder and the above prepared phosphorus-alumina binder. Stir for 30 min and then add a zeolite suspension prepared with 5 kg (dry-basis) H-ZSM-5 zeolite (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) and 6 kg deionized water. Keep blending for 30 min to form a suspension slurry. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Comparative additive C-2 is then obtained.

[0035] The comparative additive C-2 has an abrasion index of 6.2 wt %/h, a specific surface area of 81 m.sup.2/g and a P.sub.2O.sub.5 content of 17.11 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Comparative Example 3

[0036] Add 2.5 kg (dry-basis) pseudo-boehmite and 1 kg (dry-basis) REY zeolite (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 5, and content of RE.sub.2O.sub.3 is 8 wt %) to 10 kg deionized water while stirring. Stir for 30 min, a suspension with zeolite and pseudo-boehmite is obtained.

[0037] Add 3.7 kg (dry-basis) kaolinite to 14 kg deionized water while stirring, and stir at highspeed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 2 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min and then add 2 kg acidic silica sol solution (containing 40 wt % of SiO.sub.2). Stir for 20 min and then add the prepared mixture suspension of zeolite and pseudo-boehmite. Keep blending for 30 min until the solid content of the suspension slurry obtained is 25 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Comparative additive C-3 is obtained.

[0038] The comparative additive C-3 has an abrasion index of 1.1 wt %/h, a specific surface area of 284 m.sup.2/g and a P.sub.2O.sub.5 content of 0 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat and then the mixture catalyst is catalytic cracking tested. Cracking performance testing result is shown in Table 3.

Embodiment 1

[0039] Impregnating and flash drying H-ZSM-5 zeolite (SiO.sub.2/Al.sub.2O.sub.3 molar ratio is 27) with ammonium di-hydrogen phosphate, and then the flash dried zeolite is calcined at 550° C. for 2 h to obtain phosphorus-containing ZSM-5 zeolite, wherein P.sub.2O.sub.5 content in the prepared zeolite is 3.2 wt %.

[0040] Add 5 kg (dry-basis) phosphorus-containing ZSM-5 zeolite to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI zeolite suspension is obtained.

[0041] Add 2.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the prepared zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then the spray-dried material is calcined at 550° C. for 2 h. Additive LOBC-1 is obtained.

[0042] The additive LOBC-1 has an abrasion index of 1.2 wt %/h, a specific surface area of 196 m.sup.2/g and a P.sub.2O.sub.5 content of 1.47 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Embodiment 2

[0043] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) with ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. Phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 2.8 wt %.

[0044] Add 5.5 kg (dry-basis) phosphorus-containing ZSM-5 zeolite to 6 kg deionized water, and stir at high speed for 30 min. The phosphorus-containing MFI zeolite suspension is obtained.

[0045] Add 2.4 kg (dry-basis) kaolinite and 1.3 kg (dry-basis) alumina sol to 3.5 kg deionized water while stirring, and stir at high speed for 1 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 0.8 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 500° C. for 3 h. Additive LOBC-2 to both produce more low-carbon olefins and reduce slurry is obtained.

[0046] The additive LOBC-2 has an abrasion index of 0.5 wt %/h, a specific surface area of 205 m.sup.2/g and a P.sub.2O.sub.5 content of 1.54 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3

Embodiment 3

[0047] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 29) with ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. Phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 2 wt %.

[0048] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 0.9 kg (dry-basis) rare earth- and phosphorus-modified Y type zeolite (molar ratio SiO.sub.2/Al.sub.2O.sub.3 is 5, RE.sub.2O.sub.3 is 4 wt % and P.sub.2O.sub.5 is 1 wt %) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI zeolite suspension is obtained.

[0049] Add 2.6 kg (dry-basis) montmorillonite and 0.3 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the montmorillonite to be completely dispersed in the suspension, and then add 2.2 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min and then add 0.3 kg (dry-basis) acidic silica sol (containing 40 wt % of SiO.sub.2). Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 40 wt %. Homogenize and grind the suspension slurry before spray-drying, and then calcine the spray-dried material at 500° C. for 2 h. Additive LOBC-3 for both producing more low-carbon olefins and reducing slurry is obtained.

[0050] The additive LOBC-3 has an abrasion index of 2.1 wt %/h, a specific surface area of 226 m.sup.2/g and a P.sub.2O.sub.5 content of 0.89 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3

Embodiment 4

[0051] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 10) with ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 5 wt %.

[0052] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) ultra-stable Y type zeolite (molar ratio of skeleton SiO.sub.2/Al.sub.2O.sub.3 is 9) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI zeolite suspension is obtained.

[0053] Add 2.6 kg (dry-basis) attapulgite to 6 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the attapulgite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min and then add 1.4 kg (dry-basis) acidic silica sol (containing 40 wt % of SiO.sub.2). Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried suspension at 550° C. for 2 h. Additive LOBC-4 for both producing more low-carbon olefins and reducing slurry is then obtained.

[0054] The additive LOBC-4 has an abrasion index of 0.9 wt %/h, a specific surface area of 208 m.sup.2/g and a P.sub.2O.sub.5 content of 2 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3

Embodiment 5

[0055] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 50) with ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 1 wt %.

[0056] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) P-modified Y type zeolite (SiO.sub.2/Al.sub.2O.sub.3 is 5, and P.sub.2O.sub.5 is 1 wt %) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI zeolite suspension is obtained.

[0057] Add 2 kg (dry-basis) sepiolite and 2 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the sepiolite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) ground amorphous alumina-silica (with a specific surface area of 289 m.sup.2/g). Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the size before spray-drying, and then calcine the spray-dried material at 750° C. for 0.1 h. Additive LOBC-6 for both producing more low-carbon olefins and reducing slurry is obtained.

[0058] The additive LOBC-6 has an abrasion index of 0.9 wt %/h, a specific surface area of 221 m.sup.2/g and a P.sub.2O.sub.5 content of 0.5 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3

Embodiment 6

[0059] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) with ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 3.2 wt %.

[0060] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) rare earth Y type zeolite (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 5, and content of RE.sub.2O.sub.3 is 4 wt/o) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI and Y zeolites suspension is obtained.

[0061] Add 2.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension before spray-drying, and then calcine the spray dried material at 550° C. for 2 h. Additive LOBC-7 for both producing more low-carbon olefins and reducing slurry is obtained.

[0062] The additive LOBC-7 has an abrasion index of 0.8 wt %/h, a specific surface area of 217 m.sup.2/g and a P.sub.2O.sub.5 content of 1.28 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Embodiment 7

[0063] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) with ammonium di-hydrogen phosphate, and then calcine the spray dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 3.2 wt %.

[0064] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) Beta type zeolite (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 20) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI and Beta zeolites suspension is obtained.

[0065] Add 2.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at a high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the size before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Additive LOBC-8 for both producing more low-carbon olefins and reducing slurry is obtained.

[0066] The additive LOBC-8 has an abrasion index of 1.3 wt %/h, a specific surface area of 204 m.sup.2/g and a P.sub.2O.sub.5 content of 1.28 wt %. After passivation with metal and treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Embodiment 8

[0067] Impregnating and flash drying H-ZSM-5 (molar ratio of SiO.sub.2/Al.sub.2O.sub.3 is 27) with phosphoric acid, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 3.2 wt %.

[0068] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) rare earth ultra-stable Y type zeolite (SiO.sub.2/Al.sub.2O.sub.3 is 9, and RE.sub.2O.sub.3 is 4 wt %) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI and Y zeolites suspension is obtained.

[0069] Add 2.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray dried material at 550° C. for 2 h. Additive LOBC-9 for both producing more low-carbon olefins and reducing slurry is obtained.

[0070] The additive LOBC-9 has an abrasion index of 0.7 wt %/h, a specific surface area of 218 m.sup.2/g and a P.sub.2O.sub.5 content of 1.28 wt %. After passivation with metal and treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Embodiment 9

[0071] Impregnating and flash drying H-ZSM-5 (SiO.sub.2/Al.sub.2O.sub.3 is 27) with phosphoric acid, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 5 wt %.

[0072] Add 4 kg (dry-basis) phosphorus-containing ZSM-5 zeolite and 1 kg (dry-basis) rare earth ultra-stable Y type zeolite (SiO.sub.2/Al.sub.2O.sub.3 is 9, and RE.sub.2O.sub.3 is 4 wt %) into 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI and Y zeolites suspension is obtained.

[0073] Add 2.6 kg (dry-basis) kaolinite and 1.4 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Additive LOBC-10 for both producing more low-carbon olefins and reducing slurry is obtained.

[0074] The additive LOBC-10 has an abrasion index of 0.6 wt %/h, a specific surface area of 217 m.sup.2/g and a P.sub.2O.sub.5 content of 2 wt %. After passivation with metal and treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

Embodiment 10

[0075] Impregnating and flash drying H-ZSM-5 (SiO.sub.2/Al.sub.2O.sub.3 is 27) in sequence with rare-earth salt and ammonium di-hydrogen phosphate, and then calcine the flash dried zeolite at 500° C. for 2 h. The phosphorus- and rare earth-containing ZSM-5 zeolite is obtained, wherein P.sub.2O.sub.5 content in the zeolite is 3.2 wt %, and RE.sub.2O.sub.3 content is 1.8 wt %.

[0076] Add 4 kg (dry-basis) phosphorus- and rare earth-containing ZSM-5 zeolite and 1 kg (dry-basis) rare earth ultra-stable Y type zeolite (SiO.sub.2/Al.sub.2O.sub.3 is 9, and RE.sub.2O.sub.3 is 4 wt %) to 5.5 kg deionized water, and stir at high speed for 30 min. A phosphorus-containing MFI and Y zeolites suspension is obtained.

[0077] Add 2.5 kg (dry-basis) kaolinite and 1.5 kg (dry-basis) alumina sol to 4 kg deionized water while stirring, and stir at high speed for 2 h. Wait for the kaolinite to be completely dispersed in the suspension, and then add 1 kg (dry-basis) pseudo-boehmite. Adjust pH of the suspension to 2.5˜3.5 with HCl, so that the pseudo-boehmite can experience a gelation reaction. Stir for 30 min, and then add the zeolite suspension. Keep blending for 30 min until the solid content of the suspension slurry obtained is 41 wt %. Homogenize the suspension slurry before spray-drying, and then calcine the spray-dried material at 550° C. for 2 h. Additive LOBC-11 for both producing more low-carbon olefins and reducing slurry is obtained.

[0078] The additive LOBC-11 has an abrasion index of 0.6 wt %/h, a specific surface area of 212 m.sup.2/g and a P.sub.2O.sub.5 content of 1.28 wt %. After passivation with metal and steam treatment, add 15 wt % the treated additive to the selected FCC e-cat. Cracking performance testing result of the mixed catalyst is shown in Table 3.

[0079] In the said embodiments and comparative examples above, catalytic cracking reaction is assessed with miniature fluidized bed reactor (ACE) and supporting gas chromatography, while research octane number (RON) is analyzed with Agilent gas chromatography 7980A. For catalytic cracking test, an industrial FCC e-cat is chosen as main catalyst, the additive is impregnated with 4000 ppm V and 2000 ppm Ni, and then 100% steam aged at 810° C. for 10 h. The catalyst contains 85 wt % FCC e-cat and 15% the deactivated additive. The catalytic cracking reaction temperature is 540° C., oil feeding rate is 1.2 g/min, oil feeding time is 1.5 min and catalyst/oil ratio is 5. For other physicochemical analysis, refer to the National Standard of Method for Test of Petroleum and Petroleum Products (Standards Press of China, 1989).

[0080] The main physicochemical properties of FCC e-cat are shown in Table 1, and the properties of feed are given in Table 2. The catalytic cracking performance testing data with 85 wt % of FCC e-cat+15 wt % of deactivated additive in embodiments and comparative examples are shown in Table 3.

TABLE-US-00001 TABLE 1 Main Physicochemical Properties of the FCC e-cat Item Result La.sub.2O.sub.3, wt % (m) 2.43 CeO.sub.2, wt % (m) 1.23 Al.sub.2O.sub.3, wt % (m) 52.23 Fe.sub.2O.sub.3, (ppm) 4968 Na.sub.2O, (ppm) 1761 P.sub.2O.sub.5, wt % (m) 1.03 NiO, (ppm) 4663 V.sub.2O.sub.5, (ppm) 10347 Specific surface area (m.sup.2/g) 96 Microreactor activity (wt % (m)) 56.3 Particle 0~20 μm, wt % 0.00 size 0~40 μm, wt % 4.2 distribution 0~80 μm, wt % 59.4 0~105 μm, wt % 84.2 0~149 μm, wt % 98.8 D.sub.50, μm 73.3

TABLE-US-00002 TABLE 2 Properties of Feed Item Result Density, 15 degC, kg/m.sup.3 903 Sulfur content, ppmw 610 Nitrogen content, ppmw 180 Distillation range (Deg C) ASTM D-1160 15 wt % 332° C. 10 wt % 352° C. 30 wt % 401° C. 50 wt % 448° C. 70 wt % 505° C. 90 wt % 552° C. 95 wt % 575° C. H element content (wt %) 12.4 Ni, ppmw 7.8 V, PPmw 16.2 Fe, ppmw 4.0 Na, ppmw 4.6 Residual carbon (wt %) 4.6

TABLE-US-00003 TABLE 3 Performance of Catalytic Cracking of Samples in Embodiments and Comparative Examples Yield Yield Yield of Con- of of Yield of gasoline + version slurry, coke, propylene, LPG, Additive wt % wt % wt % wt % wt % No additive 73.20 9.38 8.13 4.64 62.17 Additive C-1 72.23 10.31 8.04 6.01 61.32 Additive C-2 71.56 10.92 7.93 9.03 60.80 Additive C-3 73.98 9.16 8.24 4.29 62.80 Additive 73.23 9.62 8.15 9.65 62.17 LOBC-1 Additive 73.53 9.53 8.11 9.43 62.53 LOBC-2 Additive 73.61 9.67 8.15 8.91 62.55 LOBC-3 Additive 73.11 9.77 8.16 10.21 62.04 LOBC-4 Additive 74.21 8.98 8.22 9.85 63.06 LOBC-5 Additive 73.39 9.97 8.13 8.21 63.16 LOBC-6 Additive 73.44 9.31 8.16 9.69 62.37 LOBC-7 Additive 73.58 9.61 8.13 9.74 62.55 LOBC-8 Additive 73.98 9.51 8.26 9.82 62.77 LOBC-9 Additive 73.46 9.72 8.16 9.99 62.39 LOBC-10 Additive 73.59 9.81 8.19 10.07 62.48 LOBC-11

[0081] The embodiments above are only the preferred embodiments for the invention and not used to restrict the invention. For the technicians of the field, various modifications and changes can be made within the ideas and principles of the invention, and such equivalent changes or replacements are included in the range of protection in the invention.

INDUSTRIAL APPLICABILITY

[0082] The bifunctional additive provided in the invention is used in FCC process to increase production rate of cracked LPG, yield of propylene in LPG and octane number of catalytically cracked gasoline, and to reduce the yield of slurry in the cracking products. Those features of the bifunctional additive are expected to provide wider industrial applications.