Catalytic cracking catalyst and process for preparing the same
A catalytic cracking catalyst contains 10-70 wt % of a cracking active component, 10-60 wt % of a binder and 10-70 wt % of a clay. The cracking active component has 5-100 wt % of a first Y-type molecular sieve and 0-95 wt % of a second molecular sieve. The first Y-type molecular sieve is a modified molecular sieve based on the crystal modification of kaolin and has the sodium oxide content of less than 2 wt %. The process for preparing the catalyst includes the steps of vigorously mixing and stirring a cracking active component comprising a modified molecular sieve based on the crystal modification of kaolin, a binder and a clay with water; spray drying; washing; filtering; and drying. The catalyst is used in the catalytic cracking reaction of heavy oils, and has a good coke selectivity, as well as a higher heavy oil conversion rate.
1 . A catalytic cracking catalyst, comprising 10-70 wt % of a cracking active component, 10-60 wt % of a binder and 10-70 wt % of a clay,
wherein the cracking active component comprises 5-100 wt % of a first Y molecular sieve and 0-95 wt % of a second molecular sieve;
wherein the first Y molecular sieve is obtained from a modification treatment of a molecular sieve based on crystal modification of kaolin, and has a sodium oxide content of less than 2 wt %; and
wherein, based on an XRD pattern thereof, the molecular sieve based on the crystal modification of kaolin has a crystallinity calculated by a peak height method of ≥60%, and a ratio of the crystallinity by the peak height method to a crystallinity calculated by a peak area method is K1, K1=0.76-0.89; and
wherein the molecular sieve based on the crystal modification of kaolin has a silica-alumina molar ratio measured with a unit cell constant a0 of 5.0-5.5, and a ratio of the silica-alumina molar ratio measured with the unit cell constant a0 to a silica-alumina molar ratio measured with a chemical method is K2, K2=0.87-0.93.
2 . The catalytic cracking catalyst according to claim 1 , wherein the crystallinity calculated by the peak height method is ≥80%.
3 . The catalytic cracking catalyst according to claim 1 , wherein the K1=0.80-0.89.
4 . The catalytic cracking catalyst according to claim 1 , wherein the K2=0.87-0.92.
5 . The catalytic cracking catalyst according to claim 1 , wherein the K1=0.77-0.88 and the K2=0.87-0.91.
6 . The catalytic cracking catalyst according to claim 1 , wherein the molecular sieve based on the crystal modification of kaolin has a proportion of macropores and mesopores of 10-20%.
7 . The catalytic cracking catalyst according to claim 1 , wherein the silica-alumina molar ratio measured with the unit cell constant a0 is 5.2-5.5.
8 . The catalytic cracking catalyst according to claim 1 , wherein the molecular sieve based on the crystal modification of kaolin is prepared with a process comprising the steps of:
(1) converting kaolin into metakaolin by calcining and dehydrating at 500-900° C., and pulverizing the metakaolin into metakaolin powder with a particle size of less than 10 microns;
(2) adding a directing agent, sodium silicate, a sodium hydroxide solution and water to the metakaolin powder to produce a reaction raw material A, wherein a mass ratio of the directing agent to the metakaolin is 0.01-1.0, and the reaction raw material A has a composition by molar ratio of Na 2 O:Al 2 O 3 :SiO 2 :H 2 O=1-2.5:1:4-9:40-100;
(3) crystallizing the reaction raw material A at 88-98° C. under stirring for 1-70 hours, adding thereto a second silicon source to obtain a reaction raw material B, wherein the second silicon source is silica comprising 0.1-10 wt % of the total amount of the added silicon, calculated as silica; and
(4) crystallizing the reaction raw material B under stirring at 88-98° C. and obtaining a product.
9 . The catalytic cracking catalyst according to claim 1 , wherein the first Y molecular sieve has 10-20 wt % of RE 2 O 3 .
10 . The catalytic cracking catalyst according to claim 1 , wherein the second molecular sieve is one or more selected from HY, REY, REHY, USY, REUSY, DASY, REDASY BEA structure molecular sieve, MFI structure molecular sieve, and mordenite; the binder is one or more selected form zirconia sol, silica sol, alumina sol, acidified pseudo-boehmite, and metal-modified pseudo-boehmite; the clay is one or more selected from kaolin, montmorillonite, diatomite, halloysite, metahalloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite; or
the catalytic cracking catalyst contains 10-70 wt % of a cracking active component, 1-20 wt % of a silica-alumina material, 10-60 wt % of a binder and 10-70 wt % of a clay;
wherein the cracking active component comprises 25-100 wt % of a first Y molecular sieve and 0-75 wt % of a second molecular sieve; the first Y molecular sieve is a Y molecular sieve synthesized by in-situ crystallization having a sodium oxide content of less than 2 wt %; the silica-alumina material has an anhydrous chemical formula by weight of (0-1)Na 2 O·(15-50)Al 2 O 3 ·(85-50)SiO 2 , a most probable pore size of 10-100 nm, a specific surface area of 150-600 m 2 /g, a pore volume of 0.5-1.5 mL/g, and a proportion of the pore volume of the pores having a pore diameter of greater than 10 nm to the total pore volume of 70-98%; or
the catalytic cracking catalyst comprises 10-60 wt % of a cracking active component, 20-60 wt % of a binder, and 10-70 wt % of a clay; wherein the binder comprises 1-50 wt % of a zirconia sol, and 50-99 wt % of a second binder, the zirconia sol comprises 0.5-20 wt % of ZrO 2 , a stabilizer, an alkali cation and water, wherein the molar ratio of the stabilizer to Zr is 1-6, the pH value of the zirconia sol is 1-7; the cracking active component comprises 70-100 wt % of a Y molecular sieve and 0-30 wt % of a second molecular sieve; or
the catalytic cracking catalyst comprises 10-60 wt % of a cracking active component on the dry basis, 20-60 wt % of a binder on the dry basis, and 0-70 wt % of a second clay on the dry basis; wherein, based on the dry basis weight of the binder, on the dry basis, the binder comprises 1-50 wt % of a zirconia sol, 50-99 wt % of a phosphorus-aluminum inorganic binder and 0-45 wt % of a third binder; the zirconia sol comprises 0.5-20 wt % of ZrO 2 , a stabilizer, an alkali cation and water, wherein the molar ratio of the stabilizer to Zr is 1-6, the pH value of the zirconia sol is 1-7; the phosphorus-aluminum inorganic binder contains 15-40 wt % of an aluminum source component as Al 2 O 3 , 45-80 wt % of a phosphorus component of P 2 O 5 and 0-40 wt % of a first clay on the dry basis, and has a P/Al weight ratio of 1-6, a pH value of 1-3.5 and a solid content of 15-60 wt %; or
based on the dry basis weight of the catalytic cracking catalyst, the catalytic cracking catalyst comprises 10-70 wt % of a cracking active component, 1-20 wt % of a zirconia binder, 1-20 wt % of a silica sol binder, 0-50 wt % of an alumina-based binder and 10-70 wt % of a clay, the zirconia binder is a zirconia sol, the zirconia sol comprises 0.5-20 wt % of ZrO 2 , a stabilizer, an alkali cation and water, wherein the molar ratio of the stabilizer to Zr is 1-6, the pH value of the zirconia sol is 1-7; or
the catalytic cracking catalyst comprises a molecular sieve, an alumina-based binder, a clay and a composite, based on the total amount of the catalyst, the content of the molecular sieve is 10-70 wt %, the content of the alumina-based binder is 5-30 wt %, the content of the clay is 10-70 wt %, the content of the composite is 6-50 wt %; the molecular sieve comprises a first molecular sieve and an optional second molecular sieve, based on the total amount of the molecular sieve, the content of the first molecular sieve is 70-100 wt %, the content of the second molecular sieve is 0-30 wt %; the composite comprises a zirconia sol and a silica-alumina material, the zirconia sol comprises 0.5-20 wt % of ZrO 2 , a stabilizer, an alkali cation and water, wherein the molar ratio of the stabilizer to Zr is 1-6, the pH value of the zirconia sol is 1-7; the first molecular sieve is a Y molecular sieve, wherein the content of the rare earth element in the Y molecular sieve is 0-20 wt %; the second molecular sieve is a pentasil molecular sieve.
11 . A process for preparing the catalytic cracking catalyst according to claim 1 , comprising the following steps:
(1) preparing the first Y molecular sieve;
(2) making a clay, a cracking active component and a binder form a slurry, wherein the cracking active component comprises the first Y molecular sieve and an optional second molecular sieve; and
(3) spray-drying the slurry obtained in step (2).
12 . The process for preparing the catalytic cracking catalyst according to claim 11 , wherein the process for preparing the first Y molecular sieve comprises the following steps:
S1: calcining and dehydrating kaolin at 500-900° C., and pulverizing the calcined and dehydrated kaolin to obtain a metakaolin powder;
S2: adding a directing agent, sodium silicate, a sodium hydroxide solution and water to the metakaolin powder to produce a reaction raw material A, wherein the mass ratio of the directing agent to the metakaolin is 0.01-1.0, wherein, in the reaction raw material A, the molar ratio of Na2O:Al2O3:SiO2:H2O=1-2.5:1:4-9:40-100;
S3: crystallizing the reaction raw material A at 88-98° C. under stirring for 1-70 hours, then supplementing a second silicon source to obtain a reaction raw material B, wherein, calculated based on both as silica, the second silicon source accounts for comprises 0.1-10 wt % of the total amount of added silicon in the reaction raw material B;
S4: crystallizing the reaction raw material B under stirring at 88-98° C. and obtaining a product; and
S5: ion-exchanging the product to obtain the Y molecular sieve.
13 . The catalytic cracking catalyst according to claim 8 , wherein the directing agent has a composition in which SiO2:Al2O3:Na2O:H2O=10-17:0.7-1.3:11-18:200-350.
14 . The preparation process according to claim 12 , wherein the second silicon source has the sodium content as Na 2 O of <1 wt %.
15 . The process for preparing the catalytic cracking catalyst according to claim 12 , wherein the second silicon source is a solid silica gel.
16 . The process for preparing the catalytic cracking catalyst according to claim 15 , wherein the solid silica gel has an average pore size of 1.5-2.0 nm, or the solid silica gel has an average pore size of 4.0-5.0 nm, or the solid silica gel has an average pore size of 10.0 nm or more, or the solid silica gel has an average pore size of 0.8 nm or less.
17 . The process for preparing the catalytic cracking catalyst according to claim 12 , wherein the second silicon source is a liquid silica gel.
18 . The process for preparing the catalytic cracking catalyst according to claim 17 , wherein the liquid silica gel has the SiO 2 content by weight of 1-30%.
19 . The process for preparing the catalytic cracking catalyst according to claim 12 , wherein both as silica, the second silicon source comprises 4-10 wt % of the total amount of the added silicon.
20 . The process for preparing the catalytic cracking catalyst according to claim 12 , wherein the ion-exchanging in S1 is carried out in a solution comprising an ammonium salt, a rare earth salt, or both.
21 . The process for preparing the catalytic cracking catalyst according to claim 12 , wherein further comprising calcining the ion-exchanged product obtained from S5 to obtain the first Y molecular sieve.
22 . The process for preparing the catalytic cracking catalyst according to claim 2 , wherein the first Y molecular sieve has the rare earth content as RE 2 O 3 of 10-20 wt %, and the sodium oxide content of less than 2 wt %.
23 . A catalytic cracking process, comprising: contacting a hydrocarbon oil with the catalytic cracking catalyst according to claim 1 under conditions that cause a catalytic cracking reaction.