Modified ZSM-5 zeolite, catalytic cracking catalyst, and preparation method and application thereof
阅读说明：本技术 一种改性zsm-5沸石、催化裂化催化剂及其制备方法和应用 (Modified ZSM-5 zeolite, catalytic cracking catalyst, and preparation method and application thereof ) 是由 于善青 严加松 陈惠� 袁帅 张杰潇 田辉平 于 2020-04-30 设计创作，主要内容包括：本公开涉及一种改性ZSM-5沸石、催化裂化催化剂及其制备方法和应用,以改性ZSM-5沸石的干基重量为基准,改性ZSM-5沸石含有以氧化物计的0.5-10重量％的IVB族金属元素,改性ZSM-5沸石中等强度酸中心数量占总酸量的25-55％,强酸中心数量占总酸量的10-30％,B酸与L酸的比值为4.0以上,改性ZSM-5沸石体相的IVB族金属元素的重量含量与表面的IVB族金属元素的重量含量的比值为0.05-0.60。含有本发明的改性ZSM-5沸石的催化裂化催化剂具有良好的碳四烯烃选择性和产率。(The invention relates to a modified ZSM-5 zeolite, a catalytic cracking catalyst and a preparation method and application thereof, wherein the modified ZSM-5 zeolite contains 0.5-10 wt% of IVB group metal elements calculated by oxides based on the dry weight of the modified ZSM-5 zeolite, the number of the medium-strength acid centers in the modified ZSM-5 zeolite accounts for 25-55% of the total acid amount, the number of the strong acid centers accounts for 10-30% of the total acid amount, the ratio of the B acid to the L acid is more than 4.0, and the ratio of the weight content of the IVB group metal elements in the modified ZSM-5 zeolite body to the weight content of the IVB group metal elements on the surface is 0.05-0.60. The catalytic cracking catalyst containing the modified ZSM-5 zeolite of the invention has good selectivity and yield of the carbon four-olefin.)
1. A modified ZSM-5 zeolite, based on the dry weight of the modified ZSM-5 zeolite, the modified ZSM-5 zeolite contains 0.5-10 wt% of IVB group metal elements calculated by oxides, the modified ZSM-5 zeolite contains 25-55% of medium-strength acid centers, 10-30% of strong acid centers and more than 4% of B acid and L acid, and the ratio of the weight content of the IVB group metal elements in the modified ZSM-5 zeolite to the weight content of the IVB group metal elements on the surface is 0.05-0.6.
2. The modified ZSM-5 zeolite of claim 1, wherein the modified ZSM-5 zeolite contains 1-8 wt% of the group IVB metal element on an oxide basis.
3. The modified ZSM-5 zeolite of claim 1, wherein the number of medium strength acid centers is 30-55% of the total acid content.
4. The modified ZSM-5 zeolite of claim 1, wherein the number of strong acid sites is 10-25% of the total acid content.
5. The modified ZSM-5 zeolite of claim 1, wherein the ratio of the B acid to the L acid is 4.5 or greater.
6. The modified ZSM-5 zeolite of claim 1, wherein the ratio of the weight of the group IVB metal element in the modified ZSM-5 zeolite bulk phase to the weight content of the group IVB metal element on the surface of the zeolite is in the range of 0.15 to 0.45.
7. The modified ZSM-5 zeolite of claim 1, wherein the group IVB metal element is Zr and/or Ti, preferably Zr; the weight of the Zr element is ZrO2The weight of the Ti element is calculated by TiO2And (6) counting.
8. A catalytic cracking catalyst comprising, based on the dry weight of the catalytic cracking catalyst, 10 to 40 wt% of a Y-type zeolite, 5 to 30 wt% of a beta zeolite, 10 to 70 wt% of a clay, 5 to 60 wt% of a refractory inorganic oxide, and 3 to 15 wt% of a modified ZSM-5 zeolite, wherein the modified ZSM-5 zeolite is the modified ZSM-5 zeolite of any one of claims 1 to 7.
9. The catalytic cracking catalyst of claim 8, wherein the catalytic cracking catalyst contains 15-40 wt% of the Y-type zeolite, 5-20 wt% of the beta zeolite, 10-55 wt% of the clay, 5-40 wt% of the refractory inorganic oxide, and 3-10 wt% of the modified ZSM-5 zeolite.
10. The catalytic cracking catalyst of claim 8, wherein the Y-type zeolite is selected from one or more of phosphorus and/or rare earth-containing Y-type zeolite, ultrastable Y-zeolite, and phosphorus and/or rare earth-containing ultrastable Y-zeolite;
the beta zeolite is selected from one or more of hydrogen type beta zeolite, sodium type beta zeolite and modified beta zeolite, and the modified beta zeolite contains phosphorus and/or rare earth metal elements;
the clay is selected from one or more of kaolin, rectorite, diatomite, montmorillonite, bentonite and sepiolite;
the heat-resistant inorganic oxide is selected from one or more of aluminum oxide, silicon oxide and amorphous silicon aluminum.
11. A process for preparing a modified ZSM-5 zeolite as claimed in any of claims 1 to 7, which process comprises:
(1) mixing a compound containing IVB group metal, a carbon source and a first solvent, and adjusting the pH value of the mixture to 5-10 to obtain a first slurry; the carbon source comprises a natural high molecular organic compound and/or a semi-synthetic high molecular organic compound;
(2) and stirring and mixing the first slurry and ZSM-5 zeolite at 15-100 ℃ for 10-120min, taking out the solid, and carrying out first roasting at 300-600 ℃ for 0.5-5 h.
12. The process of claim 11, wherein the group IVB metal-containing compound and the ZSM-5 zeolite are used in a weight ratio of (0.005-0.10): 1, the weight ratio of the ZSM-5 zeolite to the carbon source is 1: (0.001-0.15), the group IVB metal-containing compound being calculated as an oxide of a group IVB metal, the ZSM-5 zeolite being calculated on a dry weight basis.
13. The method according to claim 11, wherein in step (1), the pH of the mixture is adjusted to 5 to 9.
14. The method of claim 11, wherein the ZSM-5 zeolite is selected from one or more of a sodium type ZSM-5 zeolite, a hydrogen type ZSM-5 zeolite, and a phosphorous type ZSM-5 zeolite;
the compound containing IVB group metal is selected from one or more of zirconium tetrachloride, zirconium sulfate, zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium isopropoxide, titanium tetrachloride, titanyl sulfate, ammonium fluotitanate, titanium sulfate, tetrabutyl titanate, titanium trichloride and titanium sulfite;
the carbon source is selected from one or more of starch, lignin, viscose, methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose;
the first solvent is selected from one or more of deionized water, ethanol, acetone and hexane.
15. A process for preparing the catalytic cracking catalyst of any one of claims 8 to 10, which comprises: mixing the Y-type zeolite, the beta zeolite, the clay, the refractory inorganic oxide, the modified ZSM-5 zeolite of any one of claims 1 to 3, and a second solvent, granulating the resulting second slurry, and drying and/or second calcining.
16. The method of claim 15, wherein the temperature of the drying is 80-200 ℃; the temperature of the second roasting is 350-700 ℃, and the time is 0.5-6 hours.
17. Use of a modified ZSM-5 zeolite as claimed in any of claims 1 to 7 or a catalytic cracking catalyst as claimed in any of claims 8 to 10 in the catalytic cracking of heavy oils.
Technical Field
The invention relates to a modified ZSM-5 zeolite, a catalytic cracking catalyst, and a preparation method and application thereof.
Background
Along with the enhancement of environmental awareness, the quality standard of the gasoline for the automobile is continuously upgraded and updated. The new standard of motor gasoline and GB17930-2016 clearly stipulate that the national VI standard gasoline is implemented in stages in 2019, compared with the national V standard, the benzene, arene and olefin contents of the gasoline under the national VI standard are reduced, and the current national gasoline blending component scheme is difficult to meet the requirements. Because the alkylated gasoline has high octane number and zero contents of olefin, aromatic hydrocarbon and benzene, the alkylated gasoline is a good gasoline blending component under the national VI standard compared with the traditional catalytic gasoline and reformed gasoline, and the proportion of the alkylated gasoline in the gasoline blending component can be greatly improved. The main feeds to the alkylation unit are isobutane and carbon tetraolefins. Nearly 70% of the worldwide carbon tetraolefins come from catalytic crackers, and the technology for producing carbon tetraolefin fractions from catalytic crackers has the advantages of low investment and low cost, and many companies try to obtain a larger amount of carbon tetraolefin yield from the catalytic cracking process.
In order to increase the production of lower olefins, zeolites having the MFI structure are generally added to the catalyst. The MFI structure zeolite can selectively crack and isomerize straight-chain and short-chain branched alkanes in FCC gasoline fraction in the pore channels thereof to generate C3-C5 olefins, thereby improving the yield of low-carbon olefins.
U.S. Engelhard corporation, 1993, first discloses a cracking catalyst for increasing the yield of isobutene and isopentene in U.S. Pat. No. 5,5243121, wherein the unit cell size of Y zeolite in the cracking catalyst is reduced through hydrothermal treatment, so that the selectivity of the catalyst to olefin in a product during hydrocarbon cracking can be improved, and a considerable amount of ZSM-5 zeolite can be added into the catalyst as an auxiliary agent, so that the coke formation amount can be reduced, and the activity can be improved. US3758403 discloses a catalyst using ZSM-5 and large pore zeolite (mainly Y-type zeolite) as active components, which increases the octane number of gasoline and increases the yield of C3 and C4 olefins, wherein the large pore zeolite cracks the raw material to produce gasoline and diesel oil, and the ZSM-5 shape selective molecular sieve further cracks the raw material to produce lower olefins. The phosphorus modification can improve the surface acidity of the zeolite and improve the shape selectivity. USP5171921 discloses a phosphorus-modified ZSM-5 zeolite having a silica-alumina ratio of 20 to 60, which has higher activity when used in the reaction of converting C3-C20 hydrocarbon into C2-C5 olefin after being impregnated with a phosphorus-containing compound and treated with steam at 500 to 700 ℃.
Due to the structural particularity of beta zeolite, the beta zeolite has both acid catalytic property and structural selectivity, and has been rapidly developed into a novel catalytic material in recent years. There are also many reports of the application of beta zeolite to catalytic cracking catalysts for the production of lower olefins. US4837396 discloses a catalyst comprising a beta zeolite and a Y zeolite, and a metal ion-containing compound as a stabilizer to improve the hydrothermal stability and mechanical strength of the catalyst. The stabilizer can directly act with beta zeolite, and can also be introduced in the preparation process. CN1055105C discloses a cracking catalyst for producing more isobutene and isoamylene, which contains 6-30 wt% of phosphorus and rare earth five-membered ring high-silicon zeolite, 5-20 wt% of USY zeolite, 1-5 wt% of beta zeolite, 30-60 wt% of clay and 15-30 wt% of inorganic oxide. CN104998681A discloses a catalytic cracking assistant for increasing the concentration of low-carbon olefin and a preparation method thereof, wherein the assistant comprises boron modified beta molecular sieve containing phosphorus and metal, inorganic oxide binder, VIII family metal additive, phosphorus additive and optional clay. The catalytic cracking assistant is applied to catalytic cracking of petroleum hydrocarbon, can increase the concentration of isobutene in catalytic cracking liquefied gas, and reduces the yield of coke.
When the various catalysts/auxiliaries prepared by the technology are used in the catalytic cracking process, the aim of increasing the yield of low-carbon olefin can be achieved to a certain extent, but the following problems exist: firstly, the yield of the liquefied gas is increased while the propylene and the butylene are increased, so that the concentration of the propylene or the butylene in the liquefied gas is not changed greatly; on the other hand, while increasing the butene, the propylene yield also increases, resulting in a deterioration in the selectivity of butene.
From the analysis of the mechanism of generation and conversion of the carbon tetraolefin in the catalytic cracking process, the generation of the carbon tetraolefin in the catalytic cracking process mainly comes from two aspects, namely, a product obtained by cracking an active intermediate generated by a monomolecular cracking reaction or a bimolecular cracking reaction of hydrocarbon macromolecules in a raw material, and a product obtained by carrying out a secondary reaction on low-carbon olefins formed in the cracking reaction. The carbon tetraolefins generated in the catalytic cracking process can further undergo cracking reaction, isomerization reaction, dimerization reaction and hydrogen transfer reaction.
Disclosure of Invention
The invention aims to provide a modified ZSM-5 zeolite, a catalytic cracking catalyst, and preparation methods and applications thereof, wherein the modified ZSM-5 zeolite and the catalytic cracking catalyst have high-carbon four-olefin selectivity and yield.
In order to achieve the above object, a first aspect of the present invention provides a modified ZSM-5 zeolite, wherein the modified ZSM-5 zeolite contains 0.5 to 10 wt% of a group IVB metal element in terms of oxide, based on the dry weight of the modified ZSM-5 zeolite, the number of medium-strength acid centers in the modified ZSM-5 zeolite accounts for 25 to 55% of the total acid amount, the number of strong acid centers accounts for 10 to 30% of the total acid amount, the ratio of a B acid to an L acid is 4 or more, and the ratio of the weight content of the group IVB metal element in the modified ZSM-5 zeolite to the weight content of the group IVB metal element on the surface is 0.05 to 0.6.
Optionally, the modified ZSM-5 zeolite contains 1 to 8 wt% of the group IVB metal element, calculated as the oxide.
Optionally, the number of medium strength acid centers is 30-55% of the total acid amount.
Alternatively, the number of strong acid sites is 10-25% of the total acid amount.
Optionally, the ratio of the B acid to the L acid is 4.5 or more.
Optionally, the modified ZSM-5 zeolite has a ratio of the weight of the group IVB metal element in the zeolite bulk to the weight content of the group IVB metal element on the surface of the zeolite in the range of 0.15 to 0.45.
Optionally, the group IVB metal element is Zr and/or Ti, preferablyZr; the weight of the Zr element is ZrO2The weight of the Ti element is calculated by TiO2And (6) counting.
The second aspect of the invention provides a catalytic cracking catalyst, which comprises 10-40 wt% of Y-type zeolite, 5-30 wt% of beta zeolite, 10-70 wt% of clay, 5-60 wt% of heat-resistant inorganic oxide and 3-15 wt% of modified ZSM-5 zeolite based on the dry weight of the catalytic cracking catalyst, wherein the modified ZSM-5 zeolite is the modified ZSM-5 zeolite provided by the first aspect of the invention.
Alternatively, the catalytic cracking catalyst contains 15-40 wt% of the Y-type zeolite, 5-20 wt% of the beta zeolite, 10-55 wt% of the clay, 5-40 wt% of the refractory inorganic oxide, and 3-10 wt% of the modified ZSM-5 zeolite.
Optionally, the Y-type zeolite is selected from one or more of phosphorus and/or rare earth-containing Y-type zeolite, ultrastable Y-zeolite, and phosphorus and/or rare earth-containing ultrastable Y-zeolite;
the beta zeolite is selected from one or more of hydrogen type beta zeolite, sodium type beta zeolite and modified beta zeolite, and the modified beta zeolite contains phosphorus and/or rare earth metal elements;
the clay is selected from one or more of kaolin, rectorite, diatomite, montmorillonite, bentonite and sepiolite;
the heat-resistant inorganic oxide is selected from one or more of aluminum oxide, silicon oxide and amorphous silicon aluminum.
In a third aspect, the present invention provides a process for preparing a modified ZSM-5 zeolite provided in the first aspect of the present invention, the process comprising:
(1) mixing a compound containing IVB group metal, a carbon source and a first solvent, and adjusting the pH value of the mixture to 5-10 to obtain a first slurry; the carbon source comprises a natural high molecular organic compound and/or a semi-synthetic high molecular organic compound;
(2) and stirring and mixing the first slurry and ZSM-5 zeolite at 15-100 ℃ for 10-120min, taking out the solid, and carrying out first roasting at 300-600 ℃ for 0.5-5 h.
Optionally, the group IVB metal-containing compound and the ZSM-5 zeolite are used in a weight ratio of (0.005-0.10): 1, the weight ratio of the ZSM-5 zeolite to the carbon source is 1: (0.001-0.15), the group IVB metal-containing compound being calculated as an oxide of a group IVB metal, the ZSM-5 zeolite being calculated on a dry weight basis.
Optionally, in step (1), the pH of the mixture is adjusted to 5-9.
Optionally, the ZSM-5 zeolite is selected from one or more of sodium type ZSM-5 zeolite, hydrogen type ZSM-5 zeolite and phosphorus type ZSM-5 zeolite;
the compound containing IVB group metal is selected from one or more of zirconium tetrachloride, zirconium sulfate, zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium isopropoxide, titanium tetrachloride, titanyl sulfate, ammonium fluotitanate, titanium sulfate, tetrabutyl titanate, titanium trichloride and titanium sulfite;
the carbon source is selected from one or more of starch, lignin, viscose, methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose;
the first solvent is selected from one or more of deionized water, ethanol, acetone and hexane.
In a fourth aspect, the present invention provides a process for preparing a catalytic cracking catalyst provided in the second aspect of the invention, the process comprising: mixing the Y-type zeolite, the beta zeolite, the clay, the refractory inorganic oxide, the modified ZSM-5 zeolite provided by the first aspect of the present invention, and a second solvent, granulating the resulting second slurry, and drying and/or second calcining.
Optionally, the temperature of the drying is 80-200 ℃; the temperature of the second roasting is 350-700 ℃, and the time is 0.5-6 hours.
In a fifth aspect, the invention provides a use of the modified ZSM-5 zeolite provided in the first aspect of the invention or the catalytic cracking catalyst provided in the second aspect of the invention in catalytic cracking of heavy oil.
Through the technical scheme, the modified ZSM-5 zeolite has excellent physicochemical properties, has a synergistic effect when being used as an active component of a catalytic cracking catalyst together with Y-type zeolite and beta zeolite, and can ensure that the catalytic cracking catalyst has higher selectivity and yield of the carbon tetraolefin. When the catalyst is used in the catalytic cracking process of heavy oil, the concentration of the carbon tetraolefin in the liquefied gas can be further improved and the yield and the selectivity of the carbon tetraolefin can be increased under the condition that the yields of gasoline and liquefied gas are not reduced.
The method is simple, can improve the distribution state and the distribution amount of IVB group metal oxides on the ZSM-5 zeolite, adjusts the pore channel distribution of the ZSM-5 zeolite, and can prepare the modified ZSM-5 zeolite with excellent catalytic performance.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Detailed Description
The following describes in detail specific embodiments of the present disclosure. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
In a first aspect, the present invention provides a modified ZSM-5 zeolite, wherein the modified ZSM-5 zeolite contains 0.5 to 10 wt%, for example, 1 to 9 wt%, calculated as an oxide, of a group IVB metal element, the number of medium-strength acid centers in the modified ZSM-5 zeolite is 25 to 55%, for example, 38 to 50%, calculated as an oxide, based on the total weight of the modified ZSM-5 zeolite, the number of strong acid centers is 10 to 30%, for example, 12 to 25%, calculated as a total acid, the ratio of the B acid to the L acid is 4 or more, for example, 4.5 to 6.5, and the ratio of the weight content of the group IVB metal element in the modified ZSM-5 zeolite to the weight content of the group IVB metal element on the surface is 0.05 to 0.6.
Compared with the traditional ZSM-5 zeolite, the modified ZSM-5 zeolite contains IVB group metal elements, the IVB group metal elements are mainly positioned on the surface of the zeolite, the excellent acid distribution and the ratio of B acid to L acid are realized, the number of medium-strength acid centers is increased, and the number of strong acid centers is reduced; the ratio of the isomerization reaction and the cracking reaction of the carbocation in the catalytic cracking reaction process is optimized, which is beneficial to the small molecular hydrocarbon in the catalytic cracking gasoline to carry out the isomerization reaction firstly and then carry out the beta-position fracture reaction, so that the catalytic cracking gasoline has good selectivity and yield of the carbon tetraolefin.
In a preferred embodiment, the modified ZSM-5 zeolite contains 1-8 wt% of the group IVB metal element, the number of medium strength acid centers accounts for 30-55% of the total acid content, the number of strong acid centers accounts for 10-25% of the total acid content, the ratio of the B acid to the L acid is 4.5 or more, and the ratio of the weight content of the group IVB metal element in the modified ZSM-5 zeolite body phase to the weight content of the group IVB metal element on the zeolite surface is 0.15-0.45. The modified ZSM-5 zeolite having the above parameter characteristics has better selectivity and yield of the carbon four-olefin.
According to the invention, the group IVB metal element may be Zr and/or Ti, preferably Zr; zr element in weight percent ZrO2The weight of Ti element is calculated by TiO2And (6) counting.
According to the present invention, the group IVB metal element of the ZSM-5 zeolite surface may be present in the form of a group IVB metal oxide. In a preferred embodiment, the group IVB metal oxide is ZrO2And/or TiO2More preferably ZrO2。
In a second aspect, the present invention provides a catalytic cracking catalyst comprising, based on the dry weight of the catalytic cracking catalyst, from 10 to 40 wt% of a Y-type zeolite, from 5 to 30 wt% of a beta zeolite, from 10 to 70 wt% of a clay, from 5 to 60 wt% of a refractory inorganic oxide, and from 3 to 15 wt% of the modified ZSM-5 zeolite provided in the first aspect of the present invention.
The inventor of the invention finds that when the Y zeolite, the beta zeolite and the modified ZSM-5 zeolite are used as the active components of the catalytic cracking catalyst, the selectivity and the yield of the carbon tetraolefin of the catalytic cracking catalyst can be improved, the further isomerization reaction and cracking reaction of low-carbon olefin molecules in gasoline can be promoted, the yield of the carbon tetraolefin is increased, and the selectivity of the carbon tetraolefin is improved. When the catalytic cracking catalyst is used in the catalytic cracking process of heavy oil, the concentration of the carbon tetraolefin in the liquefied gas can be improved and the yield and the selectivity of the carbon tetraolefin can be increased under the condition that the yields of gasoline and liquefied gas are not reduced.
In a preferred embodiment, the catalytic cracking catalyst comprises 15-40 wt% of a Y-type zeolite, 5-20 wt% of a beta zeolite, 10-55 wt% of a clay, 5-40 wt% of a refractory inorganic oxide, and 3-10 wt% of a modified ZSM-5 zeolite.
According to the invention, the Y-type zeolite, the beta zeolite, the clay are well known to the person skilled in the art, for example, the Y-type zeolite can be selected from ultrastable Y-type zeolites and/or modified Y-type zeolites, the modified Y-type zeolites containing phosphorus and/or rare earth elements; the beta zeolite can be one or more selected from hydrogen type beta zeolite, sodium type beta zeolite and modified beta zeolite, and the modified beta zeolite contains phosphorus and/or rare earth metal elements; the clay can be one or more selected from kaolin, rectorite, diatomite, montmorillonite, bentonite and sepiolite.
According to the present invention, the refractory inorganic oxide may be selected from refractory inorganic oxides used as a matrix and/or binder component of a catalytic cracking catalyst, such as one or more of alumina, silica and amorphous silica-alumina, which are known per se and methods for preparing the same to those skilled in the art.
In a third aspect, the present invention provides a process for preparing a modified ZSM-5 zeolite provided in the first aspect of the present invention, the process comprising:
(1) mixing a compound containing IVB group metal, a carbon source and a first solvent, and adjusting the pH value of the mixture to 5-10 to obtain a first slurry; the carbon source comprises natural high molecular organic compounds and/or semi-synthetic high molecular organic compounds;
(2) the first slurry and ZSM-5 zeolite are stirred and mixed for 10-120min at the temperature of 15-100 ℃, and the solid is taken out to be subjected to first roasting for 0.5-5 h at the temperature of 300-600 ℃.
The atmosphere of the first firing is not particularly limited, and may be, for example, an air atmosphere and/or an inert atmosphere, and the inert gas in the inert atmosphere is selected from one or more of nitrogen, helium and argon. The temperature and time for mixing in step (1) are also not particularly limited, and may be, for example, from 10 to 180 minutes at 25 to 90 ℃. The manner of removing the solid is not particularly limited, and for example, filtration or drying may be employed, and filtration is preferable.
In one embodiment, in step (2), the first slurry is mixed with ZSM-5 zeolite and stirred at 40-90 ℃ for 30-90 min.
According to the present invention, the weight ratio of the amounts of the group IVB metal-containing compound and the ZSM-5 zeolite, and the weight ratio of the amounts of the ZSM-5 zeolite and the carbon source may be in a wide range, for example, the weight ratio of the amounts of the group IVB metal-containing compound and the ZSM-5 zeolite may be (0.005-0.10): the weight ratio of the amounts of the ZSM-5 zeolite and the carbon source may be 1: (0.001-0.15) a group IVB metal-containing compound calculated as the group IVB metal oxide, ZSM-5 zeolite calculated on a dry basis; preferably, the compound containing a group IVB metal and the ZSM-5 zeolite are used in a weight ratio of (0.01-0.08): 1; the weight ratio of the ZSM-5 zeolite to the carbon source is 1: (0.005-0.10); more preferably, the group IVB metal-containing compound is a Zr-containing compound and/or a Ti-containing compound.
The group IVB metal in the group IVB metal-containing compound according to the present invention may be titanium and/or zirconium, and in one embodiment, the group IVB metal-containing compound may be one or more selected from the group consisting of zirconium tetrachloride, zirconium sulfate, zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium isopropoxide, titanium tetrachloride, titanyl sulfate, ammonium fluotitanate, titanium sulfate, tetrabutyl titanate, titanium trichloride, and titanium sulfite.
According to the present invention, the ZSM-5 zeolite is well known to those skilled in the art and may be selected from one or more of sodium type ZSM-5 zeolite, hydrogen type ZSM-5 zeolite and phosphorus type ZSM-5 zeolite, for example; the kind of the first solvent is not particularly limited as long as it can dissolve the group IVB metal-containing compound and disperse the ZSM-5 zeolite, and may be, for example, one or more selected from deionized water, ethanol, acetone, and hexane.
According to the present invention, the carbon source may be an organic polymer compound, for example, a natural polymer compound and/or a semisynthetic polymer compound; in one embodiment, the carbon source may be selected from one or more of starch, lignin, viscose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose. The modified ZSM-5 zeolite prepared from the high molecular organic compound and/or the semi-synthetic high molecular organic compound has the advantages that the weight content of the IVB group metal element on the surface is higher than that of the bulk phase IVB group metal element, the catalyst performance is better, and the selectivity and the yield of the ZSM-5 zeolite to the carbon tetraene are favorably improved.
According to the present invention, in step (1), the pH of the mixture may be adjusted to 5 to 9, preferably, the pH of the first slurry is adjusted to 5 to 8.5. The manner of adjusting the pH value is not particularly limited, and for example, the pH value of the first slurry may be adjusted by adding an alkaline solution, which may be one or more of ammonia water, an aqueous water glass solution, an aqueous sodium metaaluminate solution and an aqueous sodium hydroxide solution, and is preferably ammonia water. The concentration of the alkaline solution can vary over a wide range, and in one embodiment, the alkaline solution is OH-The concentration may be 2 to 20% by weight, preferably 3 to 15% by weight. In another embodiment, the alkaline solution is dilute ammonia, and the dilute ammonia is NH3The concentration is 2 to 20% by weight, preferably 3 to 15% by weight. By adjusting the pH of the mixture, the group IVB metal ions can be precipitated as hydroxides, which is beneficial to the uniform dispersion of the precipitates containing the group IVB metal on the surface of the ZSM-5 zeolite.
In a third aspect, the present invention provides a process for preparing a catalytic cracking catalyst provided in the second aspect, the process comprising: mixing the Y-type zeolite, the beta zeolite, the clay, the refractory inorganic oxide, the modified ZSM-5 zeolite provided by the first aspect of the present invention, and the second solvent, granulating the resulting second slurry, and drying and/or second calcining.
According to the present invention, the heat-resistant inorganic oxide includes the heat-resistant inorganic oxide itself and/or a precursor of the heat-resistant inorganic oxide. The refractory inorganic oxide itself may be selected from one or more of the refractory inorganic oxides used as the matrix and binder component of the cracking catalyst, such as one or more of alumina, silica and amorphous silica-alumina; the precursor of the heat-resistant inorganic oxide refers to a substance capable of forming the heat-resistant inorganic oxide in the preparation process of the catalyst of the present invention, and the precursor of the alumina, for example, may be one or more selected from the group consisting of alumina sol, pseudo-boehmite, alumina trihydrate and amorphous aluminum hydroxide; for example, the precursor of silica may be selected from one or more of silica sol, silica gel and water glass. These refractory inorganic oxides themselves and/or precursors of refractory inorganic oxides and methods for their preparation are well known to those skilled in the art.
In a preferred embodiment, clay, refractory inorganic oxide and a first solvent are beaten, the obtained slurry is mixed with modified ZSM-5 zeolite, Y-type zeolite and beta zeolite and stirred, and the mixture is subjected to spray granulation, calcination, optional washing and drying to obtain the catalytic cracking catalyst of the invention. Preferably, the acid is added during or after pulping, the pH of the slurry is adjusted to 1-5, preferably 2-4, and aged at 30-90 ℃ for 0.5-5 hours. The acid can be inorganic acid or organic acid dissolved in water, and is preferably one or more of hydrochloric acid, nitric acid and phosphoric acid. The methods and conditions for spray drying are well known to those skilled in the art and will not be described herein.
According to the invention, the solids content of the second slurry may vary within wide limits, for example the solids content of the second slurry may be 15-60 wt%, preferably 20-50 wt%.
According to the invention, the temperature of drying can be between 80 and 200 ℃ and the time of drying can vary within wide limits and is not particularly limited, preferably the temperature is between 80 and 120 ℃; the second calcination may be performed at a temperature of 350-700 deg.C for a time of 0.5-6 hours, preferably at a temperature of 400-650 deg.C for a time of 1-4 hours, and may be performed in any atmosphere, such as an air atmosphere.
In one embodiment, the catalytic cracking catalyst of the present invention may also contain other types of MFI structure zeolites, such as ZSM-8, ZSM-11.
In a fourth aspect, the invention provides the use of a modified ZSM-5 zeolite provided in the first aspect of the invention or a catalytic cracking catalyst provided in the second aspect of the invention in the catalytic cracking of heavy oils.
The present disclosure is further illustrated by the following examples, but is not to be construed as being limited thereby.
The raw materials used in the preparation of the catalyst are illustrated below:
kaolin, manufactured by Suzhou Kaolin corporation, has a solids content of 76% by weight; the alumina content in the alumina sol was 21.5 wt%; pseudo-boehmite was produced by Shandong aluminum works and had a solid content of 62.0 wt%; the solid content of the acidified pseudoboehmite is 12.0 percent by weight, and the acidified pseudoboehmite is acidified by hydrochloric acid, wherein the molar ratio of acid (HCl) to alumina is 0.15 during acidification; the ultrastable Y zeolite USY used has a solid content of 94.7% and a unit cell constant ofIn terms of the weight percentage, Na2The O content is 1.3%; the rare earth ultrastable Y zeolite REUSY has a solid content of 84.8% and a unit cell constant ofIn terms of the weight percentage, Na2O content 1.6%, RE2O3The content is 12.0 percent; hydrogen-type beta zeolite has a solid content of 75% and SiO2/Al2O3(molar ratio) 25, Na2The O content was 0.15%. Phosphorus-modified beta zeolite has a solid content of 82.5% and SiO2/Al2O3(molar ratio) 25, Na2O content 0.15%, P2O5The content was 7.0%. ZSM-5 zeolite, SiO, used in examples and comparative examples2/Al2O3(molar ratio) 40 to 50, Na2The O content was 3.5% and the solids content was 75% by weight. Phosphorus modified ZSM-5 zeolite, SiO2/Al2O3(molar ratio) 40 to 50, Na2O content 0.12%, P2O5The content was 2.1% and the solids content was 83% by weight.
The Y-type zeolite, the beta zeolite and the ZSM-5 zeolite are all produced by China petrochemical catalyst company Limited, and the other reagents are produced by China pharmaceutical group chemical reagent company Limited, and the specifications are all analytically pure. Of the contents, those not specifically mentioned are all weight percentages.
Dilute ammonia water with NH3The calculated concentration was 12% by weight.
Testing method of modified ZSM-5 zeolite property:
(1) determination of acid amount and acid strength: adopts a thermogravimetric-temperature programmed desorption (TG-TPD) technology and adopts NH3As alkaline adsorption gas, zeolite samples are adsorbed and saturated at room temperature, and then NH in the process of temperature programmed desorption is detected by a thermogravimetric-differential thermal balance (PCT-2 type)3Weight loss of (1) as NH3The desorption amount is taken as the acid amount of the sample, the temperature regions of the weak acid center, the medium strength acid center and the strong acid center of the zeolite are respectively 120-DEG C270℃, 270-DEG C390℃ and 390-DEG C560℃, and the desorbed NH is in the corresponding temperature ranges3The molar amount corresponds to the acid amount of the zeolite.
(2) Acid B and acid L: the Nicolet 560 type infrared spectrometer of NyGao corporation in America is adopted to represent the surface acidity of the catalyst, and the wave number is 1400-1700cm-1. The acid position B in the catalyst was 1540cm-1Is characterized by the characteristic peak of 1450cm-1The ratio of the B acid to the L acid is the ratio of the peak area of the characteristic peak of the B acid to the peak area of the characteristic peak of the L acid.
(3) The weight content of the IVB group metal element on the surface of the modified ZSM-5 zeolite and the weight content of the IVB group metal element in the bulk phase are as follows: the weight content of the group IVB metal element on the surface of the modified ZSM-5 zeolite means the weight content of the group IVB metal element analyzed in the range of 2 to 5nm on the surface of the zeolite using X-ray photoelectron spectroscopy (XPS).
The weight content of the group IVB metal element of the modified ZSM-5 zeolite phase is the weight content of the group IVB metal element in the zeolite measured by chemical analysis (ICP (Jarrell-Ash, ICAP 9000) elemental analysis method).
In the present invention, the group IVB metal element contained in the modified ZSM-5 zeolite means the group IVB metal element contained in the modified ZSM-5 zeolite phase. The weight content of the IVB group metal element in terms of oxide contained in the modified ZSM-5 zeolite can be obtained by converting the measured weight content of the IVB group metal element in the modified ZSM-5 zeolite phase, and the conversion method is well known to those skilled in the art and will not be described herein again. The properties of the modified ZSM-5 zeolites prepared in the examples and comparative examples are shown in Table 1.
Analysis of catalyst composition: x-ray fluorescence spectroscopy (XRF) was used.
The results of the catalyst composition analysis are shown in tables 2-4.
Examples 1-8 are examples of the preparation of modified ZSM-5 zeolite, comparative examples 1-4 are comparative examples of the preparation of modified ZSM-5 zeolite:
example 1
(1) 2250g of deionized water, 39.23g of zirconium oxychloride (ZrOCl)2·8H2O) and 7.5g of hydroxypropyl methyl cellulose are stirred and mixed, the pH value of the mixture is adjusted to 7 by using dilute ammonia water, and the mixture is continuously stirred for 40 minutes to obtain first slurry;
(2) mixing the first slurry with 150g of ZSM-5 zeolite and stirring at 40 ℃ for 90 minutes; filtration and calcination of the resulting filter cake at 550 ℃ for 2 hours in an air atmosphere gave the modified ZSM-5 zeolite of the invention, designated B1.
Wherein the weight ratio of the zirconium oxychloride, the ZSM-5 zeolite and the hydroxypropyl methyl cellulose is 0.1: 1: 0.05, zirconium oxychloride as zirconia, ZSM-5 zeolite as dry weight basis.
Example 2
(1) Stirring and mixing 1500g of deionized water, 28.3g of zirconium isopropoxide and 3.0g of methyl cellulose, adjusting the pH value of the mixture to 9.5 by using dilute ammonia water, and continuously stirring for 60 minutes to obtain first slurry;
(2) mixing the first slurry with 150g of ZSM-5 zeolite, and stirring at 60 ℃ for 120 minutes; filtering, and calcining the obtained filter cake at 500 ℃ for 2 hours in an air atmosphere to obtain the modified ZSM-5 zeolite of the invention, which is recorded as B2.
Wherein the weight ratio of the zirconium isopropoxide to the ZSM-5 zeolite to the methylcellulose is 0.06: 1: 0.02, zirconium isopropoxide as zirconia, ZSM-5 zeolite as dry basis weight.
Example 3
(1) 750g of deionized water, 10.5g of zirconium nitrate (Zr (NO)3)4·5H2O) and 0.5g of lignin are stirred and mixed, the pH value of the mixture is adjusted to 5.5 by using dilute ammonia water, and the mixture is continuously stirred for 30 minutes to obtain first slurry;
(2) mixing the first slurry with 150g of ZSM-5 zeolite, and stirring at 80 ℃ for 120 minutes; filtration and calcination of the resulting filter cake at 550 ℃ for 1 hour in an air atmosphere gave the modified ZSM-5 zeolite of the invention, designated B3.
Wherein the weight ratio of the zirconium nitrate to the ZSM-5 zeolite to the lignin to the deionized water is 0.02: 1: 0.003, zirconium nitrate in terms of zirconium oxide, ZSM-5 zeolite in terms of dry weight.
Example 4
(1) 3000g of deionized water, 47.1g of zirconium oxychloride (ZrOCl)2·8H2O) and 15g of viscose fiber are stirred and mixed, the pH value of the mixture is adjusted to 7.5 by using dilute ammonia water, and the mixture is continuously stirred for 60 minutes to obtain first slurry;
(2) mixing the first slurry with 150g of ZSM-5 zeolite and stirring at 85 ℃ for 40 minutes; filtering, and roasting the obtained filter cake for 3 hours at 450 ℃ in an air atmosphere to obtain the modified ZSM-5 zeolite, which is recorded as B4.
Wherein, the weight ratio of the zirconium oxychloride, the ZSM-5 zeolite and the viscose fiber is 0.08: 1: 0.1, zirconium oxychloride as zirconia, ZSM-5 zeolite as dry weight basis.
Example 5
(1) Stirring and mixing 1500g of deionized water, 18.9g of zirconium isopropoxide and 6.0g of hydroxyethyl cellulose, adjusting the pH value of the mixture to 5.5 by using dilute ammonia water, and continuously stirring for 30 minutes to obtain first slurry;
(3) mixing the first slurry with 150g of phosphorus-modified ZSM-5 zeolite, and stirring at 80 ℃ for 1 hour; filtration and calcination of the resulting filter cake at 550 ℃ for 2 hours in an air atmosphere gave the modified ZSM-5 zeolite of the invention, designated B5.
Wherein the weight ratio of the zirconium isopropoxide to the ZSM-5 zeolite to the hydroxyethyl cellulose is 0.04: 1: 0.04, zirconium isopropoxide as zirconium oxide, ZSM-5 zeolite as dry weight basis.
Example 6
Modified ZSM-5 zeolite B6 was prepared in the same manner as in example 5 except that, in step (1), 1500g of deionized water, 18.9g of zirconium isopropoxide and 0.12g of hydroxypropylmethylcellulose were mixed with stirring, the pH of the mixture was adjusted to 5.5 with dilute aqueous ammonia, and stirring was continued for 30 minutes to give a first slurry.
Wherein the weight ratio of the dosages of the zirconium isopropoxide, the ZSM-5 zeolite and the hydroxypropyl methyl cellulose is 0.04: 1: 0.0008, zirconium isopropoxide as zirconia, ZSM-5 zeolite by weight on a dry basis.
Example 7
Modified ZSM-5 zeolite B7 was prepared in the same manner as in example 5 except that, in step (1), 1500g of deionized water, 21g of zirconium isopropoxide and 6.0g of hydroxypropylmethylcellulose were mixed under stirring, the pH of the mixture was adjusted to 5.5 with dilute aqueous ammonia, and stirring was continued for 30 minutes to obtain a first slurry.
Wherein the weight ratio of the dosages of the zirconium isopropoxide, the ZSM-5 zeolite and the hydroxypropyl methyl cellulose is 0.14: 1: 0.04.
example 8
Modified ZSM-5 zeolite was prepared in the same manner as in example 5, except that in step (1), the pH of the first slurry was adjusted to 9.5, and the modified ZSM-5 zeolite prepared was designated as B8.
Example 9
Modified ZSM-5 zeolite B9 was prepared in the same manner as in example 5 except that, in step (1), 1500g of deionized water, 14.24g of titanium tetrachloride and 6.0g of hydroxyethyl cellulose were mixed with stirring, the pH of the mixture was adjusted to 5.5 with dilute aqueous ammonia, and stirring was continued for 30 minutes to obtain a first slurry.
Wherein the weight ratio of the titanium tetrachloride to the ZSM-5 zeolite to the hydroxyethyl cellulose is 0.04: 1: 0.04, titanium tetrachloride as titanium oxide, ZSM-5 zeolite as dry weight basis.
Comparative example 1
A modified ZSM-5 zeolite was prepared in the same manner as in example 1, except that the pH of the first slurry was not adjusted.
(1) 2250g of deionized water, 39.2g of zirconium oxychloride ZrOCl2·8H2O and 7.5g of hydroxypropyl methyl cellulose are uniformly stirred to obtain a first slurry;
(2) mixing the first slurry with 200g of ZSM-5 zeolite, and stirring at 40 ℃ for 90 minutes; filtration and calcination of the resulting filter cake at 550 ℃ for 2 hours in an air atmosphere gave comparative modified ZSM-5 zeolite DB 1.
Comparative example 2
A modified ZSM-5 zeolite was prepared in the same manner as in example 1, except that no carbon source was added in step (1).
(1) 2250g of deionized water and 39.2g of zirconium oxychloride ZrOCl2·8H2O, after being uniformly stirred, the pH value of the mixture is adjusted to 7.0 by using dilute ammonia water, and a first slurry is obtained;
(2) mixing the first slurry with 200g of ZSM-5 zeolite, and stirring at 40 ℃ for 90 minutes; filtration and calcination of the resulting filter cake at 550 ℃ for 2 hours in an air atmosphere gave comparative modified ZSM-5 zeolite DB 2.
Comparative example 3
The modified ZSM-5 zeolite is prepared by adopting a conventional aqueous solution impregnation method.
At room temperature, 200g of ZSM-5 zeolite was slurried with 1500g of deionized water, and 45g of (NH) was added4)2SO4Mixing uniformly, then heating to 90 ℃ for exchange for 1 hour, filtering and washing with deionized water, and roasting a filter cake for 2 hours at 600 ℃ to obtain the hydrogen type ZSM-5 zeolite.
47.1g of zirconium oxychloride (ZrOCl)2·8H2O) is dissolved in 200g of deionized water to prepare an impregnating solution, the obtained impregnating solution and the treated ZSM-5 zeolite are uniformly mixed, the mixture is kept stand for 1h at room temperature, and then the mixture is roasted for 4 h at 500 ℃ to obtain the modified ZSM-5 zeolite, which is recorded as DB 3.
Comparative example 4
The modified ZSM-5 zeolite is prepared by adopting an organic solvent solution impregnation method.
At room temperature, 200g of ZSM-5 zeolite was slurried with 1500g of deionized water, and 45g of (NH) was added4)2SO4Mixing uniformly, then heating to 90 ℃ for exchange for 1 hour, filtering and washing with deionized water, and roasting a filter cake for 2 hours at 600 ℃ to obtain the hydrogen type ZSM-5 zeolite.
47.1g of zirconium oxychloride (ZrOCl)2·8H2O) was dissolved in 200g of n-hexane to prepare a dipping solution, and the obtained dipping solutionAnd uniformly mixing with the treated ZSM-5 zeolite, standing for 1h at room temperature, and then roasting for 4 h at 500 ℃ to obtain the modified ZSM-5 zeolite, which is recorded as DB 4.
Examples 10-24 are examples of catalytic cracking catalysts containing modified ZSM-5 zeolites of the present invention, and comparative examples 5-8 and 10 are comparative examples of catalytic cracking catalysts containing comparative modified ZSM-5 zeolites:
example 10
447g of kaolin, 372g of alumina sol and 563g of decationized water are added into a pulping tank for pulping, then 1666g of acidified pseudo-boehmite is added, after stirring for 60 minutes, 271g of REUSY zeolite, 133gH beta zeolite, 50g (dry basis) of the modified ZSM-5 zeolite (the modified ZSM-5 zeolite B1 prepared in example 1) and 545g of deionized water are added for pulping to form slurry, the slurry is homogenized, dispersed (stirred) for 30 minutes, then the obtained slurry is sprayed, dried and molded, and roasted for 2 hours at 500 ℃ to obtain the catalytic cracking catalyst C1 provided by the invention.
Examples 11 to 18
A catalytic cracking catalyst C2-C9 was prepared in the same manner as in example 10, except that the modified ZSM-5 zeolite used to prepare the catalytic cracking catalyst was modified ZSM-5 zeolite B2-B9 prepared in examples 2-9, respectively.
Example 19
448g of kaolin, 372g of alumina sol and 513g of decationized water are added into a pulping tank for pulping, 1666g of acidified pseudo-boehmite is added, after stirring for 60 minutes, 105g of USY zeolite, 236g of REUSY, 67g of H beta zeolite and 30g (calculated by dry basis) of modified zeolite B1 and 561g of deionized water are added for pulping to form slurry, the slurry is uniformly dispersed (stirred) for 30 minutes, the obtained slurry is sprayed, dried and molded, and roasted for 2 hours at 500 ℃, so that the catalytic cracking catalyst C10 provided by the invention is obtained.
Example 20
448g of kaolin, 372g of alumina sol and 513g of decationized water are added into a pulping tank for pulping, 1666g of acidified pseudo-boehmite is added, after stirring for 60 minutes, slurry formed by pulping 271g of REUSY, 133g of H beta zeolite, 50g (calculated by dry basis) of modified ZSM-5 zeolite B2 and 545g of deionized water is added, the mixture is uniformly dispersed (stirred) for 30 minutes, the obtained slurry is sprayed, dried and molded, and roasted for 2 hours at 500 ℃, so that the catalytic cracking catalyst C11 provided by the invention is obtained.
Example 21
448g of kaolin, 372g of alumina sol and 513g of decationized water are added into a pulping tank for pulping, 1666g of acidified pseudo-boehmite is added, after stirring for 60 minutes, slurry formed by pulping 64g of USY zeolite, 177g of REUSY, 133g of H beta zeolite and 70g (calculated by dry basis) of modified ZSM-5 zeolite B5 and 556g of deionized water is added, the mixture is uniformly dispersed (stirred) for 30 minutes, the obtained slurry is sprayed, dried and formed, and the mixture is roasted for 2 hours at 500 ℃ to obtain the catalytic cracking catalyst C12 provided by the invention.
Example 22
395g of kaolin, 465g of alumina sol and 420g of decationized water are added into a pulping tank for pulping, 1666g of acidified pseudo-boehmite is added, after 60 minutes of stirring, slurry formed by pulping 53g of USY zeolite, 177g of REUSY, 181g of phosphorus modified beta zeolite and 50g (calculated by dry basis) of modified ZSM-5 zeolite B4 and 591g of deionized water is added, the mixture is homogenized, dispersed (stirred) for 30 minutes, the obtained slurry is spray-dried and formed, and the catalyst C13 provided by the invention is obtained after roasting for 2 hours at 500 ℃.
Example 23
395g of kaolin, 465g of alumina sol and 420g of decationized water are added into a pulping tank for pulping, 1666g of acidified pseudo-boehmite is added, after stirring for 60 minutes, 212g of REUSY, 145g of phosphorus modified beta zeolite and 100g (calculated by dry basis) of modified ZSM-5 zeolite B3 and 578g of deionized water are added for pulping to form slurry, the slurry is homogenized, dispersed (stirred) for 30 minutes, and then the obtained slurry is sprayed, dried and molded, and roasted for 2 hours at 500 ℃ to obtain the catalytic cracking catalyst C14.
Example 24
197g of kaolin, 465g of alumina sol and 278g of decationized water are added into a pulping tank for pulping, 2916g of acidified pseudo-boehmite is added, after stirring for 60 minutes, 118g of Y zeolite, 333g of H beta zeolite, 50g (dry basis) of modified ZSM-5 zeolite B5 and 641g of deionized water are added for pulping to form slurry, the slurry is homogenized, dispersed (stirred) for 30 minutes, and then the obtained slurry is sprayed, dried and formed, and roasted for 2 hours at 500 ℃ to obtain the catalytic cracking catalyst C15.
Comparative examples 5 to 8
A catalytic cracking catalyst DC1-DC4 was prepared in the same manner as in example 10, except that the modified ZSM-5 zeolite used to prepare the catalytic cracking catalyst was the modified ZSM-5 zeolite DB1-DB4 prepared in comparative examples 1-4, respectively.
Comparative example 9
This comparative example prepared a catalytic cracking catalyst without beta zeolite.
A catalytic cracking catalyst was prepared in the same manner as in example 21 by adding 448g of kaolin, 372g of alumina sol and 513g of decationized water to a pulping tank and pulping, then adding 1666g of acidified pseudoboehmite and stirring for 60 minutes, then adding 169g of USY zeolite, 177g of REUSY and 70g (dry basis) of modified ZSM-5 zeolite B5 and 556g of deionized water and pulping to form a slurry, homogeneously dispersing (stirring) for 30 minutes, then spray-drying and molding the obtained slurry, and calcining at 500 ℃ for 2 hours to obtain a comparative catalytic cracking catalyst DC 5.
Comparative example 10
This comparative example prepared a catalytic cracking catalyst without the ZSM-5 zeolite.
A catalytic cracking catalyst was prepared in the same manner as in example 21 by adding 448g of kaolin, 372g of alumina sol and 513g of decationized water to a slurrying tank and slurrying, then adding 1666g of acidified pseudoboehmite and stirring for 60 minutes, then adding 137g of USY zeolite, 177g of REUSY and 133g of H β zeolite to a slurry prepared by slurrying with 556g of deionized water, homogeneously dispersing (stirring) for 30 minutes, then spray-drying the resulting slurry and molding, and calcining at 500 ℃ for 2 hours, to obtain a comparative catalytic cracking catalyst DC 6.
Comparative example 11
Phosphorus and iron modified ZSM-5 zeolite DB5 was prepared according to the method of CN107899606A example 1.
A catalytic cracking catalyst was prepared in the same manner as in example 21 by adding 448g of kaolin, 372g of alumina sol and 513g of decationized water to a slurrying tank and slurrying, then adding 1666g of acidified pseudoboehmite, after stirring for 60 minutes, 64g of USY zeolite, 177g of REUSY, 133g of H beta zeolite and 70g (on a dry basis) of phosphorus and iron modified ZSM-5 zeolite DB5 and 556g of deionized water and slurrying, homogeneously dispersing (stirring) for 30 minutes, then spray drying and molding the resulting slurry, and calcining at 500 ℃ for 2 hours to obtain a comparative catalytic cracking catalyst DC 7.
Catalytic cracking catalyst evaluation
Catalytic cracking catalysts C1-C15 and DC1-DC7 were aged in advance in a fixed bed aging apparatus at 800 ℃ for 12 hours with 100% steam, and then evaluated in a small fixed fluidized bed apparatus, wherein the properties of the reaction feed oil are shown in Table 8, the reaction temperature is 500 ℃ and the weight ratio of the catalyst to the oil is 5.92.
Wherein, the conversion rate is gasoline yield, liquefied gas yield, dry gas yield and coke yield;
the yield of the carbon tetraolefin is 1-butene yield, 2-butene yield and isobutene yield;
the concentration of the carbon tetraolefin is equal to the yield of the carbon tetraolefin/the yield of the liquefied gas;
selectivity to carbon tetraolefin/yield to carbon four cut.
The evaluation results are shown in tables 5 to 7, wherein the strong acid amount/total acid amount in the tables refers to the numerical value of the number of strong acid centers in the total acid amount, and the medium strong acid amount/total acid amount refers to the numerical value of the number of medium strong acid centers in the total acid amount.
TABLE 1 modified ZSM-5 Zeolite Properties
The results in table 1 show that, compared to comparative example 1, when the amount of the zirconium-containing compound added is the same, the modified ZSM-5 zeolite prepared in example 1 has a higher zirconia content, which indicates that adjusting the pH of the first slurry with dilute ammonia is more favorable for the zirconium-containing compound to be fully utilized, and for part of the zirconium-containing compound that does not enter the zeolite channels to be precipitated on the zeolite surface, whereas comparative example 1 does not adjust the pH, and the zirconium-containing compound is not only lost but also located more inside the molecular sieve, whereas example 1 has a lower ratio of the weight content of the IVB group metal element in the zeolite phase to the weight content of the IVB group metal element in the zeolite surface, a higher B acid/L acid ratio, and a higher number of medium-strength acid centers. In comparison with example 1, the absence of a carbon source (hydroxypropylmethylcellulose) in comparative example 2 resulted in a higher ratio of the weight content of the IVB group metal element in the zeolite phase/the weight content of the IVB group metal element on the surface of the zeolite, and the acidity of the ZSM-5 zeolite could not be adjusted well. The modified ZSM-5 zeolite prepared in example 4 had a higher ba/L acid ratio than that of comparative example 3 when the same amount of the zirconium-containing compound was added. Compared with comparative examples 1-4 and 11, the modified ZSM-5 zeolite B1-B8 prepared by the present invention has a higher medium-strength acid amount distribution and a lower number of strong acid centers.
TABLE 2 catalytic cracking catalyst composition
TABLE 3 catalytic cracking catalyst composition
TABLE 4 catalytic cracking catalyst composition
TABLE 5 evaluation results
TABLE 6 evaluation results
Table 7 evaluation results
TABLE 8
Properties of crude oil
Density (20 ℃ C.)/(kg. cm)-3)
919.3
w (carbon residue)/%)
2.62
w(C)/％
87.42
w(H)/％
11.5
w(S)/％
0.26
w(N)/％
0.0616
Mass fraction of metal/(μ g)-1)
Fe
3.2
Ni
3.8
V
3.8
The mass fraction/weight of the four components
Saturated hydrocarbons
62.1
Aromatic hydrocarbons
26.6
Glue
10.7
Asphaltenes
0.6
Reduced pressure distillation range/. degree.C
Initial boiling point
226.7
5％
280.9
10％
317
30％
400.7
50％
454.4
70％
527
End point of distillation
540
End point of distillation volume yield/%)
72.6
The results of tables 5 to 7 show that the catalysts C1 to C9 prepared in the examples of the present invention have higher total yields of gasoline and liquefied gas, lower yields of heavy oil, higher concentration of tetraolefins in liquefied gas, and increased yield and selectivity of tetraolefins, as compared with the catalysts DC1 to DC4 prepared in comparative examples 5 to 8. The modified ZSM-5 zeolite prepared by the invention has excellent yield and selectivity of the carbon four-olefin.
Compared with the comparative example 9, the cracking catalyst C12 provided by the example 21 has higher gasoline yield and lower diesel oil yield, the concentration of the carbon tetraolefin in liquefied gas is obviously improved, and the selectivity of the carbon tetraolefin is improved. The cracking catalyst C12 provided in example 21 had comparable heavy oil cracking ability, increased yields of liquefied gas and propylene, increased yields of tetraolefins, increased concentration of tetraolefins in liquefied gas, and increased selectivity for tetraolefins as compared to comparative example 10. The cracking catalyst C12 provided in example 21 has comparable heavy oil cracking ability and increased selectivity and yield of carbon tetraolefins as compared to comparative example 11.
The preferred embodiments of the present disclosure have been described in detail above, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.
It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.