CN114054071B - Catalyst, method for preparing the same and method for improving catalyst cycle life in alkylation reaction - Google Patents

Catalyst, method for preparing the same and method for improving catalyst cycle life in alkylation reaction Download PDF

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CN114054071B
CN114054071B CN202010762686.3A CN202010762686A CN114054071B CN 114054071 B CN114054071 B CN 114054071B CN 202010762686 A CN202010762686 A CN 202010762686A CN 114054071 B CN114054071 B CN 114054071B
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catalyst
molecular sieve
roasting
drying
binder
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CN114054071A (en
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周顺利
李永祥
张成喜
罗一斌
舒兴田
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
    • B01J29/082—X-type faujasite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
    • B01J29/084—Y-type faujasite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7007—Zeolite Beta
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/633—Pore volume less than 0.5 ml/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/30—Ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
    • C07C2/56—Addition to acyclic hydrocarbons
    • C07C2/58—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/12—After treatment, characterised by the effect to be obtained to alter the outside of the crystallites, e.g. selectivation

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  • Physics & Mathematics (AREA)
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Abstract

The invention relates to the field of catalysts, and discloses a catalyst, a preparation method thereof and a method for prolonging the cycle life of the catalyst in alkylation reaction, wherein the catalyst comprises a molecular sieve and a binder, the content of the molecular sieve is 20-99wt% based on the dry basis weight of the catalyst, and the content of the binder is 1-80wt%; the catalyst has a unit cell constant which is not more than 1% as compared to the unit cell constant of the molecular sieve; the total acid amount of the catalyst is increased by not more than 50% compared with the total acid amount of the molecular sieve, and the reduction is not more than 5%; the mesoporous volume of the catalyst is increased by more than 220% compared with that of the molecular sieve. The catalyst provided by the invention can effectively prolong the cycle life of the catalyst under the condition of not reducing the selectivity of a target product in the alkylation reaction.

Description

Catalyst, method for preparing the same and method for improving catalyst cycle life in alkylation reaction
Technical Field
The invention relates to the field of catalysts, in particular to a catalyst, a preparation method thereof and a method for prolonging the cycle life of the catalyst in alkylation reaction.
Background
In order to reduce the exhaust emission of fuel vehicles, the quality of the vehicle fuel is subject to a severe standard. The alkylate is an ideal blend oil because of its high octane number, no sulfur, nitride, etc. The traditional liquid acid alkylation technology uses sulfuric acid or hydrofluoric acid as a catalyst, and the technology for large-scale production of the alkylate oil at present mainly adopts two processes, namely a sulfuric acid process and a hydrofluoric acid process. The alkylated oil produced by the two methods has high yield and good selectivity, but the waste acid of the sulfuric acid process has larger discharge amount, and the waste acid has high treatment cost, great difficulty and larger environmental cost and pressure; hydrofluoric acid is a highly volatile, toxic chemical that once leaked can pose a serious hazard to the environment and surrounding residents' health. In addition, both processes have the problems of corrosion of production equipment and the like, and cause great challenges for production safety.
Compared with the traditional liquid acid technology, the solid acid has no corrosiveness and potential hazard, has no special requirements on equipment materials, and has high process safety; the method has no negative problems caused by waste acid treatment in the aspect of environmental protection, and the core of the development of the solid acid alkylation process is the development of a solid acid catalyst with excellent performance. The solid acid catalyst has the advantages of good stability, no corrosion to equipment, convenient separation from products, less environmental pollution, high relative safety in the transportation process and the like, and is an ideal form of future catalysts. Although the development of solid acid catalysts has been carried out for decades, the problem of relatively rapid deactivation of solid acid catalysts still exists, and the industrial process of the process technology is influenced.
One of the most significant problems with rapid deactivation of molecular sieve catalysts is the relatively small pore size (typically less than 0.8 nm), resulting in heat transfer and diffusion limitations in the catalytic reaction. Research has shown that diffusion properties play an important role in the industrial application of molecular sieves. At present, two approaches for reducing the size of a molecular sieve and preparing a hierarchical pore material are mainly used for improving the diffusion performance of the molecular sieve. By reducing the granularity of the molecular sieve, on one hand, the external specific surface area of the molecular sieve can be effectively improved, and more active centers are provided for the catalytic reaction of macromolecules; on the other hand, the short diffusion path is favorable for the diffusion of reaction products, and the generation of carbon deposit is reduced. However, when the molecular sieve grains become smaller, surface defects increase, surface energy increases, and stability of the molecular sieve deteriorates. Mesoporous and macroporous materials generally have good diffusion properties relative to the micropores of molecular sieves. In recent years, composite microporous and mesoporous hierarchical molecular sieve materials are paid attention to, and the materials comprise microporous/ordered mesoporous composites and hierarchical molecular sieves.
The prior preparation method of the hierarchical pore catalyst mainly comprises a template agent method and a post-treatment method, wherein the template agent method is to add chemical reagents such as an anionic reagent, an cationic reagent, a high polymer and the like in the preparation process of the molecular sieve, and the hierarchical pore structure is formed in the molecular sieve by burning organic matters in the post-treatment process of the molecular sieve. The post-treatment method is to post-treat the formed molecular sieve with acid-base reagent or anion-cation reagent to form multistage holes inside the molecular sieve. The molecular sieve prepared by the method has uniform size, but the preparation process is complex, the acid property of the catalyst is seriously damaged, and the chemical reagent used in a large amount in the treatment process can also influence the environment.
CN108408736a discloses a preparation method of a Y-type molecular sieve with a hierarchical pore structure, comprising: s1, fully stirring and mixing an aluminum source and deionized water to obtain a mixed solution A; s2, adding an alkali source into the mixed solution A, stirring, and then adding a silicon source into the mixed solution A to obtain a mixed solution B; s3, adding a proper amount of liquid Y-type molecular sieve seed crystals into the mixed solution B, then adding a proper amount of mesoporous template agent, and uniformly stirring to obtain a mixed solution C; s4, placing the mixed solution C into a reaction kettle for crystallization reaction at 130-150 ℃ for 5-30 hours, naturally cooling after the reaction is finished, and carrying out suction filtration and drying on a reaction product to obtain Y-type molecular sieve raw powder; s5, performing strong alkali washing on the molecular sieve raw powder to obtain the Y-type molecular sieve with the hierarchical pore structure. However, the method has a certain damage to the structure and acidity of the molecular sieve, and waste alkali liquid can be generated and needs to be recycled.
CN106032280a discloses a synthesis method for preparing mesoporous mordenite by using ionic surfactant, the method comprises dissolving template agent SAA in sodium hydroxide and/or potassium hydroxide solution, sequentially adding aluminum source and silicon source, pre-crystallizing at 80-100 ℃ for not less than 2 hours, crystallizing at 120-220 ℃ for not less than 12 hours, and obtaining mordenite with mesopores and micropores, but the method has certain damage to structure and acidity of mordenite molecular sieve.
Disclosure of Invention
The invention aims to solve the problems of destroying the molecular sieve structure and acidity in the existing preparation method of the catalyst, and provides a catalyst, a preparation method thereof and a method for prolonging the cycle life of the catalyst in alkylation reaction.
In the traditional catalyst preparation process, the molecular sieve is generally baked, then subjected to ion exchange, and the molecular sieve subjected to ion exchange is mixed with a binder and then subjected to secondary high-temperature baking molding. The secondary high-temperature roasting can damage the framework of the molecular sieve, so that the molecular sieve is dealuminized, the unit cells are greatly contracted, and the stability of the catalyst is damaged, thereby reducing the cycle life of the catalyst; meanwhile, mesoporous template agent is adopted to ream the molecular sieve catalyst, so that the structure and acidity of the molecular sieve can be damaged, great material loss and energy consumption are caused, pollutants such as waste gas and waste water can be generated, and the environment is seriously polluted.
In order to achieve the above object, the first aspect of the present invention provides a catalyst comprising a molecular sieve and a binder, wherein the molecular sieve is contained in an amount of 20 to 99wt% and the binder is contained in an amount of 1 to 80wt% based on the dry weight of the catalyst; the catalyst has a unit cell constant which is not more than 1% as compared to the unit cell constant of the molecular sieve; the total acid amount of the catalyst is increased by not more than 50% compared with the total acid amount of the molecular sieve, and the reduction is not more than 5%; the mesoporous volume of the catalyst is increased by more than 220% compared with that of the molecular sieve.
The second aspect of the invention provides a catalyst, which comprises a molecular sieve and a binder, wherein the content of the molecular sieve is 20-99wt% based on the dry weight of the catalyst, and the content of the binder is 1-80wt%; and is also provided with
The molecular sieve is a Y-type molecular sieve, the unit cell constant of the catalyst is 2.441-2.466nm, the total acid amount is more than 1438 mu mol/g, and the mesoporous volume is more than 0.12cm 3 /g; or alternatively
The molecular sieve is ZSM-5 molecular sieve, the unit cell constant of the catalyst is 2.004-2.024nm, the total acid amount is more than 1230 mu mol/g, and the mesoporous volume is more than 0.102cm 3 /g; or alternatively
The molecular sieve is an X-type molecular sieve, the unit cell constant of the catalyst is 2.46-2.485nm, the total acid amount is more than 1875 mu mol/g, and the mesoporous volume is more than 0.096cm 3 /g; or alternatively
The molecular sieve is beta-type molecular sieve, the unit cell constant of the catalyst is 1.249-1.262nm, the total acid amount is more than 1327 mu mol/g, and the mesoporous volume is more than 0.048cm 3 /g; or alternatively
The molecular sieve is mordenite type molecular sieve, the unit cell constant of the catalyst is 1.8-1.818nm, the total acid amount is more than 974 mu mol/g, and the mesoporous volume is more than 0.111cm 3 /g。
In a third aspect, the present invention provides a method for preparing a catalyst, the method comprising:
(1) Mixing sodium molecular sieve with heat-resistant inorganic oxide or its precursor, assistant, acid solution and water to form, drying and roasting to obtain roasting product;
(2) Sequentially carrying out ammonium exchange and acid treatment on the obtained roasting product;
wherein the roasting conditions include: the roasting temperature is 350-650 ℃, and the roasting pressure is 0.01-1MPa.
In a fourth aspect, the present invention provides a catalyst obtainable by the preparation process according to the third aspect of the present invention.
In a fifth aspect the present invention provides a process for increasing the cycle life of a catalyst in an alkylation reaction, the process comprising contacting an isoparaffin with an olefin in the presence of a catalyst under alkylation reaction conditions, the catalyst being in accordance with the first, second or fourth aspects of the present invention.
Through the technical scheme, the catalyst provided by the invention has higher mesoporous volume, and the catalyst unit cell and acidity are not destroyed, so that the catalytic activity of the catalyst is improved, and the catalyst can be effectively prolonged in cycle life and the selectivity of a target product when being applied to alkylation reaction. For example, when the catalyst prepared in example 1 of the present invention is used in alkylation reaction, the catalyst cycle life may reach 84h, C 8 The selectivity can reach 83.4%; when the catalyst prepared by the conventional process of comparative example 1 was used in alkylation, the catalyst had a cycle life of 32h and C under the same reaction conditions 8 The selectivity was 76.1%. The preparation method provided by the invention reduces one-time high-temperature roasting process, and has the advantages of simple process flow, energy conservation and emission reduction.
Drawings
FIG. 1 is a graph showing the low temperature nitrogen adsorption/desorption curves of the catalysts prepared in example 6 and comparative example 6 according to the present invention.
FIG. 2 is a graph showing the comparison of solid nuclear magnetic resonance Si spectra of the catalysts prepared in example 6 and comparative example 6 of the present invention.
FIG. 3 is a graph showing the comparison of solid nuclear magnetic resonance Al spectra of the catalysts prepared in example 6 and comparative example 6 of the present invention.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
As previously mentioned, the present invention provides in a first aspect a catalyst comprising a molecular sieve in an amount of from 20 to 99wt% and a binder in an amount of from 1 to 80wt%, based on the dry weight of the catalyst; the catalyst has a unit cell constant which is not more than 1% as compared to the unit cell constant of the molecular sieve; the total acid amount of the catalyst is increased by not more than 50% compared with the total acid amount of the molecular sieve, and the reduction is not more than 5%; the mesoporous volume of the catalyst is increased by more than 220% compared with that of the molecular sieve.
The second aspect of the invention provides a catalyst, which comprises a molecular sieve and a binder, wherein the content of the molecular sieve is 20-99wt% based on the dry weight of the catalyst, and the content of the binder is 1-80wt%; and is also provided with
The molecular sieve is a Y-type molecular sieve, the unit cell constant of the catalyst is 2.441-2.466nm, the total acid amount is more than 1438 mu mol/g, and the mesoporous volume is more than 0.12cm 3 /g; or alternatively
The molecular sieve is ZSM-5 molecular sieve, the unit cell constant of the catalyst is 2.004-2.024nm, the total acid amount is more than 1230 mu mol/g, and the mesoporous volume is more than 0.102cm 3 /g; or alternatively
The molecular sieve is an X-type molecular sieve, the unit cell constant of the catalyst is 2.46-2.485nm, the total acid amount is more than 1875 mu mol/g, and the mesoporous volume is more than 0.096cm 3 /g; or alternatively
The molecular sieve is beta-type molecular sieve, the unit cell constant of the catalyst is 1.249-1.262nm, the total acid amount is more than 1327 mu mol/g, and the mesoporous volume is more than 0.048cm 3 /g; or alternatively
The molecular sieve is mordenite type molecular sieve, the unit cell constant of the catalyst is 1.8-1.818nm, the total acid amount is more than 974 mu mol/g, and the mesoporous volume is more than 0.111cm 3 And/g. The catalyst meeting the above-defined conditions can significantly extend the cycle life of the catalyst in an alkylation reaction.
According to the invention, the molecular sieve is present in an amount of 25 to 95wt% and the binder is present in an amount of 5 to 75wt% based on the dry weight of the catalyst.
In the present invention, "dry basis weight" is defined as mass of the catalyst per unit mass after calcination at 600℃for 4 hours.
The binder of the present invention is widely selected, and preferably, the binder is at least one selected from the group consisting of alumina, silica, titania and zirconia.
The total acid amount of the catalyst is the sum of the acid amounts of the catalyst at 250 ℃, 350 ℃, 450 ℃ and 550 ℃, and ammonia gas programmed temperature rising desorption (NH) 3 -TPD) method. Wherein the amount of acid at 250 ℃ is referred to as the weak acid amount; the sum of the amounts of acids at 350℃and 450℃is referred to as the amount of medium-strong acid; the amount of acid at 550℃is referred to as the amount of strong acid. The specific test method is that about 0.15g of molecular sieve or catalyst (after extrusion molding at 20MPa, grinding to 20-40 meshes) sample is weighed and put into a quartz sample tube, and the quartz sample tube is placed into a heating furnace. Ar gas is used as carrier gas, the temperature is raised to 550 ℃, and the catalyst surface is purged for 120min to remove impurities adsorbed on the catalyst surface. Then cooling to 100 ℃, and saturated adsorbing NH 3 He mixture (5% NH) 3 +95% He) for 30min, continuing to purge with He gas for 90min to baseline plateau, and stripping off the physically adsorbed ammonia. Heating to 250 ℃ at 10 ℃/min, maintaining for 30min, removing ammonia which can be desorbed below 250 ℃, detecting the gas component change by adopting a TCD detector, continuously heating to 350 ℃, 450 ℃ and 550 ℃, and repeating the steps to detect the ammonia which can be desorbed at different temperatures. And integrating adsorption curves obtained at different temperature sections through a TCD detector, and automatically calculating the acid quantity at different temperatures through an instrument. The higher the total acid content of the catalyst, the better the catalytic activity of the catalyst, which is more advantageous for alkylation reactions. Different hydrogen forms The total acid amount of the molecular sieves may be different, for example, about 1786. Mu. Mol/g for HX type molecular sieves, about 1369. Mu. Mol/g for HY type molecular sieves, about 1263. Mu. Mol/g for Hbeta type molecular sieves, about 928. Mu. Mol/g for HMOR type molecular sieves, and about 1537. Mu. Mol/g for HZSM type molecular sieves. The invention changes the secondary high-temperature roasting in the prior art into the primary high-temperature pressurized roasting, which not only saves working procedures and reduces energy consumption, but also can control the total acid amount of the catalyst to be increased by not more than 50 percent compared with the total acid amount of the corresponding hydrogen type molecular sieve, and the reduction is not more than 5 percent, thus indicating that the total acid amount of the catalyst is not obviously destroyed.
The mesoporous volume of the catalyst of the invention is determined by the BET method. The mesoporous volume of different sodium type molecular sieves may be different, for example, the mesoporous volume of a sodium X type molecular sieve is typically 0.032cm 3 About/g, the mesoporous volume of the sodium Y-type molecular sieve is generally 0.04cm 3 About/g, the mesoporous volume of the sodium beta molecular sieve is generally 0.016cm 3 About/g, the mesoporous volume of the sodium mordenite type molecular sieve is generally 0.037cm 3 About/g, the mesoporous volume of the sodium ZSM-5 molecular sieve is generally 0.034cm 3 About/g. According to the invention, the secondary high-temperature roasting in the prior art is changed into the primary high-temperature pressurized roasting, so that the working procedure is saved, the energy consumption is reduced, and the mesoporous volume of the catalyst is increased by more than 220% compared with that of a corresponding sodium molecular sieve, thereby effectively increasing the mesoporous volume of the catalyst.
The catalyst unit cell constant referred to in the present invention is the unit cell constant of the molecular sieve in the catalyst, which is well known to those skilled in the art, and is measured by fitting the unit cell of the spectrogram in the standard XRD spectrum library by using an X-ray diffraction method (hereinafter referred to as XRD). The unit cell constants of different sodium type molecular sieves may be different, for example, the unit cell constant of a sodium X type molecular sieve is typically about 2.485nm, the unit cell constant of a sodium Y type molecular sieve is typically about 2.466nm, the unit cell constant of a sodium beta type molecular sieve is typically about 1.262nm, the unit cell constant of a sodium mordenite type molecular sieve is typically about 1.818nm, and the unit cell constant of a sodium ZSM-5 type molecular sieve is typically about 2.024 nm. According to the invention, the secondary high-temperature roasting in the prior art is changed into the primary high-temperature pressurized roasting, so that the working procedure is saved, the energy consumption is reduced, the catalyst unit cells are controlled to be very close to those of the corresponding sodium type molecular sieve, the shrinkage range is not more than 1%, and the catalyst unit cells can be effectively reserved, and the stability of the catalyst structure is improved.
In a third aspect, the present invention provides a method for preparing a catalyst, the method comprising:
(1) Mixing sodium molecular sieve with heat-resistant inorganic oxide or its precursor, assistant, acid solution and water to form, drying and roasting to obtain roasting product;
(2) Sequentially carrying out ammonium exchange and acid treatment on the obtained roasting product;
wherein the roasting conditions include: the roasting temperature is 350-650 ℃, and the roasting pressure is 0.01-1MPa.
In the prior art, the molecular sieve is usually baked firstly, then mixed with the binder and then baked at a high temperature for the second time, namely, the molecular sieve is baked for the first time before and after molding, and the molecular sieve is baked at the high temperature for the second time without pressurizing. The preparation method of the catalyst can be summarized as that the molecular sieve and the heat-resistant inorganic oxide binder are mixed and molded firstly, then the high-temperature pressurizing and roasting are carried out once, no roasting is carried out before the mixing and molding, and the roasting is carried out only after the mixing and molding, namely the one-time high-temperature pressurizing and roasting process after the molding. The invention does not include the step of first calcining the molecular sieve.
According to the present invention, in step (1), the conditions for firing include: the roasting temperature is 450-650 ℃, the roasting pressure is 0.015-0.5MPa, and the roasting time is 0.5-12h, so that the mesoporous volume of the catalyst is further improved on the premise of ensuring that the unit cell and acidity of the catalyst are not destroyed.
The firing atmosphere is not particularly limited, and firing atmospheres known in the art may be used, and examples include, but are not limited to, air atmosphere, ammonia atmosphere, water vapor atmosphere, N 2 Atmosphere, he atmosphere, or Ar atmosphere.
According to the invention, the sodium molecular sieve and the refractory inorganic oxide or the precursor thereof are used in such an amount that the weight ratio of the sodium molecular sieve to the refractory inorganic oxide in the catalyst is 99:1-20:80, preferably 95:5-25:75.
the sodium type molecular sieve is at least one selected from an X type molecular sieve, a Y type molecular sieve, a beta type molecular sieve, a ZSM-5 type molecular sieve, an MCM-22 type molecular sieve, an MCM-41 type molecular sieve and a mordenite type molecular sieve, and is preferably a Y type molecular sieve, an X type molecular sieve, a ZSM-5 type molecular sieve, a beta type molecular sieve or a mordenite type molecular sieve. Wherein the silicon-aluminum atomic ratio of the sodium molecular sieve is 1-1000, more preferably 1.5-50, and the average particle diameter is 0.01-50 μm, more preferably 0.1-40 μm.
The heat-resistant inorganic oxide of the present invention is widely selected, and preferably, the heat-resistant inorganic oxide is at least one selected from the group consisting of alumina, silica, titania and zirconia. In order to better disperse the molecular sieve, strengthen the interaction between the binder and the molecular sieve and improve the acid content of the catalyst, the alumina is preferably pseudo-boehmite, and the silica is preferably silica sol.
The heat-resistant inorganic oxide precursor is mainly aluminum salt, silicate, titanium salt and zirconium salt. The aluminum salt comprises pseudo-boehmite, aluminum chloride (AlCl) 3 ) Aluminum sulfate (Al) 2 (SO 4 ) 3 ) Etc.; the silicate comprises sodium silicate, potassium silicate, calcium silicate and the like; the titanium salt comprises titanium sulfate, titanium tetrachloride and the like; the zirconium salt includes zirconium chloride, zirconium sulfate, etc.
According to the invention, in step (1), the acid is used in an amount of 0-5wt% based on the total weight of the sodium molecular sieve and binder dry basis. In the invention, whether acid liquor is added or not is considered according to the type of the heat-resistant inorganic oxide or the precursor thereof, and if the heat-resistant inorganic oxide is alumina or the heat-resistant inorganic oxide precursor is aluminum salt, the acid liquor is added; if the refractory inorganic oxide is silica, titania, zirconia, or the refractory inorganic oxide precursor is silicate, a titanium salt, or a zirconium salt, an acid solution may or may not be added. The acid solution is selected from a wide range, and preferably the acid solution is at least one selected from a hydrochloric acid solution, a nitric acid solution, an oxalic acid solution and a citric acid solution.
According to the invention, in step (1), the auxiliary agent is used in an amount of 0 to 5wt% based on the total weight of the sodium molecular sieve and binder dry basis. In the invention, when no auxiliary agent is added, the dried mixed molding is directly roasted to obtain a roasting product; when a certain amount of auxiliary agent is added, the dried mixed molding is roasted firstly, and then air roasting is carried out for removing the organic auxiliary agent, so as to obtain a roasting product. The auxiliary agent plays roles in lubricating and pore-forming, and is preferably at least one of sesbania powder, methylcellulose, polyether, polyvinyl alcohol, cyclodextrin and chitosan.
The amount of water used in the present invention is not particularly limited as long as it can uniformly mix a mixture including a sodium type molecular sieve, a heat-resistant inorganic oxide or a precursor thereof, an acid solution, and an auxiliary agent, and preferably the ratio of the weight of water to the total weight of the dry basis of other mixture (including a sodium type molecular sieve, a heat-resistant inorganic oxide or a precursor thereof, and an auxiliary agent) is (0.8 to 1.2): 1.
according to the present invention, the drying conditions are such that the dry basis weight of the mixed molded article after drying is 60% by weight or more, and preferably the drying temperature is 100 to 130 ℃.
According to the invention, the conditions of the ammonium exchange are such that Na in the calcined product 2 The O content is reduced to below 0.5 wt.%, more preferably the ammonium exchange temperature is 30-180 ℃. The ammonium exchange according to the invention is carried out in an ammonium solution in which NH 4 + The concentration of (C) is 0.05-7mol/L. The present invention has a wide selection range of the ammonium source used for the ammonium exchange, and preferably, the ammonium source is at least one selected from the group consisting of ammonium nitrate, ammonium chloride and ammonium sulfate. In the present invention, the number of times of performing the ammonium exchange is not limited to one, and 2 or 3 times of ammonium exchange may be performed. The invention can reduce Na by carrying out ammonium exchange 2 The content of O improves the acid property of the catalyst.
In the present invention, the step further comprises washing, suction filtration and drying the ammonium-exchanged product in this order, and the present invention is not particularly limited to the above-mentioned operation, and may be performed in a manner known in the art.
According to the present invention, the conditions of the acid treatment include: the temperature is 30-100deg.C, and the time is 0.1-10h. The acid treatment is carried out in an acid solution, and the concentration of the acid solution is 0.01-40wt%. The acid solution is not particularly limited, and any acid solution known in the art may be used, including, for example, but not limited to, oxalic acid solution, hydrofluoric acid solution, citric acid solution, lactic acid solution, or hydrochloric acid solution. The invention can improve the silicon-aluminum mole ratio of the catalyst framework by carrying out acid treatment.
In the present invention, the step further comprises washing, suction filtration and drying the acid-treated product in this order, and the present invention is not particularly limited to the above-mentioned operation, and may be carried out in a manner known in the art.
In the present invention, when the calcined product is subjected to ammonium exchange and acid treatment in this order, the amount of the calcined product to be used between the ammonium solution or between the calcined product and the acid solution is not particularly limited, as long as ion exchange is possible.
According to the present invention, the method further comprises pretreating the molecular sieve prior to mixing the sodium form of the molecular sieve with other reaction raw materials, the pretreatment method comprising: and (3) carrying out ammonium exchange on the molecular sieve by adopting an ammonium solution for 0.1-10h at the temperature of 30-180 ℃, and then carrying out suction filtration and drying. NH in the ammonium solution 4 + The concentration of (C) is 0.05-7mol/L. The ammonium solution adopts at least one of ammonium nitrate solution, ammonium chloride solution and ammonium sulfate solution.
In order to clearly describe the preparation method of the catalyst of the present invention, the following provides a preferred embodiment for explanation:
(1) Under the condition of 30-180 ℃, adopting an ammonium solution to carry out ammonium exchange on the molecular sieve for 0.1-10h, and then carrying out suction filtration and drying;
(2) Mixing the ammonium exchanged molecular sieve with heat-resistant inorganic oxide, auxiliary agent, acid liquor and water in proportion, forming, drying at 100-130 ℃ to ensure that the dry basis weight of the mixed formed product after drying is more than 60wt%, and roasting at 350-650 ℃ and 0.01-1MPa for 0.5-12h;
(3) Mixing the calcined product with an ammonium solution, and performing ammonium exchange at 30-180deg.C to obtain Na in the calcined product 2 The content of O is reduced to below 0.5wt percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with acid liquor, carrying out acid treatment for 0.1-10h at 30-100 ℃, and then washing, suction filtering and drying to obtain the catalyst.
In a fourth aspect, the present invention provides a catalyst obtainable by the preparation process according to the third aspect of the present invention.
In a fifth aspect the present invention provides a process for increasing the cycle life of a catalyst in an alkylation reaction, the process comprising contacting an isoparaffin with an olefin in the presence of a catalyst under alkylation reaction conditions, the catalyst being in accordance with the first, second or fourth aspects of the present invention.
Preferably, the alkylation reaction conditions of the present invention include: the temperature is 30-100 ℃, the pressure is 1.5-5MPa, and the feeding flow is 10-3000 mL/(g.h).
In the present invention, the feed flow rate means the volume amount (mL) of isoparaffin and olefin fed per hour per unit weight (g) of catalyst.
According to the invention, the molar ratio of isoparaffin to olefin is 15-1000. Wherein the isoparaffin comprises C 4 -C 6 Isoparaffins, preferably isobutane; olefins include C 3 -C 6 Mono-olefins, preferably 1-butene and/or 2-butene.
The inventor of the present invention found through a large number of experiments that the alkylation reaction is carried out by using the catalyst which has the advantages of better unit cell and acid content and larger mesoporous volume, particularly C 4 -C 6 Isoparaffin and C 3 -C 6 The alkylation reaction of the olefin serving as the raw material can effectively prolong the cycle life of the catalyst and improve the selectivity of the target product.
Unless otherwise indicated, the pressures described herein are all indicated as gauge pressures.
The invention will be described in detail below by way of examples. In the examples below, various raw materials used were available from commercial sources without particular explanation.
1#Y type molecular sieve: the unit cell constant is 2.466nm, and the mesoporous volume is 0.04cm 3 The molar ratio of silicon to aluminum was 3, the average particle diameter was 1. Mu.m, china petrochemical catalyst Co., ltd.
ZSM-5 type molecular sieve: the unit cell constant is 2.024nm, and the mesoporous volume is 0.034cm 3 The molar ratio of silica to alumina was 10 and the average particle diameter was 40. Mu.m.
X-type molecular sieve: the unit cell constant is 2.485nm, and the mesoporous volume is 0.032cm 3 The molar ratio of silicon to aluminum is 1.8, the average grain diameter is 0.5 mu m, and the China petrochemical catalyst Co.
Beta molecular sieve: the unit cell constant is 1.262nm, and the mesoporous volume is 0.016cm 3 The molar ratio of silicon to aluminum was 50, the average particle diameter was 10. Mu.m, china petrochemical catalyst Co., ltd.
Mordenite type molecular sieve: the unit cell constant is 1.82nm, and the mesoporous volume is 0.037cm 3 The molar ratio of silicon to aluminum was 10, the average particle diameter was 5. Mu.m, china petrochemical catalyst Co., ltd.
2#Y type molecular sieve: the unit cell constant is 2.466nm, and the mesoporous volume is 0.04cm 3 The molar ratio of silicon to aluminum was 12, the average particle diameter was 2. Mu.m, china petrochemical catalyst Co., ltd.
Pseudo-boehmite: the average particle diameter was 100. Mu.m, china petrochemical catalyst Co.
In the examples below, the unit cell constants and crystallinity of the catalyst molecular sieves were determined using X-ray diffraction (XRD).
Ammonia gas temperature programmed desorption (NH) 3 TPD) method to determine the total acid amount of the catalyst.
The mesoporous volume of the catalyst and the low-temperature nitrogen adsorption and desorption amount were measured by a BET method.
The silicon and aluminum spectra of the catalysts were determined using solid state nuclear magnetic resonance (MAS NMR) analysis.
By incorporating Al 2 O 3 Agilent 7890A gas chromatography with a PONA column and a high pressure injector to obtain alkanesDistribution of the reaction product of the alkylation.
Example 1
(1) At 80℃the use of ammonium chloride solution (NH 4 + 6 mol/L) of the mixture is subjected to ammonium exchange for 2 hours on a 1#Y type molecular sieve, and then is subjected to suction filtration and drying;
(2) The weight percentage of the ammonium exchanged 1#Y molecular sieve and pseudo-boehmite is 90:10, respectively adding 2wt% of sesbania powder and 2wt% of nitric acid (based on the total weight of the dry basis of the 1#Y molecular sieve and the binder after ammonium exchange), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 0.8:1 adding deionized water, uniformly mixing, extruding and molding, drying at 110 ℃ to ensure that the dry basis weight of the dried mixed molded product is 80wt%, then roasting for 4 hours at 500 ℃ under 0.1MPa by steam, and roasting for 2 hours at 500 ℃ by air;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + At a concentration of 6 mol/L), and ammonium-exchanged at 80℃to give Na in the calcined product 2 The content of O is reduced to 0.1 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with hydrochloric acid solution (the concentration is 1 wt%) and carrying out acid treatment for 0.5h at 50 ℃, and then washing, suction filtration and drying to obtain the catalyst Y-1.
Comparative example 1
(1) At 80℃the use of ammonium chloride solution (NH 4 + 6 mol/L) of the mixture is subjected to ammonium exchange for 2 hours on a 1#Y type molecular sieve, and then is subjected to suction filtration and drying;
(2) Roasting the ammonium exchanged 1#Y molecular sieve with water vapor at 500 ℃ for 4 hours;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + At a concentration of 6 mol/L), and ammonium-exchanged at 80℃to give Na in the calcined product 2 The content of O is reduced to 0.1 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with hydrochloric acid solution (the concentration is 1 wt%) and performing acid treatment at 50 ℃ for 0.5h, and then washing, suction filtering and drying;
(5) And (3) mixing the product obtained in the step (4) with pseudo-boehmite according to the dry weight percentage of 90:10, respectively adding 2wt% of sesbania powder and 2wt% of nitric acid (based on the total weight of the dry basis of the product obtained in the step (4) and the binder), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 0.8:1 adding deionized water, uniformly mixing, extruding and molding, drying at 110 ℃ to ensure that the dry basis weight of the dried mixed molded product is 80wt%, and then roasting for 4 hours at 500 ℃ in air to obtain the catalyst DY-1.
Example 2
(1) At 130℃the use of ammonium nitrate solution (NH 4 + 4 mol/L) to carry out ammonium exchange on ZSM-5 type molecular sieve for 10 hours, and then carrying out suction filtration and drying;
(2) The weight percentage of the ZSM-5 molecular sieve and pseudo-boehmite after ammonium exchange is 50:50, respectively adding 3wt% of sesbania powder and 5wt% of nitric acid (based on the total weight of the dry basis of the ZSM-5 molecular sieve and the binder after ammonium exchange), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1.2:1 adding deionized water, uniformly mixing, extruding and molding, drying at 100 ℃ to ensure that the dry basis weight of the dried mixed molded product is 60wt%, then roasting for 1h at 600 ℃ under 0.5MPa with nitrogen, and roasting for 1h at 600 ℃ with air;
(3) The obtained calcined product was reacted with an ammonium nitrate solution (NH 4 + 4 mol/L) of the calcined product, and performing an ammonium exchange at 130 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.05 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with oxalic acid solution (the concentration is 5 wt%) and carrying out acid treatment for 2 hours at 50 ℃, and then washing, suction filtering and drying to obtain the catalyst ZSM-2.
Comparative example 2
(1) At 130℃the use of ammonium nitrate solution (NH 4 + 4 mol/L) to carry out ammonium exchange on ZSM-5 type molecular sieve for 10 hours, and then carrying out suction filtration and drying;
(2) Calcining the ammonium exchanged ZSM-5 molecular sieve at 600 ℃ for 1h under nitrogen;
(3) The obtained calcined product was reacted with an ammonium nitrate solution (NH 4 + 4 mol/L) of the calcined product, and performing an ammonium exchange at 130 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.05 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with oxalic acid solution (the concentration is 5 wt%) and making acid treatment for 2 hr at 50 deg.C, then washing, suction filtering and drying,
(5) And (3) mixing the product obtained in the step (4) with pseudo-boehmite according to the dry weight percentage of 50:50, respectively adding 2wt% of sesbania powder and 2wt% of nitric acid (based on the total weight of the dry basis of the product obtained in the step (4) and the binder), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1.2:1 adding deionized water, uniformly mixing, extruding and molding, drying at 100 ℃ to ensure that the dry basis weight of the dried mixed molded product is 60wt%, and then roasting for 4 hours at 600 ℃ in air to obtain the catalyst DZSM-2.
Example 3
(1) At 180℃with an ammonium sulfate solution (NH 4 + The concentration of (2) is 0.5 mol/L) to carry out ammonium exchange on the X-type molecular sieve for 1h, and then carrying out suction filtration and drying;
(2) The weight percentage of the X-type molecular sieve and the silica sol after ammonium exchange is 25:75, in terms of the ratio of the weight of water to the total weight of the dry basis of the other mixtures, 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 130 ℃ to ensure that the dry basis weight of the dried mixed molded product is 85wt%, and roasting at 450 ℃ and 0.3MPa for 0.5h with nitrogen;
(3) The obtained calcined product was reacted with an ammonium sulfate solution (NH 4 + 0.5 mol/L) and ammonium-exchanged at 90 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.2 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with a lactic acid solution (the concentration is 10 wt%) and carrying out acid treatment for 2 hours at 60 ℃, and then washing, suction filtration and drying to obtain the catalyst X-3.
Comparative example 3
(1) At 180℃with an ammonium sulfate solution (NH 4 + The concentration of (2) is 0.5 mol/L) to carry out ammonium exchange on the X-type molecular sieve for 1h, and then carrying out suction filtration and drying;
(2) Roasting the ammonium exchanged X-type molecular sieve for 0.5h at 450 ℃ with nitrogen;
(3) The obtained calcined product was reacted with an ammonium sulfate solution (NH 4 + 0.5 mol/L) and ammonium-exchanged at 90 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.2 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with a lactic acid solution (the concentration is 10 wt%) and carrying out acid treatment for 2 hours at 60 ℃, and then washing, suction filtration and drying;
(5) And (3) mixing the product obtained in the step (4) with silica sol according to the dry weight percentage of 25:75, in terms of the ratio of the weight of water to the total weight of the dry basis of the other mixtures, 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 130 ℃ to enable the dry basis weight of the dried mixed molded product to be 85wt%, and roasting at 450 ℃ for 6 hours by nitrogen to obtain the catalyst DX-3.
Example 4
(1) At 60℃the use of ammonium chloride solution (NH 4 + 5 mol/L) to carry out ammonium exchange on the beta-type molecular sieve for 3 hours, and then carrying out suction filtration and drying;
(2) The weight percentage of the beta-type molecular sieve after ammonium exchange and titanium dioxide is 75:25, adding sesbania powder (based on the total weight of the dry basis of the beta-molecular sieve and the binder after ammonium exchange) in an amount of 2wt%, wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1.2:1 adding deionized water, uniformly mixing, extruding and molding, drying at 120 ℃ to enable the dry basis weight of the dried mixed molded product to be 75wt%, then roasting at 650 ℃ and 0.25MPa for 0.5h with nitrogen, and roasting at 650 ℃ for 1h with air;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + 5 mol/L) and ammonium-exchanged at 60℃to allow calcinationNa in the product 2 The content of O is reduced to 0.4 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with hydrochloric acid solution (the concentration is 0.5 wt%) and performing acid treatment at 50 ℃ for 0.5h, and then washing, suction filtering and drying to obtain the catalyst beta-4.
Comparative example 4
(1) At 60℃the use of ammonium chloride solution (NH 4 + 5 mol/L) to carry out ammonium exchange on the beta-type molecular sieve for 3 hours, and then carrying out suction filtration and drying;
(2) Roasting the ammonium exchanged beta-type molecular sieve at 650 ℃ for 0.5h under nitrogen;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + 5 mol/L) and ammonium-exchanged at 60 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.4 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with hydrochloric acid solution (the concentration is 0.5 wt%) and performing acid treatment at 50 ℃ for 0.5h, and then washing, suction filtering and drying;
(5) And (3) mixing the product obtained in the step (4) with titanium dioxide according to the weight percentage of 75 on a dry basis: 25, adding sesbania powder (based on the total weight of the dry basis of the product obtained in the step (4) and the binder) in an amount of 2wt%, wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1.2:1 adding deionized water, uniformly mixing, extruding and molding, drying at 120 ℃ to enable the dry basis weight of the dried mixed molded product to be 75wt%, and then roasting for 1h at 650 ℃ in air to obtain the catalyst Dbeta-4.
Example 5
(1) At 40℃the use of ammonium nitrate solution (NH 4 + The concentration of (2) mol/L) of the mordenite type molecular sieve is subjected to ammonium exchange for 4 hours, and then is subjected to suction filtration and drying;
(2) The weight percentage of the mordenite type molecular sieve and zirconia after ammonium exchange is 95:5, mixing, adding sesbania powder (based on the total weight of the dry basis of the mordenite type molecular sieve and the binder after ammonium exchange) in an amount of 5wt%, wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 120 ℃ to ensure that the dry basis weight of the dried mixed molded product is 70wt%, then roasting for 1h at 450 ℃ under 0.015MPa with nitrogen, and roasting for 1h at 450 ℃ with air;
(3) The obtained calcined product was reacted with an ammonium nitrate solution (NH 4 + 2 mol/L) and ammonium-exchanged at 40 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.08 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with oxalic acid solution (the concentration is 0.15 wt%) and performing acid treatment at 50 ℃ for 10 hours, and then washing, suction filtering and drying to obtain the catalyst MOR-5.
Comparative example 5
(1) At 40℃the use of ammonium nitrate solution (NH 4 + The concentration of (2) mol/L) of the mordenite type molecular sieve is subjected to ammonium exchange for 4 hours, and then is subjected to suction filtration and drying;
(2) Roasting the mordenite type molecular sieve subjected to ammonium exchange with nitrogen at 450 ℃ for 1h;
(3) The obtained calcined product was reacted with an ammonium nitrate solution (NH 4 + 2 mol/L) and ammonium-exchanged at 40 ℃ to obtain Na in the calcined product 2 The content of O is reduced to 0.08 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with oxalic acid solution (the concentration is 0.15 wt%) and performing acid treatment at 50 ℃ for 10 hours, and then washing, suction filtering and drying;
(5) Mixing the product obtained in the step (4) with zirconia according to the dry weight percentage of 95:5, mixing, adding sesbania powder (based on the total weight of the dry basis of the mordenite type molecular sieve and the binder after ammonium exchange) in an amount of 5wt%, wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 120 ℃ to make the dry basis weight of the dried mixed molded product be 70wt%, and then roasting for 5 hours at 450 ℃ in air to obtain the catalyst DMOR-5.
Example 6
(1) At 80℃the use of ammonium chloride solution (NH 4 + 6 mol/L) of 2#Y molecular sieve is subjected to ammonium exchange for 1h, and then is subjected to suction filtration and drying;
(2) The ammonium exchanged 2#Y molecular sieve was combined with a binder (comprising 10wt% SiO based on the total weight of the binder) 2 Sol and 90wt% pseudo-boehmite) in dry basis of 50:50, adding 5wt% of nitric acid (based on the total weight of the dry basis of the 2#Y molecular sieve and the binder after ammonium exchange), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 110 ℃ to ensure that the dry basis weight of the dried mixed molded product is 80wt%, and then roasting for 2 hours at 550 ℃ and 0.2MPa by using water vapor;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + At a concentration of 6 mol/L), and ammonium-exchanged at 80℃to give Na in the calcined product 2 The content of O is reduced to 0.15 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with a lactic acid solution (the concentration is 20 wt%) and carrying out acid treatment for 0.5h at 50 ℃, and then washing, suction filtration and drying to obtain the catalyst Y-6.
Comparative example 6
(1) At 80℃the use of ammonium chloride solution (NH 4 + 6 mol/L) of 2#Y molecular sieve is subjected to ammonium exchange for 1h, and then is subjected to suction filtration and drying;
(2) Roasting the 2#Y molecular sieve subjected to ammonium exchange for 2 hours at 550 ℃ by water vapor;
(3) The obtained calcined product was treated with an ammonium chloride solution (NH) 4 + At a concentration of 6 mol/L), and ammonium-exchanged at 80℃to give Na in the calcined product 2 The content of O is reduced to 0.15 weight percent, and then washing, suction filtration and drying are carried out;
(4) Mixing the product obtained in the step (3) with a lactic acid solution (the concentration is 20 wt%) and carrying out acid treatment for 0.5h at 50 ℃, and then washing, suction filtration and drying;
(5) The product obtained in the step (4) is treatedWith a binder (comprising 10wt% SiO based on the total weight of the binder) 2 Sol and 90wt% pseudo-boehmite) in dry basis of 50:50, adding 5wt% of nitric acid (based on the total weight of the dry basis of the product obtained in the step (4) and the binder), wherein the ratio of the weight of water to the total weight of the dry basis of other mixtures is 1:1 adding deionized water, uniformly mixing, extruding and molding, drying at 110 ℃ to ensure that the dry basis weight of the dried mixed molded product is 80wt%, and then roasting for 2 hours by steam at 550 ℃ to obtain the catalyst DY-6.
FIG. 1 is a graph showing the low temperature nitrogen adsorption/desorption curves of the catalyst Y-6 prepared in example 6 of the present invention and the catalyst DY-6 prepared in comparative example 6, as can be seen from FIG. 1: compared with the catalyst DY-6 prepared by the traditional process, the adsorption curve of the catalyst Y-6 prepared by the invention moves downwards, which shows that the catalyst Y-6 provided by the invention has larger mesoporous volume.
FIG. 2 is a graph showing the solid nuclear magnetic resonance Si spectra of the catalyst Y-6 prepared in example 6 of the present invention and the catalyst DY-6 prepared in comparative example 6, as can be seen from FIG. 2: the Si spectra of the catalyst Y-6 prepared by the method and the Si spectra of the catalyst DY-6 prepared by the traditional process keep the same trend, which shows that the whole catalyst is reamed by adopting the preparation process of pressure roasting without obviously damaging the molecular sieve framework.
FIG. 3 is a graph showing the solid nuclear magnetic resonance Al spectra of the catalyst Y-6 prepared in example 6 of the present invention and the catalyst DY-6 prepared in comparative example 6, as can be seen from FIG. 3: the Al spectrum of the catalyst Y-6 prepared by the method and the Al spectrum of the catalyst DY-6 prepared by the traditional process keep the same trend basically, which shows that the method has little influence on the structure of the catalyst when the whole catalyst is reamed by adopting the preparation process of pressure roasting.
Example 7
A catalyst was prepared in the same manner as in example 1, except that: in the step (2), the calcination pressure was changed to 0.8MPa to obtain catalyst Y-7.
Comparative example 7
A catalyst was prepared in the same manner as in example 1 except that in step (2), the calcination pressure was changed to 1.2MPa, to obtain catalyst DY-7.
The unit cell constants and crystallinity of the catalysts prepared in the above examples and comparative examples were measured by X-ray diffraction (XRD), respectively, and the results are shown in table 1.
TABLE 1
As can be seen from the results in Table 1, the whole catalyst is reamed by adopting the preparation process of pressure roasting, the crystallinity of the molecular sieve of the catalyst is not reduced, the shrinkage amplitude of the molecular sieve unit cell is not obviously increased, and compared with the unit cell shrinkage amplitude of the corresponding sodium type molecular sieve, the unit cell of the catalyst provided by the invention is kept below 1.0%, namely, the preparation method provided by the invention has the advantages that the mesoporous volume of the catalyst is effectively improved, and meanwhile, the framework structure of the molecular sieve is not greatly damaged.
Ammonia gas temperature programmed desorption (NH) 3 TPD) method the acid amounts of the catalysts prepared in the above examples and comparative examples at 250℃at 350℃at 450℃and at 550℃respectively were measured, and the results are shown in Table 2.
TABLE 2
Table 2 (subsequent table)
As can be seen from the results in Table 2, the whole catalyst is reamed by adopting the preparation process of pressure roasting, the change degree of the total acid amount of the catalyst compared with the total acid amount of the corresponding hydrogen type molecular sieve is kept in the range of +50% to-5%, and the catalyst acid amount is not greatly destroyed while the mesoporous volume of the catalyst is effectively improved.
The mesoporous volume of the catalysts prepared in the above examples and comparative examples, respectively, was measured by the BET method, and the results are shown in Table 3.
TABLE 3 Table 3
From the results in table 3, it can be seen that the whole catalyst is reamed by adopting the preparation process of pressure roasting, so that the mesoporous volume of the catalyst can be increased by more than 220% compared with that of the corresponding sodium molecular sieve.
Examples 8 to 14
The alkylation reaction of isoparaffin and olefin contact was carried out in a fixed bed reactor using the catalysts prepared in examples 1-7, respectively, under the reaction conditions: the molar ratio of isobutane to mixed butenes (1-butene and 2-butene) was 250, the reaction temperature was 75 ℃, the reaction pressure was 3.5MPa, and the feed flow was 50 mL/(g.h). Butene is detected in the product, i.e., the catalyst is considered to be deactivated, and the reaction time before deactivation of the catalyst is defined as the catalyst's cycle life. The results of the alkylation reaction are shown in Table 4, C 8 Selectivity represents the average result over the lifetime of the cycle.
Example 15
The alkylation of isoparaffin with olefin contact was carried out in a fixed bed reactor using the catalyst numbered Y-1 prepared in example 6.
Reaction conditions: the molar ratio of isobutane to mixed butenes (1-butene and 2-butene) was 150, the reaction temperature was 40 ℃, the reaction pressure was 2MPa, and the feed flow rate was 10 mL/(g.h). The results of the alkylation reaction are shown in Table 4.
Example 16
The alkylation of isoparaffin with olefin contact was carried out in a fixed bed reactor using the catalyst numbered Y-1 prepared in example 6.
Reaction conditions: the molar ratio of isobutane to mixed butene was 500, the reaction temperature was 75 ℃, the reaction pressure was 3MPa, and the feed flow was 1000 mL/(g.h). The results of the alkylation reaction are shown in Table 4.
Example 17
The alkylation of isoparaffin with olefin contact was carried out in a fixed bed reactor using the catalyst numbered Y-1 prepared in example 6.
Reaction conditions: the molar ratio of the isobutane to the mixed butene is 1000, the reaction temperature is 100 ℃, the reaction pressure is 5MPa, and the feeding flow is 3000 mL/(g.h). The results of the alkylation reaction are shown in Table 4.
Comparative examples 8 to 14
Alkylation was performed according to the method of example 8 described above, except that the catalysts prepared in comparative examples 1 to 7 were used, respectively, and the results of the alkylation reaction are shown in Table 4.
TABLE 4 Table 4
From the results shown in Table 4, it can be seen that the catalyst provided by the invention can effectively improve the cycle life of the catalyst without reducing the selectivity of the target product when being used for the alkylation reaction of isoparaffin and olefin. The catalyst prepared by the traditional process has lower cycle life and selectivity of target products.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (13)

1. A catalyst, which is characterized by comprising a molecular sieve and a binder, wherein the content of the molecular sieve is 20-99wt% based on the dry weight of the catalyst, and the content of the binder is 1-80wt%; the catalyst has a unit cell constant which is not more than 1% as compared to the unit cell constant of the molecular sieve; the total acid amount of the catalyst is increased by not more than 50% compared with the total acid amount of the molecular sieve, and the reduction is not more than 5%; the mesoporous volume of the catalyst is increased by more than 220% compared with that of a molecular sieve; the molecular sieve is at least one of a Y-type molecular sieve, a ZSM-5 type molecular sieve, a beta-type molecular sieve and a mordenite type molecular sieve;
the catalyst is prepared by a preparation method comprising the following steps:
(1) Mixing sodium molecular sieve with heat-resistant inorganic oxide or its precursor, assistant, acid solution and water to form, drying and roasting to obtain roasting product;
the auxiliary agent is at least one selected from sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, cyclodextrin and chitosan;
(2) Sequentially carrying out ammonium exchange on the obtained roasting product, washing, suction filtration and drying;
then, carrying out acid treatment on the obtained product, and then washing, suction filtration and drying to obtain a catalyst;
wherein the roasting conditions include: the roasting temperature is 350-650 ℃, and the roasting pressure is 0.01-1MPa.
2. A catalyst, which is characterized by comprising a molecular sieve and a binder, wherein the content of the molecular sieve is 20-99wt% based on the dry weight of the catalyst, and the content of the binder is 1-80wt%; and is also provided with
The molecular sieve is a Y-type molecular sieve, and the unit cell constant of the catalyst is 2.441-2.466nm, total acid content greater than 1438 mu mol/g, mesoporous volume greater than 0.12cm 3 /g; or alternatively
The molecular sieve is ZSM-5 molecular sieve, the unit cell constant of the catalyst is 2.004-2.024nm, the total acid amount is more than 1230 mu mol/g, and the mesoporous volume is more than 0.102cm 3 /g; or alternatively
The molecular sieve is an X-type molecular sieve, the unit cell constant of the catalyst is 2.46-2.485nm, the total acid amount is more than 1875 mu mol/g, and the mesoporous volume is more than 0.096cm 3 /g; or alternatively
The molecular sieve is beta-type molecular sieve, the unit cell constant of the catalyst is 1.249-1.262nm, the total acid amount is more than 1327 mu mol/g, and the mesoporous volume is more than 0.048cm 3 /g; or alternatively
The molecular sieve is mordenite type molecular sieve, the unit cell constant of the catalyst is 1.8-1.818nm, the total acid amount is more than 974 mu mol/g, and the mesoporous volume is more than 0.111cm 3 /g；
The catalyst is prepared by a preparation method comprising the following steps:
(1) Mixing sodium molecular sieve with heat-resistant inorganic oxide or its precursor, assistant, acid solution and water to form, drying and roasting to obtain roasting product;
the auxiliary agent is at least one selected from sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, cyclodextrin and chitosan;
(2) Sequentially carrying out ammonium exchange on the obtained roasting product, washing, suction filtration and drying;
then, carrying out acid treatment on the obtained product, and then washing, suction filtration and drying to obtain a catalyst;
wherein the roasting conditions include: the roasting temperature is 350-650 ℃, and the roasting pressure is 0.01-1MPa.
3. The catalyst of claim 1 or 2, wherein the molecular sieve is present in an amount of 25 to 95wt% and the binder is present in an amount of 5 to 75wt%, based on the dry weight of the catalyst.
4. The catalyst of claim 1 or 2, wherein the binder is selected from at least one of alumina, silica, titania, and zirconia.
5. The catalyst according to claim 1 or 2, wherein the calcination conditions include: the roasting temperature is 450-650 ℃, the roasting pressure is 0.015-0.5MPa, and the roasting time is 0.5-12h.
6. The catalyst of claim 1 or 2, wherein in step (1), the sodium molecular sieve and the refractory inorganic oxide or precursor thereof are used in amounts such that the weight ratio of sodium molecular sieve to refractory inorganic oxide in the catalyst on a dry basis is 99:1-20:80.
7. the catalyst of claim 6, wherein in step (1), the sodium molecular sieve and the refractory inorganic oxide or a precursor thereof are used in an amount such that the weight ratio of sodium molecular sieve to refractory inorganic oxide in the catalyst on a dry basis is 95:5-25:75.
8. the catalyst according to claim 1 or 2, wherein the refractory inorganic oxide is selected from at least one of alumina, silica, titania and zirconia.
9. The catalyst of claim 8, wherein the alumina is pseudo-boehmite.
10. The catalyst according to claim 1 or 2, wherein in the step (1), the drying condition is such that the dry basis weight of the mixture molded article after drying is 60wt% or more.
11. The catalyst of claim 1 or 2, wherein in step (1) the acid is used in an amount of 0-5wt% based on the total weight of the sodium molecular sieve and binder dry basis.
12. Catalyst according to claim 1 or 2, wherein the auxiliary agent is used in an amount of 0-5wt% of the total weight of the sodium molecular sieve and binder dry basis.
13. A method for increasing the cycle life of a catalyst in an alkylation reaction, the method comprising contacting an isoparaffin with an olefin in the presence of a catalyst under alkylation reaction conditions, wherein the catalyst is a catalyst according to any one of claims 1-12.
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Publication number Priority date Publication date Assignee Title
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