CN114433197B

CN114433197B - Supported metal catalyst for olefin isomerization reaction and preparation method thereof

Info

Publication number: CN114433197B
Application number: CN202210360131.5A
Authority: CN
Inventors: 李江成; 李�昊
Original assignee: Shaanxi Tanwei Rixin Chemical Co ltd; Beijing Tanwei Fine Chemical Technology Co ltd
Current assignee: Shaanxi Tanwei Rixin Chemical Co ltd; Beijing Tanwei Fine Chemical Technology Co ltd
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2022-06-14
Anticipated expiration: 2042-04-07
Also published as: CN114433197A

Abstract

The application relates to a supported metal catalyst for olefin isomerization reaction and a preparation method thereof. The catalyst comprises: the catalyst comprises a molecular sieve and a load metal loaded on the molecular sieve, wherein the silicon-aluminum ratio of the catalyst is 200-2000: 1; a specific surface area of 500 m or more²(iv) g; the load metal is selected from one or more of magnesium, calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper and zinc; the content of the supported metal is 0.1-5wt%, calculated by the oxide of the supported metal and based on the dry weight of the molecular sieve; the proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 60 vol%, the mesopore volume and the total pore volume of the molecular sieve are measured by adopting a nitrogen adsorption BET specific surface area method, and the pore diameter range of the mesopore volume is more than 2 nanometers and less than 100 nanometers.

Description

Supported metal catalyst for olefin isomerization reaction and preparation method thereof

Technical Field

The application relates to a catalyst for olefin isomerization reaction, a preparation method and application thereof, in particular to a metal-loaded modified catalyst for olefin skeletal isomerization, and a preparation method and application thereof.

Background

In recent years, the rapid progress of the global crude oil price fluctuation and new energy technology promotes the development of the global petrochemical industry to the raw material diversification and low cost, particularly the rapid expansion of petrochemical production energy in areas rich in middle east light hydrocarbon resources, the development of north american shale gas and Chinese coal chemical industry and the like, brings huge impact to the traditional petrochemical industry taking naphtha as a raw material, and the energy demand trend of international carbon dioxide emission reduction also makes the traditional fossil energy industry challenged. Therefore, much attention is paid to the development of high value-added chemical production technologies with strong competitiveness.

Olefin is a typical skeleton structure of an organic compound, and related products of the olefin are widely applied to the fields of petrochemical industry, fine chemical industry, biological pharmacy and the like. Because of the reactive C ═ C functionality it contains, a range of reactions such as elimination, reduction, coupling, condensation, addition and isomerization and rearrangement can be derived to meet the requirements of different reaction types for olefin synthesis. Where isomerization is an atom-economical reaction that can create new olefins by C ═ C position migration or cis-trans isomeric conversion without changing the organic compound backbone. Olefin isomerization plays an important role in the petrochemical industry, for example, the disproportionation reaction of ethylene and butene-2 to prepare propylene, the oligomerization of ethylene to produce alpha-olefin and the like are typical industrial technologies for olefin isomerization, and have obvious economic benefits.

Carbon four and carbon five (C4, C5) are valuable resources for chemical comprehensive utilization, and the initial mixed utilization gradually turns to the separation of single components, and the development is towards the preparation of refined, diversified and high-end products. With the changing supply forms of petrochemical materials and the upgrading of petrochemical industry structures in the world, the high-value utilization of C4 and C5 resources is becoming the development focus. In the by-product C4/C5 fraction of a petroleum processing catalytic cracking unit, isoolefins usually account for about 50 mass% of the total olefin components; the byproduct C4/C5 in the coal chemical MTO accounts for more than 10 percent of the total hydrocarbon, the C5 mainly comprises 1-pentene, 2-pentene and methyl butene, and the mono-olefin accounts for more than 60 percent. Therefore, a new technology for increasing the yield of isoolefins by converting C4/C5 olefins into isobutene, isopentene and the like through skeletal isomerization becomes one of research hotspots.

The technical approaches for isomerizing the olefins C ═ C mainly include acid catalysis, base catalysis, molecular sieve catalysis, transition metal compound catalysis and other catalytic modes.

CN112337468A discloses an olefin isomerization catalyst, a preparation method and an application thereof, the catalyst is a boron modified silicon-containing alumina catalyst, and the catalyst has the advantages of high selectivity, high product yield and difficult inactivation.

CN106431810B discloses a method for preparing isoamylene by skeletal isomerization of n-pentene, wherein the catalyst is a flaky ZSM-35 molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 10-100, and the conversion rate of the n-pentene is far higher than that of ZSM-35 with other shapes.

CN110201713A discloses a catalyst, a preparation method thereof and an application thereof in olefin isomerization reaction, wherein a novel ionic liquid loaded metal with a tetranuclear structure is used as the catalyst, the catalyst can catalyze olefin double bond isomerization with high activity and high selectivity under mild process conditions, and the catalyst has stable activity and long service life.

CN106040293B discloses a normal olefin isomerization catalyst, a preparation method and an application thereof, the catalyst consists of molecular sieves SAPO-11 and ZSM-5, the catalyst has higher normal olefin isomerization activity, higher yield of isomerized olefin, longer time maintenance, longer one-way operation period, smaller reduction of multiple scorching regeneration performance, and is suitable for the process of preparing isoamylene from normal pentene through isomerization reaction.

CN113122313A discloses an olefin isomerization method, wherein the used isomerization catalyst is a sodium type ZSM-35 molecular sieve, and the catalyst has a nano lamellar structure and is used for isomerization reaction of C4-C6 normal olefins. The catalyst adopts metal salt to modify a catalyst carrier, and then adopts ammonium salt solution to carry out ion exchange on a catalyst intermediate product. The catalyst is matched with specific isomerization reaction conditions to ensure that normal olefins have higher isomerization selectivity, wherein the conversion rate of the normal amylene reaches more than 80 percent.

In the prior art, the research on olefin skeleton isomerization is limited, the reaction is mostly carried out on an acid catalyst, the catalyst mainly comprises an MFI type molecular sieve, an SAPO type molecular sieve, magnesium basic zeolite and the like, and the catalyst is mostly an alumina and silica supported metal catalyst, and the isomerization effect of magnesium oxide, calcium and transition metal is obvious. However, the acidic catalyst often has the problems of easy coking and deactivation on the surface of the catalyst, and the long-pass service life of the catalyst is limited. Multiple regenerations and frequent replacements of the catalyst indirectly increase the cost of industrialization of olefin isomerization. In order to solve the above problems, it is necessary to provide a new and highly efficient isomerization catalyst to meet the demand of high activity and long single-pass operation period of olefin catalysts in industrial production processes.

Disclosure of Invention

In order to solve the problems that an olefin isomerization catalyst is easy to coke and deactivate and has a long single-pass service life, the application provides a metal-loaded modified catalyst for olefin skeletal isomerization and a preparation method and application thereof. The olefin isomerization catalyst has the characteristics of difficult coking, difficult inactivation, high reaction activity, long one-way operation period and the like.

The molecular sieve catalyst prepared by the method has a pore channel structure with proper size and quantity, and the pore channels are stable and uniformly distributed, such as: the proportion of mesopore volume to the total pore volume is not less than 60 vol% (e.g., > 70 vol%); the total pore volume is Vtotal = 0.30-0.55 cm ³The most probable distribution is 10-100 nm. In the catalytic reaction process, the diffusion rate of reactants or products is high, coke is not easy to generate, the catalytic performance is high, and the service life is long.

The specific invention content is as follows:

embodiment 1. a supported metal catalyst for an olefin isomerization reaction, said catalyst comprising: a silica-alumina type molecular sieve and a supported metal supported thereon,

wherein n (SiO) of the catalyst₂)/n(Al₂O₃) (i.e., the silicon to aluminum ratio) is 200-2000: 1; a specific surface area of 500 m or more²/g；

The load metal is selected from one or more of magnesium, calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper and zinc;

the content of the supported metal is 0.1-5wt%, calculated by the oxide of the supported metal and based on the dry weight of the molecular sieve;

the proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 60 vol%, the mesopore volume and the total pore volume of the molecular sieve are measured by a nitrogen adsorption BET specific surface area method, and the mesopore volume refers to the pore volume of which the pore diameter is more than or equal to 2 nanometers and less than or equal to 100 nanometers.

Embodiment 2. the catalyst according to embodiment 1, wherein the silica-alumina type molecular sieve is one or more of silica-alumina type MFI, MTT, FER topological structure molecular sieves.

Embodiment 3. the catalyst of embodiment 1, wherein the silica alumina-type molecular sieve is selected from one or more of ZSM-5, ZSM-23, ZSM-35.

Embodiment 4. the catalyst of embodiment 1, wherein n (SiO) of the catalyst₂)/n(Al₂O₃) 400-1800: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 500-1600: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 700-1500: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 800-1450: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) Is 1000-1350: 1.

Embodiment 5. the catalyst of embodiment 1, wherein the catalyst has a crystallinity of 60% to 90%, 65% to 88%, 72% to 85%.

Embodiment 6. the catalyst of embodiment 1, wherein the catalyst has a specific surface area of greater than or equal to 600 m²(ii)/g; preferably, the specific surface area is 700 m or more²/g。

Embodiment 7. the catalyst of embodiment 1, wherein the supported metal oxide particle size D₅₀From 1 to 10nm, for example from 1 to 5nm, for example from 3 to 7 nm.

Embodiment 8. the catalyst of embodiment 1, wherein the catalyst has a mesopore volume ratio of more than or equal to 70 vol% of the total pore volume; the total pore volume is Vtotal = 0.30-0.55 cm³The most probable distribution is 10 to 100 nm.

Embodiment 9. a method of making the catalyst of any of embodiments 1-8, comprising the steps of:

a first crystallization step a, mixing a silicon source, sodium aluminate, sodium hydroxide, an organic amine template agent and water in a proportion of 1: (0.02-0.2): (0.055-0.2): (0.15-0.60): (10-80) placing the mixture in a crystallization kettle according to the molar ratio, uniformly mixing, crystallizing the mixture for 20-80 hours at 110-160 ℃, and then crystallizing the mixture for 40-95 hours at 165-180 ℃ to obtain a crystallized silicon-aluminum type molecular sieve;

a first cleaning step b, filtering, washing and drying the crystallized silicon-aluminum type molecular sieve slurry obtained in the step a to obtain a Na type molecular sieve (also called as a water-washed molecular sieve);

a first ammonium exchange step c, carrying out ammonium exchange treatment on the Na-type molecular sieve obtained in the step b and ammonium salt to obtain an ammonium exchange molecular sieve;

a first roasting step d, carrying out high-temperature roasting treatment on the ammonium exchange molecular sieve obtained in the step c, and removing the organic amine template agent to obtain an H-type molecular sieve;

a dealumination step e, namely, preparing the H-type molecular sieve obtained in the step d into a molecular sieve (also called a dealumination molecular sieve) with a high silica-alumina ratio and a certain T atom defect vacancy after acid treatment and dealumination;

and f, secondary crystallization and metal loading, washing the molecular sieve with the high silica-alumina ratio obtained in the step e with deionized water until the pH is = 6.0-7.0, mixing the molecular sieve with an organic amine template, water and 0.1-5wt% of loaded metal, performing a second crystallization step, and performing a second cleaning step, a second ammonium exchange step and a second roasting step on the obtained slurry to obtain the catalyst.

Embodiment 10 and the method according to embodiment 9, characterized in that: in the step a, the silicon source is silica gel; the organic amine template agent is one or more of ethylenediamine, n-butylamine, tetraethylammonium hydroxide, cyclohexylamine and pyridine; the molecular sieve in the crystallized molecular sieve slurry is one or more of MFI, MTT and FER topological structure molecular sieves, and the silicon-aluminum ratio is 10-85.

Embodiment 11 and the method according to embodiment 9, wherein: in step b, the Na-type molecular sieve has a sodium content of less than 5wt% based on the total dry weight of the Na-type molecular sieve based on sodium oxide.

Embodiment 12 is the production method according to embodiment 9, wherein: in the step c, the ammonium salt is one or more of ammonium chloride, ammonium sulfate and ammonium nitrate; provided that the weight ratio of molecular sieve, ammonium salt and water, on a dry basis, is 1: (0.1-1): (5-10), the temperature is between room temperature and 100 ℃, and the time is 0.2-4 hours; the ammonium exchanged molecular sieve has a sodium content of less than 0.2 wt.% based on sodium oxide and based on total dry basis weight of the ammonium exchanged molecular sieve.

Embodiment 13, the method according to embodiment 9, characterized in that: in step e, the acid in the acid treatment process is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, citric acid and hydrofluoric acid; the concentration range of the used acid is 4-12 mol/L, the volume ratio of the molecular sieve to the acid based on the dry weight is 1: 5-20, the temperature of acid treatment is 50-100 ℃, and the treatment time is 2-24 h; the silicon-aluminum ratio of the molecular sieve subjected to acid treatment and dealumination is 800-2200: 1, and the BET total specific surface area is S _{General assembly}Greater than or equal to 500 m²(e.g., 500 to 750 m)²(g) total pore volume vtotai = 0.30-0.55 cm³The most probable distribution is 10 to 100 nm.

Embodiment 14 is the production method according to embodiment 9, wherein: in the step f, the organic amine template agent adopted by the secondary crystallization is one or more of quaternary ammonium hydroxide, quaternary ammonium salt, triethylamine, ethylenediamine and pyrrolidine; the molar ratio of the dealuminized molecular sieve to the organic amine template to the water is 1: (0.2-0.5): (5-30); the load metal M is one or more of magnesium, calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper and zinc, and the content of the added metal M is 0.1-5wt% based on the oxide of the load metal and the dry basis weight of the molecular sieve; the crystallization conditions are that the crystallization reaction is carried out for 40-60 hours at the temperature of 100-140 ℃ and the crystallization is carried out for 40-85 hours at the temperature of 160-185 ℃; the roasting atmosphere is a mixed gas containing nitrogen and oxygen, wherein the volume ratio of the nitrogen to the oxygen is 2.0-8.0, the roasting temperature is 400-800 ℃, and the roasting time is 0.5-12 hours; the particle size of the metal oxide loaded on the molecular sieve is 1-5 nm.

Embodiment 15 and the production method according to embodiment 9, wherein the production method further includes: enrichment of the supported metal The silicon-aluminum ratio of the mesoporous molecular sieve is 800-2000: 1, and the BET total specific surface area is S_{General (1)} =560~760 m²Per g, total pore volume Vtotal = 0.45-0.85 cm³The most probable distribution is 10-100 nm.

Embodiment 16 is a process for isomerizing olefins characterized by using the catalyst of any one of embodiments 1 to 8 to catalyze the isomerization of at least one member selected from the group consisting of C4 to C12 linear olefins, branched internal olefins, linear terminal olefins, and branched terminal olefins.

The catalyst has the characteristics of high catalytic activity, long one-way running period and the like. According to the silicon-aluminum type molecular sieve synthesized by crystallization, rich defect positions are formed by acid dealumination, and then the secondary crystallization process is accompanied with the removal of unstable silicon (high-concentration organic/inorganic alkali-soluble silicon) and the uniform dispersion of metal in the molecular sieve, so that the possibility is provided for the stable high dispersion of nano metal particles in a pore canal with a high specific surface area.

Due to the high silica-alumina ratio, rich mesoporous volume and uniformly dispersed active metal, the normal olefin isomerization catalyst can maintain high isomerization activity of normal olefin and yield of an isomerized olefin product in a long one-way operation period, and can effectively solve the problem of contradiction between carbon deposition coking and isomerization activity in the prior art.

The catalyst provided by the application can be used for catalyzing isomerization reaction of C4-C12 linear chain olefin, branched chain internal olefin, linear chain terminal olefin or terminal olefin with branched chain, wherein the isomerization effect of low carbon olefin such as C5 olefin is more obvious; additional features and advantages of the present application will be described in detail in the detailed description which follows.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description relate only to some embodiments of the present disclosure and are not limiting to the present disclosure.

FIG. 1 is an X-ray diffraction pattern (XRD) of catalyst 1 of example 1;

FIG. 2 is a high resolution scanning transmission electron micrograph (SEM) of catalyst 2 from example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.

The term MFI topological molecular sieve (MFI Zeolite) was first invented by mobil corporation of america, and was recognized in 1978 by the International molecular sieve Association (International Zeolite Association) for topological structure and code definition, having the meaning commonly understood by those skilled in the art, and is a type of artificially synthesized molecular sieve having a framework type of MFI. The MFI molecular sieve has a double ten-membered ring cross channel system. Parallel to the [001] direction is a ten-membered ring main channel, the aperture of which is 0.51nm multiplied by 0.55 nm; parallel to the [010] direction, the pore size is 0.53nm by 0.56 nm. Among them, ZSM-5 molecular sieves are typical representatives of this type of molecular sieve.

The term MTT-topology molecular sieve (MTT Zeolite) in this application was first invented by Mobil corporation, usa in 1985, and was recognized in 1987 by the International Zeolite Association (International Zeolite Association) for topology and code definition, and has a meaning generally understood by those skilled in the art, and is a type of artificially synthesized molecular sieve having a framework type of MTT. The MTT molecular sieve is a molecular sieve with one-dimensional ten-membered ring linear channels, and the pore diameter is 0.45nm multiplied by 0.52 nm. Most typical of these are ZSM-23, SSZ-32 molecular sieves, and the like.

The term FER topological molecular sieve (FER Zeolite) in the present application was used in 1978 to identify the topology and define the code by the International Zeolite Association (International Zeolite Association), has the meaning generally understood by those skilled in the art, and is a type of artificially synthesized molecular sieve having a framework structure type of FER. FER type molecular sieves are mesoporous zeolites having a two-dimensional cross-channel system. The main channel of the ten-membered ring is parallel to the [001] direction, and the pore diameter is 0.54nm multiplied by 0.42 nm; parallel to [010] is an eight-membered ring secondary channel with a pore size of 0.48nm by 0.35 nm. Among them, ZSM-35 molecular sieve and ferrierite are representative of such molecular sieves.

The term "specific surface area" in the present application is a parameter describing the porous solid catalyst, and specifically refers to the total surface area per unit mass of the solid catalyst. The specific surface area measurement method includes two types, i.e., a gas adsorption method and a solution adsorption method. The specific surface area parameter in the present application is measured by the nitrogen adsorption BET specific surface area method.

The diameter of the pores in the catalyst has a certain distribution law in the catalyst, usually close to a normal distribution. The term "most probable distribution" in the present application refers to the most probable distribution, in particular to the pore diameter where the probability of occurrence in the catalyst is the greatest.

In one aspect, the present application provides a supported metal catalyst for olefin isomerization reactions, the catalyst comprising: a silica-alumina type molecular sieve and a supported metal supported thereon,

The proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 60 vol%, the mesopore volume and the total pore volume of the molecular sieve are measured by a nitrogen adsorption BET specific surface area method, and the mesopore volume refers to the pore volume of which the pore diameter is more than or equal to 2 nanometers and less than or equal to 100 nanometers. In some embodiments, the supported metal is present in an amount of 1 to 5 wt.%, 2 to 4 wt.%, 2.5 to 3.5 wt.%, 2 to 3 wt.%, based on the oxide of the supported metal and on the dry weight of the molecular sieve.

The inventor of the application unexpectedly finds that the catalyst with the characteristics has the characteristics of difficult coking, high catalytic efficiency, long service life, high conversion rate, strong selectivity to a target product and high yield when being used for catalyzing the isomerization reaction of olefin. Although not being limited by theory, the catalyst of the application is low in aluminum content, rich in defect sites formed by dealumination, high in specific surface area and large in mesopore volume, so that the supported metal can be uniformly dispersed in the catalyst, the catalyst is particularly suitable for catalyzing isomerization reaction of olefin, and has the characteristics of difficult coking, high catalytic efficiency, long service life, high conversion rate, strong selectivity to target products and high yield.

The structure of the molecular sieve is not particularly limited in the present application, and the excellent catalytic effect can be obtained by using a catalyst satisfying the above parameter limitations. The silica-alumina type molecular sieves can have different structures that vary depending on the specific method of preparation and the ratio of the reaction raw materials. Specifically, the topological structure of the silica-alumina molecular sieve changes according to the conditions of crystallization synthesis and preparation, and the types and proportions of the silica source, the aluminum source, the organic amine template and the inorganic base. In some embodiments of the catalyst, wherein the molecular sieve is a typical MFI, MTT, FER structure molecular sieve.

In the present application, there is no particular limitation on the type of the specific molecular sieve of the above structure, as long as the catalyst satisfying the above parameter definition can obtain the excellent catalytic effect. In some embodiments of the catalyst, the silicalite is selected from one or more of ZSM-5, ZSM-23, ZSM-35, SSZ-32. These configurations all have the meaning commonly understood by those skilled in the art.

In the application, the ZSM-5 molecular sieve refers to a five-finger characteristic peak of a typical MFI structure existing in the range of 22.5-25 degrees of 2 theta of an X-ray diffraction spectrogram of raw powder of the molecular sieve.

In the application, the ZSM-23 molecular sieve refers to typical MTT structural characteristic peaks of X-ray diffraction patterns of molecular sieve raw powder at 19.8 degrees, 21 degrees, 22.9 degrees, 23.0 degrees, 24.0 degrees, 24.2 degrees, 24.8 degrees and 35.8 degrees in 2 theta.

In the application, the ZSM-35 molecular sieve refers to typical FER structural characteristic peaks existing at 15.2 degrees, 22.2 degrees, 22.4 degrees, 22.9 degrees, 23.5 degrees, 25.0 degrees, 25.2 degrees, 25.5 degrees, 28.3 degrees, 29.0 degrees and 30.0 degrees of the 2 theta of an X-ray diffraction spectrum of raw powder of the molecular sieve.

The specific silica to alumina ratio in the catalyst may vary without particular limitation, and in general, higher silica to alumina ratios generally correspond to higher specific surface areas, depending on the method of preparation. In some embodiments of the catalyst, wherein n (SiO) of the catalyst₂)/n(Al₂O₃) 400-1800: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 500-1600: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 700-1500: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) 800-1450: 1; n (SiO) of the catalyst₂)/n(Al₂O₃) Is 1000-1350: 1.

The crystallinity of the catalyst is not particularly limited in the present application, but the crystallinity is considered to be favorable for increasing the catalytic effect and the strength of the catalyst within a certain range, and further, the crystallinity is favorable for the operation period of the catalyst. In some embodiments of the catalyst, wherein the crystallinity of the catalyst is from 60% to 90%, from 65% to 88%, from 72% to 85%.

The specific surface area of the catalyst is an important indicator of the performance of the catalyst, and generally higher specific surface area catalysts have better catalytic performance. Thus, in some preferred embodiments of the catalyst, wherein the specific surface area of the catalyst is greater than or equal to 600 m²(iv) g; a specific surface area of 700 m or more²/g。

The particle size of the loaded metal is an important factor for playing the catalytic effect, and the application adopts a hydrothermal crystallization method to load metal ions on the porous molecular sieve, so that the uniform high-dispersion nano-scale metal oxide effect on the catalyst is obtained, and the catalytic effect of the catalyst is increasedAnd (5) the effect is improved. In some embodiments of the catalyst, wherein the metal-supporting oxide particle size D₅₀From 1 to 10nm, for example from 1 to 5nm, for example from 3 to 7 nm. In this application, D₅₀The particle size is the corresponding particle size when the cumulative percentage of particle size distribution of a sample reaches 50% by mass. Its physical meaning is that the particle size is greater than 50% of its particles and less than 50% of its particles, D50 also being referred to as the median or median particle size.

In some embodiments of the catalyst, wherein the proportion of mesopore volume of the catalyst to the total pore volume is ≧ 70 vol%; the total pore volume is Vtotal = 0.30-0.55 cm ³The most probable distribution is 10-100 nm. The mesopores referred to herein may also be referred to as mesopores, which refer to pores having a pore diameter in the range of 2 to 100 nm. The mesopore volume is the pore volume of pores having a diameter of 2 nm or more and 100 nm or less as measured by the nitrogen adsorption BET specific surface area method.

In another aspect, the present application provides a method of making a catalyst as described in any of the preceding claims, comprising the steps of:

a first crystallization step a, mixing a silicon source, sodium aluminate, sodium hydroxide, an organic amine template agent and water in a proportion of 1: (0.02-0.2): (0.055-0.2): (0.15-0.60): (10-80) putting the mixture in a crystallization kettle according to the molar ratio, uniformly mixing, crystallizing the mixture at 110-160 ℃ for 20-80 hours, and crystallizing the mixture at 165-180 ℃ for 40-95 hours to obtain a crystallized silicon-aluminum type molecular sieve;

A dealumination step e, carrying out acid treatment on the H-type molecular sieve obtained in the step d to dealuminate, and preparing a molecular sieve (also called as a dealumination molecular sieve) with a high silica-alumina ratio and a certain T atom defect vacancy;

and f, secondary crystallization and metal loading, washing the molecular sieve with the high silica-alumina ratio obtained in the step e with deionized water until the pH is = 6.0-7.0, mixing the molecular sieve with an organic amine template, water and 0.1-5wt% of loaded metal, performing a second crystallization step, and performing a second cleaning step, a second ammonium exchange step and a second roasting step on the obtained slurry to obtain the catalyst. In the method, the second cleaning step, the second ammonium exchange step and the second roasting step may be respectively and independently the same as or different from the corresponding steps in steps b, c and d, and can be selected by a person skilled in the art according to actual needs. For example, the second firing step may employ a different firing atmosphere than in the first firing step.

In the method, the silicon-aluminum type molecular sieve synthesized by crystallization is dealuminized by acid treatment to form rich defect sites, and the secondary crystallization process is accompanied with the removal of unstable silicon (high-concentration organic/inorganic alkali-soluble silicon) and the uniform dispersion process of metal ions in the molecular sieve, so that the possibility is provided for the stable existence of high-dispersion nano metal particles in the pore canal with high specific surface area. The catalyst formed by the method is particularly suitable for isomerization of normal olefins, and due to the high silica-alumina ratio, rich mesoporous volume and uniformly dispersed active metal, the catalyst can maintain high isomerization activity of normal olefins and yield of isomerized olefin products in a long one-way operation period, and can effectively solve the problem of contradiction between carbon deposition coking and isomerization activity in the prior art. The catalyst prepared by the method can be used for catalyzing isomerization reaction of C4-C12 linear chain olefin, branched chain internal olefin, linear chain terminal olefin or terminal olefin with branched chain, wherein the isomerization effect of low carbon olefin such as C5 olefin is more obvious.

The high silica to alumina ratio molecular sieve formed by the process of the present application, although not directly used as such in the absence of a supported metal for catalytic reactions, is a key intermediate for the preparation of the catalyst of the present application and, therefore, the present application also provides a high silica to alumina ratio molecular sieve prepared by the above-described step abcde and a process for preparing a high silica to alumina ratio molecular sieve comprising a first crystallization step a, a first washing step b, a first ammonium exchange step c, a first calcination step d, and a dealumination step e.

In some embodiments of the method, in step a, the silicon source is silica gel; the organic amine template agent is one or more of ethylenediamine, n-butylamine, tetraethylammonium hydroxide, cyclohexylamine and pyridine; the molecular sieve in the silicon-aluminum molecular sieve slurry obtained by crystallization is one or more of silicon-aluminum type MFI, MTT and FER topological structure molecular sieves, and the silicon-aluminum ratio is 10-85.

In some embodiments of the process, in step b, the Na-type molecular sieve has a sodium content of less than 5wt%, based on sodium oxide and on the total dry weight basis of the Na-type molecular sieve.

The specific production conditions and the reactant ratios in the production method of the present application are not limited as long as the objective product can be formed. In some embodiments of the method, in step c, the ammonium salt is one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate; the ammonium exchange conditions are that the weight ratio of the molecular sieve, the ammonium salt and the water is 1: (0.1-1): (5-10), the temperature is between room temperature and 100 ℃, and the time is 0.2-4 hours; the ammonium exchanged molecular sieve has a sodium content of less than 0.2 wt.% based on sodium oxide and based on total dry basis weight of the ammonium exchanged molecular sieve.

In some embodiments of the method, in step e, the acid of the acid treatment process is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, citric acid, and hydrofluoric acid; the concentration range of the used acid is 4-12 mol/L, the volume ratio of the molecular sieve to the acid based on the weight of a dry basis is 1: 5-20, the temperature of acid treatment is 50-100 ℃, and the treatment time is 2-24 h; the silicon-aluminum ratio of the molecular sieve subjected to acid treatment and dealumination is 800-2200: 1, and the BET total specific surface area is S_{General (1)}Greater than or equal to 500 m²G (e.g. 500 to 750 m)²(iv)/g) total pore volume of vtotal = 0.30-0.55 cm³The most probable distribution is 10-100 nm.

In some embodiments of the method, in step f, the organic amine template used for the second crystallization is one or more of quaternary ammonium base, quaternary ammonium salt, triethylamine, ethylenediamine and pyrrolidine; the molar ratio of the dealuminized molecular sieve to the organic amine template to water is 1: (0.2-0.5): (5-30); the load metal M is one or more of magnesium, calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper and zinc, and the content of the added metal M is 0.1-5wt% based on the oxide of the load metal and the dry basis weight of the molecular sieve; the crystallization conditions are that the crystallization reaction is carried out for 40-60 hours at the temperature of 100-140 ℃ and the crystallization is carried out for 40-85 hours at the temperature of 160-185 ℃; the roasting atmosphere is a mixed gas containing nitrogen and oxygen, wherein the volume ratio of the nitrogen to the oxygen is 2.0-8.0, the roasting temperature is 400-800 ℃, and the roasting time is 0.5-12 hours; the particle size of the metal oxide loaded by the molecular sieve is 1-5 nm.

In some embodiments of the method, the metal-loaded mesoporous molecular sieve has a silica to alumina ratio of 800 to 2000:1 and a BET total specific surface area of S_{General (1)} =560~760 m²(iv) per gram, total pore volume vtotai = 0.45-0.85 cm³The most probable distribution is 10-100 nm.

Another aspect of the present application provides an olefin isomerization process characterized by employing the catalyst according to any one of the preceding claims for catalyzing an isomerization reaction of at least one selected from the group consisting of C4-C12 linear olefins, branched internal olefins, linear terminal olefins, or branched terminal olefins.

The production equipment used in this application is equipment commonly used in the art, such as crystallization vessels, catalytic reactors are known in the art.

The specific implementation mode of the application is mainly divided into two steps: firstly, preparing a target catalyst, and characterizing the performances of the catalyst, including crystallinity, silicon-aluminum ratio, content of loaded metal, specific surface area, pore volume, sodium content, metal particle size and the like; then, the synthesized catalyst was applied to the isomerization reaction of n-pentene, and the catalytic performance of the catalyst was evaluated.

The preparation of the target catalyst is the core of the application, and the application aims to synthesize the high-yield catalyst which is difficult to coke, high in catalytic efficiency, long in service life, high in conversion rate and strong in selectivity on the target product.

In order to prepare the target catalyst, the base catalyst 1 is prepared, and then the catalyst 1 is further processed, for example, the catalyst is subjected to acid dealumination treatment, and then is subjected to secondary crystallization and metal ion loading. Various catalysts are prepared by changing parameters in the treatment process.

After the catalyst is prepared, the physical and chemical indexes of the catalyst are characterized, and the method mainly comprises the following steps:

the crystallinity of the present application was determined using the standard method of ASTM D5758-2001(2011) e 1.

N (SiO) of the present application₂)/n(Al₂O₃) I.e. the silicon-aluminum ratio, is calculated by the contents of silicon oxide and aluminum oxide, and the contents of silicon oxide and aluminum oxide are measured by the GB/T30905-2014 standard method.

The content of the load metal is determined by adopting a GB/T30905-2014 standard method.

The specific surface area of the present application was determined using the GB5816 standard method.

The pore volume of the present application was determined using the GB5816 standard method.

The sodium content of the sodium-containing material is determined by adopting a GB/T30905-2014 standard method.

The micro-inversion conversion rate of the present application is determined by the ASTM D5154-2010 standard method.

The metal particle size of the present application is characterized by a high resolution scanning transmission electron microscope.

After the target catalyst is prepared, the catalytic performance of the catalyst is evaluated by applying the catalyst to perform catalytic reaction.

The evaluation of the catalytic performance of the catalyst is mainly realized by conversion rate, yield and selectivity. For example, for the isomerization of n-pentene:

conversion = (mass of n-pentene in starting material-mass of n-pentene in product) ÷ (mass of n-pentene in starting material) × 100%

Yield = (mass of isopentene in product) ÷ (mass of n-pentene in raw material) × 100%

Selectivity = yield/conversion 100%

The isomerization reaction of n-pentene is one embodiment taken in the evaluation of the catalytic performance of the catalyst, and the catalyst prepared herein may also be used to catalyze at least one selected from the group consisting of C4-C12 linear olefins, branched internal olefins, linear terminal olefins, or branched terminal olefins.

By comparing various embodiments and examples, the present application finds a catalyst with excellent performance, specifically as follows:

the present application provides a supported metal catalyst for olefin isomerization reactions, said catalyst comprising: a silica-alumina type molecular sieve and a supported metal supported thereon,

the silicon-aluminum type molecular sieve is one or more of silicon-aluminum type MFI, MTT and FER topological structure molecular sieves, and is selected from one or more of ZSM-5, ZSM-23 and ZSM-35;

N (SiO) of the catalyst₂)/n(Al₂O₃) 200-2000: 1; preferably, n (SiO) of the catalyst₂)/n(Al₂O₃) 400-1800: 1; more preferably, n (SiO) of the catalyst₂)/n(Al₂O₃) 500-1600: 1; more preferably, n (SiO) of the catalyst₂)/n(Al₂O₃) 700-1500: 1; more preferably, n (SiO) of the catalyst₂)/n(Al₂O₃) 800-1450: 1; more preferably, n (SiO) of the catalyst₂)/n(Al₂O₃) 1000-1350: 1;

the specific surface area of the catalyst is greater than or equal to 500 m²(ii)/g; preferably, the specific surface area of the catalyst is greater than or equal to 600 m²(ii)/g; more preferably, the specific surface area is 700 m or more²/g ；

the content of the supported metal is 0.1-5wt% calculated by the oxide of the supported metal and calculated by the dry basis weight of the molecular sieveThe amount is taken as a reference; the particle diameter D of the metal-supporting oxide₅₀From 1 to 10nm, preferably from 1 to 5nm, more preferably from 3 to 7 nm;

the proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 60 vol%, the mesopore volume and the total pore volume of the molecular sieve are measured by adopting a nitrogen adsorption BET specific surface area method, and the mesopore volume refers to the pore volume with the pore diameter of more than 2 nanometers and less than 100 nanometers; preferably, the proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 70 vol%; the total pore volume is Vtotal = 0.30-0.55 cm ³The most probable distribution is 10-100 nm.

The crystallinity of the catalyst may optionally be from 60% to 90%, preferably from 65% to 88%, more preferably from 72% to 85%.

The present application also provides a method for preparing the above catalyst, which comprises the following steps:

a first crystallization step a, mixing a silicon source, sodium aluminate, sodium hydroxide, an organic amine template agent and water in a ratio of 1: (0.02-0.2): (0.055-0.2): (0.15-0.60): (10-80) placing the mixture in a crystallization kettle according to the molar ratio, uniformly mixing, crystallizing the mixture for 20-80 hours at 110-160 ℃, and then crystallizing the mixture for 40-95 hours at 165-180 ℃ to obtain crystallized silicon-aluminum type structure molecular sieve slurry;

preferably, the silicon source is silica gel; the organic amine template agent is one or more of ethylenediamine, n-butylamine, tetraethylammonium hydroxide, cyclohexylamine and pyridine; the molecular sieve in the molecular sieve slurry obtained by crystallization is a silicon-aluminum type molecular sieve such as a ZSM-35 molecular sieve, and the silicon-aluminum ratio is 10-85.

A first cleaning step b, filtering, washing and drying the molecular sieve slurry with the crystallized structure obtained in the step a to obtain a Na-type molecular sieve (also called as a water-washed molecular sieve);

preferably, the Na-type molecular sieve has a sodium content of less than 5wt%, e.g., 1%, 2%, 4%, based on sodium oxide and based on the total dry weight of the Na-type molecular sieve.

preferably, the ammonium salt is one or more of ammonium chloride, ammonium sulfate and ammonium nitrate; the ammonium exchange conditions are that the weight ratio of the molecular sieve, the ammonium salt and the water is 1: (0.1-1): (5-10), the temperature is between room temperature and 100 ℃, and the time is 0.2-4 hours; the ammonium exchanged molecular sieve has a sodium content of less than 0.2 wt.% based on sodium oxide and based on total dry basis weight of the ammonium exchanged molecular sieve.

A first roasting step d, carrying out high-temperature roasting treatment on the ammonium exchange molecular sieve obtained in the step c, and removing the organic amine template agent to obtain an H-type molecular sieve; the roasting comprises roasting in an air atmosphere, roasting in an oxygen atmosphere, roasting in a steam atmosphere and the like, and the roasting can also be carried out in a mode of combining the three. For example, the temperature is slowly raised from 550 ℃ to 650 ℃ in the air atmosphere for roasting for 3-4 hours, and then steam is introduced for roasting for 2 hours.

Preferably, the acid of the acid treatment process is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, citric acid and hydrofluoric acid; the concentration range of the used acid is 4-12 mol/L, the volume ratio of the molecular sieve to the acid based on the dry weight is 1: 5-20, the temperature of acid treatment is 50-100 ℃, and the treatment time is 2-24 h; the silicon-aluminum ratio of the molecular sieve subjected to acid treatment and dealumination is 800-2200: 1, and the BET total specific surface area is S_{General assembly}Greater than or equal to 500 m²A/g, e.g. 500 to 750 m²(iv) per gram, total pore volume vtotai = 0.30-0.55 cm³The most probable distribution is 10 to 100 nm.

And f, secondary crystallization and metal loading step, washing the high silica-alumina ratio molecular sieve obtained in the step e with deionized water to pH = 6.0-7.0, mixing the washed molecular sieve with an organic amine template, water and 0.1-5wt% (such as 1-5wt%, 2-4wt%, 2.5-3.5wt%, 2-3 wt%) of a metal load, and performing secondary crystallization, wherein the second crystallization is relative to the first crystallization, and the reaction conditions can be the same as the first crystallization, such as: crystallizing at 110-160 ℃ for 20-80 hours, then crystallizing at 165-180 ℃ for 40-95 hours, and sequentially carrying out secondary cleaning, secondary ammonium exchange and secondary roasting on the obtained slurry according to the same methods as those of b, c and d to obtain the catalyst.

In the method, the second cleaning step, the second ammonium exchange step and the second roasting step may be respectively and independently the same as or different from the corresponding steps in steps b, c and d, and can be selected by a person skilled in the art according to actual needs. For example, the second firing step may employ a different firing atmosphere than in the first firing step.

In the above method, the first crystallization step a may also be performed as follows: mixing a silicon source, sodium aluminate, sodium hydroxide, an organic amine template agent and water in a proportion of 1: (0.02-0.2): (0.055-0.09): (0.15-0.40): (10-50) placing the mixture in a crystallization kettle in the molar ratio, uniformly mixing, crystallizing the mixture at 110-145 ℃ for 20-60 hours, and then crystallizing the mixture at 165-180 ℃ for 40-75 hours to obtain crystallized silicon-aluminum type structure molecular sieve slurry which is a crystallized FER structure molecular sieve.

In the preparation method, preferably, the ratio of silicon to aluminum of the metal-loaded mesoporous-rich catalyst is 800-2000: 1, and the total BET specific surface area is S_{General assembly} =560~760 m²(iv) per gram, total pore volume vtotai = 0.45-0.85 cm³The most probable distribution is 10-100 nm.

The present application also provides a process for isomerization of olefins characterized by using the catalyst according to any one of claims 1 to 9 for catalyzing at least one selected from the group consisting of C4-C12 linear olefins, branched internal olefins, linear terminal olefins, and branched terminal olefins.

Examples

The present application will be further illustrated by the following examples, but the present application is not limited thereto, and the instruments and reagents used in the examples of the present application are those commonly used by those skilled in the art, unless otherwise specified.

Preparation and characterization of the first part of the catalyst

Example 1

(1) Preparation of catalyst 1

A method for synthesizing a silicon-aluminum type molecular sieve comprises the following steps:

first crystallization step a

Mixing silica gel, sodium aluminate, sodium hydroxide, ethylenediamine and water in a proportion of 1: 0.15: 0.07: 0.3: the molar ratio of 35 is placed in a crystallization kettle to be uniformly mixed, and the mixture is crystallized for 32 hours at the temperature of 130 ℃ and is crystallized for 65 hours at the temperature of 180 ℃ to obtain crystallized silicon-aluminum type molecular sieve slurry;

first cleaning step b

Filtering mother liquor of the crystallized silicon-aluminum type molecular sieve slurry obtained in the step a, and washing the mother liquor until the mother liquor is Na₂The O content (calculated by dry basis) is lower than 2 wt%, and the Na type molecular sieve (also called water-washed molecular sieve) is obtained by filtering and drying, namely the catalyst 1.

The crystallinity, silica-alumina ratio, supported metal content, specific surface area, pore volume, sodium content, metal particle diameter and the like of the catalyst 1 were measured with reference to the above-mentioned standards.

The X-ray diffraction pattern (XRD) of catalyst 1 is shown in fig. 1, and the physicochemical properties and micro-reverse evaluation data are shown in table 1. as can be seen from fig. 1, catalyst 1 is a typical molecular sieve with FER structure, namely, ZSM-35 molecular sieve. Applicants have also found that the configuration of the molecular sieve is already formed after the first crystallization reaction, and the second crystallization reaction does not have a substantial effect on the configuration of the molecular sieve.

Example 2

Preparation of catalyst 2 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of raw powder of the catalyst 1 into 800g of water for pulping, and adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h to Na₂The O content (calculated by dry basis) is lower than 0.2 wt%, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

Drying the filter cake obtained in the step c, and roasting for 4 hours at 550 ℃ in air atmosphere;

dealuminizing step e

Weighing 10.0 g of the roasted product obtained in the step d, and adding 200 mL of HNO₃And (3) heating the solution to 100 ℃ with the acid solution concentration of 6 mol/L, continuously stirring for 8 h, cooling the liquid to room temperature, filtering, washing with deionized water to be neutral, and drying a filter cake.

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 3.84g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 2.

The physicochemical properties and the micro-inverse evaluation data are shown in Table 1, and a high-resolution scanning transmission electron microscope image of the metal particle size is shown in FIG. 2. The particle size of the supported metal is seen below 10nm, about 3 nm in fig. 2. The X-ray diffraction pattern of catalyst 2 is substantially identical to that of catalyst 1, and the characteristic peak position of ZSM-35 is still retained by the molecular sieve XRD peak.

Example 3

Preparation of catalyst 3 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of the raw powder of the catalyst 1 into 800g of water for pulping, adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h until Na₂The O content (calculated by dry basis) is lower than 0.2 wt%, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

dealumination step e

Weighing 10.0 g of the roasted product obtained in the step d, and adding 200 mL of HNO₃Heating the solution to the concentration of 8 mol/L with acid solution at 100 ℃, continuously stirring for 8 h, cooling the liquid to room temperature, filtering, washing with deionized water to neutrality, and drying the filter cake.

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 3.84g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 3.

Example 4

Preparation of catalyst 4 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of raw powder of the catalyst 1 into 800g of water for pulping, and adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h until Na₂The content of O (calculated by dry basis) is lower than 0.2 wt%, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

dealumination step e

Weighing 10.0 g of the roasted product obtained in the step d, and adding 200 mL of HNO₃Heating the solution to 100 ℃ with the acid solution concentration of 10 mol/L, continuously stirring for 8 h, cooling the liquid to room temperature, filtering, washing with deionized water to be neutral, and drying the filter cake.

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 3.84g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 4.

Example 5

Preparation of catalyst 5 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of the raw powder of the catalyst 1 into 800g of water for pulping, adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h to Na₂The content of O (calculated by dry basis) is lower than 0.2 wt%, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

dealumination step e

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 1.28g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 5.

Example 6

Preparation of catalyst 6 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of raw powder of the catalyst 1 into 800g of water for pulping, and adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h to Na₂The O content (calculated by dry basis) is lower than 0.2 percent by weight, and the molecular sieve filter cake is obtained by filtering and washing;

first calcination step d

dealumination step e

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 2.56g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 6.

Example 7

Preparation of catalyst 7 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of the raw powder of the catalyst 1 into 800g of water for pulping, adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h until Na₂The content of O (calculated by dry basis) is lower than 0.2 weight percent, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

dealumination step e

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 5.12g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 7.

Example 8

Preparation of catalyst 8 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

Adding 100g (dry basis) of raw powder of the catalyst 1 into 800g of water for pulping, and adding 40 g of NH₄Cl, heating to 80 ℃, and carrying out exchange treatment for 1 h to Na₂The content of O (calculated by dry basis) is lower than 0.2 weight percent, and the molecular sieve filter cake is obtained after filtration and washing;

first calcination step d

dealumination step e

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 6.4g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 8.

Example 9

Preparation of catalyst 9 catalyst 1 from example 1 was further processed as follows:

first ammonium exchange step c

first calcination step d

dealumination step e

Secondary crystallization and metal loading step f

Weighing 20.0g of the dried product obtained in the step e after acid treatment, mixing and pulping the dried product with tetraethylammonium hydroxide and water according to the molar ratio of 1: 0.4: 10, adding 7.55g of magnesium nitrate hexahydrate, reacting at 125 ℃ for 40 h, reacting at 180 ℃ for 60 h, filtering, washing and drying the slurry according to the method of the first cleaning step in the embodiment 1 after the reaction is finished, then performing ammonium exchange again according to the method of the first ammonium exchange step c, and then performing roasting again according to the method of the first roasting step d to obtain the catalyst 9.

The crystallinity, silica to alumina ratio, supported metal content, specific surface area, pore volume, sodium content, metal particle size, etc. of catalysts 1-9 were measured with reference to the criteria described above.

Evaluation of the catalyst in the second part

The evaluation of the catalyst in the invention is mainly realized by the conversion rate and yield of the catalyst in the catalytic n-pentene isomerization reaction.

The catalyst samples obtained in the above examples were each separatelyTabletting and grinding the mixture to 20-40 mesh particles, wherein the filling volume of the catalyst is 10mL, the reactant is n-pentene, and the liquid volume space velocity is 2h^-1The reaction was carried out at normal pressure and at a reaction temperature of 310 ℃.

Experiments were conducted for 24 hours and 32 hours of reaction according to the above reaction conditions, respectively, and then the product conversion and yield were calculated. The data of the micro-reverse evaluation are shown in Table 1, as follows: conversion and yield.

Conversion = (mass of n-pentene in feed-mass of n-pentene in product) ÷ (mass of n-pentene in feed) × 100%

Yield = (mass of isoamylene in product) ÷ (mass of n-pentene in raw material) × 100%

The selectivity can also be calculated accordingly as yield/conversion 100%.

Table 1 shows the parameters of examples 1 to 9, including the parameters of catalyst synthesis, the properties of the catalyst, and the evaluation of the catalyst at 24 hours and 32 hours.

TABLE 1 summary of experimental data in examples 1-9

The isoolefin selectivities for the reactions of 24h in examples 1-9 are respectively as follows: 92.8%, 96.0%, 97.9%, 97.6%, 95.0%, 95.1%, 96%, 96.8%, 97.0%.

In addition, experiments were also conducted on metals calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper, zinc as the load metals, and the results were obtained similarly to the case of using magnesium as the load metal.

The above description is intended to be merely exemplary embodiments of the present disclosure and is not intended to limit the scope of the present disclosure, which is defined by the claims appended hereto.

Claims

1. A supported metal catalyst for an olefin isomerization reaction comprising: a silica-alumina type molecular sieve and a supported metal supported thereon,

wherein the catalyst has a silicon to aluminum ratio800-1450: 1, specific surface area greater than or equal to 600 m²/g；

the content of the supported metal is 2-3wt%, calculated by the oxide of the supported metal and based on the dry weight of the molecular sieve;

the proportion of the mesopore volume of the catalyst in the total pore volume is more than or equal to 60 vol%, the mesopore volume and the total pore volume of the molecular sieve are measured by a nitrogen adsorption BET specific surface area method, the mesopore volume refers to the pore volume with the pore diameter of more than or equal to 2 nanometers and less than or equal to 100 nanometers, wherein the crystallinity of the catalyst is 65-88%,

The silicon-aluminum type molecular sieve is one or more of silicon-aluminum type MFI, MTT and FER topological structure molecular sieves.

2. The catalyst of claim 1, wherein the catalyst has a silica to alumina ratio of 1000 to 1350: 1.

3. The catalyst of claim 1, wherein the crystallinity of the catalyst is from 72% to 85%.

4. The catalyst of claim 1, wherein the catalyst has a specific surface area of greater than or equal to 700 m²/g。

5. The catalyst of claim 1, wherein the metal-supporting oxide particle size D₅₀Is at least one selected from the group consisting of: 1-10nm, 1-5nm and 3-7 nm.

6. The catalyst of claim 1, wherein the proportion of mesopore volume of the catalyst to the total pore volume is at least 70 vol%; the total pore volume is 0.30-0.55 cm³The most probable distribution is 10 to 100 nm.

7. A process for preparing the catalyst of any one of claims 1-6, comprising the steps of:

a first crystallization step a, mixing a silicon source, sodium aluminate, sodium hydroxide, an organic amine template agent and water in a ratio of 1: (0.02-0.2): (0.055-0.2): (0.15-0.60): (10-80) placing the mixture in a crystallization kettle according to the molar ratio, uniformly mixing, crystallizing the mixture for 20-80 hours at 110-160 ℃, and then crystallizing the mixture for 40-95 hours at 165-180 ℃ to obtain crystallized silicon-aluminum type molecular sieve slurry;

A first cleaning step b, filtering, washing and drying the crystallized silicon-aluminum type molecular sieve slurry obtained in the step a to obtain a Na type molecular sieve;

a dealumination step e, namely preparing the molecular sieve with the high silica-alumina ratio by dealuminating the H-type molecular sieve obtained in the step d through acid treatment;

8. The method of claim 7, wherein: in the step a, the silicon source is silica gel; the organic amine template agent is one or more of ethylenediamine, n-butylamine, tetraethylammonium hydroxide, cyclohexylamine and pyridine; the molecular sieve in the molecular sieve slurry obtained by crystallization is in a structure of one or more of silicon-aluminum type MFI, MTT and FER topological structures, and the silicon-aluminum ratio is 10-85.

9. The method of claim 7, wherein: in step b, the Na-type molecular sieve has a sodium content of less than 5wt% based on the total dry weight of the Na-type molecular sieve calculated by sodium oxide.

10. The method for producing according to claim 7, characterized in that: in the step c, the ammonium salt is one or more of ammonium chloride, ammonium sulfate and ammonium nitrate; the ammonium exchange conditions are that the weight ratio of the molecular sieve, the ammonium salt and the water is 1: (0.1-1): (5-10), the temperature is between room temperature and 100 ℃, and the time is 0.2-4 hours; the ammonium exchanged molecular sieve has a sodium content of less than 0.2 wt.% based on sodium oxide and based on total dry basis weight of the ammonium exchanged molecular sieve.

11. The method of claim 7, wherein: in step e, the acid in the acid treatment process is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, citric acid and hydrofluoric acid; the concentration range of the used acid is 4-12 mol/L, the volume ratio of the molecular sieve to the acid based on the dry weight is 1: 5-20, the temperature of acid treatment is 50-100 ℃, and the treatment time is 2-24 h; the silicon-aluminum ratio of the acid-treated high-silicon-aluminum-ratio molecular sieve is 800-2200: 1, and the BET total specific surface area is more than or equal to 500 m ²(ii) a total pore volume of 0.30 to 0.55 cm³The most probable distribution is 10 to 100 nm.

12. The method of claim 7, wherein: in the step f, the organic amine template agent adopted by the secondary crystallization is one or more of quaternary ammonium hydroxide, quaternary ammonium salt, triethylamine, ethylenediamine and pyrrolidine; the molar ratio of the molecular sieve with high silica-alumina ratio, the organic amine template and the water is 1: (0.2-0.5): (5-30); the load metal M is one or more of magnesium, calcium, barium, scandium, titanium, vanadium, chromium, nickel, copper and zinc, and the content of the added metal M is 0.1-5wt% based on the oxide of the load metal and the dry basis weight of the molecular sieve; the crystallization conditions are that the crystallization reaction is carried out for 40-60 hours at the temperature of 100-140 ℃ and the crystallization is carried out for 40-85 hours at the temperature of 160-185 ℃; the roasting atmosphere is a mixed gas containing nitrogen and oxygen, wherein the volume ratio of the nitrogen to the oxygen is 2.0-8.0, the roasting temperature is 400-800 ℃, and the roasting time is 0.5-12 hours; the particle size of the metal oxide loaded on the molecular sieve is 1-5 nm.

13. A process for the isomerization of olefins, characterized in that a catalyst according to any of claims 1 to 6 is used for the isomerization of at least one olefin selected from the group consisting of C4-C12 linear olefins, branched internal olefins, linear terminal olefins and branched terminal olefins.