CN110732344A - Isobutane dehydrogenation catalyst with illite composite material with three-dimensional cubic and hexagonal pore channel structure as carrier, and preparation method and application thereof - Google Patents
Isobutane dehydrogenation catalyst with illite composite material with three-dimensional cubic and hexagonal pore channel structure as carrier, and preparation method and application thereof Download PDFInfo
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- 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
- B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
- B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
- B01J29/0316—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing iron group metals, noble metals or copper
- B01J29/0325—Noble metals
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
- C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
- C07C5/333—Catalytic processes
- C07C5/3332—Catalytic processes with metal oxides or metal sulfides
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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
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/03—Catalysts comprising molecular sieves not having base-exchange properties
Abstract
The invention relates to the field of catalysts, and discloses a method for preparing an isobutane dehydrogenation catalyst by , the isobutane dehydrogenation catalyst prepared by the method, and a method for preparing isobutene by isobutane dehydrogenation.
Description
Technical Field
The invention relates to the field of catalysts, in particular to a method for preparing an isobutane dehydrogenation catalyst by , the isobutane dehydrogenation catalyst prepared by the method and a method for preparing isobutene by isobutane dehydrogenation.
Background
Isobutene is very important organic chemical raw materials and is mainly used for preparing various organic raw materials and fine chemicals such as methyl tert-butyl ether, butyl rubber, methyl ethyl ketone, polyisobutylene, methyl methacrylate, isoprene, tert-butyl phenol, tert-butyl amine, 1, 4-butanediol, ABS resin and the like, and the main sources of isobutene are a C4 fraction which is a byproduct of a naphtha steam cracking ethylene preparation device, a C4 fraction which is a byproduct of a refinery Fluid Catalytic Cracking (FCC) device and tert-butyl alcohol (TAB) which is a byproduct in the synthesis of propylene oxide by a Halcon method.
In recent years, with the development and utilization of downstream products of isobutene, the demand of isobutene is increased year by year, and the traditional isobutene production cannot meet the huge demand of isobutene in the chemical industry, so the research and development work of a new isobutene production technology becomes a major hotspot in the chemical industry.
The catalysts for preparing isobutene by isobutane dehydrogenation mainly comprise two types: oxide catalysts and noble metal catalysts. Oxide catalystMainly comprises Cr2O3、V2O5、Fe2O3、MoO3ZnO, etc., and a composite oxide thereof, such as V-Sb-O, V-Mo-O, Ni-V-O, V-Nb-O, Cr-Ce-O, molybdate, etc. Compared with noble metal catalysts, oxide catalysts are less expensive. However, the catalyst is easy to deposit carbon, and the catalytic activity, selectivity and stability are low. In addition, most oxide catalysts contain components with high toxicity, which is not favorable for environmental protection. The research on dehydrogenation reactions on noble metal catalysts has a long history, and noble metal catalysts have higher activity, better selectivity, and are more environmentally friendly than other metal oxide catalysts. However, the catalyst cost is high due to the expensive price of noble metals, and the performance of such catalysts has not yet reached a satisfactory level.
In order to improve the reaction performance of the catalyst for preparing isobutene by isobutane dehydrogenation, researchers have done a lot of work. Such as: the catalyst performance is improved by changing the preparation method of the catalyst (industrial catalysis, 2014, 22(2): 148-. However, the specific surface area of the currently used carrier is small, which is not beneficial to the dispersion of the active metal component on the surface of the carrier, and is also not beneficial to the diffusion of raw materials and products in the reaction process.
Therefore, how to improve the reaction performance of the isobutane dehydrogenation catalyst is problems to be solved urgently in the field of isobutene preparation by isobutane dehydrogenation.
Illite is kinds of potassium-rich silicate mica clay minerals, and its name is found in illite island of the United states at the earliest0.75(Al1.75R)[Si3.5Al0.5O10](OH)2The crystal mainly belongs to a monoclinic system hydrous layered structure silicate mineral.In the formula R2+Represents a divalent metal cation, mainly Mg2+﹑Fe2+And the like. The chemical composition of illite clay (rock) is changed greatly due to the content of other impurities, except SiO2、 Al2O3In addition to the large difference in content, K2O and Na2O is relatively stable, -like K 26 to 9 percent of O and 0.5 to 1.5 percent of Na 2O. The illite has the advantages of rich potassium, high aluminum, low iron, smoothness, brightness, fineness, heat resistance and other excellent chemical and physical properties, can freely release negative ions and far infrared rays, and can adsorb various harmful heavy metals and harmful gases.
In the conventional supported catalysts, a mesoporous molecular sieve material is generally used as a carrier. The mesoporous molecular sieve material has the advantages of ordered pore channels, adjustable pore diameter, larger specific surface area and pore volume and the like, so that the supported catalyst prepared by using the mesoporous molecular sieve material as a carrier has many advantages in the preparation process of organic catalytic reaction, such as high catalytic activity, less side reaction, simple post-treatment and the like, however, the large specific surface area and the high pore volume ensure that the mesoporous molecular sieve material has stronger water absorption and moisture absorption capacity, and the supported catalyst can be agglomerated in the catalytic reaction process.
Therefore, if the advantages of the mesoporous material and the illite are combined, novel spherical composite materials are synthesized, and the novel composite materials have the advantages of the illite and the mesoporous material, so that the characteristics of the mesoporous molecular sieve material, such as high specific surface area, large pore volume, large pore diameter, special pore channel structure and the like, can be reserved, the uniform dispersion, the catalytic activity, the stability and the carbon deposition resistance of the noble metal active component of the isobutane dehydrogenation catalyst are improved, the agglomeration of the mesoporous molecular sieve material can be reduced, and the fluidity of the mesoporous molecular sieve material is improved.
Disclosure of Invention
The invention aims to overcome the defects of uneven dispersion of noble metal active components and poor catalytic activity and stability of the existing isobutane dehydrogenation catalyst, and provides a method for preparing the isobutane dehydrogenation catalyst, the isobutane dehydrogenation catalyst prepared by the method and a method for preparing isobutene by isobutane dehydrogenation.
In order to achieve the above object, an aspect of the present invention provides a method for preparing an isobutane dehydrogenation catalyst, the method comprising the steps of:
(a) in the presence of a second template agent, contacting a silicon source with an ammonia water solution, and crystallizing and filtering a mixture obtained after the contact to obtain a No. 2 mesoporous material filter cake;
(b) contacting water glass with inorganic acid, and filtering a product obtained after the contact to obtain a silica gel filter cake;
(c) mixing and ball-milling the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and illite, pulping solid powder obtained after ball-milling with water, then performing spray drying, and removing the template agent from the obtained product to obtain a spherical double-mesoporous illite composite material carrier;
(d) and (c) dipping the spherical double-mesoporous illite composite material carrier obtained in the step (c) in a solution containing a Pt component precursor and a Zn component precursor, and then sequentially carrying out solvent removal treatment, drying and roasting.
A second aspect of the invention provides isobutane dehydrogenation catalysts prepared by the aforementioned process.
The third aspect of the invention provides applications of the isobutane dehydrogenation catalyst prepared by the method in preparing isobutene through isobutane dehydrogenation, wherein the method for preparing isobutene through isobutane dehydrogenation comprises the step of carrying out dehydrogenation reaction on isobutane in the presence of the catalyst and hydrogen.
The carrier structure of the noble metal catalyst (including physical structures such as specific surface area, pore volume, pore size distribution and the like and chemical structures such as surface acid sites, electronic properties and the like) not only has important influence on the dispersion degree of active metal components, but also directly influences mass transfer and diffusion in the reaction process. Thus, the catalytic properties of heterogeneous catalysts, such as activity, selectivity and stability, depend both on the catalytic characteristics of the active component and on the characteristics of the catalyst support. In order to reduce the content of noble metal in the catalyst as much as possible and improve the activity and stability of the catalyst at the same time, the preparation process of the carrier is of great importance. Most commercially available activated alumina has too many surface hydroxyl groups and too strong acidity. When the aluminum oxide is used as a carrier to prepare the dehydrogenation catalyst, the surface of the catalyst is easy to deposit carbon in the reaction process, and the rapid inactivation is caused.
The inventor of the invention discovers through research that by introducing illite in the preparation process of the isobutane dehydrogenation catalyst, a supported catalyst carrier with a special pore channel structure can be obtained under a simple operation condition by using common and easily available raw materials, the carrier has the characteristics of a porous structure, a large specific surface area and a large pore volume of a mesoporous molecular sieve material, and the prepared catalyst can achieve good dehydrogenation activity, selectivity, stability and carbon deposition resistance under the condition of low noble metal loading capacity by combining the strong adsorption capacity of natural illite due to the large specific surface area and the large pore structure.
Compared with the prior art, the isobutane dehydrogenation catalyst prepared by the method provided by the invention has the following advantages:
(1) the method for preparing the isobutane dehydrogenation catalyst provided by the invention has the advantages of simple preparation process, easily controlled conditions and good product repeatability;
(2) the isobutane dehydrogenation catalyst prepared by the method provided by the invention can achieve better dehydrogenation activity, selectivity, stability and carbon deposition resistance under the condition of low loading of main active components (namely noble metals), and can effectively reduce the preparation cost of the isobutane dehydrogenation catalyst;
(3) in the isobutane dehydrogenation catalyst prepared by the method provided by the invention, the stability of a Zn center with an oxidized structure is very high under a high-temperature reduction condition, the inactivation of a single Pt loaded on a carrier can be inhibited, carbon deposition is reduced, a strong acid center on the surface of the carrier is effectively neutralized, the surface of the carrier is free from acidity, and the dispersion degree of the Pt component is improved through a geometric effect, so that the carbon deposition risk in the reaction process of preparing isobutene by anaerobic dehydrogenation of isobutane can be remarkably reduced, the selectivity of a target product is improved, and the stability of the isobutane dehydrogenation catalyst is improved;
(4) the dispersity of the noble metal active component on the isobutane dehydrogenation catalyst prepared by the method provided by the invention is higher, so that the isobutane dehydrogenation catalyst is not easy to deactivate due to the agglomeration of active metal particles in the reaction process;
(5) the isobutane dehydrogenation catalyst prepared by the method provided by the invention shows good catalytic performance when used for preparing isobutene by anaerobic dehydrogenation of isobutane, and has the advantages of high isobutane conversion rate, high isobutene selectivity, good catalyst stability and low carbon deposition.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and constitute a part of this specification, and together with the following detailed description , serve to explain the invention without limiting it.
FIG. 1 is an X-ray diffraction pattern of the spherical double mesoporous illite composite carrier of example 1;
fig. 2 is an SEM scanning electron micrograph of the spherical double mesoporous illite composite support of example 1.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
For numerical ranges, between the endpoints of each range and the individual points, and between the individual points may be combined with each other to yield new numerical ranges or ranges, which should be considered as specifically disclosed herein.
As previously mentioned, an th aspect of the invention provides a process for the preparation of an isobutane dehydrogenation catalyst, the process comprising the steps of:
(a) in the presence of a second template agent, contacting a silicon source with an ammonia water solution, and crystallizing and filtering a mixture obtained after the contact to obtain a No. 2 mesoporous material filter cake;
(b) contacting water glass with inorganic acid, and filtering a product obtained after the contact to obtain a silica gel filter cake;
(c) mixing and ball-milling the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and illite, pulping solid powder obtained after ball-milling with water, then performing spray drying, and removing the template agent from the obtained product to obtain a spherical double-mesoporous illite composite material carrier;
(d) and (c) dipping the spherical double-mesoporous illite composite material carrier obtained in the step (c) in a solution containing a Pt component precursor and a Zn component precursor, and then sequentially carrying out solvent removal treatment, drying and roasting.
In the formation process of the isobutane dehydrogenation catalyst, the No. 1 mesoporous material filter cake is a mesoporous molecular sieve material with a three-dimensional cubic pore channel distribution structure; the No. 2 mesoporous material filter cake is a mesoporous molecular sieve material with a two-dimensional hexagonal pore channel distribution structure.
In the process of forming the spherical double-mesoporous illite composite material carrier, the pore size distribution is controlled to be bimodal mainly by controlling the composition of the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and the illite, the spherical double-mesoporous illite composite material has a double-pore distribution structure, and the micro-morphology of the spherical double-mesoporous illite composite material carrier is controlled to be spherical by controlling a forming method (namely, the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and the illite are mixed and ball-milled, then the obtained solid powder is slurried with water and then spray-dried), so that the mesoporous molecular sieve material with a three-dimensional cubic pore channel distribution structure and the mesoporous molecular sieve material with a two-dimensional hexagonal pore channel distribution structure can be synthesized by using common and easily-obtained raw materials under simple operation conditions, The spherical double-mesoporous illite composite material carrier has the advantages of the illite and the spherical carrier, not only has the characteristics of a porous structure, large specific surface area and large pore volume of a mesoporous molecular sieve material, but also has the characteristics of large specific surface area, special microporous structure and strong adsorption capacity of natural illite, and the isobutane dehydrogenation catalyst with no acidity on the surface, good dehydrogenation activity, high selectivity, strong stability and good carbon deposition resistance can be prepared by carrying a Pt component and a Zn component through impregnation treatment.
For example, in the step (a), the molar ratio of the th template, butanol and ethyl orthosilicate can be 1: 10-100: 10-90, preferably 1: 60-90: 50-75, and the molar ratio of the ammonia and the water in the silicon source, the second template and the ammonia water is 1: 0.1-1: 0.1-5: 100-200, preferably 1: 0.2-0.5: 1.5-3.5: 120-180.
According to the present invention, in order to make the obtained filter cake of mesoporous material No. 1 have a three-dimensional cubic pore channel distribution structure, the type of the template is preferably triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene, wherein the template can be obtained commercially (for example, from Aldrich company, under the trade name of P123, with the molecular formula of EO)20PO70EO20) When the th template is polyoxyethylene-polyoxypropylene-polyoxyethylene, the mole number of the template is calculated according to the average molecular weight of polyoxyethylene-polyoxypropylene-polyoxyethylene.
According to the invention, in order to make the obtained filter cake of the No. 2 mesoporous material have a two-dimensional hexagonal pore channel distribution structure, the type of the second template agent is preferably Cetyl Trimethyl Ammonium Bromide (CTAB).
According to the present invention, the acidic agent may be any of various substances or mixtures (e.g., solutions) conventionally used for adjusting pH. The acid agent is preferably used in the form of an aqueous solution. Preferably, the acid agent is a hydrochloric acid solution, and the pH value of the acid agent is 1-6.
According to the invention, the butanol is preferably n-butanol.
According to the invention, the silicon source can be at least of tetraethoxysilane, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol, and preferably, the silicon source is tetraethoxysilane.
According to the invention, the conditions under which the tetraethoxysilane is contacted with the acid agent may include: the temperature is 10-60 ℃, the time is 10-72 hours, and the pH value is 1-7; preferably, the conditions for contacting the tetraethoxysilane with the acid agent may include: the temperature is 10-30 deg.C, the time is 20-40 hr, and the pH value is 3-6. In order to facilitate uniform mixing of the substances, the contact of the tetraethoxysilane with the acid agent is preferably carried out under stirring. The dosage of the acid agent is preferably such that the pH value of the contact reaction system of the tetraethoxysilane and the acid agent is 1-7, and more preferably 3-6.
According to the present invention, the conditions for contacting the silicon source with the ammonia water may include: the temperature is 25-100 ℃, and the time is 10-72 hours; preferably, the conditions for contacting the silicon source and the aqueous ammonia solution may include: the temperature is 30-150 ℃ and the time is 10-72 hours.
The crystallization conditions of the present invention may include: the temperature is 30-150 ℃ and the time is 10-72 hours, and preferably, the crystallization conditions comprise: the temperature is 40-80 ℃ and the time is 20-40 hours. The crystallization is carried out by a hydrothermal crystallization method.
In addition, the contact mode among the th template agent, the butanol, the acid agent and the tetraethoxysilane is not particularly limited, for example, the four substances can be simultaneously mixed and contacted, or a plurality of substances can be firstly mixed and contacted, and then the rest substances can be added into the obtained mixture to be continuously mixed and contacted, preferably, the contact mode is that the th template agent, the butanol and the acid agent are firstly stirred and mixed at 10-100 ℃, then the tetraethoxysilane is added and is continuously stirred and mixed.
According to the method for preparing an isobutane dehydrogenation catalyst provided by the present invention, in the step (b), the conditions for contacting the water glass with the inorganic acid may include: the temperature can be 10-60 ℃, preferably 20-40 ℃; the time may be 1 to 5 hours, preferably 1.5 to 3 hours, and the pH value is 2 to 4. In order to further facilitate uniform mixing between the substances, the contact of the water glass with the mineral acid is preferably carried out under stirring conditions.
According to the invention, the water glass is an aqueous solution of sodium silicate conventional in the art, and its concentration may be 10 to 50% by weight, preferably 12 to 30% by weight.
According to the invention, the inorganic acid can be or more of sulfuric acid, nitric acid and hydrochloric acid, the inorganic acid can be used in a pure state or in an aqueous solution, the inorganic acid is preferably used in an amount such that the pH value of a reaction system under the condition of contact between water glass and the inorganic acid is 2-4, and preferably, the weight ratio of the water glass to the inorganic acid is 3-6: 1.
In addition, in the above process for preparing the filter cake of the mesoporous material No. 1, the filter cake of the mesoporous material No. 2, and the filter cake of silica gel, the process for obtaining the filter cake by filtration may include: after filtration, washing with distilled water was repeated (the number of washing may be 2 to 10), followed by suction filtration. Preferably, the washing during the preparation of the filter cake of mesoporous material No. 2 is such that the pH of the filter cake is 7, and the washing during the preparation of the silica gel filter cake is such that the sodium ion content is less than 0.02 wt%.
According to the present invention, in the step (c), the amounts of the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and the illite may be selected according to the components of the spherical double mesoporous illite composite material carrier to be obtained, and preferably, the silica gel filter cake may be used in an amount of 1 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the total amount of the No. 1 mesoporous material filter cake and the No. 2 mesoporous material filter cake; the illite can be used in an amount of 1-50 parts by weight, preferably 20-50 parts by weight; the weight ratio of the No. 1 mesoporous material filter cake to the No. 2 mesoporous material filter cake can be 1: 0.1-10, preferably 1: 0.5-2.
According to the invention, the specific operation method and conditions of the ball milling are based on that the structure of the mesoporous material is not damaged or basically not damaged and the silica gel and the illite enter the pore canal of the mesoporous material. One skilled in the art can select various suitable conditions to implement the present invention based on the above principles. Specifically, the ball milling is carried out in a ball mill, wherein the diameter of the milling balls in the ball mill can be 2-3 mm; the number of the grinding balls can be reasonably selected according to the size of the ball milling tank, and for the ball milling tank with the size of 50-150mL, 1 grinding ball can be generally used; the material of the grinding ball can be agate, polytetrafluoroethylene and the like, and agate is preferred. The ball milling conditions include: the rotation speed of the grinding ball can be 300-500r/min, the temperature in the ball milling tank can be 15-100 ℃, and the ball milling time can be 0.1-100 hours.
In the present invention, the specific operation method and conditions of the spray drying are preferably: adding a slurry prepared from the solid powder and water into an atomizer, and rotating at a high speed to realize spray drying. Wherein the spray drying conditions may include: the temperature can be 100-300 ℃, and the rotating speed can be 10000-15000 r/min; preferably, the spray drying conditions include: the temperature is 150-250 ℃, and the rotating speed is 11000-13000 r/min; most preferably, the spray drying conditions include: the temperature is 200 ℃, and the rotating speed is 12000 r/min.
According to the invention, the method for removing the template agent is preferably a calcination method. The conditions for removing the template agent may include: the temperature is 300-600 ℃, preferably 350-550 ℃, and most preferably 500 ℃; the time is 10 to 80 hours, preferably 20 to 30 hours, most preferably 24 hours.
According to the invention, in the step (d), the metal component loaded on the spherical double-mesoporous illite composite material carrier can enter the pore channel of the spherical double-mesoporous illite composite material carrier by adopting an impregnation mode and depending on the capillary pressure of the pore channel structure of the carrier, and simultaneously the metal component can be adsorbed on the surface of the spherical double-mesoporous illite composite material carrier until the metal component reaches adsorption balance on the surface of the carrier, the impregnation treatment can be co-impregnation treatment or step-by-step impregnation treatment, the impregnation treatment is preferably co-impregnation treatment for saving the preparation cost and simplifying the experimental process, and the co-impregnation treatment condition comprises that the spherical double-mesoporous illite composite material carrier is mixed and contacted with a Pt component precursor solution containing Pt components, the impregnation temperature can be 25-50 ℃, and the impregnation time can be 2-6 hours.
According to the invention, the Pt component precursor is preferably H2PtCl6The Zn component precursor is preferably Zn (NO)3)2。
The concentration of the solution containing the Pt component precursor and the Zn component precursor is not particularly limited in the present invention, and may be conventionally selected in the art, for example, the concentration of the Pt component precursor may be 0.001 to 0.003mol/L, and the concentration of the Zn component precursor may be 0.015 to 0.1 mol/L.
According to the present invention, the solvent removal treatment can be carried out by a method conventional in the art, for example, a rotary evaporator can be used to remove the solvent in the system.
According to the present invention, in the step (d), the drying may be performed in a drying oven, and the firing may be performed in a muffle furnace. The drying conditions may include: the temperature is 110-150 ℃ and the time is 3-6 h; the conditions for the firing may include: the temperature is 600 ℃ and 650 ℃, and the time is 5-8 h.
According to the invention, in the step (d), the spherical double mesoporous illite composite material carrier, the Pt component precursor and the Zn component precursor are used in amounts such that the content of the carrier is 98-99.4 wt%, the content of the Pt component calculated by Pt element is 0.1-0.5 wt% and the content of the Zn component calculated by Zn element is 0.5-1.5 wt% in the prepared isobutane dehydrogenation catalyst based on the total weight of the isobutane dehydrogenation catalyst.
Preferably, the spherical double mesoporous illite composite material carrier, the Pt component precursor and the Zn component precursor are used in amounts such that, in the prepared isobutane dehydrogenation catalyst, based on the total weight of the isobutane dehydrogenation catalyst, the content of the carrier is 98.4-99 wt%, the content of the Pt component calculated by the Pt element is 0.2-0.4 wt%, and the content of the Zn component calculated by the Zn element is 0.8-1.2 wt%.
In a second aspect, the present invention provides an isobutane dehydrogenation catalyst prepared by the aforementioned process.
According to the invention, the isobutane dehydrogenation catalyst comprises a carrier, and a Pt component and a Zn component which are loaded on the carrier, wherein the carrier is a spherical double-mesoporous illite composite material carrier, the spherical double-mesoporous illite composite material carrier contains illite, a mesoporous molecular sieve material with a three-dimensional cubic pore channel distribution structure and a mesoporous molecular sieve material with a two-dimensional hexagonal pore channel distribution structure, the average particle size of the spherical double-mesoporous illite composite material carrier is 20-50 mu m, and the specific surface area of the spherical double-mesoporous illite composite material carrier is 150-600 m-2The pore volume is 0.5-1.5mL/g, the pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal are 2-5nm and 5-25nm respectively.
According to the invention, in the isobutane dehydrogenation catalyst, the spherical double-mesoporous illite composite material carrier serving as the carrier has a special three-dimensional cubic and two-dimensional hexagonal pore channel distribution structure, the average particle size of particles is measured by adopting a laser particle size distribution instrument, and the specific surface area, the pore volume and the most probable pore diameter are measured by a nitrogen adsorption method. In the present invention, the particle size refers to the particle size of the raw material particles, and is expressed by the diameter of the sphere when the raw material particles are spherical, by the side length of the cube when the raw material particles are cubic, and by the mesh size of the screen that can sieve out the raw material particles when the raw material particles are irregularly shaped.
According to the invention, the spherical double-mesoporous illite composite material carrier is prepared by mixing spheresThe particle size of the spherical double-mesoporous illite composite material carrier is controlled within the range, the spherical double-mesoporous illite composite material carrier is ensured not to be easily agglomerated, and the conversion rate of reaction raw materials in the reaction process of preparing isobutene through isobutane dehydrogenation can be improved by using the supported catalyst prepared from the spherical double-mesoporous illite composite material carrier as the carrier. When the specific surface area of the spherical double mesoporous illite composite material carrier is less than 150m2When the volume/g and/or pore volume is less than 0.5mL/g, the catalytic activity of the supported catalyst prepared by using the supported catalyst is remarkably reduced; when the specific surface area of the spherical double mesoporous illite composite material carrier is more than 600m2When the volume/g and/or the pore volume is more than 1.5mL/g, the supported catalyst prepared by using the supported catalyst as the carrier is easy to agglomerate in the reaction process of preparing isobutene by isobutane dehydrogenation, so that the conversion rate of the reaction raw material in the reaction process of preparing isobutene by isobutane dehydrogenation is influenced.
Preferably, the average particle diameter of the spherical double mesoporous illite composite material carrier is 20-50 μm, and the specific surface area is 180-600m2The pore volume is 0.8-1.5mL/g, the pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal are 2-4.5nm and 6-24nm respectively.
According to the invention, based on the total weight of the isobutane dehydrogenation catalyst, the content of the carrier is 98-99.4 wt%, the content of the Pt component calculated by Pt element is 0.1-0.5 wt%, and the content of the Zn component calculated by Zn element is 0.5-1.5 wt%.
Preferably, the content of the carrier is 98.4-99 wt%, the content of the Pt component calculated by Pt element is 0.2-0.4 wt%, and the content of the Zn component calculated by Zn element is 0.8-1.2 wt%, based on the total weight of the isobutane dehydrogenation catalyst.
step, the average particle diameter of the isobutane dehydrogenation catalyst is 20-50 μm, and the specific surface area is 150-400m2The pore volume is 0.6-1.2mL/g, the pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal are 2.1-4.5nm and 8-23nm respectively.
According to the present invention, in the spherical double mesoporous illite composite material carrier, the content of the illite may be 1 to 50 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the total weight of the mesoporous molecular sieve material having the three-dimensional cubic pore channel distribution structure and the mesoporous molecular sieve material having the two-dimensional hexagonal pore channel distribution structure; the weight ratio of the contents of the mesoporous molecular sieve material with the three-dimensional cubic pore channel distribution structure to the mesoporous molecular sieve material with the two-dimensional hexagonal pore channel distribution structure can be 1: 0.1 to 10, preferably 1: 0.5-2.
According to the present invention, the spherical double mesoporous illite composite material support may further contain silica introduced through silica gel. The term "silica introduced through silica gel" refers to a silica component which is brought into the finally prepared spherical double-mesoporous illite composite material carrier by using silica gel as a preparation raw material during the preparation process of the spherical double-mesoporous illite composite material carrier. In the spherical double mesoporous illite composite material carrier, the content of the silica introduced through the silica gel may be 1 to 200 parts by weight, preferably 50 to 150 parts by weight, with respect to 100 parts by weight of the total weight of the mesoporous molecular sieve material having the three-dimensional cubic pore channel distribution structure and the mesoporous molecular sieve material having the two-dimensional hexagonal pore channel distribution structure.
According to the invention, the mesoporous molecular sieve material with the three-dimensional cubic pore channel distribution structure and the mesoporous molecular sieve material with the two-dimensional hexagonal pore channel distribution structure can be mesoporous molecular sieve materials which are conventionally used in the field, and can be prepared according to a conventional method.
As mentioned above, the third aspect of the invention provides applications of the isobutane dehydrogenation catalyst prepared by the method in preparing isobutene through isobutane dehydrogenation, wherein the method for preparing isobutene through isobutane dehydrogenation comprises the step of carrying out dehydrogenation reaction on isobutane in the presence of the catalyst and hydrogen.
When the isobutane dehydrogenation catalyst prepared by the method provided by the invention is used for catalyzing isobutane to dehydrogenate to prepare isobutene, the conversion rate of isobutane and the selectivity of isobutene can be greatly improved.
According to the present invention, in order to increase the isobutane conversion rate and prevent the catalyst from coking, it is preferable that the molar ratio of the amount of isobutane to the amount of hydrogen is 0.5 to 1.5: 1.
the conditions for the dehydrogenation reaction in the present invention are not particularly limited and may be conventionally selected in the art, and for example, the conditions for the dehydrogenation reaction may include: the reaction temperature is 550-650 ℃, the reaction pressure is 0.05-0.2MPa, the reaction time is 20-40h, and the mass space velocity of isobutane is 2-5h-1。
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples, the triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene, available from Aldrich, is abbreviated as P123 and has the formula EO20PO70EO20The substance having a registration number of 9003-11-6 in the American chemical Abstract had an average molecular weight Mn of 5800.
In the following examples and comparative examples, X-ray diffraction analysis was carried out on an X-ray diffractometer, model D8Advance, available from Bruker AXS, Germany; scanning electron microscopy analysis was performed on a scanning electron microscope, model XL-30, available from FEI, USA; the nitrogen adsorption and desorption experiments of the samples are carried out on an ASAP2020M + C type full-automatic physicochemical adsorption analyzer produced by Micromeritics in America, the samples are degassed for 4 hours in vacuum at 350 ℃ before being measured, the specific surface area of the samples is calculated by adopting a BET method, and the pore volume and the average pore diameter are calculated by adopting a BJH model; the particle size distribution of the sample is carried out on a Malvern laser particle sizer; NH of sample3TPD experiments were carried out on an AUTOCHEM2920 full-automatic chemisorption apparatus, manufactured by Micromeritics, USA: the sample was first incubated at 480 ℃ and 10% H2Reduction in an Ar atmosphere of-90% for 1 hour. Heating to 700 ℃ in He atmosphere, standing for 1 hour, cooling to 40 ℃ to adsorb ammonia gas until saturation, purging for 1 hour in He atmosphere, heating to 700 ℃ from 40 ℃ at a speed of 10 ℃/min, and recording ammonia desorption data by using a TCD (thermal desorption detector); the rotary evaporator is produced by German IKA company, and the model is RV10 digital; the loading amount of the active component of the isobutane dehydrogenation catalyst is in the wavelength dispersion X-ray fluorescence which is purchased from Pynaudi, Netherlands and has the model of Axios-AdvancedMeasuring on a spectrometer; analysis of the reaction product composition was performed on a gas chromatograph available from Agilent under model 7890A.
In the following experimental examples and experimental comparative examples, the conversion (%) of isobutane was equal to the amount of isobutane consumed by the reaction/initial amount of isobutane × 100%;
the selectivity (%) of isobutylene was defined as the amount of isobutane consumed for producing isobutylene/total consumption of isobutane × 100%.
Example 1
This example is illustrative of an isobutane dehydrogenation catalyst and a method for preparing the same.
(1) Preparation of spherical double-mesoporous illite composite material carrier
Dissolving 6g (0.001mol) of triblock copolymer surfactant P123 in 10ml of hydrochloric acid aqueous solution with the pH value of 4 and 220ml of deionized water solution, stirring for 4 hours until the P123 is dissolved to form transparent solution, adding 6g (0.08mol) of n-butyl alcohol into the transparent solution, stirring for 1 hour, then placing the solution in a water bath at 40 ℃, slowly dripping 12.9g (0.062mol) of ethyl orthosilicate into the solution, stirring for 24 hours under the condition that the temperature is kept at about 40 ℃ and the pH value is 4.5, then carrying out hydrothermal treatment for 24 hours at 100 ℃, then carrying out filtration and washing for 4 times by deionized water, and then carrying out suction filtration to obtain a filter cake A1 of the mesoporous molecular sieve material No. 1 with three-dimensional cubic pores;
adding hexadecyl trimethyl ammonium bromide and ethyl orthosilicate into an ammonia water solution with the concentration of 25 weight percent, wherein the adding amount of the ethyl orthosilicate is 1g, and the mol ratio of ammonia to water in the ethyl orthosilicate, the hexadecyl trimethyl ammonium bromide and the ammonia water is 1: 0.37: 2.8: 142 and stirring for 24h at 80 ℃, then carrying out hydrothermal treatment for 24h at 100 ℃, then carrying out filtration and washing with deionized water for 4 times, and then carrying out suction filtration to obtain a filter cake A2 of the No. 2 mesoporous molecular sieve material with a two-dimensional hexagonal pore structure.
Mixing 15 wt% water glass and 12 wt% sulfuric acid solution in a weight ratio of 5:1, reacting at 30 deg.c for 2 hr, regulating the pH to 3 with 98 wt% sulfuric acid, suction filtering the obtained reaction material, and washing with distilled water to sodium ion content of 0.02 wt% to obtain silica gel filter cake B1.
The preparation method comprises the steps of putting 5g of the prepared filter cake A1, 5g of the prepared filter cake A2, 10g of the prepared filter cake B1 and 10g of illite into a 100ml ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of the grinding balls is 3mm, the number of the grinding balls is 1, the rotation speed is 400r/min, the ball milling tank is closed, ball milling is carried out in the ball milling tank at the temperature of 60 ℃ for 1 hour, 30g of solid powder is obtained, the solid powder is dissolved in 30g of deionized water, spray drying is carried out at the rotation speed of 12000r/min at the temperature of 200 ℃, a product obtained after spray drying is calcined in a muffle furnace at the temperature of 500 ℃ for 24 hours, a template agent is removed, and 30g of a spherical double-mesoporous illite composite material carrier C1 with a three-dimensional cubic pore passage and two-dimensional hexagonal pore passage distribution structure.
(2) Preparation of isobutane dehydrogenation catalyst
0.080g H2PtCl6·6H2O and 0.457g Zn (NO)3)2·6H2Dissolving O in 100ml of deionized water to obtain a mixture solution, soaking 10g of the spherical double-mesoporous illite composite material carrier C1 prepared in the step (1) in the mixture solution, soaking at 25 ℃ for 5h, evaporating solvent water in a system by using a rotary evaporator to obtain a solid product, and placing the solid product in a drying oven at 120 ℃ for drying for 3 h. And then roasting the mixture in a muffle furnace at the temperature of 600 ℃ for 6 hours to obtain the isobutane dehydrogenation catalyst Cat-1 (based on the total weight of the isobutane dehydrogenation catalyst Cat-1, the content of a Pt component in terms of Pt is 0.3 wt%, the content of a Zn component in terms of Zn is 1 wt%, and the balance is a carrier).
The spherical double mesoporous illite composite material carrier C1 and the isobutane dehydrogenation catalyst Cat-1 are characterized by an XRD, a scanning electron microscope and an ASAP2020-M + C type adsorption instrument.
Fig. 1 is an X-ray diffraction pattern in which the curve is an XRD pattern of spherical double mesoporous illite composite carrier C1, the abscissa is 2 θ, the ordinate is intensity, and the XRD pattern of spherical double mesoporous illite composite carrier C1 has a hexagonal channel structure of 2D specific to the mesoporous material, as can be seen from the small-angle peaks appearing in the XRD pattern;
FIG. 2 is an SEM (scanning electron microscope) image, which shows that the microscopic morphology of the spherical double mesoporous illite composite material carrier C1 is mesoporous spheres with the granularity of 20-50 μm;
table 1 shows the pore structure parameters of the spherical double mesoporous illite composite material carrier C1 and the isobutane dehydrogenation catalyst Cat-1.
TABLE 1
| Sample (I) | Specific surface area (m)2/g) | Pore volume (ml/g) | Most probable aperture*(nm) | Particle size (. mu.m) |
| Vector C1 | 255 | 1.5 | 3，22 | 20-50 |
| Catalyst Cat-1 | 232 | 1.2 | 2.1，18.2 | 20-50 |
the most probable aperture and the second most probable aperture and the third most probable aperture are separated by commas, in order from left to right, the most probable aperture and the second most probable aperture.
As can be seen from the data of table 1, the specific surface area and the pore volume of the spherical double mesoporous illite composite support were reduced after the Pt component and the Zn component were loaded, which indicates that the Pt component and the Zn component entered the interior of the spherical double mesoporous illite composite support during the loading reaction.
Comparative example 1
This comparative example serves to illustrate a reference isobutane dehydrogenation catalyst and a process for its preparation.
The carrier and the isobutane dehydrogenation catalyst were prepared according to the method of example 1, except that the same weight of alumina carrier was used instead of the spherical dual mesoporous illite composite carrier C1 in the preparation of the carrier, thereby preparing the carrier D1 and the isobutane dehydrogenation catalyst Cat-D-1, respectively.
Comparative example 2
This comparative example serves to illustrate a reference isobutane dehydrogenation catalyst and a process for its preparation.
A carrier and an isobutane dehydrogenation catalyst were prepared according to the method of example 1, except that Zn (NO) was not added during the impregnation process for preparing the isobutane dehydrogenation type catalyst3)2·6H2O, addition of only 0.080g H2PtCl6·6H2And O, only loading a single Pt component on the spherical double-mesoporous illite composite material carrier by a co-impregnation method, thereby preparing the isobutane dehydrogenation catalyst Cat-D-2, wherein the content of the Pt component in terms of Pt element is 0.3 wt% and the balance is the carrier on the basis of the total weight of the isobutane dehydrogenation catalyst Cat-D-2).
Comparative example 3
This comparative example serves to illustrate a reference isobutane dehydrogenation catalyst and a process for its preparation.
The same weight of an oxide catalyst such as ZnO was used as the isobutane dehydrogenation catalyst Cat-D-3.
Example 2
This example is illustrative of an isobutane dehydrogenation catalyst and a method for preparing the same.
(1) Preparation of spherical double-mesoporous illite composite material carrier
Dissolving 6g (0.001mol) of triblock copolymer surfactant P123 in 10ml of hydrochloric acid aqueous solution with the pH value of 4 and 220ml of deionized water solution, stirring for 4h until the P123 is dissolved to form transparent solution, adding 6.7g (0.09mol) of n-butyl alcohol into the transparent solution, stirring for 1h, then placing the solution in a water bath at 40 ℃, slowly dripping 10.4g (0.05mol) of ethyl orthosilicate into the solution, stirring for 24h under the condition that the temperature is kept at about 40 ℃ and the pH value is 5, then carrying out hydrothermal treatment for 36h at 90 ℃, then carrying out filtration and washing for 4 times by using deionized water, and then carrying out suction filtration to obtain a filter cake A3 of the mesoporous molecular sieve material No. 1 with three-dimensional cubic pore channels;
adding hexadecyl trimethyl ammonium bromide and ethyl orthosilicate into an ammonia water solution with the concentration of 25 weight percent, wherein the adding amount of the ethyl orthosilicate is 1g, and the mol ratio of ammonia to water in the ethyl orthosilicate, the hexadecyl trimethyl ammonium bromide and the ammonia water is 1: 0.5: 3.2: 140 and stirring for 24h at 90 ℃, then carrying out hydrothermal treatment for 36h at 90 ℃, then carrying out filtration and washing with deionized water for 4 times, and then carrying out suction filtration to obtain a filter cake A4 of the No. 2 mesoporous molecular sieve material with a two-dimensional hexagonal pore structure.
Mixing 15 wt% water glass and 12 wt% sulfuric acid solution in a weight ratio of 4:1, reacting at 40 deg.c for 1.5 hr, regulating the pH value to 2 with 98 wt% sulfuric acid, suction filtering the obtained reaction material, and washing with distilled water to sodium ion content of 0.02 wt% to obtain silica gel filter cake B2.
13g of the filter cake A3, 7g of the filter cake A4, 10g of the filter cake B2 and 8g of illite are put into a 100ml ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, grinding balls are made of agate, the diameter of the grinding balls is 3mm, the number of the grinding balls is 1, the rotating speed is 300r/min, the ball milling tank is closed, ball milling is carried out in the ball milling tank at the temperature of 80 ℃ for 0.5 hour, 38g of solid powder is obtained, the solid powder is dissolved in 12g of deionized water, spray drying is carried out at the rotating speed of 11000r/min at the temperature of 250 ℃, products obtained after spray drying are calcined in a muffle furnace at the temperature of 500 ℃ for 15 hours, template agents are removed, and 35g of spherical mesoporous bi-illite composite material carrier C2 with a three-dimensional cubic pore passage and two-dimensional hexagonal pore passage distribution structure is obtained.
(2) Preparation of isobutane dehydrogenation catalyst
0.080g H2PtCl6·6H2O and 0.457g Zn (NO)3)2·6H2Dissolving O in 100ml of deionized water to obtain a mixture solution, soaking 10g of the spherical double-mesoporous illite composite material carrier C2 prepared in the step (1) in the mixture solution, soaking at 25 ℃ for 5h, evaporating solvent water in a system by using a rotary evaporator to obtain a solid product, and placing the solid product in a drying oven at 120 ℃ for drying for 3 h. And then roasting the mixture in a muffle furnace at the temperature of 600 ℃ for 6 hours to obtain the isobutane dehydrogenation catalyst Cat-2 (based on the total weight of the isobutane dehydrogenation catalyst Cat-2, the content of a Pt component in terms of Pt is 0.3 wt%, the content of a Zn component in terms of Zn is 1 wt%, and the balance is a carrier).
Table 2 shows the pore structure parameters of the spherical double mesoporous illite composite material carrier C2 and the isobutane dehydrogenation catalyst Cat-2.
TABLE 2
| Sample (I) | Specific surface area (m)2/g) | Pore volume (ml/g) | Most probable aperture*(nm) | Particle size (. mu.m) |
| Vector C2 | 260 | 1.3 | 2.6，21 | 25-45 |
| Catalyst Cat-2 | 225 | 1.1 | 2.2，19.1 | 25-45 |
the most probable aperture and the second most probable aperture are separated by commas, in order from left to right, the most probable aperture and the second most probable aperture.
As can be seen from the data of table 2, the specific surface area and the pore volume of the spherical double mesoporous illite composite carrier were reduced after the Pt component and the Zn component were loaded, which indicates that the Pt component and the Zn component entered the interior of the spherical double mesoporous illite composite carrier during the loading reaction.
Example 3
This example is illustrative of an isobutane dehydrogenation catalyst and a method for preparing the same.
(1) Preparation of spherical double-mesoporous illite composite material carrier
Dissolving 6g (0.001mol) of triblock copolymer surfactant P123 in 10ml of hydrochloric acid aqueous solution with the pH value of 4 and 220ml of deionized water solution, stirring for 4h until the P123 is dissolved to form transparent solution, adding 5.2g (0.07mol) of n-butyl alcohol into the transparent solution, stirring for 1h, then placing the solution in a water bath at 40 ℃, slowly dripping 12.5g (0.06mol) of tetraethoxysilane into the solution, stirring for 24h under the condition that the temperature is kept at about 40 ℃ and the pH value is 5, then carrying out hydrothermal treatment for 36h at 100 ℃, then carrying out filtration and washing for 4 times by using deionized water, and then carrying out suction filtration to obtain a filter cake A5 of the mesoporous molecular sieve material No. 1 with three-dimensional cubic pore channels;
adding hexadecyl trimethyl ammonium bromide and ethyl orthosilicate into an ammonia water solution with the concentration of 25 weight percent, wherein the adding amount of the ethyl orthosilicate is 1g, and the mol ratio of ammonia to water in the ethyl orthosilicate, the hexadecyl trimethyl ammonium bromide and the ammonia water is 1: 0.3: 3: 150, stirring for 24h at 90 ℃, then carrying out hydrothermal treatment for 24h at 90 ℃, then filtering and washing with deionized water for 4 times, and then carrying out suction filtration to obtain a filter cake A6 of the No. 2 mesoporous molecular sieve material with a two-dimensional hexagonal pore structure.
Mixing 15 wt% water glass and 12 wt% sulfuric acid solution in the weight ratio of 6:1, contacting and reacting at 20 deg.c for 3 hr, regulating the pH value to 4 with 98 wt% sulfuric acid, suction filtering the obtained reaction material, and washing with distilled water to sodium ion content of 0.02 wt% to obtain silica gel filter cake B3.
The preparation method comprises the steps of putting 7g of the prepared filter cake A5, 13g of the prepared filter cake A6, 30g of the prepared filter cake B3 and 12g of illite into a 100ml ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, grinding balls are made of agate, the diameter of the grinding balls is 3mm, the number of the grinding balls is 1, the rotation speed is 550r/min, the ball milling tank is closed, ball milling is carried out in the ball milling tank at the temperature of 40 ℃ for 10 hours, 55g of solid powder is obtained, the solid powder is dissolved in 30g of deionized water, spray drying is carried out at the rotation speed of 13000r/min at the temperature of 150 ℃, a product obtained after spray drying is calcined in a muffle furnace at the temperature of 450 ℃ for 70 hours, a template agent is removed, and 53g of spherical double-mesoporous illite composite material carrier C3 with a three-dimensional cubic pore passage and two-dimensional hexagonal pore passage distribution structure is obtained.
(2) Preparation of isobutane dehydrogenation catalyst
0.080g H2PtCl6·6H2O and 0.457g Zn (NO)3)2·6H2Dissolving O in 100ml of deionized water to obtain a mixture solution, soaking 10g of the spherical double-mesoporous illite composite material carrier C3 prepared in the step (1) in the mixture solution, soaking at 25 ℃ for 5h, evaporating solvent water in a system by using a rotary evaporator to obtain a solid product, and placing the solid product in a drying oven at 120 ℃ for drying for 3 h. Then roasting the mixture for 6 hours in a muffle furnace at the temperature of 600 ℃ to obtain isobutaneA hydrogen catalyst Cat-3 (based on the total weight of the isobutane dehydrogenation catalyst Cat-3, the content of a Pt component calculated by a Pt element is 0.3 wt%, the content of a Zn component calculated by a Zn element is 1 wt%, and the balance is a carrier).
Table 3 shows the pore structure parameters of the spherical double mesoporous illite composite material carrier C3 and the isobutane dehydrogenation catalyst Cat-3.
TABLE 3
| Sample (I) | Specific surface area (m)2/g) | Pore volume (ml/g) | Most probable aperture*(nm) | Particle size (. mu.m) |
| |
300 | 1.1 | 2.7，20 | 30-50 |
| Catalyst Cat-3 | 287 | 1 | 2.4，17.5 | 30-50 |
The st most probable aperture and the second most probable aperture are separated by commas, namely the st most probable aperture and the second most probable aperture in sequence from left to right.
As can be seen from the data of table 3, the specific surface area and the pore volume of the spherical double mesoporous illite composite carrier were reduced after the Pt component and the Zn component were loaded, which indicates that the Pt component and the Zn component entered the interior of the spherical double mesoporous illite composite carrier during the loading reaction.
Experimental example 1
This example is intended to illustrate the preparation of isobutene using the isobutane dehydrogenation catalyst of the present invention
0.5g of isobutane dehydrogenation catalyst Cat-1 was loaded into a fixed bed quartz reactor, the reaction temperature was controlled at 590 ℃, the reaction pressure was 0.1MPa, and the isobutane: the molar ratio of hydrogen is 1: 1, the reaction time is 24 hours, and the mass space velocity of the isobutane is 4 hours-1. By Al2O3The reaction product separated by the S molecular sieve column was directly fed into an Agilent 7890A gas chromatograph equipped with a hydrogen flame detector (FID) for on-line analysis, and the isobutane conversion and isobutene selectivity were obtained as shown in Table 4. After the reaction, the amount of carbon deposition in the isobutane dehydrogenation catalyst Cat-1 was measured using a TGA/DSC1 thermogravimetric analyzer from METTLER-TOLEDO, as shown in table 4.
Experimental examples 2 to 3
Isobutene was prepared by dehydrogenation of isobutane according to the method of experimental example 1, except that isobutane dehydrogenation catalyst Cat-2 and isobutane dehydrogenation catalyst Cat-3 were used instead of isobutane dehydrogenation catalyst Cat-1, respectively. The isobutane conversion, isobutene selectivity and carbon deposition amount of the isobutane dehydrogenation catalyst are shown in table 4.
Experimental comparative examples 1 to 3
Isobutene is prepared by isobutane dehydrogenation according to the method of the experimental example 1, except that isobutane dehydrogenation catalysts Cat-D-1 to Cat-D-3 are respectively adopted to replace the isobutane dehydrogenation catalyst Cat-1. The isobutane conversion, isobutene selectivity and carbon deposition amount of the isobutane dehydrogenation catalyst are shown in table 4.
TABLE 4
| Dehydrogenation catalyst | Isobutane conversion rate | Selectivity to isobutene | Carbon deposit amount of catalyst | |
| Experimental example 1 | Cat-1 | 34％ | 92％ | 1.2wt％ |
| Experimental example 2 | Cat-2 | 33.5％ | 91.5％ | 1.1wt％ |
| Experimental example 3 | Cat-3 | 32.8％ | 90.6％ | 1.2wt％ |
| Experimental comparative example 1 | Cat-D-1 | 11.2％ | 70.2％ | 5.3wt％ |
| Experimental comparative example 2 | Cat-D-2 | 7.2％ | 50.2％ | 5.7wt％ |
| Experimental comparative example 3 | Cat-D-3 | 7％ | 0％ | 5.8wt％ |
As can be seen from table 4, when the isobutane dehydrogenation catalyst prepared by using the spherical double mesoporous illite composite material carrier of the present invention is used in the reaction of preparing isobutene by isobutane dehydrogenation, a higher isobutane conversion rate and isobutene selectivity can be obtained after 24 hours of reaction, which indicates that the isobutane dehydrogenation catalyst of the present invention has not only a better catalytic performance, but also good stability and low carbon deposition amount.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (11)
1, A process for the preparation of an isobutane dehydrogenation catalyst, characterized in that it comprises the steps of:
(a) in the presence of a second template agent, contacting a silicon source with an ammonia water solution, and crystallizing and filtering a mixture obtained after the contact to obtain a No. 2 mesoporous material filter cake;
(b) contacting water glass with inorganic acid, and filtering a product obtained after the contact to obtain a silica gel filter cake;
(c) mixing and ball-milling the No. 1 mesoporous material filter cake, the No. 2 mesoporous material filter cake, the silica gel filter cake and illite, pulping solid powder obtained after ball-milling with water, then performing spray drying, and removing the template agent from the obtained product to obtain a spherical double-mesoporous illite composite material carrier;
(d) and (c) dipping the spherical double-mesoporous illite composite material carrier obtained in the step (c) in a solution containing a Pt component precursor and a Zn component precursor, and then sequentially carrying out solvent removal treatment, drying and roasting.
2. The method as claimed in claim 1, wherein in step (a), the molar ratio of the th template, butanol and tetraethoxysilane is 1: 10-100: 10-90, and the molar ratio of the ammonia and water in the silicon source, the second template and the ammonia water is 1: 0.1-1: 0.1-5: 100-;
preferably, the th template agent is triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene, the second template agent is cetyl trimethyl ammonium bromide, the acid agent is hydrochloric acid with a pH value of 1-6, the butanol is n-butanol, and the silicon source comprises at least of tetraethoxysilane, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol;
preferably, the contact condition of tetraethoxysilane and acid agent includes 10-60 deg.C, 10-72 hr, pH 1-7, the contact condition of silicon source and ammonia water solution includes 25-100 deg.C, 10-72 hr, and the crystallization condition includes 30-150 deg.C, 10-72 hr.
3. The method according to claim 1, wherein in the step (b), the water glass is contacted with the inorganic acid or more selected from sulfuric acid, nitric acid and hydrochloric acid under the conditions of 10-60 ℃ for 1-5 hours and pH 2-4.
4. The method according to claim 1, wherein, in the step (c), the silica gel cake is used in an amount of 1 to 200 parts by weight, preferably 50 to 150 parts by weight, the illite is contained in an amount of 1 to 50 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the total amount of the filter cake of the mesoporous material No. 1 and the filter cake of the mesoporous material No. 2, and the weight ratio of the filter cake of the mesoporous material No. 1 to the filter cake of the mesoporous material No. 2 is 1: 0.1-10, preferably 1: 0.5-2.
5. The method according to claim 1, wherein in the step (d), the spherical dual mesoporous illite composite support, the Pt component precursor and the Zn component precursor are used in amounts such that the support is contained in an amount of 98-99.4 wt%, the Pt component is contained in an amount of 0.1-0.5 wt% in terms of Pt element, and the Zn component is contained in an amount of 0.5-1.5 wt% in terms of Zn element, based on the total weight of the isobutane dehydrogenation catalyst, in the prepared isobutane dehydrogenation catalyst.
6. An isobutane dehydrogenation catalyst produced by the process of any of claims from 1 to 5.
7. An isobutane dehydrogenation catalyst according to claim 6, wherein the isobutane dehydrogenation catalyst comprises a carrier and a Pt component and a Zn component supported on the carrier, wherein the carrier is a spherical double mesoporous illite composite material carrier, the spherical double mesoporous illite composite material carrier contains illite, a mesoporous molecular sieve material with a three-dimensional cubic pore channel distribution structure and a mesoporous molecular sieve material with a two-dimensional hexagonal pore channel distribution structure, the average particle size of the spherical double mesoporous illite composite material carrier is 20-50 μm, and the specific surface area is 150-600 m-2The pore volume is 0.5-1.5mL/g, the pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal are 2-5nm and 5-25nm respectively.
8. An isobutane dehydrogenation catalyst according to claim 7, wherein the carrier is present in an amount of 98-99.4 wt%, the Pt component is present in an amount of 0.1-0.5 wt% calculated as Pt element, and the Zn component is present in an amount of 0.5-1.5 wt% calculated as Zn element, based on the total weight of the isobutane dehydrogenation catalyst;
preferably, the average particle diameter of the isobutane dehydrogenation catalyst is 20-50 mu m, and the specific surface area is 150-400m2The pore volume is 0.6-1.2mL/g, the pore size distribution is bimodal, and the most probable pore sizes corresponding to the bimodal are 2.1-4.5nm and 8-23nm respectively.
9. The isobutane dehydrogenation catalyst according to claim 7, wherein the weight of the illite is 1-50 parts by weight, preferably 20-50 parts by weight, based on 100 parts by weight of the total weight of the mesoporous molecular sieve material having a three-dimensional cubic pore distribution structure and the mesoporous molecular sieve material having a two-dimensional hexagonal pore distribution structure, the weight ratio of the mesoporous molecular sieve material having a three-dimensional cubic pore distribution structure and the mesoporous molecular sieve material having a two-dimensional hexagonal pore distribution structure being 1: 0.1 to 10, preferably 1: 0.5-2.
10. Use of the isobutane dehydrogenation catalyst of any of claims in the production of isobutene by the dehydrogenation of isobutane, wherein the isobutane dehydrogenation process for producing isobutene comprises subjecting isobutane to a dehydrogenation reaction in the presence of a catalyst and hydrogen.
11. Use according to claim 10, wherein the molar ratio of the amount of isobutane to the amount of hydrogen is between 0.5 and 1.5: 1;
preferably, the dehydrogenation reaction conditions include: the reaction temperature is 550-650 ℃, the reaction pressure is 0.05-0.2MPa, the reaction time is 20-40h, and the mass space velocity of isobutane is 2-5h-1。
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| KR20180041794A (en) * | 2016-10-14 | 2018-04-25 | 한국에너지기술연구원 | Formic acid dehydrogenation catalysts supported by 3-dimensional interconnected mesoporous silica, preparation method thereof |
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