Low-carbon alkane dehydrogenation catalyst, preparation method and application thereof, and method for preparing olefin through low-carbon alkane dehydrogenation

Abstract

The invention relates to the field of preparation of alkane dehydrogenation catalysts, and discloses a low-carbon alkane dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing olefin through low-carbon alkane dehydrogenation. The low-carbon alkane dehydrogenation catalyst comprises a modified carrier, an active component and a first auxiliary agent, the active component and the first auxiliary agent are loaded on the modified carrier, and the modified carrier comprises a carrier and a second auxiliary agent; wherein the first auxiliary agent is a noble metal, and the second auxiliary agent is an IVA group element; the average particle size of the first auxiliary agent is 0.4 to 1.7 nm; the active components comprise Zn and Ga, and the mass ratio of Zn to Ga is (0.1-20): 1 in terms of metal elements. The low-carbon alkane dehydrogenation catalyst provided by the invention is used for a low-carbon alkane dehydrogenation olefin preparation reaction, and has relatively high activity and olefin selectivity.

Description

Technical Field

[0001] The invention relates to the field of alkane dehydrogenation catalyst preparation, and in particular to a low-carbon alkane dehydrogenation catalyst and a preparation method and application thereof, and a method for preparing olefins by dehydrogenating low-carbon alkanes. Background Art

[0002] The catalytic dehydrogenation of low-carbon alkanes to produce corresponding olefins is an important chemical process. Low-carbon olefins are very important chemical raw materials and are widely used in the chemical industry. For example, ethylene, as one of the most important raw materials in the petrochemical industry, is widely used in the preparation of various chemicals such as ethanol, acetaldehyde, ethylene oxide, synthetic plastics, synthetic rubber, and synthetic fibers; propylene is the basic organic chemical raw material with the largest consumption besides ethylene, and is widely used in the production of polypropylene, acetone, acrylonitrile, propylene oxide, acrylic acid and other chemical products; isobutylene is the main raw material for the production of methyl tert-butyl ether (MTBE); butene is mainly used in the alkylation, superposition, isomerization and dimerization processes to synthesize useful gasoline components and synthesize MTBE and ETBE gasoline additives and other fuel fields, and is widely used in the chemical field. In recent years, the catalytic dehydrogenation process of low-carbon alkanes has developed rapidly and has become an important source of ethylene / propylene / isobutylene.

[0003] Due to the limitation of thermodynamic equilibrium, the dehydrogenation reaction of low-carbon alkanes must be carried out under harsh conditions of high temperature and low pressure. Excessively high reaction temperature will lead to the occurrence of alkane cracking reaction and deep dehydrogenation reaction of alkanes, which will eventually accelerate the carbon deposition rate of the catalyst and deactivate the catalyst. The catalysts currently used in industry are mainly supported Pt-based catalysts and non-precious metal oxide Cr-based catalysts. Pt-based catalysts are relatively expensive due to the high cost of precious metals, and the problem of catalyst cost has not been solved in the process of industrial application; Cr-based catalysts will cause a certain degree of damage to the environment during recycling and treatment. Therefore, it is urgent to develop low-carbon alkane dehydrogenation catalysts with non-precious metals as active components, low price, and environmentally friendly.

[0004] US4786625A, US4827072A and CN1018619B reported that Pt metals were impregnated on the surface by forming chemical complexes with organic acid chelates. The complexes strongly attracted the refractory oxide carrier, so that the Pt metals were mainly retained on the outer surface of the carrier. The above catalyst is suitable for C 2 ~C 30 Dehydrogenation of alkanes, especially long chain alkanes.

[0005] The catalyst of US5012027A contains, in addition to Pt, a second auxiliary agent selected from iridium and osmium, and a third auxiliary agent selected from IVA group metals. The concentration gradient of the second auxiliary agent metal is greater than that of the Pt group metal, and the second auxiliary agent is an eggshell-type surface impregnation. This catalyst is also suitable for dehydrogenation of alkanes containing 2 to 30 carbon atoms, especially long-chain alkanes.

[0006] CN101612583B reports a long-chain alkane dehydrogenation catalyst with non-uniformly distributed active components. The platinum metal in the catalyst is mainly distributed on the catalyst surface as an active component, and tin, alkali metals and group VIII metals selected from iron, cobalt, nickel and palladium are uniformly distributed in the carrier as auxiliary agents. The carrier is γ-alumina. The catalyst is suitable for C 10 ~C 15 Dehydrogenation of long straight-chain alkanes.

[0007] CN103861619A discloses a sulfide catalyst for alkane dehydrogenation reaction, comprising an active component and a carrier, wherein the active component is one or more of Fe, Co, Ni, Cu, Zn, Mo, W and Mn elements, and the carrier is SiO 2 、Al 2 O 3 、ZrO 2 ,La 2 O 3 、CeO 2 , CaO, P 2 O 5 , Nb 2 O 5 and MgO to form a mixed oxide or composite oxide, the active components on the surface of the alkane dehydrogenation sulfide catalyst exist in the form of sulfide. The catalyst preparation steps are complicated, and the oxidized catalyst obtained after calcination needs to be pre-sulfurized with hydrogen sulfide.

[0008] CN105582929A discloses a catalyst for the dehydrogenation reaction of low-carbon alkanes and its preparation method, which mainly solves the problem of low activity and poor stability of the dehydrogenation catalyst prepared by the prior art. It is prepared by impregnation precipitation method, including the following components: a) 0.1 to 5 parts of Pt or its oxide; b) 0.1 to 5 parts of Sn or its oxide; c) 0.1 to 5 parts of alkali metal or its oxide; d) 0.1 to 5 parts of Ga, In, Tl, Cr, Mn or its oxide; e) 0.1 to 10 parts of Ce-La-O solid solution; f) 80 to 99 parts of carrier Al 2 O 3 The catalyst has good performance, but due to the presence of a high content of Pt, the cost is high and issues such as regeneration of deactivated catalyst and Pt recovery are involved.

[0009] CN104936696A discloses a manganese-containing catalyst for dehydrogenation reaction, and its preparation method and use, comprising components (A)-(G), (A) is a catalyst matrix, (B) is platinum with a total content of 0.5-1.5wt%, (C) is at least one of germanium, tin, lead, gallium, indium and titanium, with a total content of 0.2-5wt%, (D) is phosphorus with a total content of 1-3wt%, (E) is at least one of magnesium, calcium, strontium, barium, radium and lanthanide elements, with a total content of 0.1-5wt%, (F) is chloride with a total content of 0.1-2wt%, and (G) is manganese. The catalyst is used for propane dehydrogenation to propylene reaction, the olefin selectivity decreases rapidly, and it also involves the problem of recovering high-content Pt.

[0010] Therefore, there is an urgent need to develop a low-carbon alkane dehydrogenation catalyst that is inexpensive and environmentally friendly while ensuring excellent catalytic performance so as to be suitable for industrial applications. Summary of the invention

[0011] The purpose of the present invention is to overcome the problems existing in the prior art and provide a low carbon alkane dehydrogenation catalyst and its preparation method, application and a method for dehydrogenating low carbon alkane to olefins. The low carbon alkane dehydrogenation catalyst of the present invention is used for the reaction of dehydrogenating low carbon alkane to olefins and has high activity and olefin selectivity.

[0012] In order to achieve the above object, the present invention provides a catalyst for dehydrogenation of light alkanes, the catalyst comprising: a modified carrier and an active component and a first auxiliary agent supported on the modified carrier, the modified carrier comprising a carrier and a second auxiliary agent;

[0013] The first additive is a noble metal, and the second additive is an IVA group element;

[0014] The average particle size of the first auxiliary agent is 0.4-1.7nm;

[0015] The active components include Zn and Ga, and the mass ratio of Zn to Ga is 0.1-20:1 calculated as metal elements.

[0016] A second aspect of the present invention provides a method for preparing a light alkane dehydrogenation catalyst, the method comprising the following steps:

[0017] (1) loading a modified carrier containing a second auxiliary agent with a compound containing an active component and a compound containing a first auxiliary agent to obtain a solid product, wherein the second auxiliary agent is an IVA group element;

[0018] (2) activating the solid product with water chlorine at 400-600° C.;

[0019] Wherein, the first auxiliary agent-containing compound is a noble metal-containing compound;

[0020] The compound containing active components comprises a zinc-containing compound and a gallium-containing compound. The amount of the zinc-containing compound and the gallium-containing compound is such that the mass ratio of Zn to Ga in the prepared catalyst is 0.1-20:1, calculated as metal elements.

[0021] Preferably, step (1) comprises: loading a modified carrier containing a second auxiliary agent with a compound containing an active component and a compound containing a first auxiliary agent in sequence to obtain a solid product, wherein the second auxiliary agent is an IVA group element.

[0022] Preferably, the temperature of the water chlorine activation in step (2) is 400-550°C.

[0023] Preferably, the water-chlorine activation is carried out in the presence of an oxygen-containing gas, a chlorine-containing gas and water vapor.

[0024] Preferably, the total volume space velocity of the oxygen-containing gas, the chlorine-containing gas and the water vapor is 1500-4000h -1 , preferably 1500-3000h -1 .

[0025] Preferably, the chlorine-containing gas comes from a chlorine-containing compound, and the chlorine-containing compound is selected from at least one of hydrochloric acid, hypochlorous acid and perchloric acid.

[0026] Preferably, the chlorine-containing compound is hydrochloric acid, hypochlorous acid and / or perchloric acid, and the molar ratio of hydrochloric acid to hypochlorous acid and / or perchloric acid is 1:1-5.

[0027] The third aspect of the present invention provides an application of the light alkane dehydrogenation catalyst described in the first aspect or the light alkane dehydrogenation catalyst prepared by the preparation method described in the second aspect in the alkane dehydrogenation reaction to produce olefins.

[0028] A fourth aspect of the present invention provides a method for dehydrogenating low-carbon alkanes to produce olefins, the method comprising: contacting and reacting low-carbon alkanes with a diluent material in the presence of a catalyst;

[0029] Wherein, the catalyst is the light alkane dehydrogenation catalyst described in the first aspect or the light alkane dehydrogenation catalyst prepared by the preparation method described in the second aspect.

[0030] Through the above technical solution, the beneficial effects of the present invention include:

[0031] The catalyst of the present invention is formulated with a carrier modified by a second auxiliary agent, an active component containing a specific ratio of Zn element and Ga element, and a first auxiliary agent (precious metal), and the first auxiliary agent is dispersed on the carrier surface in a single atom form, so that the catalyst of the present invention has high catalytic performance and stability. The catalyst of the present invention is environmentally friendly. Preferably, the content of the first auxiliary agent is low, which can reduce costs and has good industrial application prospects. The catalyst of the present invention is used for the dehydrogenation of low-carbon alkanes to olefins, and has high activity and olefin selectivity.

[0032] The catalyst of the present invention has stable performance in the reaction of dehydrogenating low-carbon alkanes to produce olefins, has good activity after continuous operation for 200 hours, and can be reused after regeneration. DETAILED DESCRIPTION

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] In one aspect, the present invention provides a catalyst for dehydrogenation of light alkanes, the catalyst comprising: a modified carrier and an active component and a first auxiliary agent supported on the modified carrier, the modified carrier comprising a carrier and a second auxiliary agent;

[0035] The first additive is a noble metal, and the second additive is an IVA group element;

[0036] The average particle size of the first auxiliary agent is 0.4-1.7nm;

[0037] The active components include Zn and Ga, and the mass ratio of Zn to Ga is 0.1-20:1 calculated as metal elements.

[0038] The average particle size of the first auxiliary agent of the present invention is measured by a high-angle annular dark field scanning transmission electron microscope (HADDF-STEM) method.

[0039] According to the present invention, preferably, the average particle size of the first auxiliary agent is 0.6-1.2 nm. By adopting this preferred embodiment, the dispersion of the noble metal is improved, thereby improving the atomic utilization rate.

[0040] In the present invention, the mass ratio of Zn to Ga is 0.1-20:1, preferably 1-10:1, calculated as metal elements, such as 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, and any value in the range formed by any two of these values. The use of this preferred embodiment is conducive to improving the catalytic activity of the catalyst. When it is lower than this range, the interaction between Zn and Ga is weak, and the catalytic activity of the catalyst is reduced; when it exceeds this range, the acidity of the catalyst is weak, which affects the reactivity of the catalyst.

[0041] According to the present invention, preferably, calculated as metal elements, the mass content of the active component is 1-30% of the mass content of the modified carrier, preferably 5-25%, for example 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, and any value in the range formed by any two of these values.

[0042] According to the present invention, preferably, in terms of metal elements, the mass content of the first auxiliary agent is 0.01-2% of the mass content of the modified carrier, preferably 0.05-0.15%, more preferably 0.05-0.1%, for example 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, and any value in the range formed by any two of these values.

[0043] Controlling the contents of the above components within the range of the present invention is beneficial to improving the catalytic performance of the catalyst.

[0044] The present invention has no particular limitation on the content of the second auxiliary agent, which can be a conventional choice in the art. In order to further improve the catalytic performance of the catalyst, preferably, in terms of metal elements, the mass content of the second auxiliary agent is 0.01-5% of the mass content of the modified carrier, preferably 0.05-3%, for example, 0.01%, 0.05%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, and any value in the range formed by any two of these values.

[0045] The contents of the above components in the low-carbon alkane dehydrogenation catalyst of the present invention are measured by ICP-AES method.

[0046] The first auxiliary agent of the present invention can be any common noble metal. Preferably, the first auxiliary agent is selected from at least one of ruthenium, rhodium, palladium, iridium and platinum. In order to improve the catalytic performance of the catalyst, it is further preferred that the first auxiliary agent is platinum.

[0047] Preferably, the second auxiliary agent is germanium and / or tin. In order to further improve the catalytic performance of the catalyst, more preferably, the second auxiliary agent is tin.

[0048] According to the present invention, preferably, the carrier is a heat-resistant inorganic oxide, preferably at least one selected from alumina, zirconium oxide, titanium oxide and silicon oxide, more preferably alumina. With this preferred embodiment, the acidity and alkalinity of the catalyst and the chlorine holding capacity of the catalyst can be appropriately adjusted.

[0049] The present invention has no particular limitation on the source of the modified carrier, which can be obtained commercially or prepared by conventional methods.

[0050] A second aspect of the present invention provides a method for preparing a light alkane dehydrogenation catalyst, the method comprising the following steps:

[0051] (1) loading a modified carrier containing a second auxiliary agent with a compound containing an active component and a compound containing a first auxiliary agent to obtain a solid product, wherein the second auxiliary agent is an IVA group element;

[0052] (2) activating the solid product with water chlorine at 400-600° C.;

[0053] Wherein, the first auxiliary agent-containing compound is a noble metal-containing compound;

[0054] The compound containing active components comprises a zinc-containing compound and a gallium-containing compound. The amount of the zinc-containing compound and the gallium-containing compound is such that the mass ratio of Zn to Ga in the prepared catalyst is 0.1-20:1, calculated as metal elements.

[0055] In the preparation method of the low-carbon alkane dehydrogenation catalyst of the present invention, the carrier modified by the second auxiliary agent is further modified by using an active component containing a specific ratio of Zn element and Ga element and a first auxiliary agent (precious metal), so that the activity of the catalyst is greatly improved; then, through a water-chlorine activation process performed at a specific temperature, the catalyst of the present invention has higher catalytic performance and stability. The low-carbon alkane dehydrogenation catalyst of the present invention is used for the reaction of dehydrogenating low-carbon alkanes to olefins, and has higher activity and olefin selectivity.

[0056] In the present invention, the temperature of the water chlorine activation in step (2) is 400-600°C, preferably 400-550°C, such as 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, and any value in the range formed by any two of these values. This preferred embodiment is more conducive to improving the catalytic performance of the catalyst.

[0057] According to the present invention, preferably, the zinc-containing compound and the gallium-containing compound are used in such an amount that, in the prepared catalyst, the mass ratio of Zn to Ga, calculated as metal elements, is 1-10:1.

[0058] According to the present invention, preferably, the amount of the compound containing the active component is such that in the prepared catalyst, the mass content of the active component, calculated as metal element, is 1-30%, preferably 5-25% of the mass content of the modified carrier.

[0059] According to the present invention, preferably, the amount of the first auxiliary compound is such that in the prepared catalyst, the mass content of the first auxiliary, calculated as metal element, is 0.01-2%, preferably 0.05-0.15%, more preferably 0.05-0.1% of the mass content of the modified carrier.

[0060] According to the present invention, preferably, the mass content of the second auxiliary agent is 0.01-5%, preferably 0.05-3%, of the mass content of the modified carrier, calculated as metal elements.

[0061] In the present invention, there is no specific limitation on the method of loading the compound containing the active component and the compound containing the first auxiliary agent in step (1), and it can be carried out by conventional methods in the art. The present invention preferably adopts an impregnation method. Preferably, the loading process in step (1) comprises: impregnating the modified support containing the second auxiliary agent with an impregnation solution of the compound containing the active component and / or the compound containing the first auxiliary agent, followed by drying and optional calcination.

[0062] The present invention has no particular limitation on the specific method of impregnation, and the method can be carried out according to conventional methods in the art to obtain the above-mentioned contents of the active component and the first auxiliary agent in the catalyst of the present invention.

[0063] The present invention has no particular limitation on the loading order of the compound containing the active component and the compound containing the first auxiliary agent, and they can be loaded separately or together. Preferably, the loading process of step (1) comprises: loading the modified carrier containing the second auxiliary agent with the compound containing the active component and the compound containing the first auxiliary agent in sequence to obtain a solid product, wherein the second auxiliary agent is an element of group IVA. By adopting this preferred embodiment, the bonding degree between the active component and the modified carrier can be increased, and the atomic exposure ratio of the noble metal of the first auxiliary agent can be increased to avoid being covered by the active metal, thereby improving the atomic utilization rate of the noble metal.

[0064] Preferably, the modified carrier containing the second auxiliary agent is first impregnated with an impregnation solution containing the active component compound, and then dried and optionally calcined to obtain a catalyst precursor; the catalyst precursor is impregnated with an impregnation solution containing the first auxiliary agent compound, and then dried to obtain a solid product.

[0065] According to a preferred embodiment of the present invention, the modified carrier containing the second auxiliary agent is first impregnated with an impregnation solution of a compound containing an active component, and then subjected to rotary evaporation, drying and optional calcination in sequence to obtain a catalyst precursor; the catalyst precursor is impregnated with an impregnation solution of a compound containing a first auxiliary agent, and then subjected to rotary evaporation and drying to obtain a solid product.

[0066] The present invention has no particular limitation on the specific conditions of the rotary evaporation treatment, as long as the purpose of removing excess water (catalyst non-adhesion) can be achieved. Preferably, the conditions of the rotary evaporation treatment include: a temperature of 40-80°C and a rotation speed of 30-100 rpm.

[0067] The present invention has no particular limitation on the specific conditions of the drying, and the drying can be carried out according to conventional methods in the art, which will not be described in detail herein.

[0068] The calcination conditions of the present invention can be conventionally selected in the art. Preferably, the calcination conditions include: a temperature of 500-800°C and a time of 1-28 hours. The calcination is generally carried out in an air atmosphere, which can include a flowing atmosphere or a static atmosphere.

[0069] Preferably, the second auxiliary agent is germanium and / or tin. In order to further improve the catalytic performance of the catalyst, more preferably, the second auxiliary agent is tin.

[0070] The first auxiliary agent compound of the present invention can be a common compound containing various precious metals. Preferably, the first auxiliary agent compound is selected from at least one of a ruthenium-containing compound, a rhodium-containing compound, a palladium-containing compound, an iridium-containing compound and a platinum-containing compound. In order to improve the catalytic performance of the catalyst, it is further preferred that the first auxiliary agent compound is a platinum-containing compound, preferably selected from at least one of chloroplatinic acid, tetraammine platinum nitrate and platinum chloride. The above substances are all conventional choices in the art and can be obtained commercially.

[0071] Preferably, the first auxiliary agent-containing compound is provided in the form of an aqueous solution, and the concentration of the first auxiliary agent-containing aqueous solution is 1-15 mg / mL.

[0072] According to the present invention, preferably, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride and zinc carbonate. The above substances are conventionally selected in the art and can be obtained commercially.

[0073] According to the present invention, preferably, the selected gallium-containing compound is selected from at least one of gallium nitrate, gallium carbonate and gallium chloride. The above substances are conventionally selected in the art and can be obtained commercially.

[0074] According to the present invention, preferably, the carrier is a heat-resistant inorganic oxide, preferably at least one selected from alumina, zirconia, titanium oxide and silicon oxide, more preferably alumina.

[0075] According to the present invention, preferably, the pore volume of the carrier is 0.1-1.8 mL / g, preferably 0.4-1.1 mL / g.

[0076] According to the present invention, preferably, the specific surface area of ​​the carrier is 50-300m 2 / g, preferably 80-200m 2 / g.

[0077] The present invention has no particular limitation on the preparation method of the modified carrier, and the modified carrier can be prepared by conventional methods in the art or obtained commercially, as long as the ratio of the mass content of the second auxiliary agent in the modified carrier to the mass content of the modified carrier is within the above range.

[0078] According to the present invention, preferably, the time for water chlorine activation in step (2) is 2-10 hours.

[0079] According to the present invention, preferably, the water-chlorine activation is performed in the presence of an oxygen-containing gas, a chlorine-containing gas and water vapor.

[0080] According to the present invention, preferably, the total volume space velocity of the oxygen-containing gas, the chlorine-containing gas and the water vapor is 1500-4000h -1 , preferably 1500-3000h-1 By adopting this preferred embodiment, the catalytic performance of the catalyst of the present invention is improved.

[0081] Preferably, the water-chlorine molar ratio is 1-50:1, preferably 1-40:1, for example, it can be 1:1, 4:1, 8:1, 12:1, 16:1, 20:1, 24:1, 28:1, 32:1, 36:1, 40:1, 50:1, and any value in the range formed by any two of these values.

[0082] In the present invention, the water-chlorine molar ratio refers to the molar ratio of water vapor to chlorine in the chlorine-containing gas.

[0083] The chlorine-containing gas of the present invention can be chlorine gas or a chlorine-containing compound. In order to optimize the water chlorine activation effect, preferably, the chlorine-containing gas comes from a chlorine-containing compound, preferably selected from at least one of hydrochloric acid, hypochlorous acid and perchloric acid.

[0084] Further preferably, the chlorine-containing compound is hydrochloric acid, hypochlorous acid and / or perchloric acid.

[0085] Preferably, in the chlorine-containing gas, the molar ratio of hydrogen chloride to hypochlorous acid and / or perchloric acid is 1:1-5. By adopting this preferred embodiment, the catalytic performance of the catalyst of the present invention is further improved.

[0086] According to a preferred embodiment of the present invention, the oxygen-containing gas is first contacted with the chlorine-containing gas and water vapor, and then contacted with the solid product.

[0087] According to a specific embodiment of the present invention, the oxygen-containing gas is first passed through a liquid storage tank containing water and a chlorine-containing compound solution, and then contacted with the solid product obtained in step (1).

[0088] The present invention has no particular limitation on the amount of water and chlorine-containing compounds in the solution, as long as the water-chlorine ratio is within the above range.

[0089] Preferably, the oxygen-containing gas is oxygen or air.

[0090] According to the present invention, preferably, the method further comprises: reducing the product obtained by water chlorine activation to obtain a catalyst.

[0091] The reduction of the present invention can be carried out before the catalyst is loaded into the reactor, or can be carried out after the catalyst is loaded into the reactor and before the dehydrogenation reaction of the light alkane.

[0092] The present invention has no particular limitation on the specific conditions of the reduction, and the reduction can be carried out according to conventional methods in the art. Preferably, the reduction conditions include: a temperature of 500-700° C. and a time of 1-10 h.

[0093] According to the present invention, preferably, the reduction is carried out under the action of a reducing atmosphere, which is hydrogen and optionally a balancing gas.

[0094] In the present invention, the optional balance gas means that during the reduction process of the product obtained by water-chlorine activation, the balance gas may or may not be introduced.

[0095] According to the present invention, preferably, in the reducing atmosphere, the volume fraction of hydrogen is 10-100%.

[0096] According to the present invention, preferably, the balancing gas is selected from at least one of helium, nitrogen and argon.

[0097] According to a specific embodiment of the present invention, protective gas is first used for purging, and then the product obtained by water chlorine activation is reduced to obtain a catalyst. With this preferred embodiment, hydrogen and air are prevented from mixing and explosion is avoided.

[0098] Preferably, the protective gas is selected from at least one of nitrogen, argon and helium, preferably nitrogen.

[0099] The third aspect of the present invention provides an application of the light alkane dehydrogenation catalyst described in the first aspect or the light alkane dehydrogenation catalyst prepared by the method described in the second aspect in the reaction of dehydrogenating alkanes to produce olefins, preferably in the reaction of dehydrogenating alkanes to produce olefins.

[0100] According to the present invention, preferably, the low carbon alkane is C 2 -C 5 of alkanes.

[0101] A fourth aspect of the present invention provides a method for dehydrogenating low-carbon alkanes to produce olefins, the method comprising: contacting and reacting low-carbon alkanes with a diluent material in the presence of a catalyst;

[0102] Wherein, the catalyst is the light alkane dehydrogenation catalyst described in the first aspect or the light alkane dehydrogenation catalyst prepared by the method described in the second aspect.

[0103] According to the present invention, preferably, the conditions of the contact reaction include: temperature of 400-800°C, preferably 550-700°C; pressure of 0.1-1MPa, preferably 0.1-0.5MPa; volume space velocity of low carbon alkane and dilution material of 0.1-30L / (g·h), preferably 0.5-20L / (g·h).

[0104] In the present invention, unless otherwise specified, the pressure of the contact reaction refers to the absolute pressure.

[0105] According to the present invention, preferably, the volume ratio of the diluent material to the low-carbon alkane is 1-10:1, preferably 3-8:1.

[0106] According to the present invention, preferably, the low carbon alkane is C 2 -C 5 The alkane is preferably propane, n-butane, isobutane or pentane, more preferably propane or isobutane.

[0107] According to the present invention, preferably, the diluent material is hydrogen and optionally a balance gas.

[0108] In the present invention, the optional balance gas means that during the reaction process, the balance gas may or may not be introduced.

[0109] According to the present invention, preferably, the balancing gas is selected from at least one of helium, nitrogen and nitrogen.

[0110] Preferably, in the diluted material, the volume ratio of hydrogen to balance gas is 1:1-10.

[0111] The reaction of the present invention can be carried out in various reactors commonly used in the art. Preferably, the reaction is carried out in a fixed bed reactor.

[0112] The catalyst of the present invention can be reused by regeneration. The present invention has no particular limitation on the method for regenerating the catalyst, and the catalyst can be regenerated by referring to conventional regeneration methods in the art. The present invention preferably adopts a method of first air calcination and then hydrogen reduction for regeneration.

[0113] The air roasting of the present invention can remove carbon deposits on the surface of the catalyst. Preferably, the conditions of the air roasting include: a temperature of 500-700°C; and a time of 1-5 hours.

[0114] Preferably, the conditions for hydrogen reduction include: temperature of 500-700° C.; time of 1-10 h.

[0115] The present invention will be described in detail below through examples.

[0116] In the following embodiments,

[0117] Propane conversion calculation formula:

[0118]

[0119] Propylene selectivity calculation formula:

[0120]

[0121] Where n(C 3 H 8 )in Indicates the amount of propane in the reaction gas; n(C 3 H 8 ) out Indicates the amount of propane in the product; n(C 3 H 6 ) out Indicates the amount of propylene in the product;

[0122] Unless otherwise specified, all reagents used in the following examples are commercially available and of analytical grade.

[0123] Example 1

[0124] (1) Weigh Zn(NO 3 ) 2 6H 2 O and Ga(NO 3 ) 3 9H 2 O solid in a beaker, add 160 mL of deionized water and mix well, then add Sn-doped Al 2 O 3 The specific surface area of ​​the carrier (alumina carrier is 200m 2 / g, pore volume 0.5mL / g), shake and mix evenly. After immersion at room temperature for 4h, remove excess water by rotary evaporation (speed 30rpm) in an 80℃ water bath, and then dry in a 120℃ oven for 12h. The dried sample was transferred to a tube furnace and calcined at 650℃ in air atmosphere for 4h to obtain catalyst precursor 1#.

[0125] (2) Take H 2 PtCl 6 6H 2 O aqueous solution (Pt content 4.5mg / mL) was placed in a beaker, 100mL of deionized water was added and mixed evenly, then 60g of the above-prepared catalyst precursor 1# was added, and after immersion at room temperature for 4h, excess water was removed by rotary evaporation (speed of 30rpm) in an 80℃ water bath, and then dried in an oven at 120℃ for 12h. The dried sample was activated with water and chlorine: air was first passed into a storage tank of a mixed solution of water, hydrogen chloride and hypochlorous acid, and then into a reaction tube to contact the catalyst precursor for activation, wherein the molar ratio of water to chlorine was 4:1, the molar ratio of hydrogen chloride to hypochlorous acid was 1:1, and the total volume space velocity of air, water, hydrogen chloride and hypochlorous acid was 1500h -1 , the water chlorine activation temperature is 510°C, and the water chlorine activation time is 4 hours. The product activated by water chlorine is cooled down to 500°C by nitrogen purge, and switched to a reducing atmosphere. At this temperature, the catalyst is reduced by high-purity hydrogen for 4 hours to obtain the catalyst, which is recorded as C1. The specific composition of the catalyst is shown in Table 1.

[0126] Example 2

[0127] (1) Weigh Zn(NO 3 ) 2 6H 2 O and Ga(NO 3 ) 3 9H 2 O solid in a beaker, add 160 mL of deionized water and mix well, then add Sn-doped Al 2 O 3 The specific surface area of ​​the carrier (alumina carrier is 200m 2 / g, pore volume of 0.5mL / g), shake and mix evenly, soak at room temperature for 4h, remove excess water by rotary evaporation (speed of 30rpm) in a 80℃ water bath, and then dry in a 120℃ oven for 12h. The dried sample was transferred to a tube furnace and calcined at 650℃ in air atmosphere for 4h to obtain catalyst precursor 1#.

[0128] (2) Take H 2 PtCl 6 6H 2 O solution (Pt content 4.5 mg / mL) is placed in a beaker, 100 mL of deionized water is added and mixed evenly, then 60 g of the above-prepared catalyst precursor 1# is added. After immersion at room temperature for 4 hours, excess water is removed by rotary evaporation (speed is 30 rpm) in an 80°C water bath, and then dried in an oven at 120°C for 12 hours. The dried sample is activated with water and chlorine: air is first passed into a storage tank of a mixed solution of water, hydrogen chloride and hypochlorous acid, and then enters the reaction tube to contact the catalyst precursor for activation, wherein the molar ratio of water to hydrogen chloride is 4:1, the molar ratio of hydrogen chloride to hypochlorous acid is 1:2, and the total volume space velocity of air, water, hydrogen chloride and hypochlorous acid is 2000 h -1 . Water chlorine activation: temperature 580°C, time 1h. After water chlorine activation, the material was cooled down to 500°C by nitrogen purge, and switched to reducing atmosphere. At this temperature, the catalyst was reduced by high-purity hydrogen for 4h to obtain the catalyst, which was recorded as C2. The specific composition of the catalyst is shown in Table 1.

[0129] Example 3

[0130] The method of Example 1 was followed, except that in step (1), H 2 PtCl 6 6H 2 O aqueous solution (Pt content 4.5 mg / mL) and Zn(NO 3 ) 2 6H 2 O.Ga(NO 3 ) 3 9H 2O solid in a beaker, add 160 mL of deionized water and mix well, then add Sn-doped Al 2 O 3 The carrier is shaken and mixed evenly. After immersion at room temperature for 4 hours, excess water is removed by rotary evaporation in an 80°C water bath, and then dried in an oven at 120°C for 12 hours. The dried sample is activated with water and chlorine: air is first passed into a storage tank containing a mixed solution of water, hydrogen chloride and hypochlorous acid, and then enters the reaction tube to contact the catalyst precursor for activation. The molar ratio of water to chlorine is 4:1, the molar ratio of hydrogen chloride to hypochlorous acid is 1:1, and the total volume space velocity of air, water, hydrogen chloride and hypochlorous acid is 1500h -1 , the water chlorine activation temperature is 510°C, and the water chlorine activation time is 4 hours. The product activated by water chlorine is cooled down to 500°C by nitrogen purge, and switched to a reducing atmosphere. At this temperature, the catalyst is reduced by high-purity hydrogen for 4 hours to obtain the catalyst, which is recorded as C3. The specific composition of the catalyst is shown in Table 1.

[0131] Example 4

[0132] The method of Example 1 is followed, except that in step (2), the temperature of water chlorine activation is 600°C.

[0133] The catalyst is obtained and is recorded as C4. The specific composition of the catalyst is shown in Table 1.

[0134] Comparative Example 1

[0135] The method of Example 1 was followed, except that Ga(NO 3 ) 3 9H 2 O solid to obtain the catalyst, which is recorded as D1. The specific composition of the catalyst is shown in Table 1.

[0136] Comparative Example 2

[0137] The method of Example 1 was followed, except that Zn(NO 3 ) 2 6H 2 O solid. The catalyst is obtained and is recorded as D2. The specific composition of the catalyst is shown in Table 1.

[0138] Comparative Example 3

[0139] The method of Example 1 was followed, except that H 2 PtCl 6 6H 2 O aqueous solution. The catalyst is obtained and is recorded as D3. The specific composition of the catalyst is shown in Table 1.

[0140] Table 1

[0141]

[0142] Test Example 1

[0143] The catalysts prepared in the examples and comparative examples were placed in a continuous fixed bed reactor to carry out propane dehydrogenation to propylene reaction. The test conditions were: reaction temperature 580°C, C 3 H 8 :H 2 :He=2:1:1 (volume ratio), the total pressure of the gas introduced into the fixed bed reactor is atmospheric pressure, the total volume space velocity of propane, hydrogen and helium is 18L / (g·h), and the results of the reaction for 150min are shown in Table 2.

[0144] Table 2

[0145] Catalyst No. Propane conversion, % Propylene selectivity, % C1 43.42 98.19 C2 49.95 97.04 C3 42.35 96.88 C4 42.43 96.35 D1 35.66 92.83 D2 37.61 93.54 D3 32.43 94.62

[0146] From the results in Table 2, it can be seen that the catalyst of the present invention has significantly higher propane conversion rate and propylene selectivity when applied to the propane dehydrogenation reaction to produce propylene, with the propane conversion rate up to 49.95% and the propylene selectivity up to 98.19%. This shows that the catalyst provided by the present invention has excellent catalytic performance.

[0147] Test Example 2

[0148] This test example is used to illustrate the stability of the catalyst of the present invention.

[0149] The catalysts prepared in Example 1 and Comparative Examples 1-3 were placed in a continuous fixed bed reactor to carry out propane dehydrogenation to propylene reaction. The test conditions were: reaction temperature 580°C, C 3 H 8 :H 2 :He=2:1:1 (volume ratio), the total pressure of the gas introduced into the fixed bed reactor is atmospheric pressure, and the total space velocity of propane, hydrogen and helium is 10h -1-1 The catalyst which had been reacted for 200 hours was then activated by calcination in air (temperature: 550°C, time: 60 min), and then regenerated by hydrogen reduction (temperature: 500°C, time: 2 h), and then continued to react for 90 hours under the above conditions.

[0150] Table 3

[0151]

[0152] From the results in Table 3, it can be seen that the catalyst of the present invention still has a high propylene selectivity in the reaction of dehydrogenating low-carbon alkanes to olefins after regeneration, which shows that the catalyst of the present invention has a high stability.

[0153] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst for dehydrogenation of light alkanes, comprising: A modified carrier and an active component and a first auxiliary agent loaded on the modified carrier, wherein the modified carrier comprises a carrier and a second auxiliary agent; The first additive is a noble metal, and the second additive is an IVA group element; The average particle size of the first auxiliary agent is 0.4-1.7nm; The active components include Zn and Ga, and the mass ratio of Zn to Ga is 0.1-20:1 calculated as metal elements.

2. The catalyst according to claim 1, wherein The average particle size of the first auxiliary agent is 0.6-1.2nm; Preferably, the mass ratio of Zn to Ga is 1-10:1, calculated as metal elements; Preferably, the mass content of the active component is 1-30% of the mass content of the modified carrier, preferably 5-25% in terms of metal element; Preferably, the mass content of the first auxiliary agent is 0.01-2% of the mass content of the modified carrier, preferably 0.05-0.15%, more preferably 0.05-0.1% based on the metal element; Preferably, calculated as metal elements, the mass content of the second auxiliary agent is 0.01-5%, preferably 0.05-3%, of the mass content of the modified carrier.

3. The catalyst according to claim 1 or 2, wherein The first auxiliary agent is platinum; Preferably, the second auxiliary agent is tin; Preferably, the support is a heat-resistant inorganic oxide, preferably alumina.

4. A method for preparing a light alkane dehydrogenation catalyst, the method comprising the following steps: (1) loading a modified carrier containing a second auxiliary agent with a compound containing an active component and a compound containing a first auxiliary agent to obtain a solid product, wherein the second auxiliary agent is an IVA group element; (2) activating the solid product with water chlorine at 400-600° C.; Wherein, the first auxiliary agent-containing compound is a compound containing a precious metal; The compound containing active components comprises a zinc-containing compound and a gallium-containing compound. The amount of the zinc-containing compound and the gallium-containing compound is such that the mass ratio of Zn to Ga in the prepared catalyst is 0.1-20:1, calculated as metal elements.

5. The method according to claim 4, wherein: The zinc-containing compound and the gallium-containing compound are used in such an amount that the mass ratio of Zn to Ga in the prepared catalyst, calculated as metal elements, is 1-10:1; Preferably, the amount of the compound containing the active component is such that, in the prepared catalyst, the mass content of the active component, calculated as metal element, is 1-30%, preferably 5-25%, of the mass content of the modified carrier; Preferably, the amount of the compound containing the first additive is such that, in the prepared catalyst, the mass content of the first additive, calculated as metal element, is 0.01-2% of the mass content of the modified carrier, preferably 0.05-0.15%, more preferably 0.05-0.1%; Preferably, calculated as metal elements, the mass content of the second auxiliary agent is 0.01-5%, preferably 0.05-3%, of the mass content of the modified carrier.

6. The method according to claim 4, wherein: The second auxiliary agent is tin; Preferably, the first auxiliary agent-containing compound is a platinum-containing compound, preferably at least one selected from chloroplatinic acid, tetraammine platinum nitrate and platinum chloride; Preferably, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride and zinc carbonate; Preferably, the selected gallium-containing compound is selected from at least one of gallium nitrate, gallium carbonate and gallium chloride; Preferably, the support is a heat-resistant inorganic oxide, preferably alumina; Preferably, the pore volume of the carrier is 0.1-1.8 mL / g, preferably 0.4-1.1 mL / g; Preferably, the specific surface area of ​​the carrier is 50-300m 2 / g, preferably 80-200m 2 / g.

7. The method according to any one of claims 4 to 6, wherein: Step (1) comprises: loading a modified carrier containing a second auxiliary agent with a compound containing an active component and a compound containing a first auxiliary agent in sequence to obtain a solid product; Preferably, the modified carrier containing the second auxiliary agent is first impregnated with an impregnation solution containing the active component compound, and then dried and optionally calcined to obtain a catalyst precursor; the catalyst precursor is impregnated with an impregnation solution containing the first auxiliary agent compound, and then dried to obtain a solid product.

8. The method according to any one of claims 4 to 7, wherein: The temperature of the water chlorine activation in step (2) is 400-550°C; Preferably, the water chlorine activation time in step (2) is 2-10h; Preferably, the water-chlorine activation is carried out in the presence of oxygen-containing gas, chlorine-containing gas and water vapor; Preferably, the total volume space velocity of the oxygen-containing gas, the chlorine-containing gas and the water vapor is 1500-4000h -1 , preferably 1500-3000h -1 ; Preferably, the water:chlorine molar ratio is 1-50:1, preferably 1-40:

1.

9. The method according to claim 8, wherein: The chlorine-containing gas comes from a chlorine-containing compound, and the chlorine-containing compound is selected from at least one of hydrochloric acid, hypochlorous acid and perchloric acid; Preferably, the chlorine-containing compound is hydrochloric acid, and hypochlorous acid and / or perchloric acid. Preferably, in the chlorine-containing gas, the molar ratio of hydrogen chloride to hypochlorous acid and / or perchloric acid is 1:1-5.

10. The method according to any one of claims 4 to 9, wherein: The method further comprises: reducing the product obtained by water chlorine activation to obtain a catalyst; Preferably, the reduction conditions include: temperature of 500-700°C and time of 1-10h; Preferably, the reducing atmosphere is hydrogen and optionally a balance gas; preferably, in the reducing atmosphere, the volume fraction of hydrogen is 10-100%; Preferably, the balance gas is selected from at least one of helium, nitrogen and argon.

11. Use of the light alkane dehydrogenation catalyst according to any one of claims 1 to 3 or the light alkane dehydrogenation catalyst prepared by the preparation method according to any one of claims 4 to 10 in the reaction of dehydrogenating alkanes to produce olefins, preferably in the reaction of dehydrogenating alkanes to produce olefins; Preferably, the low carbon alkane is a C2-C5 alkane.

12. A method for dehydrogenating low-carbon alkanes to produce olefins, the method comprising: In the presence of a catalyst, a low carbon alkane is contacted with a diluent material for reaction; Wherein, the catalyst is the light alkane dehydrogenation catalyst according to any one of claims 1 to 3 or the light alkane dehydrogenation catalyst prepared by the preparation method according to any one of claims 4 to 10; Preferably, the contact reaction conditions include: temperature of 400-800°C, preferably 550-700°C; pressure of 0.1-1MPa, preferably 0.1-0.5MPa; volume space velocity of low carbon alkane and diluent material of 0.1-30L / (g·h), preferably 0.5-20L / (g·h); Preferably, the volume ratio of the diluent material to the light alkane is 1-10:1, preferably 3-8:1; Preferably, the low carbon alkane is a C2-C5 alkane, preferably propane, n-butane, isobutane or pentane, more preferably propane or isobutane; Preferably, the diluent material is hydrogen and optionally a balance gas; Preferably, the balance gas is selected from at least one of helium, nitrogen and nitrogen; preferably, in the diluted material, the volume ratio of hydrogen to the balance gas is 1:1-10.

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