A light alkane conversion catalyst, its preparation method and application

Abstract

The application relates to a preparation method of a light alkane conversion catalyst, which comprises the following steps: impregnating an alumina carrier with a water solution containing a platinum compound, drying, roasting and reducing to obtain a catalyst precursor; impregnating the catalyst precursor with a hydrocarbon solution of alkyl aluminum chloride under the protection of dry inert gas, and then removing the solvent to obtain a pre-chlorination product; and supplementally chlorinating the pre-chlorination product with AlCl3 to obtain the catalyst. The catalyst prepared by the method has high initial catalytic activity, selectivity and better activity stability in a C4-C6 alkane conversion reaction.

Description

Technical Field

[0001] The present invention relates to a light alkane conversion catalyst, a preparation method and application thereof, and specifically to a light alkane conversion catalyst, especially a catalyst capable of converting C4-C6 alkanes into their corresponding isomers, and a preparation method and application thereof. Background Art

[0002] C4-C6 light alkanes are valuable light hydrocarbon resources. Isobutane, in addition to being used in the production of alkylate, is also a feedstock for chemical processes such as isobutane dehydrogenation, C3 / C4 mixed dehydrogenation, and propylene / isobutane co-oxidation to produce propylene oxide and methyl tert-butyl ether (PO / MTBE). n-Butane is a feedstock for steam cracking to produce ethylene and oxidation to produce maleic anhydride. n-Pentane and n-hexane are high-quality feedstocks for ethylene cracking. Isopentane and highly branched C6 isoparaffins are important high-octane gasoline blending components.

[0003] In recent years, my country's gasoline upgrading has accelerated, with new gasoline standards placing stricter requirements on olefins and aromatics. The National V gasoline standard stipulates olefin and aromatic content of 24% and 40% by volume, respectively, compared to 15% and 35% by volume, respectively, for the National VIB standard. Olefins and aromatics are high-octane components, and restrictions on their content require the addition of other high-octane components. Isoparaffins, with their high octane rating, effectively adjust the octane distribution of the gasoline pool and improve vehicle starting performance, and are considered the "ultimate" blending component of the gasoline pool. Isobutane-butene alkylation and C5 / C6 isomerization, as the primary means of producing light isoparaffins, have become supporting technologies for gasoline upgrading. They have gained widespread application in recent years, driving a rapid increase in demand for isobutane and C5 / C6 isomerization feedstocks.

[0004] With rapid economic development and industrial restructuring, the chemical industry has entered a boom cycle. As the leading chemical industry, ethylene plants have released significant production capacity, with a clear trend toward larger plants and lighter raw materials. The acquisition of high-quality ethylene cracking feedstock, including C4-C6 normal alkanes, is gaining increasing attention. Furthermore, with rising environmental awareness and the implementation of policies such as the plastic ban, biodegradable materials face enormous development opportunities. Maleic anhydride, a key raw material for the production of biodegradable materials, has seen its price rise rapidly, creating a growing demand gap. Many companies are planning and constructing maleic anhydride plants. n-Butane is an essential raw material for the oxidation process of maleic anhydride, and its price accounts for over 80% of the production cost. Obtaining sufficient n-butane is a matter of great concern and urgent concern for maleic anhydride companies.

[0005] With the continuous increase in refining and chemical capacity, a large amount of C4-C6 alkanes are produced as by-products in reforming, hydrogenation, extraction, cracking and other units. These light alkanes are usually mixed alkanes. Although the resources are abundant, separation alone often cannot meet the personalized needs of downstream users for normal alkanes or isoalkanes. Corresponding conversion technologies are urgently needed to achieve flexible conversion of normal and isoalkanes.

[0006] The technology for isomerization of light alkanes is relatively mature, with catalysts at its core. There are three main types of catalyst systems. The first is a Pt- or Pd-loaded molecular sieve (usually mordenite or β molecular sieve), also known as a medium-temperature molecular sieve catalyst. The isomerization reaction temperature is 240-280°C. The second is typically a Pt-loaded sulfated zirconium oxide catalyst, also known as a solid superacid catalyst, with a reaction temperature of 170-210°C. The third is a Pt-loaded chlorided alumina catalyst, also known as a low-temperature catalyst, with a reaction temperature of 120-200°C.

[0007] Among the three types of light alkane isomerization catalysts, low-temperature catalysts offer the highest isomerization activity and the lowest isomerization reaction temperature, making them widely used worldwide. These catalysts are typically supported on alumina and prepared by first introducing Pt to create a Pt / Al2O3 base catalyst. This base catalyst is then treated with a chlorine-containing reagent to produce a chlorinated alumina catalyst with a high chlorine content.

[0008] CN104549376B discloses a method for preparing an alkane isomerization catalyst, comprising the steps of impregnating a carrier alumina with a solution containing a Group VIII metal compound, drying the impregnated solid, calcining or treating with water and chlorine, then impregnating with an alkane solution containing an alkylaluminum chloride, and then drying in the presence of an inert gas under anhydrous conditions to produce a catalyst. The catalyst has a Group VIII metal content of 0.01-3.0% by mass and a chlorine content of 4.0-10.0% by mass, calculated on a dry basis on the alumina. Although this preparation method has a high initial activity, due to the lack of high-temperature treatment after loading the alkylaluminum chloride, excess alkylaluminum chloride is physically adsorbed on the catalyst. The alkylaluminum chloride itself also has strong isomerization performance, so the catalyst exhibits a high initial isomerization activity. However, under isomerization reaction conditions, the physically adsorbed alkylaluminum chloride gradually desorbs from the catalyst surface and enters the reaction mass, where it is carried away. As the alkylaluminum chloride is lost from the catalyst, the catalyst performance continuously declines.

[0009] US6150296A discloses a method for preparing a hydrocarbon isomerization catalyst. The method includes first preparing a composition containing a Group VIII noble metal and an alumina support, then contacting the composition with a hydrocarbyl aluminum compound for reaction. The resulting solid product is activated with a hydrogen-containing gas at a temperature above 500°C to obtain an isomerization catalyst having a chlorine content exceeding 2.5% by mass. The catalyst prepared by this method has low activity.

[0010] US5004859A discloses a method for preparing an alkane isomerization catalyst. The method involves impregnating an alumina strip carrier with an aqueous solution of chloroplatinic acid, followed by drying, water-chlorine activation, and reduction to produce a Pt-containing base catalyst. The Pt-containing base catalyst is then treated with AlCl vapor carried by hydrogen at 550°C for 45 minutes to produce the catalyst. The catalyst prepared by this method has insufficient acid sites and low isomerization activity.

[0011] US6297418B1 discloses a method for preparing a chlorided alumina-type alkane isomerization catalyst, comprising first impregnating a spherical or strip-shaped carrier of γ-type and / or η-type alumina with an aqueous solution of chloroplatinic acid, then drying and calcining, and finally chlorinating with CCl4 to obtain a catalyst having a chlorine content of 4.5% to 15% by mass.

[0012] CN104117369B discloses a method for preparing a normal alkane isomerization catalyst. The method comprises impregnating a γ-Al2O3 carrier with chloroplatinic acid, drying, oxidizing, and reducing the carrier. The resulting product is then inorganically chlorinated with AlCl3. The inorganic chlorination product is then organically chlorinated with one or both of CCl4 and C2H6AlCl to obtain the isomerization catalyst. The mass of AlCl3 is 15-50% of the mass of the γ-Al2O3 carrier, and the volume of the organic chlorinating agent is 30-50% of the volume of the γ-Al2O3 carrier.

[0013] There are few reports on the conversion of isoparaffins into normal paraffins. CN110385142A discloses a catalyst for isobutane normalization reaction and its preparation method. The catalyst uses MCM-41 molecular sieve as a carrier and Pt / SO4 2- / ZrO2 is the active component. The MCM-41 carrier is first impregnated with a zirconium salt solution and a sulfate solution, and then dried and calcined to produce SO4 2- / ZrO2-MCM-41, and then introducing Pt by the equal volume impregnation method to produce a solid superacid catalyst. This catalyst is used in the normalization reaction of isobutane at a reaction temperature of 150-350°C, a pressure of 1.5-4.5 MPa, an isobutane mass space velocity of 0.5-3.0 h⁻¹, and a hydrogen to isobutane feed volume ratio of 200:1. Summary of the Invention

[0014] One of the purposes of the present application is to provide a preparation method of light alkane conversion catalyst to solve the problems of low acid center formation density, low activity, partial destruction at high temperature and poor stability in the prior art. Another purpose of the present application is to provide a light alkane conversion catalyst. A third purpose of the present application is to provide the application of the light alkane conversion catalyst.

[0015] To achieve one of the purposes of the present application, the present application provides a preparation method of light alkane conversion catalyst, which comprises the following steps:

[0016] (1) impregnating an alumina carrier with an aqueous solution containing a platinum compound, drying, calcining and then reducing to obtain a catalyst precursor;

[0017] (2) protecting the catalyst precursor in (1) with an inert gas and impregnating with a hydrocarbon solution of alkyl aluminum chloride, and then removing the solvent to obtain a pre-chlorinated product;

[0018] (3) supplementally chlorinating the pre-chlorinated product in (2) with AlCl3 sublimated at 450-700℃ carried by H2 carrier gas to obtain a catalyst, the Pt content of which is 0.01-1.0% by mass based on dry basis alumina.

[0019] To achieve the second purpose of the present application, the present application further provides a light alkane conversion catalyst prepared by the above-mentioned method of the present application.

[0020] To achieve the third purpose of the present application, the present application further provides the application of the above-mentioned light alkane conversion catalyst.

[0021] The preparation method provided by the present application can first occupy the hydroxyl groups on the surface of the carrier in the base catalyst through pre-chlorination of alkyl aluminum chloride. During the heating process before the supplementally chlorination of AlCl3, the excess alkyl aluminum chloride is removed, at this time most of the hydroxyl groups have reacted to form —OAlCl2. The supplementally chlorination of AlCl3 chlorinates the remaining hydroxyl groups, thereby increasing the density of —OAlCl2 as much as possible. In addition, HCl is also generated during the supplementally chlorination of AlCl3. Since the surface of the catalyst at this time is mainly —OAlCl2, HCl will combine with —OAlCl2 to form a part of —OAlCl3 - H + The method of the present application has a higher acid center density than the prior art, and contains a part of —OAlCl3 with very high activity - H + Therefore, the catalyst prepared by the method of the present application exhibits excellent isomerization activity. In addition, since the catalyst undergoes high temperature during the preparation process, there is no physically adsorbed chlorine-containing species on the surface of the catalyst, so the catalyst composition is stable and exhibits good activity stability. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below by way of examples, but the present invention is not limited thereto.

[0023] The preparation method of the light alkane conversion catalyst provided by the present invention comprises the following steps:

[0024] (1) impregnating an alumina support with an aqueous solution containing a platinum compound, drying, calcining, and then reducing to obtain a catalyst precursor;

[0025] (2) protecting the catalyst precursor described in (1) with an inert gas and impregnating it with a hydrocarbon solution of alkylaluminum chloride, and then removing the solvent to obtain a pre-chlorinated product;

[0026] (3) The pre-chlorinated product described in (2) is supplementally chlorinated at 450-700° C. using a carrier gas containing H 2 to carry sublimed AlCl 3 to prepare a catalyst, wherein the Pt content of the catalyst is 0.01-1.0% by mass calculated based on dry aluminum oxide.

[0027] In the method described, (1) is the preparation of a catalyst precursor, which is to load platinum on a carrier and reduce it. (1) The alumina carrier is selected from γ-Al2O3 and / or η-Al2O3. The platinum-containing compound is chloroplatinic acid, platinum tetrachloride, ammonium chloroplatinate or dinitrosodiamine platinum. Preferably, the aqueous solution of the platinum-containing compound also contains a competitive adsorbent, and the competitive adsorbent is selected from one or more of hydrochloric acid, trichloroacetic acid and nitric acid. The mass ratio of the impregnation solution used in the impregnation process to the mass of the γ-Al2O3 carrier is preferably 0.5-2.0. The drying temperature is preferably 80-140°C, more preferably 100-130°C, and the drying time is preferably 5-30h, more preferably 8-24h. The calcination is carried out in air or oxygen at 450-650°C, preferably 480-600°C, for 1-10h, preferably 3-5h. The reduction is carried out in a hydrogen-containing atmosphere at 400-600° C., the gas / agent volume ratio of the reduction process is preferably 300-1500, the reduction temperature is preferably 400-600° C., more preferably 450-580° C., and the reduction time is preferably 1-10 h, more preferably 3-5 h.

[0028] In the method, step (2) is to pre-chlorinate the catalyst precursor by impregnating the catalyst precursor with a hydrocarbon solution containing alkylaluminum chloride under the protection of an inert gas, and then removing the solvent. (2) The inert gas is selected from one or more of nitrogen, argon or helium. The alkylaluminum chloride is selected from one or more of dichloromethylaluminum, dimethylaluminum chloride, dichloroethylaluminum, dichloropropylaluminum, dichloroisobutylaluminum and dichloroisobutylaluminum. The hydrocarbon is selected from C5-C 11One or more of alkanes, toluene, xylene, and ethylbenzene, with n-hexane, n-heptane, and toluene being preferred. The concentration of alkylaluminum chloride in the hydrocarbon solution of alkylaluminum chloride is 10-50% by mass. During the impregnation process with the hydrocarbon solution of alkylaluminum chloride, the liquid / solid mass ratio is 0.5-2:1, preferably 0.8-1.5:1, the impregnation temperature is 0-120°C, preferably 10-100°C, more preferably 20-60°C, and the impregnation time is 0.1-2 hours, preferably 0.2-1.5 hours. During the desolventization process, inert gas protection is still required, and preferably, the water content in the inert gas is less than 10 ppmv. During the desolventization process, the gas / agent volume ratio is preferably 100-1500, the desolventization temperature is 0-250°C, preferably 10-200°C, more preferably 20-150°C, and the time is 0.5-10 hours, preferably 0.5-5 hours.

[0029] In the method, (3) the pre-chlorinated product is supplementally chlorinated by treating the pre-chlorinated product with sublimed AlCl3. (3) The AlCl3 is heated to a sublimation temperature of 178°C or above, and then H2-containing gas is used as a carrier gas to carry the sublimed AlCl3 vapor to contact the pre-chlorinated product for supplementary chlorination. The chlorination temperature is preferably 450-650°C. The mass ratio of the AlCl3 to the catalyst precursor contained in the pre-chlorinated product is 0.01-0.3:1, preferably 0.03-0.14:1. The H2-containing carrier gas is a mixture of pure H2 or hydrogen and one or more selected from nitrogen, argon, and helium, preferably pure H2. The gas volume ratio of the H2-containing carrier gas to the pre-chlorinated product is 100-1000:1. The pressure of the supplementary chlorination process is 0.1MPa-0.5MPa, and the time is 0.1-10h, preferably 0.2-2.0h. The catalyst has a Pt content of 0.01-1.0% by mass, preferably 0.05-0.8% by mass, calculated based on dry aluminum oxide, and a Cl content of 3.0-10.0% by mass.

[0030] The present invention also provides a light alkane conversion catalyst prepared by the above-mentioned method of the present invention.

[0031] The present invention further provides the use of the above-mentioned light alkane conversion catalyst.

[0032] The application includes the use of the catalyst in the reaction of isomeric alkanes to normal alkanes, or the application includes the use of the catalyst in the isomerization of light alkanes. When the catalyst is used in the reaction of C5 and C6 isomeric alkanes to normal alkanes or the isomerization of C5 and C6 normal alkanes, the Pt content of the catalyst is preferably 0.01-1.0% by mass, more preferably 0.1-0.5% by mass, and more preferably 0.2-0.3% by mass, based on the dry basis of the alumina. When the catalyst is used in the isomerization of n-butane or the normalization of isobutane, the Pt content of the catalyst is preferably 0.01-1.0% by mass, more preferably 0.05-0.3% by mass, and more preferably 0.1-0.2% by mass, based on the dry basis of the alumina.

[0033] The process for the conversion of light alkanes includes contacting the light alkanes with the catalyst prepared by the method of the present application under the conditions of 100-300°C, 0.5-7.0 MPa (absolute pressure), and a hydrogen / hydrocarbon molar ratio of 0.01-5.0. Preferably, the conditions are 100-200°C, preferably 1.0-5.0 MPa, and a hydrogen / hydrocarbon molar ratio of 0.05-10. The mass space velocity of the light alkanes contacting the catalyst prepared by the method of the present application is 0.5-10.0 hr -1 -1 -1 .

[0034] The light alkanes are preferably C4-C6 alkanes, such as isobutane, n-butane, isopentane, isohexane, n-pentane, and n-hexane. The alkane feedstock can be pure alkanes, such as n-butane, isobutane, n-pentane, isopentane, and n-hexane, or a mixture of C4-C6 normal alkanes or C4-C6 isomeric alkanes, such as a reformate overhead enriched in C5 / C6 normal alkanes.

[0035] The specific surface area and pore volume of the supports and catalysts in the examples and comparative examples were measured by a Micromeritics ASAP 2400 static nitrogen adsorption instrument. The measurement method was as follows: the sample was degassed at 300°C under 1.33 Pa for 4 h, liquid nitrogen was contacted with the sample at -196°C, and static adsorption equilibrium was reached. The specific surface area and pore volume were calculated by the BET method according to the difference between the nitrogen gas inlet amount and the nitrogen gas volume remaining in the gas phase after adsorption. The pore size distribution was calculated by the BJH formula.

[0036] The Pt content of the catalyst was measured by a Shimadzu UV2401PC ultraviolet-visible spectrophotometer. The sample was first dissolved with hydrochloric acid, then complexed with stannous chloride, and the Pt content was measured by colorimetry.

[0037] The Cl content of the catalyst was determined using a Swiss Metrohm potentiometric titrator 905. The sample was first dissolved with NaOH to extract chloride ions, and then titrated with silver nitrate to determine the Cl content.

[0038] Example 1

[0039] (1) Preparation of catalyst precursor

[0040] Take 60.0g BET specific surface area of ​​209.8m 2 / g, a pore volume of 0.570ml / g, a diameter of 1.4-1.6mm, and a length of 3-6mm, was added to 90.0ml of an aqueous solution containing 0.1050g of chloroplatinic acid and 2% by mass of hydrochloric acid, and immersed at 25°C for 1h. The water in the solution was then evaporated, dried at 130°C for 12h, calcined at 510°C for 4h, and then reduced with hydrogen at 500°C for 4h. The gas / agent volume ratio during reduction was 800, and a catalyst precursor was obtained.

[0041] (2) Pre-chlorination of catalyst precursor

[0042] 14.0 g of the catalyst precursor was weighed and placed in a two-necked round-bottom flask. The flask was replaced and purged with flowing N2 at 100 ml / min. Under N2 protection, 12.0 g of a 20% by mass n-heptane solution of ethylaluminum dichloride was injected into the two-necked flask and immersed at 50°C for 1 hour. Then, under nitrogen protection, the flask was transferred to a tubular reactor. Under N2 purge conditions with a gas / agent volume ratio of 500, the reactor was heated to 140°C at a rate of 5°C / min and maintained at 140°C for 4 hours to remove the solvent, obtaining a pre-chlorinated product.

[0043] (3) Preparation of catalyst

[0044] Under N2 protection, the pre-chlorinated product obtained in step (2) was loaded into a tubular reactor, and then the carrier gas was switched to H2 with a gas / agent volume ratio of 300. The reactor was heated to 550°C at a rate of 8°C / min. Sublimated AlCl3 vapor was introduced into the reactor using H2 as a carrier gas at normal pressure (absolute pressure 0.1 MPa) to supplement the pre-chlorinated product with 1.4 g of AlCl3, a chlorination temperature of 550°C, and a chlorination time of 1 h. After the chlorination was completed, H2 was continued to be passed, and the reactor was naturally cooled to below 50°C to obtain Catalyst A. The characterization results of the Pt content and Cl content of Catalyst A are listed in Table 1.

[0045] Example 2

[0046] The catalyst was prepared according to the method of Example 1, except that the mass of chloroplatinic acid in the impregnation solution in step (1) was 0.0525 g. The characterization results of the Pt content and Cl content of the prepared catalyst B are shown in Table 1.

[0047] Example 3

[0048] The catalyst was prepared according to the method of Example 1, except that the solution used for impregnation of the catalyst precursor in step (2) was a toluene solution of ethylaluminum dichloride. The characterization results of the Pt content and Cl content of the prepared catalyst C are shown in Table 1.

[0049] Example 4

[0050] The catalyst was prepared according to the method of Example 1, except that the solution used for impregnation of the catalyst precursor in step (2) was a n-heptane solution of diethylaluminum monochloride. The characterization results of the Pt content and Cl content of the prepared catalyst D are shown in Table 1.

[0051] Example 5

[0052] The catalyst was prepared according to the method of Example 1, except that the amount of AlCl3 used in step (3) was 0.7 g. The Pt content and Cl content of the prepared catalyst E are shown in Table 1 of the characterization results.

[0053] Comparative Example 1

[0054] A catalyst was prepared according to the method of Example 1, except that 22.0 g of a 20 mass % ethylaluminum dichloride n-heptane solution was used in step (2), and step (3) was omitted, to obtain Catalyst F. The Pt content and Cl content of Catalyst F are shown in Table 1.

[0055] Comparative Example 2

[0056] A pre-chlorinated product was prepared according to the method of steps (1) and (2) in Example 1, except that the amount of 20% by mass ethylaluminum dichloride n-heptane solution used in step (2) was 22.0 g. Under N2 protection, the pre-chlorinated product was charged into a tubular reactor, and then the carrier gas was switched to H2 with a gas / agent volume ratio of 300. The reactor was heated to 550°C at a rate of 8°C / min, and the pre-chlorinated product was treated at normal pressure (absolute pressure 0.1 MPa) using H2 as a carrier gas. After treating at 550°C for 1 hour, H2 was continued to flow, and the reactor was naturally cooled to below 50°C to obtain Catalyst G. The characterization results of the Pt content and Cl content of Catalyst G are shown in Table 1.

[0057] Comparative Example 3

[0058] A catalyst was prepared according to the method of Example 1, except that step (2) was omitted. The catalyst precursor prepared in step (1) was directly chlorinated using the method of step (3). The amounts of AlCl3 and catalyst precursor used were 3.1 g and 14.0 g, respectively. Other conditions were the same, to prepare Catalyst H. The characterization results of the Pt content and Cl content of Catalyst H are shown in Table 1.

[0059] Comparative Example 4

[0060] A catalyst was prepared according to the method of Example 1, except that the order of steps (2) and (3) was reversed. The catalyst precursor prepared in step (1) was first chlorinated using the method of step (3), and the chlorinated product was treated according to the method of (2) to prepare Catalyst I. The characterization results of the Pt content and Cl content of Catalyst I are shown in Table 1.

[0061] Comparative Example 5

[0062] A catalyst was prepared according to the method of Comparative Example 2, except that the mass of chloroplatinic acid in the impregnation solution in step (1) was 0.0525 g, to obtain catalyst J. The characterization results of the Pt content and Cl content of catalyst J are shown in Table 1.

[0063] Table 1

[0064] Example Catalyst number Pt content, mass % Cl content, mass % 1 A 0.24 4.52 2 B 0.13 4.41 3 C 0.24 4.52 4 D 0.24 4.47 5 E 0.24 4.51 Comparative Example 1 F 0.24 5.69 Comparative Example 2 G 0.24 3.96 Comparative Example 3 H 0.24 4.19 Comparative Example 4 I 0.24 5.62 Comparative Example 5 J 0.13 3.81

[0065] Examples 6-10

[0066] The following examples investigate the C5 / C6 isomerization reaction performance of catalysts A to E of the present invention.

[0067] The initial activity of catalysts A to E was evaluated in a small fixed-bed reactor using a hydrocarbon mixture containing 10% n-pentane and 90% n-hexane as the raw material. The evaluation conditions were: reaction temperature 130°C, reaction pressure (gauge pressure) 3.2 MPa, feed mass space velocity 1.5 hr -1 , hydrogen / hydrocarbon molar ratio 1, and the results of evaluation for 5 hours are listed in Table 2.

[0068] Table 2

[0069] C5 isomerization rate = (mass of isopentane in the product / mass of C5 alkanes in the product) × 100%;

[0070] C6 isomerization rate = (1-(mass of n-hexane in the product / mass of C6 alkanes in the product)) × 100%;

[0071] C6 selectivity = (mass of 2,2-dimethylbutane in the product / mass of C6 alkanes in the product) × 100%

[0072] Comparative Examples 6-10

[0073] Comparative Examples 6-10 investigate the C5 / C6 isomerization reaction performance of comparative catalysts F to J.

[0074] The evaluation method was the same as that of Example 6, except that catalyst A was replaced by comparative catalysts F to J, respectively. The results are listed in Table 2.

[0075] Table 2

[0076]

[0077] As can be seen from Table 2, when the platinum content of the catalysts is the same, the catalysts A, C, D, and E of the present invention have higher C5 isomerization rates, C6 isomerization rates, and C6 selectivity than the comparative catalysts F, G, H, and I, and the catalyst B of the present invention has higher C5 isomerization rates, C6 isomerization rates, and C6 selectivity than the comparative catalyst J.

[0078] Examples 11-15

[0079] Examples 11-15 investigate the isobutane normalization reaction performance of catalysts A to E of the present invention.

[0080] Using isobutane with a purity of >99.8% by mass as the reaction raw material, the initial activity of catalysts A to E of the present invention was evaluated in a small fixed-bed reactor. The evaluation conditions were: 170°C, 2.5 MPa, and a feed mass space velocity of 4.0 hr -1 , the hydrogen / hydrocarbon molar ratio was 0.1, and the results of the evaluation for 5 hours are listed in Table 3.

[0081] Table 3

[0082] Isobutane conversion = ((mass of isobutane in feedstock - mass of isobutane in product) / mass of isobutane in feedstock) × 100%;

[0083] n-Butane selectivity = (mass of n-butane in product / (mass of isobutane in feedstock - mass of isobutane in product)) × 100%

[0084] Comparative Examples 11-15

[0085] Comparative Examples 11-15 investigate the isobutane normalization reaction performance of comparative catalysts F to J.

[0086] The evaluation method was the same as that of Example 11, except that catalyst A was replaced by comparative catalysts F to J, respectively. The results are listed in Table 3.

[0087] Table 3

[0088]

[0089] As shown in Table 3, the catalyst of the present invention has higher isobutane conversion rate and n-butane selectivity than the comparative catalyst.

[0090] Examples 16-20

[0091] This example investigates the activity and stability of catalysts A to E of the present invention in a C5 / C6 isomerization reaction.

[0092] Catalysts A to E of the present invention were evaluated in a small fixed-bed reactor using a hydrocarbon mixture containing 10% by mass of n-pentane and 90% by mass of n-hexane as a raw material. The evaluation conditions were: reaction temperature 130°C, reaction pressure (gauge pressure) 3.2 MPa, feed mass space velocity 1.5 hr -1 , hydrogen / hydrocarbon molar ratio 1, and the results of evaluation for 200h are listed in Table 4.

[0093] Table 4

[0094] C5 isomerization rate = (mass of isopentane in the product / mass of C5 alkanes in the product) × 100%;

[0095] C6 isomerization rate = (1-(mass of n-hexane in the product / mass of C6 alkanes in the product)) × 100%;

[0096] C6 selectivity = (mass of 2,2-dimethylbutane in the product / mass of C6 alkanes in the product) × 100%

[0097] Comparative Examples 16-19

[0098] This comparative example investigates the activity and stability of comparative catalysts F to I in the C5 / C6 isomerization reaction.

[0099] The evaluation method is the same as that of Example 16, except that catalyst A is replaced by comparative catalysts F to I, respectively. The results are listed in Table 4.

[0100] Table 4

[0101]

[0102]

[0103] As can be seen from Table 4, the catalyst of the present invention has higher activity and stability in the C5 / C6 isomerization reaction than the comparative catalyst.

[0104] Examples 21-25

[0105] The following examples investigate the activity and stability of catalysts A to E of the present invention in the normalization reaction of isobutane.

[0106] Using isobutane with a purity of >99.8% by mass as the reaction raw material, catalysts A to E of the present invention were evaluated in a small fixed-bed reactor under the following conditions: 170°C, 2.5 MPa, and a feed mass space velocity of 4.0 hr -1 , the hydrogen / hydrocarbon molar ratio was 0.1, and the results of the evaluation for 200 hours are listed in Table 5.

[0107] Isobutane conversion = ((mass of isobutane in feedstock - mass of isobutane in product) / mass of isobutane in feedstock) × 100%;

[0108] n-Butane selectivity = (mass of n-butane in product / (mass of isobutane in feedstock - mass of isobutane in product)) × 100%

[0109] Comparative Examples 20-23

[0110] This comparative example investigates the activity and stability of Comparative Catalysts F-I in the normalization reaction of isobutane. The evaluation method is the same as that of Example 21, except that Catalyst A is replaced by Comparative Catalysts F-I, respectively. The results are listed in Table 5.

[0111] Table 5

[0112]

[0113]

[0114]

[0115] As shown in Table 5, the catalyst of the present invention has higher activity and stability in the normalization reaction of isobutane than the comparative catalyst.

Claims

1. A method for preparing a light alkane conversion catalyst, comprising the following steps: (1) impregnating an alumina support with an aqueous solution containing a platinum compound, drying, calcining, and then reducing to obtain a catalyst precursor; (2) The catalyst precursor described in (1) is protected by an inert gas and impregnated with a hydrocarbon solution of alkylaluminum chloride, and then the solvent is removed to obtain a pre-chlorinated product, wherein the concentration of alkylaluminum chloride in the hydrocarbon solution is 10-50% by mass and the impregnation temperature is 20-60° C.; (3) The pre-chlorinated product described in (2) is supplementally chlorinated at 450-700° C. using a carrier gas containing H 2 to carry sublimed AlCl 3 to prepare a catalyst, wherein the Pt content of the catalyst is 0.01-1.0% by mass calculated based on dry aluminum oxide.

2. The method according to claim 1, characterized in that (1) The alumina carrier is selected from γ-Al2O3 and / or η-Al2O3.

3. The method according to claim 1, characterized in that (1) The platinum-containing compound is selected from chloroplatinic acid, platinum tetrachloride, ammonium chloroplatinate or dinitrosodiamine platinum.

4. The method according to claim 1, characterized in that (1) The calcination is carried out in air or oxygen at 450-650°C.

5. The method according to claim 1, characterized in that (1) The reduction is carried out at 400-600°C in a hydrogen-containing atmosphere.

6. The method according to claim 1, characterized in that (2) The inert gas is selected from one or more of nitrogen, argon or helium.

7. The method according to claim 1, characterized in that (2) The alkylaluminum chloride is selected from one or more of dichloromethylaluminum, dimethylaluminum monochloride, ethylaluminum dichloride, diethylaluminum monochloride, dichloropropylaluminum, dichloroisobutylaluminum and dichloroisobutylaluminum.

8. The method according to claim 1, characterized in that (2) The hydrocarbon is selected from C5-C 11 One or more of alkanes, toluene, xylene and ethylbenzene.

9. The method according to claim 1, characterized in that (2) The immersion in the hydrocarbon solution of alkyl aluminum chloride has a liquid / solid mass ratio of 0.5-2:1 and a time of 0.1-2 hours.

10. The method according to claim 1, characterized in that (2) The temperature of the solvent removal is 20-200°C and the time is 0.5-10h.

11. The method according to claim 1, characterized in that (3) The mass ratio of the AlCl3 to the catalyst precursor contained in the pre-chlorination product is 0.01-0.3:

1.

12. The method according to claim 1, characterized in that (3) The H2-containing carrier gas is a mixture of pure H2 or hydrogen and one or more gases selected from nitrogen, argon, and helium.

13. The method according to claim 1, characterized in that (3) The volume ratio of the H2-containing carrier gas to the pre-chlorination product is 100-1000:

1.

14. The method according to claim 1, characterized in that (3) The supplementary chlorination process has a pressure of 0.1 MPa-0.5 MPa and a time of 0.1-10 h.

15. A light alkane conversion catalyst prepared by the method of any one of claims 1 to 14.

16. Use of the light alkane conversion catalyst according to claim 15.

17. Use according to claim 16, characterized in that The catalyst is used in the reaction of converting isoparaffins into normal paraffins.

18. Use according to claim 16, characterized in that The catalyst is used in the isomerization reaction of light alkanes.

Images