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CN-122010667-A - Method for preparing isopropylbenzene

CN122010667ACN 122010667 ACN122010667 ACN 122010667ACN-122010667-A

Abstract

The invention relates to the field of cumene preparation, and discloses a method for preparing cumene. The method comprises the steps of sequentially carrying out two-stage reaction by taking a hydrocarbon material containing alpha, alpha dimethyl benzyl alcohol as a raw material, wherein the first-stage reaction is carried out in the presence of a first catalyst, the second-stage reaction is carried out in the presence of a second catalyst, the first catalyst is selected from at least one of inorganic heat-resistant oxide, molecular sieve and active carbon, the sodium content calculated by elements in the first catalyst is not more than 0.75g/L, the second catalyst comprises a carrier, platinum noble metal loaded on the carrier, and metal auxiliary agents and/or non-metal auxiliary agents, the metal auxiliary agents are selected from at least one of copper, silver and molybdenum, and the non-metal auxiliary agents are selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen. The method has the advantages of high conversion rate of alpha, alpha dimethyl benzyl alcohol, high selectivity of isopropylbenzene and few byproducts.

Inventors

  • ZHAO DUO
  • LIU ZHONGNENG
  • Lv Yuhao
  • MA WENDI
  • HUANG LE

Assignees

  • 中国石油化工股份有限公司
  • 中石化（上海）石油化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A method for preparing isopropylbenzene is characterized by comprising the steps of sequentially carrying out two-stage reaction by taking hydrocarbon materials containing alpha, alpha dimethyl benzyl alcohol as raw materials, wherein the first-stage reaction is carried out in the presence of a first catalyst, and the second-stage reaction is carried out in the presence of a second catalyst; wherein the first catalyst is at least one of inorganic heat-resistant oxide, molecular sieve and active carbon, and the sodium content in element is not more than 0.75g/L; The second catalyst comprises a carrier, a platinum group noble metal supported on the carrier, and a metal auxiliary agent and/or a non-metal auxiliary agent, wherein the metal auxiliary agent is selected from at least one of copper, silver and molybdenum, and the non-metal auxiliary agent is selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen.
  2. 2. The method of claim 1, wherein, In the first catalyst, the sodium content calculated as element is not more than 0.5g/L; preferably, when the first catalyst is an inorganic refractory oxide, the average pore diameter of the first catalyst is not less than 15nm, preferably 15 to 30nm; preferably, the first catalyst is selected from at least one of alumina, silica, ZSM-5 molecular sieve, SAPO-34 molecular sieve, and activated carbon; Preferably, the preparation method of the first catalyst comprises the steps of activating a precursor of the first catalyst, wherein the activation process comprises first drying and first roasting; preferably, the conditions of the first calcination include a temperature of 500-1000 ℃ and a time of 2-8 hours.
  3. 3. The method of claim 2, wherein, The first catalyst is modified silicon dioxide, and the modified silicon dioxide is prepared by modifying silicon dioxide by adopting a silanization reagent; Preferably, the silylating agent is an amino-containing silane, preferably at least one selected from the group consisting of aminopropyl triethoxysilane, aminopropyl trimethoxysilane and n-butylaminopropyltrimethoxysilane.
  4. 4. The method according to claim 3, wherein the modified silica is produced by immersing the activated silica in a solution containing a silylating agent, followed by a second drying and a second calcination to obtain the modified silica; preferably, the activation process of the silica comprises a first drying and a first calcination, the conditions of which preferably comprise a temperature of 500-1000 ℃ for a time of 2-8 hours.
  5. 5. The method of claim 4, wherein, The amount of silylating agent is 0.5 to 20g, preferably 5 to 15g, relative to 1L of activated silica; Preferably, the mass fraction of the silylating agent in the solution containing the silylating agent is 1-5wt%; Preferably, the conditions of the second calcination include a temperature of 400-600 ℃ for 2-8 hours.
  6. 6. The method according to any one of claims 1 to 5, wherein, In the second catalyst, the platinum group noble metal is palladium; preferably, in the second catalyst, the metal auxiliary agent is copper; Preferably, in the second catalyst, the nonmetallic aid is sulfur; preferably, in the second catalyst, the support is selected from at least one of inorganic refractory oxide, molecular sieve and inorganic carbon material, preferably at least one selected from alumina, silica, ZSM-5 molecular sieve, SAPO-34 molecular sieve and activated carbon.
  7. 7. The method according to any one of claims 1-6, wherein, In the second catalyst, the content of the platinum group noble metal is 0.06g/L-30g/L, preferably 0.5g/L-5g/L, the content of the metal auxiliary agent is 0g/L-10g/L, preferably 0.06g/L-1g/L, and the content of the nonmetal auxiliary agent is 0g/L-1g/L, preferably 0.006g/L-0.2g/L.
  8. 8. The method according to any one of claims 1-7, wherein, The reaction conditions of the first stage reaction comprise a reaction temperature of 140-300 ℃, preferably 220-260 ℃, a reaction pressure of 0.01-1MPa, preferably 0.1-1MPa, and a liquid phase volume space velocity of 1-20h -1 , preferably 1-6h -1 ; preferably, the first stage reaction is carried out under an inert atmosphere.
  9. 9. The method according to any one of claims 1-8, wherein, The reaction conditions of the second stage reaction comprise a reaction temperature of 30-80 ℃, preferably 35-65 ℃, a reaction pressure of 0.1-2MPa, preferably 0.3-0.8MPa, and a liquid phase volume space velocity of 2-20h -1 , preferably 2-8h -1 ; preferably, the second stage reaction is carried out under a hydrogen atmosphere; preferably, the molar ratio of hydrogen to α, α -dimethylbenzyl alcohol in the feedstock is not less than 1.2, preferably in the range 1.5 to 3.
  10. 10. The method according to any one of claims 1-9, wherein, In the hydrocarbon material, the mass content of the alpha, alpha dimethyl benzyl alcohol is 1-80wt%; Preferably, the hydrocarbon feed further comprises an inert solvent, preferably cumene; preferably, the mass content of the inert solvent in the hydrocarbon material is 20-90wt%.

Description

Method for preparing isopropylbenzene Technical Field The invention relates to the field of cumene preparation, in particular to a method for preparing cumene. Background Propylene Oxide (PO) is a third largest propylene derivative other than polypropylene and acrylonitrile, and is an important basic organic chemical synthesis raw material. Currently, the cumene oxidation process (CHP process) for producing propylene oxide is a production process commonly used in the art. However, in the technology of producing propylene oxide by CHP method, a large amount of byproduct containing α, α -dimethylbenzyl alcohol (DMBA) is produced in propylene epoxidation process, cumene is required to be produced by hydrogenation and hydrogenolysis reaction, and the reaction cycle is re-participated. US7442843B2 proposes a process for improving the yield of cumene, which adopts a palladium-based catalyst, and uses alpha, alpha-dimethylbenzyl alcohol and hydrogen as raw materials to produce the cumene through hydrogenolysis or dehydration hydrogenation, wherein the hydrogen contains 0.1-10% of CO, so that the conversion rate of dimethylbenzyl alcohol and the selectivity of the cumene can be obviously improved. US4075254 discloses a technique for producing alkylbenzenes from alpha-methyl alkylstyrene using Cu-Cr catalysts at high temperatures of 100-250 ℃. The over-hydrogenation of the cumene is inhibited by improving the introduction of CO/H 2 and using a Cu-Cr catalyst with poor hydrogenation capacity to benzene rings, thereby improving the yield and the product quality of the cumene. It can be seen that in order to improve cumene selectivity, either a CO component is introduced into the system or a Cu-based catalyst with relatively poor hydrogenation activity and stability is used in the prior art, which necessarily increases additional material and energy consumption. CN101733093a reports that using alumina or zeolite supported metal Pd or a mixture of Pd and Pt as a reaction, the conversion rate of α, α -dimethylbenzyl alcohol is greater than 99.5% and the selectivity of cumene is greater than 99.5% under the condition that the reaction temperature is lower than 160 ℃, but under the condition that the Pd catalyst is very easy to cause the cumene to produce over-hydrogenated isopropyl cyclohexane in the initial stage, and the catalyst can obviously cause polymerization of methyl styrene as a dehydration intermediate product of α, α -dimethylbenzyl alcohol. Disclosure of Invention The invention aims to overcome the problems in the prior art and provides a method for preparing isopropylbenzene. The method has the advantages of high conversion rate of alpha, alpha-dimethylbenzyl alcohol, high selectivity of isopropylbenzene and few byproducts. In order to achieve the above object, the present invention provides a method for preparing cumene, comprising sequentially carrying out two-stage reactions with a hydrocarbon material containing α, α -dimethylbenzyl alcohol as a raw material, the first-stage reaction being carried out in the presence of a first catalyst, and the second-stage reaction being carried out in the presence of a second catalyst; wherein the first catalyst is at least one of alumina, silicon dioxide, molecular sieve and active carbon, and the sodium content in element is not more than 0.75g/L; The second catalyst comprises a carrier, a platinum group noble metal supported on the carrier, and a metal auxiliary agent and/or a non-metal auxiliary agent, wherein the metal auxiliary agent is selected from at least one of copper, silver and molybdenum, and the non-metal auxiliary agent is selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen. Through the technical scheme, the beneficial effects of the invention include: The method for preparing the isopropylbenzene provided by the invention has the advantages that the selection of the catalyst in the two-stage reaction is controlled, the first-stage reaction realizes that the alpha, alpha-dimethylbenzyl alcohol is completely dehydrated and converted into the alpha-methylstyrene, the second-stage reaction realizes that the alpha-methylstyrene is selectively hydrogenated into the isopropylbenzene, and the method can realize higher conversion rate of the alpha, alpha-dimethylbenzyl alcohol and selectivity of the isopropylbenzene, and greatly reduce the generation of isopropyl cyclohexane as a byproduct. The catalyst provided by the invention has higher catalytic activity and stability, and the first catalyst provided by the invention does not need to load active metal, so that the cost is greatly reduced. Detailed Description The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and t