Method for preparing cumene
By using a two-stage reaction process and a specific catalyst combination, the problems of low conversion rate and selectivity in the preparation of cumene were solved, achieving efficient cumene production and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
In existing processes for preparing cumene, the conversion rate of α,α-dimethylbenzyl alcohol and the selectivity of cumene are not high, and by-products are generated, the catalyst is easily deactivated, and the cost is high.
A two-stage reaction process is adopted. In the first stage, alumina, silica or molecular sieve with a sodium-free content of no more than 0.75 g/L are used as catalysts to dehydrate and generate α-methylstyrene. In the second stage, a catalyst of platinum group metals and additives is used to selectively hydrogenate to generate cumene at low temperature.
It improved the conversion rate of α,α-dimethylbenzyl alcohol and the selectivity of cumene, reduced the formation of by-products, enhanced catalyst activity and stability, and reduced costs.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of cumene preparation, and more specifically to a method for preparing cumene. Background Technology
[0002] Propylene oxide (PO) is the third largest propylene derivative after polypropylene and acrylonitrile, and is an important basic raw material for organic chemical synthesis. Currently, the cumene oxidation process (CHP process) is a commonly used production process for propylene oxide. However, in the CHP process, a large amount of byproduct containing α,α-dimethylbenzyl alcohol (DMBA) is generated during the propylene epoxidation process, which needs to be converted into cumene through hydrogenolysis to re-enter the reaction cycle.
[0003] US7442843B2 discloses a process for improving the yield of cumene. This technology uses a palladium-based catalyst and α,α-dimethylbenzyl alcohol and hydrogen as raw materials to produce cumene via hydrogenolysis or dehydration hydrogenation. The hydrogen used contains 0.1-10% CO, which significantly improves the conversion rate of dimethylbenzyl alcohol and the selectivity of cumene. US4075254 discloses a technology for producing alkylbenzenes from α-methylalkylstyrene using a Cu-Cr catalyst at high temperatures of 100-250°C. By improving the introduction of CO / H2 and using a Cu-Cr catalyst with poor hydrogenation ability of the benzene ring, the over-hydrogenation of cumene is suppressed, thereby improving the yield and product quality of cumene. It can be seen that in the prior art, to improve the selectivity of cumene, either a CO component is introduced into the system or a Cu-based catalyst with relatively poor hydrogenation activity and stability is used, which inevitably increases additional material and energy consumption.
[0004] CN101733093A reports the use of alumina or zeolite-supported metal Pd or a mixture of Pd and Pt as the reaction medium. Under reaction temperatures below 160°C, the conversion rate of α,α-dimethylbenzyl alcohol is greater than 99.5%, and the selectivity of cumene is greater than 99.5%. However, under these reaction conditions, the Pd catalyst readily induces the over-hydrogenation of isopropylcyclohexane in cumene in the initial stage, and the use of this catalyst significantly leads to the polymerization of methylstyrene, the dehydration intermediate of α,α-dimethylbenzyl alcohol. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for preparing cumene. The method of this invention has the advantages of high conversion rate of α,α-dimethylbenzyl alcohol, high selectivity for cumene, and few byproducts.
[0006] To achieve the above objectives, the present invention provides a method for preparing cumene, the method comprising: using a hydrocarbon material containing α,α-dimethylbenzyl alcohol as raw material to sequentially carry out a two-stage reaction, 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;
[0007] The first catalyst is selected from at least one of alumina, silica, molecular sieve and activated carbon; the sodium content in the first catalyst, calculated by element, is not greater than 0.75 g / L.
[0008] The second catalyst includes a support and a platinum group noble metal supported on the support, as well as a metal additive and / or a non-metal additive, wherein the metal additive is selected from at least one of copper, silver and molybdenum, and the non-metal additive is selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen.
[0009] The beneficial effects of the present invention through the above technical solution include:
[0010] The method for preparing cumene provided by this invention controls the selection of catalysts in two stages of reaction. In the first stage, α,α-dimethylbenzyl alcohol is completely dehydrated and converted to α-methylstyrene. In the second stage, α-methylstyrene is selectively hydrogenated to cumene. The method described in this invention can achieve a high conversion rate of α,α-dimethylbenzyl alcohol and a high selectivity for cumene, as well as greatly reduce the formation of the byproduct isopropylcyclohexane.
[0011] The catalyst provided by this invention has high catalytic activity and stability; moreover, the first catalyst provided by this invention does not require loading of active metal, which greatly reduces costs. Detailed Implementation
[0012] The endpoints and any values of the ranges disclosed herein 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 the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0013] The present invention provides a method for preparing cumene, the method comprising: using a hydrocarbon material containing α,α-dimethylbenzyl alcohol as raw material to carry out two-stage reactions sequentially, 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;
[0014] The first catalyst is selected from at least one of inorganic heat-resistant oxides, molecular sieves and activated carbon; the sodium content in the first catalyst, calculated by element, is not greater than 0.75 g / L.
[0015] The second catalyst includes a support and a platinum group noble metal supported on the support, as well as a metal additive and / or a non-metal additive, wherein the metal additive is selected from at least one of copper, silver and molybdenum, and the non-metal additive is selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen.
[0016] According to the present invention, the sodium content in the first catalyst, calculated as elemental, is not greater than 0.75 g / L. Specifically, it can be 0.75 g / L, 0.7 g / L, 0.65 g / L, 0.6 g / L, 0.55 g / L, 0.5 g / L, 0.45 g / L, 0.4 g / L, 0.35 g / L, 0.3 g / L, 0.25 g / L, 0.2 g / L, 0.15 g / L, 0.1 g / L, 0.05 g / L, 0.01 g / L, and the range of any two values from these values, preferably not greater than 0.5 g / L. Controlling the sodium content in the first catalyst within the above range can significantly improve the reaction conversion rate and selectivity.
[0017] According to the present invention, preferably, the first catalyst is selected from at least one of alumina, silica, ZSM-5 molecular sieve, SAPO-34 molecular sieve, and activated carbon. This preferred embodiment is beneficial for improving the dehydration efficiency of the first stage reaction.
[0018] The present invention does not have any particular limitation on the first catalyst. It can be obtained commercially or prepared by conventional methods in the art, as long as the sodium content is not greater than 0.75 g / L.
[0019] According to the present invention, preferably, when the first catalyst is an inorganic heat-resistant oxide, the average pore size of the first catalyst is not less than 15 nm, preferably 15-30 nm, specifically 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, and any range of any two of these values. This preferred embodiment is more conducive to improving dehydration activity.
[0020] According to the present invention, preferably, the method for preparing the first catalyst includes activating the precursor of the first catalyst, wherein the activation process includes a first drying and a first calcination. Using the above preparation process to prepare the first catalyst is beneficial for improving dehydration activity and product selectivity.
[0021] According to the present invention, preferably, the conditions for the first calcination include: a temperature of 500-1000°C and a time of 2-8 hours.
[0022] The present invention does not have any particular limitation on the first drying process, and it can be carried out with reference to conventional methods in the art.
[0023] According to the present invention, preferably, the silicon dioxide is modified silicon dioxide, which is prepared by modifying silicon dioxide with a silanizing agent.
[0024] According to the present invention, preferably, the silanizing agent is an amino-containing silane, and more preferably selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, and n-butylaminopropyltrimethoxysilane. This preferred embodiment is advantageous for improving dehydration activity and product selectivity.
[0025] According to the present invention, preferably, the method for preparing the modified silica includes: immersing activated silica in a solution containing a silanizing agent, and then performing a second drying and a second calcination to obtain modified silica.
[0026] The activation process of silicon dioxide described in this invention can be carried out with reference to the activation process in the first catalyst preparation method described above.
[0027] According to the present invention, preferably, the amount of silanizing agent used is 0.5-20g, more preferably 5-15g, relative to 1L of activated silicon dioxide.
[0028] According to the present invention, preferably, the silanizing agent in the solution contains a mass fraction of 1-5 wt%.
[0029] The present invention allows for a wide range of solvent choices in the solution containing the silanizing reagent, including various organic solvents commonly used in the art. An exemplary embodiment of the present invention uses ethanol as the solvent.
[0030] The present invention does not have any particular limitation on the second drying process, and it can be carried out with reference to conventional methods in the art.
[0031] According to the present invention, preferably, the conditions for the second calcination include: a temperature of 400-600°C and a time of 2-8 hours.
[0032] The present invention has a wide range of choices for the types of platinum group noble metals in the second catalyst. Preferably, the platinum group noble metal in the second catalyst is platinum and / or palladium, more preferably palladium.
[0033] According to the present invention, preferably, the metal additive in the second catalyst is copper.
[0034] According to the present invention, preferably, in the second catalyst, the non-metallic additive is sulfur.
[0035] The present invention has a wide range of choices for the type of support. Preferably, in the second catalyst, the support is selected from at least one of inorganic heat-resistant oxides, molecular sieves and inorganic carbon materials, and more preferably from at least one of alumina, silica, ZSM-5 molecular sieve, SAPO-34 molecular sieve and activated carbon.
[0036] According to a more preferred embodiment of the present invention, in the second catalyst, the support is alumina.
[0037] According to the present invention, preferably, in the second catalyst, the content of platinum group noble metals is 0.06 g / L-30 g / L, more preferably 0.5 g / L-5 g / L; the content of metal additives is 0 g / L-10 g / L, more preferably 0.06 g / L-1 g / L; and the content of non-metal additives is 0 g / L-1 g / L, more preferably 0.006 g / L-0.2 g / L.
[0038] According to a more preferred embodiment of the present invention, the second catalyst comprises an alumina support and a platinum group noble metal, a metal additive, and a non-metal additive supported on the alumina support, wherein the platinum group noble metal is palladium, the metal additive is copper, and the non-metal additive is sulfur. Using this second catalyst, the metal hydrogenation activity and cumene selectivity are higher.
[0039] The second catalyst of the present invention can be prepared by conventional methods in the art, as long as the composition meets the above conditions.
[0040] In the method provided by the present invention, the first stage reaction achieves complete dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene at a higher temperature, and the second stage reaction achieves selective hydrogenation of α-methylstyrene to cumene at a lower temperature.
[0041] Preferably, the reaction temperature of the first stage reaction is 140-300℃, and more preferably 220-260℃.
[0042] Preferably, the reaction temperature of the second stage reaction is 30-80℃, and more preferably 35-65℃.
[0043] According to the present invention, preferably, the reaction conditions for the first stage reaction include: a reaction temperature of 140-300℃, more preferably 220-260℃; a reaction pressure of 0.01-1MPa, more preferably 0.1-1MPa; and a liquid hourly space velocity of 1-20 h⁻¹. -1 Preferably 1-6h -1 .
[0044] According to the present invention, preferably, the first stage reaction is carried out under an inert atmosphere. This preferred embodiment is advantageous in increasing the catalyst's lifespan.
[0045] The present invention allows for a wide range of choices regarding the type of inert atmosphere, which can be conventional choices in the art. Preferably, the inert atmosphere is selected from at least one of nitrogen, helium, neon, and argon.
[0046] According to the present invention, preferably, the reaction conditions for the second stage reaction include: a reaction temperature of 30-80°C, more preferably 35-65°C; a reaction pressure of 0.1-2 MPa, more preferably 0.3-0.8 MPa; and a liquid hourly space velocity of 2-20 h⁻¹. -1 Preferably 2-8h -1 .
[0047] According to the present invention, preferably, the second stage reaction is carried out under a hydrogen atmosphere.
[0048] According to the present invention, preferably, the molar ratio of hydrogen to α,α-dimethylbenzyl alcohol in the raw material is not less than 1.2, and more preferably 1.5-3.
[0049] In the two-stage reaction of this invention, a liquid-phase circulation process may or may not be used, and the circulation ratio of each stage reaction is controlled to be 0-10. The liquid-phase circulation process can be carried out with reference to conventional methods in the art.
[0050] The present invention allows for a wide selection range for the content of α,α-dimethylbenzyl alcohol in the hydrocarbon material. Preferably, the mass content of α,α-dimethylbenzyl alcohol in the hydrocarbon material is 1-80 wt%.
[0051] According to the present invention, preferably, the hydrocarbon material further includes an inert solvent, wherein the inert solvent is preferably cumene.
[0052] According to the present invention, preferably, the inert solvent content in the hydrocarbon material is 20-90 wt%.
[0053] The hydrocarbon materials described in this invention may contain n-propylbenzene, methylstyrene, acetophenone, and other impurities.
[0054] The cumene obtained by the method described in this invention can be used to prepare propylene oxide. This invention does not specifically limit the method for preparing propylene oxide from the cumene; conventional methods in the art can be used.
[0055] Preferably, a method for preparing propylene oxide includes the following steps:
[0056] 1) Oxidize cumene to obtain cumene hydroperoxide;
[0057] 2) In the presence of a solid catalyst, cumene hydroperoxide and propylene are reacted and then separated to obtain propylene oxide and hydrocarbon materials containing α,α-dimethylbenzyl alcohol;
[0058] 3) The method provided by the present invention is used to process hydrocarbon materials containing α,α-dimethylbenzyl alcohol to obtain cumene, which is then recycled back to step 1).
[0059] The above process can be carried out with reference to conventional methods in the field, and will not be described in detail here.
[0060] The present invention will be described in detail below through embodiments.
[0061] In the following examples, the content of catalyst components was determined by X-ray fluorescence analysis.
[0062] In the following examples, the average pore size of the first catalyst was determined by the BET method;
[0063] The conversion rates of α,α-dimethylbenzyl alcohol and the yield of cumene were calculated using the following formulas:
[0064] α,α-Dimethylbenzyl alcohol conversion (%) = [(W 0 1-W t 1) / W 0 1]×100%;
[0065] Cumene yield (%) = [(W t 2-W 0 2) / W 0 1×M1 / M2×100%;
[0066] w 0 1 and w t 1: These represent the mass percentages of α,α-dimethylbenzyl alcohol in the raw materials and the finished product, respectively.
[0067] w 0 2 and w t 2: These represent the mass percentage of cumene in the raw materials and the finished product, respectively.
[0068] M1 and M2: Relative molecular weights of α,α-dimethylbenzyl alcohol and cumene, respectively.
[0069] Example 1
[0070] (1) Preparation of the first catalyst
[0071] Catalyst 1 was prepared by drying 1 liter of silica (sodium content 0.03 g / L) at 110 °C for 8 hours and calcining it at 750 °C for 4 hours. The average BET pore size of catalyst 1 was 18 nm.
[0072] (2) Preparation of the second catalyst
[0073] One liter of alumina was mixed with 2000 g of an aqueous solution of chloropalladium containing 1.5 g of palladium, dried at 110 °C for 8 hours, and calcined at 500 °C for 4 hours to obtain a palladium-based catalyst precursor. The above palladium-based catalyst precursor was mixed with a cyclohexane solution containing 0.1 g of sulfur and tert-nonyl polysulfide, and dried at 60 °C for 8 hours to obtain palladium-based catalyst 2.
[0074] (3) Preparation of cumene
[0075] Two fixed-bed reactors connected in series were used, each loaded with catalyst 1 and palladium-based catalyst 2, respectively. Hydrocarbons containing α,α-dimethylbenzyl alcohol (composition shown in Table 1) were used as feedstock for a two-stage reaction. The first stage reaction was carried out in the presence of catalyst 1, and the second stage reaction was carried out in the presence of catalyst 2. The average results after 300 hours of evaluation are shown in Table 2.
[0076] The operating conditions for the first stage reaction are as follows:
[0077] Reaction temperature: 220℃
[0078] Reaction pressure: 0.1 MPa (nitrogen gas)
[0079] Raw material volumetric hourly space velocity: 3h -1
[0080] Liquid phase circulation ratio: 0
[0081] The operating conditions for the second stage reaction are as follows:
[0082] Reaction temperature: 35℃
[0083] Reaction pressure: 0.3 MPa
[0084] Liquid hourly space velocity: 2h -1
[0085] Liquid phase circulation ratio: 3
[0086] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1
[0087] Example 2
[0088] The procedure is carried out according to the method of Example 1, except that...
[0089] (1) Preparation of the first catalyst
[0090] Catalyst 1 was prepared by drying 1 liter of silica (sodium content 0.03 g / L) at 110 °C for 8 hours and calcining it at 950 °C for 4 hours. The average BET pore size of catalyst 1 is 21 nm.
[0091] The operating conditions for the first stage reaction are as follows:
[0092] Reaction temperature: 240℃
[0093] Reaction pressure: 0.1 MPa (nitrogen gas)
[0094] Raw material volumetric hourly space velocity: 4h -1
[0095] Liquid phase circulation ratio: 0
[0096] The operating conditions for the second stage reaction are as follows:
[0097] Reaction temperature: 45℃
[0098] Reaction pressure: 0.5 MPa
[0099] Liquid hourly space velocity: 5h -1
[0100] Liquid phase circulation ratio: 3
[0101] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1
[0102] The average results of the 300-hour evaluation are shown in Table 2.
[0103] Example 3
[0104] (1) Preparation of the first catalyst
[0105] Activated silica was prepared by drying 1 liter of silica (sodium content 0.03 g / L) at 110 °C for 8 hours and calcining it at 750 °C for 4 hours. Activated silica was prepared by mixing 5 g of aminopropyltriethoxysilane and ethanol at 40 °C to obtain a 1 wt% solution, adding the activated silica, and then drying the solution at 110 °C for 8 hours and calcining it at 500 °C for 4 hours. Catalyst 1 had a sodium content of 0.03 g / L and an average BET pore size of 18 nm.
[0106] (2) Preparation of the second catalyst
[0107] One liter of alumina was mixed with 2000 g of an aqueous solution of chloropalladium acid-copper nitrate containing 1.5 g of palladium and 0.2 g of copper. The mixture was dried at 110 °C for 8 hours and calcined at 500 °C for 4 hours to obtain a palladium-based catalyst precursor. The above palladium-based catalyst precursor was mixed with a cyclohexane solution containing 0.1 g of sulfur and tert-nonyl polysulfide, and dried at 60 °C for 8 hours to obtain palladium-based catalyst 2.
[0108] (3) Preparation of cumene
[0109] Two fixed-bed reactors connected in series were used, each loaded with catalyst 1 and palladium-based catalyst 2, respectively. Hydrocarbons containing α,α-dimethylbenzyl alcohol (composition shown in Table 1) were used as feedstock for a two-stage reaction. The first stage reaction was carried out in the presence of catalyst 1, and the second stage reaction was carried out in the presence of catalyst 2. The average results after 300 hours of evaluation are shown in Table 2.
[0110] The operating conditions for the first stage reaction are as follows:
[0111] Reaction temperature: 260℃
[0112] Reaction pressure: 0.1 MPa (nitrogen gas)
[0113] Fresh oil volume hourly space velocity: 3h -1
[0114] Liquid phase circulation ratio: 0
[0115] The operating conditions for the second stage reaction are as follows:
[0116] Reaction temperature: 65℃
[0117] Reaction pressure: 0.8 MPa
[0118] Liquid hourly space velocity: 8h -1
[0119] Liquid phase circulation ratio: 3
[0120] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1
[0121] Example 4
[0122] The procedure is carried out according to the method of Example 1, except that...
[0123] (1) Preparation of the first catalyst
[0124] Activated silica was prepared by drying 1 liter of silica (sodium content 0.5 g / L) at 110 °C for 8 hours and calcining it at 750 °C for 4 hours. Activated silica was prepared by mixing 10 g of aminopropyltrimethoxysilane and ethanol at 40 °C to obtain a 2 wt% solution, adding the activated silica, and then drying the solution at 110 °C for 8 hours and calcining it at 500 °C for 4 hours. Catalyst 1 had a sodium content of 0.5 g / L and an average BET pore size of 18 nm.
[0125] Example 5
[0126] (1) Preparation of the first catalyst
[0127] Catalyst 1 was prepared by drying 1 liter of ZSM-5 molecular sieve (sodium content 0.3 g / L, silicon-aluminum molar ratio 80) at 110℃ for 8 hours and calcining at 500℃ for 4 hours.
[0128] (2) Preparation of the second catalyst
[0129] One liter of alumina was mixed with 2000 g of an aqueous solution of chloropalladium containing 1.5 g of palladium, dried at 110 °C for 8 hours, and calcined at 500 °C for 4 hours to obtain a palladium-based catalyst precursor. The above palladium-based catalyst precursor was mixed with a cyclohexane solution containing 0.1 g of sulfur and tert-nonyl polysulfide, and dried at 60 °C for 8 hours to obtain palladium-based catalyst 2.
[0130] (3) Preparation of cumene
[0131] Two fixed-bed reactors connected in series were used, each loaded with catalyst 1 and palladium-based catalyst 2, respectively. Hydrocarbons containing α,α-dimethylbenzyl alcohol (composition shown in Table 1) were used as feedstock for a two-stage reaction. The first stage reaction was carried out in the presence of catalyst 1, and the second stage reaction was carried out in the presence of catalyst 2. The average results after 300 hours of evaluation are shown in Table 2.
[0132] The operating conditions for the first stage reaction are as follows:
[0133] Reaction temperature: 220℃
[0134] Reaction pressure: 0.1 MPa (nitrogen gas)
[0135] Raw material volumetric hourly space velocity: 3h -1
[0136] Liquid phase circulation ratio: 0
[0137] The operating conditions for the second stage reaction are as follows:
[0138] Reaction temperature: 35℃
[0139] Reaction pressure: 0.3 MPa
[0140] Liquid hourly space velocity: 2h -1
[0141] Liquid phase circulation ratio: 3
[0142] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1
[0143] Example 6
[0144] (1) Preparation of the first catalyst
[0145] Catalyst 1 was prepared by drying 1 liter of activated carbon (sodium content 0.2 g / L) at 110 °C for 8 hours and calcining it at 500 °C for 4 hours.
[0146] (2) Preparation of the second catalyst
[0147] One liter of alumina was mixed with 2000 g of an aqueous solution of chloropalladium containing 1.5 g of palladium, dried at 110 °C for 8 hours, and calcined at 500 °C for 4 hours to obtain a palladium-based catalyst precursor. The above palladium-based catalyst precursor was mixed with a cyclohexane solution containing 0.1 g of sulfur and tert-nonyl polysulfide, and dried at 60 °C for 8 hours to obtain palladium-based catalyst 2.
[0148] (3) Preparation of cumene
[0149] Two fixed-bed reactors connected in series were used, each loaded with catalyst 1 and palladium-based catalyst 2, respectively. Hydrocarbons containing α,α-dimethylbenzyl alcohol (composition shown in Table 1) were used as feedstock for a two-stage reaction. The first stage reaction was carried out in the presence of catalyst 1, and the second stage reaction was carried out in the presence of catalyst 2. The average results after 300 hours of evaluation are shown in Table 2.
[0150] The operating conditions for the first stage reaction are as follows:
[0151] Reaction temperature: 220℃
[0152] Reaction pressure: 0.1 MPa (nitrogen gas)
[0153] Raw material volumetric hourly space velocity: 3h -1
[0154] Liquid phase circulation ratio: 0
[0155] The operating conditions for the second stage reaction are as follows:
[0156] Reaction temperature: 35℃
[0157] Reaction pressure: 0.3 MPa
[0158] Liquid hourly space velocity: 2h -1
[0159] Liquid phase circulation ratio: 3
[0160] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1
[0161] Comparative Example 1
[0162] The procedure is carried out according to the method of Example 1, except that...
[0163] (1) Preparation of the first catalyst
[0164] Catalyst 1 was prepared by drying 1 liter of silica (sodium content 0.9 g / L) at 110 °C for 8 hours and calcining it at 750 °C for 4 hours. The average BET pore size of catalyst 1 was 18 nm.
[0165] The average results of the 300-hour evaluation are shown in Table 2.
[0166] Comparative Example 2
[0167] (1) Preparation of the first catalyst
[0168] Catalyst 1 was prepared by drying 1 liter of silica (sodium content 0.03 g / L) at 110 °C for 8 hours and calcining it at 750 °C for 4 hours. The average BET pore size of catalyst 1 was 18 nm.
[0169] (2) Preparation of the second catalyst
[0170] One liter of alumina was mixed with 2000 grams of an aqueous solution of chloropalladic acid containing 1.5 grams of palladium. The mixture was dried at 110°C for 8 hours and calcined at 500°C for 4 hours to obtain palladium-based catalyst 2.
[0171] (3) Preparation of cumene
[0172] Two fixed-bed reactors connected in series were used, each loaded with catalyst 1 and palladium-based catalyst 2, respectively. Hydrocarbons containing α,α-dimethylbenzyl alcohol (composition shown in Table 1) were used as feedstock for a two-stage reaction. The first stage reaction was carried out in the presence of catalyst 1, and the second stage reaction was carried out in the presence of catalyst 2. The average results after 300 hours of evaluation are shown in Table 2.
[0173] The operating conditions for the first stage reaction are as follows:
[0174] Reaction temperature: 220℃
[0175] Reaction pressure: 0.1 MPa (nitrogen gas)
[0176] Raw material volumetric hourly space velocity: 3h -1
[0177] Liquid phase circulation ratio: 0
[0178] The operating conditions for the second stage reaction are as follows:
[0179] Reaction temperature: 35℃ Reaction pressure: 0.3MPa
[0180] Liquid hourly space velocity: 2h -1
[0181] Liquid phase circulation ratio: 3
[0182] Hydrogen / α,α-dimethylbenzyl alcohol molar ratio: 2:1 Table 1
[0183] Raw material composition weight composition (wt%) Cumene 64.9 n-Propane 0.12 Methylstyrene 0.13 Acetophenone 0.82 α,α-Dimethylbenzyl alcohol 33.3
[0184] Note: The balance represents other impurities.
[0185] Table 2
[0186]
[0187]
[0188] As can be seen from the results in Table 2, the method described in this invention has the advantages of high conversion rate of α,α-dimethylbenzyl alcohol, high selectivity of cumene, and few byproducts.
[0189] In addition, the first catalyst of the present invention does not require the introduction of active metals, which greatly reduces the application cost.
[0190] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing cumene, characterized in that, The method includes: using hydrocarbon materials containing α,α-dimethylbenzyl alcohol as raw materials to carry out two-stage reactions sequentially, 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; The first catalyst is selected from at least one of inorganic heat-resistant oxides, molecular sieves and activated carbon; the sodium content in the first catalyst, calculated by element, is not greater than 0.75 g / L. The second catalyst includes a support and a platinum group noble metal supported on the support, as well as a metal additive and / or a non-metal additive, wherein the metal additive is selected from at least one of copper, silver and molybdenum, and the non-metal additive is selected from at least one of sulfur, boron, silicon, phosphorus and nitrogen.
2. The method according to claim 1, wherein, In the first catalyst, the sodium content, calculated by element, is no more than 0.5 g / L; Preferably, when the first catalyst is an inorganic heat-resistant oxide, the average pore size of the first catalyst is not less than 15 nm, and more preferably 15-30 nm; 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 includes activating the precursor of the first catalyst, the activation process including a first drying and a first calcination; Preferably, the conditions for the first calcination include: a temperature of 500-1000℃ and a time of 2-8 hours.
3. The method according to claim 2, wherein, The first catalyst is modified silica, which is prepared by modifying silica with a silanizing agent; Preferably, the silanizing agent is an amino-containing silane, and is preferably selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, and n-butylaminopropyltrimethoxysilane.
4. The method according to claim 3, wherein, The method for preparing the modified silica includes: immersing activated silica in a solution containing a silanizing agent, followed by a second drying and a second calcination to obtain modified silica; Preferably, the activation process of silica includes a first drying and a first calcination, wherein the conditions for the first calcination preferably include a temperature of 500-1000℃ and a time of 2-8h.
5. The method according to claim 4, wherein, The amount of silanizing agent used relative to 1L of activated silica is 0.5-20g, preferably 5-15g; Preferably, the silanizing agent in the solution contains 1-5 wt% by mass; Preferably, the conditions for the second calcination include: a temperature of 400-600℃ and a time of 2-8h.
6. The method according to any one of claims 1-5, wherein, In the second catalyst, the platinum group noble metal is palladium; Preferably, in the second catalyst, the metal additive is copper; Preferably, in the second catalyst, the non-metallic additive is sulfur; Preferably, in the second catalyst, the support is selected from at least one of inorganic heat-resistant oxides, molecular sieves and inorganic carbon materials, and more preferably from at least one of alumina, silica, ZSM-5 molecular sieve, SAPO-34 molecular sieve and activated carbon.
7. The method according to any one of claims 1-6, wherein, In the second catalyst, the content of platinum group noble metals is 0.06 g / L-30 g / L, preferably 0.5 g / L-5 g / L; the content of metal additives is 0 g / L-10 g / L, preferably 0.06 g / L-1 g / L; and the content of non-metal additives is 0 g / L-1 g / L, preferably 0.006 g / L-0.2 g / L.
8. The method according to any one of claims 1-7, wherein, The reaction conditions for the first stage reaction include: a reaction temperature of 140-300℃, preferably 220-260℃; a reaction pressure of 0.01-1MPa, preferably 0.1-1MPa; and a liquid hourly space velocity of 1-20 h⁻¹. -1 Preferably 1-6h -1 ; Preferably, the first stage of the reaction is carried out under an inert atmosphere.
9. The method according to any one of claims 1-8, wherein, The reaction conditions for the second stage reaction include: a reaction temperature of 30-80℃, preferably 35-65℃; a reaction pressure of 0.1-2MPa, preferably 0.3-0.8MPa; and a liquid hourly space velocity of 2-20h⁻¹. -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 raw material is not less than 1.2, and more preferably 1.5-3.
10. The method according to any one of claims 1-9, wherein, The hydrocarbon material contains 1-80 wt% α,α-dimethylbenzyl alcohol. Preferably, the hydrocarbon material further includes an inert solvent, and the inert solvent is preferably cumene; Preferably, the inert solvent content in the hydrocarbon material is 20-90 wt%.