Method for preparing styrene through side chain alkylation of toluene and synthesis gas

Abstract

The invention discloses a method for preparing styrene by side chain alkylation of toluene and synthesis gas, which comprises the following raw materials: a main raw material: toluene with the purity of not less than 99.5%; the molar ratio of the synthesis gas to the H2 to the CO is (1.5-2.5): 1; according to the formula of the catalyst, a hydrogen type ZSM-5 molecular sieve, a hydrogen type EU-1 molecular sieve and macroporous alumina are used as carriers, and zinc oxide, copper oxide and cerium oxide are used as active components; the invention relates to the technical field of chemical production. According to the method for preparing styrene through side chain alkylation of toluene and synthesis gas, hydrogen-type ZSM-5 and hydrogen-type EU-1 molecular sieves are used as one part of a carrier, the two molecular sieves have unique pore structures and acidity, can provide a good catalytic environment and are beneficial to side chain alkylation reaction, and macroporous alumina is introduced as one part of the carrier, so that the side chain alkylation reaction is facilitated. The high specific surface area and pore volume of the catalyst are beneficial to uniform dispersion of active components, the activity of the catalyst is improved, the catalyst has better stability, the catalytic activity can be kept for a long time, and the replacement frequency and production cost of the catalyst are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, in particular to a method for preparing styrene by side chain alkylation of toluene and synthesis gas. Background Art

[0002] Styrene (ST) is the most widely used chemical product among benzene derivatives and is also the most basic aromatic chemical. It can be used to manufacture a variety of downstream chemical products such as polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), expanded polystyrene (EPS), and styrene-butadiene rubber (SBR).

[0003] The invention with publication number CN106278778A discloses a method for preparing styrene from toluene and synthesis gas with high selectivity, wherein synthesis gas is used as a side chain alkylation agent for toluene to prepare styrene, thereby avoiding the hydrogen transfer reaction between styrene and methanol in the toluene-methanol side chain alkylation reaction, and improving the styrene / ethylbenzene ratio of the product, which not only effectively inhibits the formation of ethylbenzene in the product, but also reduces the raw material cost of the toluene side chain alkylation reaction; the bifunctional catalyst used has good stability, and no obvious deactivation phenomenon is observed after continuous operation for 500 hours in a fixed bed reactor.

[0004] The above styrene preparation process effectively improves stability and output. However, when the catalyst is used directly in a fixed bed reactor for catalytic reaction, the catalyst efficiency will be affected by factors such as surface area, which in turn will affect the efficiency and quality of styrene preparation. In addition, the existing preparation process consumes a lot of raw materials and heat energy, and it is difficult to reduce costs. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for preparing styrene by side chain alkylation of toluene and synthesis gas, which solves the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing styrene by side chain alkylation of toluene and synthesis gas, specifically comprising the following steps:

[0007] (1) Raw material formula:

[0008] Main raw materials: toluene, purity not less than 99.5%; synthesis gas, molar ratio of H2 to CO is 1.5-2.5:1;

[0009] Catalyst formula: contains hydrogenated ZSM-5, hydrogenated EU-1 molecular sieve and macroporous alumina as carriers, zinc oxide, copper oxide and cerium oxide as active components;

[0010] (2) Preparation steps:

[0011] Carrier preparation: ① ZSM-5, EU-1 molecular sieve and macroporous alumina are mixed according to a set ratio;

[0012] ② Add inorganic acid as a peptizing agent, adjust the pH value to 4-5, and stir until a uniform slurry is formed;

[0013] ③ The slurry is subjected to molding treatment, dried, and then calcined to obtain a molded carrier;

[0014] Catalyst preparation: ① Treat the shaped carrier with acid and alkali in sequence, wash it to neutrality and then dry it after each treatment, and recycle the washing water for later use;

[0015] ② Carry out ammonium exchange treatment, wash until no chloride ions are detected, and then dry;

[0016] ③ Impregnation with a metal salt solution, followed by drying and calcination to obtain a catalyst precursor;

[0017] ④ Reduction treatment under hydrogen atmosphere to obtain the catalyst;

[0018] Reaction steps: ① The catalyst is loaded into a fixed bed reactor and the synthesis gas is introduced for activation treatment;

[0019] ② introducing gasified toluene and synthesis gas in proportion to carry out side chain alkylation reaction;

[0020] ③ Control the reaction environment parameters, collect the product styrene through condensation and separation devices, recover and recycle the unreacted raw materials and by-products, and recover heat between similar reaction equipment.

[0021] Preferably, the carrier specifically comprises:

[0022] 20% hydrogenated ZSM-5 molecular sieve, SiO2:Al2O3 molar ratio is 50:1;

[0023] 10% hydrogen-type EU-1 molecular sieve, SiO2:Al2O3 molar ratio is 50:1;

[0024] 40% macroporous alumina, with a specific surface area of ​​about 370m 2 / g, pore volume is about 0.8mL / g;

[0025] The active components specifically include: 10% zinc oxide, 15% copper oxide, and 5% cerium oxide.

[0026] Preferably, the slurry is extruded and then dried at 110° C. for 12 hours, and then calcined at 550° C. for 4 hours to obtain a shaped carrier.

[0027] Preferably, the acid treatment uses a 0.1M dilute sulfuric acid solution for immersion for 1 hour, the alkali treatment uses a 0.1M sodium hydroxide solution for immersion for 0.5 hour, and the ammonia treatment uses a 1M ammonium chloride solution for immersion for 2 hours, and the drying temperature is 110°C;

[0028] The metal salt-impregnated support was dried at 120°C and then calcined at 450°C for 4 hours.

[0029] Preferably, deionized water is used for washing, and the waste water after washing is recovered, filtered, purified and concentrated for later use.

[0030] Preferably, the reduction treatment is to reduce the catalyst precursor at 400° C. for 2 hours.

[0031] Preferably, the reaction environment parameters controlled are: reaction temperature at 350-400°C, pressure at 2-3 MPa, and space velocity (GHSV) at 1000-2000h.

[0032] Preferably, in continuous production, the toluene liquid is heated and gasified by high-temperature exhaust gas generated by high-temperature roasting, and in the condensation step, the toluene liquid to be used is used to participate in condensation, and the absorbed heat is used to preheat the toluene liquid.

[0033] Beneficial Effects

[0034] The present invention provides a method for preparing styrene by side chain alkylation of toluene and synthesis gas. Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The method for preparing styrene by side chain alkylation of toluene and synthesis gas uses hydrogen-type ZSM-5 and hydrogen-type EU-1 molecular sieves as part of the carrier. These two molecular sieves have unique pore structures and acidity, can provide a good catalytic environment, and are conducive to the side chain alkylation reaction. The introduction of macroporous alumina as part of the carrier has a high specific surface area and pore volume that is conducive to the uniform dispersion of active components, improves the activity of the catalyst, has better stability, can maintain catalytic activity for a long time, and reduces the replacement frequency and production cost of the catalyst. The preparation process of the catalyst is carried out through acid-base treatment, ammonium exchange treatment, metal salt solution impregnation and reduction treatment under hydrogen atmosphere. These steps can optimize the pore structure, active sites and surface properties of the catalyst, thereby improving its catalytic activity and selectivity. Finally, the product styrene is collected by a condensation and separation device, and the unreacted raw materials and by-products are recovered and recycled, which improves the utilization rate of the raw materials and the yield of the product, and has significant economic and environmental benefits.

[0036] 2. The method for preparing styrene by side chain alkylation of toluene and synthesis gas selects zinc oxide, copper oxide and cerium oxide as active components. These metal oxides show good activity and selectivity in catalytic side chain alkylation reactions, which are helpful to improve the yield and purity of styrene; the surface properties and acidity of the carrier are adjusted through acid-base treatment and ammonium exchange treatment, and the catalytic performance of the catalyst is optimized; the active components are loaded onto the carrier by metal salt solution impregnation method, ensuring the uniform distribution and efficient utilization of the active components; deionized water is used in the washing process, and the waste water is recovered for filtration, purification and concentration for standby use, reducing the consumption of water resources and the discharge of waste water; heat is recovered and utilized between similar reaction equipment, which improves the energy utilization efficiency and reduces energy consumption. The utilization rate of raw materials is improved, the waste of raw materials is reduced, and the production cost is reduced.

[0037] 3. The method for preparing styrene by side chain alkylation of toluene with synthesis gas utilizes the high-temperature waste gas generated by high-temperature roasting to heat and gasify toluene, which not only realizes the effective utilization of waste gas but also reduces additional energy consumption. At the same time, the toluene liquid itself absorbs heat for preheating during the condensation process, which further improves the energy utilization efficiency and processing efficiency of the overall production process. In addition, reducing energy consumption also helps to reduce carbon emissions and other environmental costs in the production process. Integrating waste heat recovery and preheating steps into the continuous production process makes the production process more compact and efficient. This helps to reduce material loss and waste in the production process and improve production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The present invention provides three technical solutions:

[0041] Figure 1 The first embodiment is shown: a method for preparing styrene by side chain alkylation of toluene and synthesis gas, which specifically comprises the following steps:

[0042] (1) Raw material formula:

[0043] Main raw material: toluene, purity not less than 99.5%; in order to ensure that the purity of toluene reaches above 99.5%, precise distillation and filtration technology is required to remove impurities. In actual operation, toluene may need to undergo multi-stage distillation and pass through a molecular sieve or activated carbon filter to remove residual organic solvents, water and other non-hydrocarbon impurities. In addition, in order to avoid the influence of moisture on the reaction, toluene also needs to be dried, such as using anhydrous sodium sulfate or molecular sieve desiccant;

[0044] Synthesis gas, the molar ratio of H2 to CO is 1.5 to 2.5:1; in actual operation, the preparation of synthesis gas may require natural gas reforming, coal gasification or biomass gasification and other processes. Before the synthesis gas enters the reaction system, it needs to be strictly purified to remove impurities such as sulfur, nitrogen, and chlorine that may poison the catalyst;

[0045] Catalyst formula: contains hydrogenated ZSM-5, hydrogenated EU-1 molecular sieve and macroporous alumina as carriers, zinc oxide, copper oxide and cerium oxide as active components;

[0046] (2) Preparation steps:

[0047] Carrier preparation: ① ZSM-5, EU-1 molecular sieve and macroporous alumina are mixed according to a set ratio;

[0048] ② Add inorganic acid as a peptizing agent, adjust the pH value to 4-5, and stir until a uniform slurry is formed;

[0049] ③ The slurry is subjected to molding treatment, dried, and then calcined to obtain a molded carrier;

[0050] Catalyst preparation: ① Treat the shaped carrier with acid and alkali in sequence, wash it to neutrality and then dry it after each treatment, and recycle the washing water for later use;

[0051] ② Carry out ammonium exchange treatment, wash until no chloride ions are detected, and then dry;

[0052] ③ Impregnation with a metal salt solution, followed by drying and calcination to obtain a catalyst precursor;

[0053] ④ Reduction treatment under hydrogen atmosphere to obtain the catalyst;

[0054] Reaction steps: ① The catalyst is loaded into a fixed bed reactor and the synthesis gas is introduced for activation treatment;

[0055] ② introducing gasified toluene and synthesis gas in proportion to carry out side chain alkylation reaction;

[0056] ③ Control the reaction environment parameters, collect the product styrene through condensation and separation devices, recover and recycle the unreacted raw materials and by-products, and recover heat between similar reaction equipment.

[0057] Hydrogenated ZSM-5 and hydrogenated EU-1 molecular sieves are used as part of the carrier. These two molecular sieves have unique pore structures and acidity, which can provide a good catalytic environment and are conducive to the side chain alkylation reaction. The introduction of macroporous alumina as part of the carrier has a high specific surface area and pore volume that is conducive to the uniform dispersion of active components, improves the activity of the catalyst, has better stability, can maintain catalytic activity for a long time, and reduces the replacement frequency and production cost of the catalyst. The preparation process of the catalyst undergoes acid-base treatment, ammonium exchange treatment, metal salt solution impregnation, and reduction treatment under hydrogen atmosphere. These steps can optimize the pore structure, active sites, and surface properties of the catalyst, thereby improving its catalytic activity and selectivity. Finally, the product styrene is collected by a condensation and separation device, and the unreacted raw materials and by-products are recovered and recycled, which improves the utilization rate of the raw materials and the yield of the product, and has significant economic and environmental benefits.

[0058] The second embodiment is mainly different from the first embodiment in that the carrier specifically comprises:

[0059] 20% hydrogenated ZSM-5 molecular sieve, SiO2:Al2O3 molar ratio is 50:1;

[0060] 10% hydrogen-type EU-1 molecular sieve, SiO2:Al2O3 molar ratio is 50:1;

[0061] 40% macroporous alumina, with a specific surface area of ​​about 370m 2 / g, pore volume is about 0.8mL / g;

[0062] The active components specifically include: 10% zinc oxide, 15% copper oxide, and 5% cerium oxide.

[0063] The slurry was extruded and then dried at 110°C for 12 hours, and then calcined at 550°C for 4 hours to obtain a molded carrier.

[0064] The acid treatment uses a 0.1M dilute sulfuric acid solution for immersion for 1 hour, the alkali treatment uses a 0.1M sodium hydroxide solution for immersion for 0.5 hour, and the ammonia treatment uses a 1M ammonium chloride solution for immersion for 2 hours, and the drying temperature is 110°C;

[0065] The metal salt-impregnated support was dried at 120°C and then calcined at 450°C for 4 hours.

[0066] Deionized water is used for washing, and the waste water after washing is recovered, filtered, purified and concentrated for use.

[0067] The reduction treatment is to reduce the catalyst precursor at 400° C. for 2 hours.

[0068] The controlled reaction environment parameters are: reaction temperature at 350-400°C, pressure at 2-3MPa, and space velocity (GHSV) at 1000-2000h.

[0069] Zinc oxide, copper oxide and cerium oxide were selected as active components. These metal oxides showed good activity and selectivity in catalytic side chain alkylation reactions, which helped to improve the yield and purity of styrene. The surface properties and acidity of the carrier were adjusted through acid-base treatment and ammonium exchange treatment, and the catalytic performance of the catalyst was optimized. The active components were loaded onto the carrier by metal salt solution impregnation method, ensuring the uniform distribution and efficient utilization of the active components. Deionized water was used in the washing process, and the wastewater was recovered for filtration, purification and concentration before standby, reducing the consumption of water resources and the discharge of wastewater. Heat was recovered between similar reaction equipment to improve energy utilization efficiency and reduce energy consumption. The utilization rate of raw materials was improved, the waste of raw materials was reduced, and the production cost was reduced.

[0070] The second implementation mode is mainly different from the first implementation mode in that: in continuous production, the toluene liquid is heated and gasified by the high-temperature exhaust gas generated by high-temperature roasting, and in the condensation step, the toluene liquid to be used is used to participate in the condensation, and the absorbed heat is used to preheat the toluene liquid.

[0071] By utilizing the high-temperature waste gas generated by high-temperature roasting to heat and gasify toluene, not only is the waste gas effectively utilized, but additional energy consumption is also reduced. At the same time, the heat absorbed by the toluene liquid itself is used for preheating during the condensation process, which further improves the energy utilization efficiency and processing efficiency of the overall production process. In addition, reducing energy consumption also helps reduce carbon emissions and other environmental costs in the production process. Integrating waste heat recovery and preheating steps into the continuous production process makes the production process more compact and efficient. This helps reduce material loss and waste in the production process and improves production efficiency and product quality.

[0072] Comparison case:

[0073] The production data of an existing similar process for preparing styrene is compared with that of this process. The comparison table is as follows:

[0074]

[0075]

[0076] As can be seen from the table, this process is superior to the traditional process in terms of raw material cost, catalyst cost, catalyst life, output, styrene purity, energy consumption, by-product generation, by-product recovery rate and waste treatment cost. These advantages make the total cost of the new process lower, improve economic benefits, and also have better environmental benefits.

[0077] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0078] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0079] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing styrene by side chain alkylation of toluene and synthesis gas, characterized in that: include: (1) Raw material formula: Main raw materials: toluene, purity not less than 99.5%; synthesis gas, molar ratio of H2 to CO is 1.5-2.5:1; Catalyst formula: contains hydrogenated ZSM-5, hydrogenated EU-1 molecular sieve and macroporous alumina as carriers, zinc oxide, copper oxide and cerium oxide as active components; (2) Preparation steps: Carrier preparation: ① ZSM-5, EU-1 molecular sieve and macroporous alumina are mixed according to a set ratio; ② Add inorganic acid as a peptizing agent, adjust the pH value to 4-5, and stir until a uniform slurry is formed; ③ The slurry is subjected to molding treatment, dried, and then calcined to obtain a molded carrier; Catalyst preparation: ① Treat the shaped carrier with acid and alkali in sequence, wash it to neutrality and then dry it after each treatment, and recycle the washing water for later use; ② Carry out ammonium exchange treatment, wash until no chloride ions are detected, and then dry; ③ Impregnation with a metal salt solution, followed by drying and calcination to obtain a catalyst precursor; ④ Reduction treatment under hydrogen atmosphere to obtain the catalyst; Reaction steps: ① The catalyst is loaded into a fixed bed reactor and the synthesis gas is introduced for activation treatment; ② introducing gasified toluene and synthesis gas in proportion to carry out side chain alkylation reaction; ③ Control the reaction environment parameters, collect the product styrene through condensation and separation devices, recover and recycle the unreacted raw materials and by-products, and recover heat between similar reaction equipment.

2. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: The carrier specifically comprises: 20% hydrogenated ZSM-5 molecular sieve, SiO2:Al2O3 molar ratio is 50:1; 10% hydrogen-type EU-1 molecular sieve, SiO2:Al2O3 molar ratio is 50:1; 40% macroporous alumina, with a specific surface area of ​​about 370m 2 / g, pore volume is about 0.8mL / g; The active components specifically include: 10% zinc oxide, 15% copper oxide, and 5% cerium oxide.

3. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: The slurry was extruded and then dried at 110°C for 12 hours, and then calcined at 550°C for 4 hours to obtain a molded carrier.

4. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: The acid treatment uses a 0.1M dilute sulfuric acid solution for immersion for 1 hour, the alkali treatment uses a 0.1M sodium hydroxide solution for immersion for 0.5 hour, and the ammonia treatment uses a 1M ammonium chloride solution for immersion for 2 hours, and the drying temperature is 110°C; The metal salt-impregnated support was dried at 120°C and then calcined at 450°C for 4 hours.

5. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: Deionized water is used for washing, and the waste water after washing is recovered, filtered, purified and concentrated for use.

6. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: The reduction treatment is: reducing the catalyst precursor at 400° C. for 2 hours.

7. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: The controlled reaction environment parameters are: reaction temperature at 350-400°C, pressure at 2-3MPa, and space velocity (GHSV) at 1000-2000h.

8. The method for preparing styrene by side chain alkylation of toluene and synthesis gas according to claim 1, characterized in that: In continuous production, the toluene liquid is heated and gasified by the high-temperature exhaust gas generated by high-temperature roasting. In the condensation step, the toluene liquid to be used is used to participate in the condensation, and the absorbed heat is used to preheat the toluene liquid.

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