Method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene with ethanol or ethylene

Abstract

The present invention relates to a method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene with ethanol or ethylene in the field of chemical synthesis technology. In a reaction device, the catalyst Mn@ZSM-5 is loaded in a fixed reaction bed, the reaction raw materials are ethylbenzene and ethanol or ethylene, the reaction temperature is 280-320 °C, the reaction pressure is 0.5 Mpa-1.5 MPa, the molar ratio of ethylbenzene to ethanol or ethylene is 10-14:1, and the weight hourly space velocity is 0.5 h-1. In the present invention, the Mn@ZSM-5 catalyst adjusts the surface acid distribution and pore channels of the ZSM-5 molecular sieve through Mn elements to obtain a catalyst for mixed diethylbenzene with high yield and high selectivity. Finally, the yield of mixed diethylbenzene is ≥28 wt%, and the selectivity of mixed diethylbenzene is ≥98 wt%. At the same time, its reaction temperature is lower than that of the prior art, and the present invention is applicable to the production of mixed diethylbenzene.

Description

Technical Field

[0001] The present invention relates to a method for synthesizing mixed diethylbenzene, specifically to a method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene with ethanol or ethylene, and belongs to the field of chemical engineering technology. Background Art

[0002] Mixed diethylbenzene, also known as mixed diethyl benzene, is an organic raw material. Mixed diethylbenzene refers to a mixture of p - diethylbenzene (abbreviated as PDEB) and m - diethylbenzene (abbreviated as MDEB). p - Diethylbenzene is mainly used for producing adsorbent desorbent for p - xylene (abbreviated as PX) and p - divinylbenzene; the main use of mixed diethylbenzene is to produce divinylbenzene (abbreviated as DVB), and it is also used as a pharmaceutical intermediate and solvent, etc.

[0003] At present, the methods for producing mixed diethylbenzene in China are all chemical synthesis methods: (1) Producing ethylbenzene by benzene alkylation and by - product polyethylbenzene from styrene production unit, and then separating by rectification to obtain mixed diethylbenzene; (2) Using benzene or ethylbenzene alkylation with ethylene or ethanol, but the main disadvantage of this method is that the reaction temperature is relatively high, generally between 350 - 450 °C, resulting in more by - products in the reaction, low utilization rate of alkylating agent, short catalyst life, frequent regeneration, high raw material consumption, low yield of mixed diethylbenzene, and high production cost.

[0004] Although certain progress has been made in the research of adsorption separation method, especially the product purity is not high, generally about 95 - 98%, which cannot meet the requirements for producing high - quality desorbent. Other methods for producing mixed diethylbenzene mainly include: superfractionation method, crystallization method, coordination method, etc., all of which are in the research and development stage.

[0005] CN113333014A discloses a solid catalyst for alkylation of ethylbenzene with ethanol / ethylene to produce diethylbenzene, which is depositing MgO on strip - shaped nano - HZSM - 5 molecular sieve, and the mass ratio of MgO to strip - shaped nano - HZSM - 5 molecular sieve is 0.5 - 6.0%. The preparation method is to impregnate the strip - shaped nano - HZSM - 5 molecular sieve in a magnesium salt solution for 6 - 8 hours, take the solid and dry it at 80 - 120 °C, and then calcine it at 500 - 600 °C in air atmosphere for 4 h. The magnesium salt is at least one of Mg(NO3)2, Mg(CH3COO)2, MgCl2 and MgSO4, and the concentration of the magnesium salt solution is based on the mass ratio of MgO obtained after calcination at 500 - 600 °C for 4 h to strip - shaped HZSM - 5 molecular sieve being 0.5 - 6.0%. The reaction temperature is 320 - 380 °C, the conversion rate of ethylbenzene ≥ 16 wt%, the yield of mixed diethylbenzene ≥ 15 wt%, and the highest content of by - product benzene is 13.06 wt%.

[0006] CN105381814 discloses an ethylbenzene and ethanol alkylation reaction catalyst, which is made from the following raw materials in weight percentages: 10% - 30% of alumina, and 70% - 90% of modified hydrogen-type eutectic ZSM-5 / ZSM-11 molecular sieve; the modified hydrogen-type ZSM-5 / ZSM-11 molecular sieve is the hydrogen-type ZSM-5 / ZSM-11 molecular sieve modified by citric acid. In addition, the present invention also discloses a preparation method of the catalyst, and the method is as follows: (1) knead the raw materials and then dry them to obtain a mixture; (2) roast the mixture in a water vapor atmosphere to obtain the catalyst. When the catalyst of the present invention is used in the alkylation reaction of ethylbenzene and ethanol to prepare p-diethylbenzene, it can, while obtaining a relatively high conversion rate of ethylbenzene (ethanol), greatly inhibit side reactions such as alkyl transfer, and improve the selectivity of the reaction product diethylbenzene or p-diethylbenzene.

[0007] CN107913727 discloses a preparation method of a catalyst for efficiently alkylating ethylbenzene to p-diethylbenzene, belonging to the technical field of catalyst preparation. The method mixes nano hydrogen-type ZSM-5 molecular sieve with a binder and an extrusion aid, adds an inorganic acid solution and a modified component magnesium and phosphorus mixed peptizing agent during the kneading process, and after extrusion molding, performs hydrothermal aging treatment to improve the catalyst stability. The carrier only obtains the catalyst by impregnating a modified component silicon in one step. The pore size and the external surface acidity of the molecular sieve in the catalyst are significantly improved in terms of reaction performance and stability under the synergistic modification of magnesium, silicon, and phosphorus. Compared with the prior art, in the preparation method provided by the present invention, the modified components magnesium and phosphorus can be directly introduced during extrusion, simplifying the preparation process and reducing the industrial production cost.

[0008] CN1605390 discloses a catalyst and a preparation method for the alkylation synthesis of p-diethylbenzene from ethanol and ethylbenzene. Using an H-ZSM-5 molecular sieve with an Si / Al ratio of 50 as the base material, the surface acidity and pore channels of the catalyst are adjusted by B, Mg, and Co, and it is a high-efficiency p-diethylbenzene synthesis industrial catalyst with an ideal pore size distribution and an acidic distribution in the pore channels and strong anti-coking ability. Among them, the precursor of B is boric acid, the precursor of Mg is magnesium nitrate, and the precursor of Co is cobalt nitrate. The mass ratio of B to the H-ZSM-5 molecular sieve is 1% - 3%, the mass ratio of Mg to the H-ZSM-5 molecular sieve is 0.1% - 1%, and the mass ratio of Co to the H-ZSM-5 molecular sieve is 1% - 3%.

[0009] Its disadvantages are as follows: The key technology of mixed diethylbenzene is the catalytic alkylation method of ethylbenzene and ethanol or ethylene, and the core technology is the activity and selectivity of the alkylation catalyst. Existing catalysts such as ZSM-5, hydrogen-type ZSM-5, and Mg-ZSM-5 catalysts generally have problems such as a relatively high reaction temperature and low selectivity of mixed diethylbenzene. Summary of the Invention

[0010] The object of the present invention is to provide a method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene with ethanol or ethylene, aiming to solve the problems existing in the synthesis of mixed diethylbenzene, so that the catalyst has high activity, and the purpose of improving the product yield and selectivity is achieved.

[0011] The object of the present invention is achieved as follows: A method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene with ethanol or ethylene. In the reaction device, the catalyst is loaded in a fixed reaction bed, the reaction raw materials are ethylbenzene and ethanol or ethylene, the reaction temperature is 280 - 320 °C, the reaction pressure is 0.5 Mpa - 1.5 MPa, the molar ratio of ethylbenzene to ethanol or ethylene is 10 - 14:1, and the weight hourly space velocity is 0.5 h-1; the catalyst is Mn@ZSM-5.

[0012] Further, the catalyst Mn@ZSM-5 is obtained through the following steps:

[0013] 1) Mix an aqueous solution of manganese nitrate with ZSM-5 fine powder and heat with stirring for 3 - 4 h;

[0014] 2) Heat and evaporate until it can be extruded into strips. After extrusion into strips, vacuum dry at 100 - 120 °C for 2 - 3 h;

[0015] 3) Finally, after calcination in a muffle furnace at 550 ± 10 °C for 9 - 10 h, the Mn@ZSM-5 catalyst is obtained.

[0016] Preferably, in ZSM-5, the silicon-aluminum molar ratio is 400:1.

[0017] Preferably, the mass ratio of manganese nitrate to ZSM-5 molecular sieve is 1:4 - 8.

[0018] Compared with the prior art, the beneficial effect of the present invention lies in that the Mn@ZSM-5 catalyst adjusts the surface acidity distribution and pore channels of the ZSM-5 molecular sieve through the Mn element, obtaining a catalyst for mixed diethylbenzene with high yield and high selectivity. Finally, the yield of mixed diethylbenzene ≥ 28 wt%, and the selectivity of mixed diethylbenzene ≥ 98 wt%. At the same time, its reaction temperature is lower than that of the prior art, and the present invention is applicable to the production of mixed diethylbenzene. Specific Embodiments

[0019] Example 1:

[0020] Weigh 16.67 g of manganese nitrate and dissolve it in 300 g of distilled water. Then weigh 100 g of ZSM-5 molecular sieve fine powder with a silicon-aluminum molar ratio of 400 and disperse it therein. Mix and heat with stirring for 3 - 4 h; then heat and evaporate until it can be extruded into strips. After extrusion into strips, vacuum dry at 120 °C for 2 - 3 h; after drying, calcine in a muffle furnace at 550 ± 10 °C for 9 - 10 h to obtain the Mn@ZSM-5 molecular sieve catalyst.

[0021] The above-mentioned Mn@ZSM-5 catalyst was loaded in a fixed reaction bed, the reaction temperature was 300 °C, the reaction pressure was 1.0 MPa, the molar ratio of ethylbenzene to ethanol was 12:1, and the weight hourly space velocity was 0.5 h -1 . The yield of mixed diethylbenzene was 30.9 wt%, and the selectivity of mixed diethylbenzene was 99.4 wt%.

[0022] Example 2-1:

[0023] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:4", and the others are the same as in Example 1.

[0024] Example 2-2:

[0025] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:5, and the others are the same as in Example 1.

[0026] Example 2-3:

[0027] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:7", and the others are the same as in Example 1.

[0028] Example 2-4:

[0029] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:8", and the others are the same as in Example 1.

[0030] Comparative Example 2-a:

[0031] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:3", and the others are the same as in Example 1.

[0032] Comparative Example 2-b:

[0033] Change to "wherein the mass ratio of manganese nitrate to ZSM-5 is 1:9", and the others are the same as in Example 1.

[0034] Table 1 Comparison table of the influence of Mn loading on the yield and selectivity of mixed diethylbenzene

[0035]

[0036] According to the comparison results in Table 1, as the Mn loading gradually decreases, the yield and selectivity first increase and then decrease. It is better to use a mass ratio of manganese nitrate to ZSM-5 of 1:4 - 8, and preferably 1:6.

[0037] Example 3-1:

[0038] Change to "the reaction temperature is 280 °C", and the others are the same as in Example 1.

[0039] Example 3-2:

[0040] Change to "the reaction temperature is 290 °C", and the others are the same as in Example 1.

[0041] Example 3-3:

[0042] Change to "reaction temperature is 310 °C", and the others are the same as in Example 1.

[0043] Example 3-4:

[0044] Change to "reaction temperature is 320 °C", and the others are the same as in Example 1.

[0045] Comparative Example 3-a:

[0046] Change to "reaction temperature is 270 °C", and the others are the same as in Example 1.

[0047] Comparative Example 3-b:

[0048] Change to "reaction temperature is 330 °C", and the others are the same as in Example 1.

[0049] Table 2 Comparative Table of the Influence of Reaction Temperature on the Yield and Selectivity of Mixed Diethylbenzene

[0050]

[0051] According to the comparison results in Table 2, as the reaction temperature gradually increases, the yield and selectivity first increase and then decrease. It is better to use a reaction pressure of 280 - 320 °C, and preferably 300 °C.

[0052] Example 4-1:

[0053] Change to "maintain the reaction pressure at 0.5 Mpa", and the others are the same as in Example 1.

[0054] Example 4-2:

[0055] Change to "maintain the reaction pressure at 0.8 Mpa", and the others are the same as in Example 1.

[0056] Example 4-3:

[0057] Change to "maintain the reaction pressure at 1.2 Mpa", and the others are the same as in Example 1.

[0058] Example 4-4:

[0059] Change to "maintain the reaction pressure at 1.5 Mpa", and the others are the same as in Example 1.

[0060] Comparative Example 4-a:

[0061] Change to "maintain the reaction pressure at 0.4 Mpa", and the others are the same as in Example 1.

[0062] Comparative Example 4-b:

[0063] Change to "maintain the reaction pressure at 1.6 Mpa", and the others are the same as in Example 1.

[0064] Table 3 Comparison table of the influence of reaction pressure on the yield and selectivity of mixed diethylbenzene

[0065]

[0066] According to the comparison results in Table 3, as the reaction pressure gradually increases, the yield and selectivity first increase and then decrease. It is better to use a reaction pressure of 0.1 - 1.5 MPa, and preferably 1.0 MPa.

[0067] Example 5-1:

[0068] Change to "the molar ratio of ethylbenzene to ethanol is 10:1", and the others are the same as in Example 1.

[0069] Example 5-2:

[0070] Change to "the molar ratio of ethylbenzene to ethanol is 11:1", and the others are the same as in Example 1.

[0071] Example 5-3:

[0072] Change to "the molar ratio of ethylbenzene to ethanol is 13:1", and the others are the same as in Example 1.

[0073] Example 5-4:

[0074] Change to "the molar ratio of ethylbenzene to ethanol is 14:1", and the others are the same as in Example 1.

[0075] Comparative Example 5-a:

[0076] Change to "the molar ratio of ethylbenzene to ethanol is 9:1", and the others are the same as in Example 1.

[0077] Comparative Example 5-b:

[0078] Change to "the molar ratio of ethylbenzene to ethanol is 15:1", and the others are the same as in Example 1.

[0079] Table 4 Comparison table of the influence of the molar ratio of ethylbenzene to ethanol on the yield and selectivity of mixed diethylbenzene

[0080]

[0081] According to the comparison results in Table 4, as the molar ratio of ethylbenzene to ethanol gradually increases, the yield and selectivity first increase and then decrease. It is better to use a molar ratio of 10 - 14:1, and preferably 12:1.

[0082] Example 6-1:

[0083] Change to "the molar ratio of ethylbenzene to ethylene is 10:1", and the others are the same as in Example 1.

[0084] Example 6-2:

[0085] Change to "the molar ratio of ethylbenzene to ethylene is 11:1", and the others are the same as in Example 1.

[0086] Example 6-3:

[0087] Change to "the molar ratio of ethylbenzene to ethylene is 13:1", and the others are the same as in Example 1.

[0088] Example 6-4:

[0089] Change to "the molar ratio of ethylbenzene to ethylene is 14:1", and the others are the same as in Example 1.

[0090] Comparative Example 6-a:

[0091] Change to "the molar ratio of ethylbenzene to ethylene is 10:1", and the others are the same as in Example 1.

[0092] Comparative Example 6-b:

[0093] Change to "the molar ratio of ethylbenzene to ethylene is 14:1", and the others are the same as in Example 1.

[0094] Table 5 Comparative Table of the Influence of the Mass Ratio of Ethylbenzene to Ethylene on the Yield and Selectivity of Mixed Diethylbenzene

[0095]

[0096] According to the comparison results in Table 5, as the molar ratio of ethylbenzene to ethylene gradually increases, the yield and selectivity of mixed diethylbenzene first increase and then decrease. A molar ratio of 10-14:1 is preferred, and 12:1 is more preferred.

[0097] Example 7-1

[0098] Change the silicon-aluminum molar ratio to 300:1, and the others are the same as in Example 1.

[0099] Example 7-2

[0100] Change the silicon-aluminum molar ratio to 200:1, and the others are the same as in Example 1.

[0101] Example 7-3

[0102] Change the silicon-aluminum molar ratio to 500:1, and the others are the same as in Example 1.

[0103] Example 7-4

[0104] Change the silicon-aluminum molar ratio to 600:1, and the others are the same as in Example 1.

[0105] Table 6 Comparative Table of the Influence of the Silicon-Aluminum Molar Ratio of ZSM-5 on the Yield and Selectivity of Mixed Diethylbenzene

[0106]

[0107] According to the comparison results in Table 6, with the increase and decrease of the silica-alumina ratio, the yield and selectivity of mixed diethylbenzene will both decrease sharply, and a molar ratio of 400:1 is the best.

[0108] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and deformations to some of the technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A method for synthesizing mixed diethylbenzene by alkylation of ethylbenzene and ethanol, characterized in that: In the reaction device, the catalyst is loaded in a fixed reaction bed. The reaction raw materials are ethylbenzene and ethanol. The reaction temperature is 280 - 320 °C, the reaction pressure is 0.5 Mpa - 1.5 MPa, the molar ratio of ethylbenzene to ethanol is 10 - 14:1, and the weight hourly space velocity is 0.5 h-1; the catalyst is Mn@ZSM-5; The catalyst Mn@ZSM-5 is obtained through the following steps: 1) Mix an aqueous solution of manganese nitrate with ZSM-5 fine powder and heat with stirring for 3 - 4 h; in ZSM-5, the molar ratio of silicon to aluminum is 400:1; the mass ratio of manganese nitrate to ZSM-5 molecular sieve is 1:4 - 8; 2) Heat and evaporate until it can be extruded into strips. After extrusion into strips, vacuum dry at 100 - 120 °C for 2 - 3 h; 3) Finally, after calcination in a muffle furnace at 550 ± 10 °C for 9 - 10 h, the Mn@ZSM-5 catalyst is obtained.

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