Technique for producing styrene by alkylating toluene and methanol side chains

Abstract

The invention discloses a technique for producing styrene by alkylating toluene and methanol side chains. The method comprises the steps of mixing and heating methanol vapor and air to obtain a mixture, enabling the mixture to enter a reactor producing formaldehyde by using methanol, and generating formaldehyde under the action of a catalyst; condensing a product, enabling the condensed product to enter a rectifying tower so as to remove water generated in the reaction, pressurizing a product at the tower top, enabling the pressurized product to enter a high-pressure separator, discharging noncondensable gas containing hydrogen from the top of the high-pressure separator, mixing and heating and a product at the bottom and toluene, enabling the mixture to enter a side chain alkylation reactor, enabling a gaseous product to return to therectifying tower after a product obtained in the reaction is subjected to separation by a gas-liquid separator, enabling a liquid product to enter a toluene tower, an ethylbenzene tower and a styrene tower sequentially, enabling toluene to return to the side chain alkylation reactor, and discharging ethylbenzene, styrene and C9<+>heavy aromatics. The technique is of a two-step method for toluene and methanol side chain alkylation, not only can the generation degree of a side reaction between styrene and hydrogen be effectively inhibited, but also the hydrothermal deactivation of the catalyst for side chain alkylation can be alleviated.

Description

technical field [0001] The invention relates to a process for preparing styrene by side-chain alkylation of toluene and methanol. Background technique [0002] Styrene is an important organic chemical product and petrochemical raw material, which can produce various synthetic resins, such as general-purpose polystyrene (GPS), high-impact polystyrene (HIPS), AS, ABS, PS, EPS, MBS and various modified polystyrene resins are widely used in industrial sectors such as automobile manufacturing, household appliances and toy manufacturing. Styrene-butadiene rubber made of styrene and butadiene is widely used in tire manufacturing, styrene-butadiene latex is used in textile and papermaking, and styrene-butadiene block copolymer SBS thermoplastic elastomer is used in light industrial fields such as shoemaking. In recent years, as the demand for polystyrene and ABS resin, the downstream products of styrene, continues to increase, the demand for raw material styrene is huge. Since my ...

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Problems solved by technology

Although this method achieves the purpose of avoiding its decomposition by not using methanol, the reaction conversion rate is low, and the hydrogen rich in the raw material is prone to side reactions with the generated styrene, the yield of styrene is low, and carbon monoxide is an acidic gas, which is easy to react with the catalyst The basic site combined to deactivate the catalyst;

[0005] Patent CN201210325048.0 discloses a process for producing ethylbenzene and styrene by side-chain alkylation of toluene and methanol, which uses toluene and the first stream of methanol to enter the first reaction zone and contact with the catalyst to generate stream 1, stream 1 Enter at least one second reaction zone with the second methanol, contact with catalyst, generate stream 2, stream 2 enter at least one third reaction zone, contact with catalyst, generate the technical scheme of stream 3 containing ethylbenzene and styrene to solve The problems of easy decomposition and low utilization rate of methanol existing in the prior art

There are many reactors in this process, the investment and energy consumption are huge, the hydrogen produced by the decomposition of methanol gradually accumulates, and has a side reaction with the generated styrene to form ethylbenzene. The yield of styrene is low, the cost is high, and the income is low, so it is difficult to industrialize

[0006] Due to the hydrogen and water that will be generated during the methanol-to-formaldehyde reaction, the hydrogen will react with the product styrene to form ethylbenzene, resulting in a styrene yield of only about 5%; the generated water will cause side chain alkylation catalyst water Thermal inactivation, the existing process does not solve these problems

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