Method for preparing benzaldehyde by continuously oxidizing methylbenzene through tubular reactor

Abstract

The invention discloses a method for preparing benzaldehyde by continuously oxidizing methylbenzene through a tubular reactor, and belongs to the technical field of organic synthesis processes. The method is a process technology that a methylbenzene compound is adopted as a raw material, a metal ion complex of one or more of cobalt, molybdenum and bromine is adopted as a catalyst, hydrogen peroxide is adopted as an oxidizing agent, acetic acid is adopted as a solvent, and methylbenzene is continuously oxidized in the tubular reactor to prepare benzaldehyde. The method is mild in condition, short in reaction time, high in raw material utilization rate, capable of achieving effective control in the reaction process, safe, stable and high in production efficiency and achieves continuous operation.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis technology, and relates to a method for preparing benzaldehyde by continuous oxidation of toluene under liquid-phase reaction conditions, more specifically, using toluene as a substrate, hydrogen peroxide as an oxidant, and a compound of cobalt, molybdenum and bromine Or several metal ion complexes are used as catalysts, monocarboxylic acid is used as solvent, and benzaldehyde products are prepared continuously in tubular reactors with different microstructures. Background technique [0002] Benzaldehyde is an important fine chemical product, which is widely used in industrial fields such as medicine, dyestuff, fragrance, pesticide and materials. [0003] The traditional industrial production methods of benzaldehyde mainly include the following three methods: toluene chlorination and hydrolysis, benzoic acid (fat) reduction method and toluene direct oxidation method, wherein the toluene ...

AI Technical Summary

Problems solved by technology

In the Chinese patent with patent number CN101607867 in 2009, the method of connecting multi-stage oxidation reactors and gas-liquid separators in series was adopted, the conversion rate of toluene reached more than 95%, and the total selectivity of benzaldehyde and benzyl alcohol reached more than 50% , but the conversion rate of the single-stage reactor is low and the energy consumption is high

In summary, the existing technology has many disadvantages such as high cost, high energy consumption, complicated process, and low selectivity of benzaldehyde.

[0007] The above-mentioned methods optimize and improve the preparation of benzaldehyde by oxidation of toluene from different angles, but there are still some problems to be solved: firstly, batch production in batch still is mainly used in large-scale production; secondly, in the above-mentioned method, there are still traditional The mass heat transfer effect is poor, the utilization rate of the oxidant is low, and the phenomenon of "flying temperature" easily occurs due to local overheating, which also causes the use of a large amount of oxidant in the above process, increased side reactions, and low selectivity and yield of the target product. In addition, in the above-mentioned intermittent production method, the decomposition rate of hydrogen peroxide is relatively fast, which is likely to cause safety accidents, which is also the reason why hydrogen peroxide oxidation has no large-scale application.

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