A process for continuously producing m-toluic acid

Abstract

The invention discloses a process for continuously producing m-toluic acid. The process comprises a synthesizing production process corresponding to a synthesizing workshop section and a rectifying production process corresponding to a rectifying workshop section. The process for continuously producing m-toluic acid comprises a work flow of (1) synthesizing process, namely synthesizing by adopting a multi-level outer-loop serial connection process; and (2) rectifying process, namely rectifying by utilizing an m-xylene recovery tower, a m-tolualdehyde recovery tower and a m-toluic acid rectifying tower. The process has the advantages of reasonable structural design and continuous operation, a gaseous phase and a liquid phase are sufficiently contacted by means of countercurrent to react, so that the reaction efficiency can be greatly improved, the product production capacity in unit interval can be improved, and operation energy consumption can be reduced. Furthermore, the continuous rectification process can be used for greatly shortening the time for heating a to-be-separated mixture and remarkably inhibiting generation of deep byproducts, so that the once through yield can be greatly improved, and the production benefit can be remarkably increased.

Description

technical field [0001] The invention belongs to a continuous production process of m-toluic acid. Background technique [0002] At present, the existing process adopts a batch method to produce m-toluic acid, that is, m-xylene is added into the bubble column and air is introduced to carry out oxidation reaction to generate the target product m-toluic acid. The main by-products include m-methylbenzaldehyde, m-methylbenzyl alcohol, isophthalic acid, benzoic acid, etc. The specific process flow is: add metered m-xylene to the bottom of the bubble tower and heat it, then pass compressed air from the bottom of the bubble tower to induce the reaction. After the reaction starts, increase the air intake while controlling the required reaction temperature. The unreacted air carries the unreacted m-xylene and the water generated by the reaction into the condenser at the top of the bubble column, and the m-xylene and water enter the phase separator after being condensed, and the liqu...

AI Technical Summary

Problems solved by technology

For the batch bubble tower, the liquid phase is in a static state, and the gas phase passes through the liquid layer to react with it, and the gas-liquid contact is insufficient, resulting in low reaction efficiency. At the same time, the production capacity per unit time is not high, and because each reaction The heating and cooling process is required, resulting in high energy consumption for process operation

[0006] In addition, the batch reaction must pass through excess air, which also leads to the excess of the reactant m-xylene.

For the batch rectification section, the yield per unit time is low, the process energy consumption is high, the operation is cumbersome, the control is complicated, the product quality is poor, and because the mixture to be separated is heated for too long in the batch rectification process, the by-products increase

[0007] In addition, the mode of operation of batch rectification causes the single-pass yield of the final product m-toluic acid to be low, only about 70%, which increases the production cost of the product to a certain extent and causes waste

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