Hydrogenation process for benzoic acid

Abstract

The invention discloses a hydrogenation process for benzene carboxylic acid, characterized in that, the reacted mixture is separated through liquid rotation and centrifugal separation, wherein the putrid fluid after rotation separation is circulated into the reactor, and the clear liquid is fed into centrifugal separator. The process provided by the invention can effectively separate nickel auxiliary agent, further increase Pd / C activity, thus possesses higher reaction processing capacity and productive efficiency.

Description

technical field [0001] The invention relates to a hydrogenation method of benzoic acid. Background technique [0002] The hydrogenation of benzoic acid is an important step in the process of preparing caprolactam by SNIA technology. The traditional benzoic acid hydrogenation process uses Pd / C as a catalyst, and the mixture of Pd / C and benzoic acid passes through four serially connected stirring hydrogenation reactors for hydrogenation reaction. The operating pressure and operating temperature of the four reactors are basically the same, the operating temperature is 165°C, and the operating pressure range is 1.2-1.35MPa. The materials in the four reactors exist in three phases of gas, liquid and solid, of which 90% are liquid phase, 8% are gas phase and 2% are solid phase. More than 96% of the liquid phase is hexahydrobenzoic acid (abbreviated as CCA), more than 98% of the gas phase is hydrogen, and the solid phase is a Pd / C catalyst. The flow mode is turbulent overflow mo...

AI Technical Summary

Problems solved by technology

However, the disadvantage of this method is that due to the limited capacity of the centrifugal separator, the nickel additive flowing into the subsequent system will reduce the incineration rate of Pd / C, prolong the incineration time, and affect the incineration process of Pd recovery, thereby affecting the entire reaction. hydrogenation efficiency

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