Device and method for producing methylaniline by continuous liquid-phase catalytic hydrogenation reduction of nitrotoluene

Abstract

The invention discloses a device and method for producing methyl aniline through performing continuous liquid-phase catalytic hydrogenation reduction on nitrotoluene. The method comprises the steps as follows: firstly, nitrotoluene and a precious metal catalyst are put into a hydrogenation reactor for coating backing material, and air in system is displaced completely through nitrogen gas and hydrogen gas in sequence; secondly, a feeding valve is opened, and the nitrotoluene is sent into the hydrogenation reactor continuously, wherein the mass ratio of the nitrotoluene to the precious metal catalyst is 1: (0.001 to 0.005); thirdly, the hydrogen gas is introduced for conducting the hydrogenation reaction, wherein the reaction temperature is 60-100 DEG C and the pressure is 0.5-1.5 MPa; fourthly, a hydrogenated liquid enters a heat exchanger through a circulating pump and then passes through a cross flow filter, and the catalyst and part of the hydrogenated liquid as well as fresh raw materials jointly enter an injector for circulating, while the other part of the hydrogenated liquid is extracted continuously and subjected to follow-up processing for obtaining the methyl aniline. According to the invention, the production period is short, the yield is high, the quality is stable, the production cost is low, the device efficiency is high, and the production continuity is achieved.

Description

technical field [0001] The invention relates to a production device and method for methylaniline, in particular to a device and method for producing methylaniline through continuous liquid-phase catalytic hydrogenation reduction of nitrotoluene. Background technique [0002] Methylaniline is a kind of important organic chemical raw material, has wide application in industries such as medicine, dyestuff, rubber, and in recent years, its demand keeps growing. Traditional methylaniline synthetic method mainly contains nitrotoluene reduction method (JournalofCatalysis 191 (2000): 467? 473), methylphenol amination method (US Patent 3272865) and halogenated toluene amination method (Catalysis Today 37 (1997): 121? 136) etc., in addition, Chinese patent CN1706808A proposes to use ammonia water as the ammoniating agent, U.S. Patent 3919155, US Patent 6933409B1 uses ammonia gas as the ammoniating agent, all can directly synthesize methylaniline from toluene, although the above method...

AI Technical Summary

Problems solved by technology

The chemical reduction method includes iron powder reduction and alkali sulfide reduction. The process is mature, but the pollution is heavy, the energy consumption is high, the yield is low, and the product quality is poor.

The catalytic hydrogenation reduction method is divided into liquid-phase catalytic hydrogenation and gas-phase catalytic hydrogenation. The gas-phase catalytic hydrogenation reduction method has the advantages of no solvent, low operating pressure, and large production scale. However, the process has high energy consumption and hydrogen consumption. Large amount, high reaction temperature, large equipment investment

Compared with the gas-phase catalytic hydrogenation reduction method, the liquid-phase catalytic hydrogenation reduction method has the advantages of low reaction temperature, low energy consumption, low production cost, less waste, and high product yield. Production, the process has long production cycle, many side reactions, cumbersome operation, high labor intensity, unstable product quality, large investment, low equipment utilization rate, and low production efficiency

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