Method for preparing methylaniline by reducing nitrotoluene through liquid phase continuous catalytic hydrogenation

Abstract

The invention discloses a method for preparing methylaniline by reducing nitrotoluene through liquid phase continuous catalytic hydrogenation. The method comprises the following steps: S1, preparationstage: weighing o-nitrotoluene, m-methylnitrobenzene, p-nitrotoluene and a nano-catalyst, and enabling the addition mass ratio of the nitrotoluene to the methylaniline to be 4:10 and the addition amount of the nano-catalyst to be 10 percent that of the nitrotoluene; S2, start stage: feeding the weighed o-nitrotoluene, meta-methylnitrobenzene, p-nitrotoluene and nano-catalyst into a high-pressurereactor, and opening a pressure reducing valve and a pressure regulating valve of a hydrogen gas cylinder. The method for preparing the methylaniline by reducing the nitrotoluene through the liquid phase continuous catalytic hydrogenation, disclosed by the invention, has the advantages that methanol or ethanol as a solvent is replaced with the o-nitrotoluene, the meta-methylnitrobenzene and the p-nitrotoluene, so that loss in the reaction process is reduced, and easy explosion due to over-great internal pressure is prevented; in addition, a skeleton Ni is replaced with the nano-catalyst, so that the production cost of the material is reduced; the characteristics of cycle use and stability of the nano-catalyst are utilized.

Description

technical field [0001] The invention relates to the technical field of producing methylaniline, in particular to a method for preparing methylaniline through liquid-phase continuous catalytic hydrogenation reduction of nitrotoluene. Background technique [0002] Methylaniline is a chemical formula C 7 h 9 The chemical substance of N includes three isomers of o-toluidine, m-toluidine and p-toluidine. The three isomers have different physical properties but have the same chemical properties. The melting point of methylaniline is minus 57 degrees Celsius , the boiling point is 196.25 degrees Celsius, its relative density is 0.9891, and its refractive index is 1.5684. It is slightly soluble in water, soluble in ethanol, ether, and chloroform. This chemical substance is an intermediate, acid absorbent and solvent for organic synthesis, and a dye In the industry, it is used in the production of cationic brilliant red FG, anionic pink B and active yellow brown KGR. [0003] At p...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the deficiencies of the prior art, the present invention provides a method for preparing methylaniline by liquid phase continuous catalytic hydrogenation reduction of nitrotoluene, which solves the current domestic liquid phase solvent intermittent hydrogenation reduction process, using ethanol or methanol as a solvent , with the skeleton Ni as a catalyst, hydrogenation reaction is carried out to prepare methylaniline. This process introduces additional solvent methanol or ethanol in the reaction. The loss of solvent methanol or ethanol is large, the energy consumption is high, and it is flammable, explosive and prone to accidents. Methanol is toxic, so the production cost of the whole process is increased, and the safety factor is low, and it is not environmentally friendly.