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

Abstract

The invention discloses a method for preparing methylaniline by continuous catalytic hydrogenation reduction of nitrotoluene through a liquid phase. The method comprises the following steps that: S1,the preparing stage: ortho-nitrotoluene, meta-methylnitrobenzene, paranitrotoluene and a nano-catalyst are weighed, the mass ratio of nitrotoluene to methylaniline is 4:10, the addition quantity of the nano-catalyst is 10% of the addition quantity of the nitrotoluene; S2: the starting stage: the well weighed ortho-nitrotoluene, meta-methylnitrobenzene, paranitrotoluene and the nano-catalyst are added into a high pressure reaction kettle, and a hydrogen steel cylinder reducing valve and a pressure regulating valve are opened. According to the method for preparing the methylaniline by continuouscatalytic hydrogenation reduction of the nitrotoluene through the liquid phase, the ortho-nitrotoluene, the meta-methylnitrobenzene and the paranitrotoluene replace a solvent methyl alcohol or ethylalcohol, the loss in the reaction process is reduced, the explosion easily caused by the excessively large internal pressure is prevented, meanwhile, the nano-catalyst replaces a skeleton Ni, the costof the material is reduced, and the characteristics of recycling and stability of the nano-catalyst are used.

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 substance with a molecular formula of C7H9N, including 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, and 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 used in organic synthesis , acid absorbent and solvent, used in the dye industry for the production of cationic brilliant red FG, anionic pink B and reactive yellow brown KGR. [0003] At pre...

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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.