Process for synthesis of toluenediamine by low pressure hydrogenation of dinitrotoluene, catalyst and preparation method of catalyst

Abstract

A process for synthesis of toluenediamine (TDA) by low pressure hydrogenation of dinitrotoluene (DNT) is as follows: preparing a fresh Raney nickel catalyst and DNT into fresh catalyst slurry, adding the fresh catalyst slurry into a hydrogenation reactor; respectively adding raw material DNT and hydrogen into the hydrogenation reactor for reaction, leading a liquid reaction product into a catalyst separator I for separation, sending an upper clear liquid to a catalyst separator II, sending a gas phase into a purge gas separator, and returning settled catalyst slurry to the hydrogenation reactor; and filtering a clear liquid in the central part of the catalyst separator II with a filter to obtain a crude TDA product. The process has the advantages of low equipment investment, low energy consumption, and synthesis of the toluenediamine (TDA) by hydrogenation of the dinitrotoluene in the absence of an externally added solvent and under the low pressure condition of 1MPa.

Description

technical field [0001] The invention belongs to a process for industrially synthesizing toluene diamine, a catalyst and a preparation method of the catalyst, in particular to a process for synthesizing toluene diamine through low-pressure hydrogenation of dinitrotoluene, a Raney nickel catalyst used and a preparation method of the catalyst. Background technique [0002] Toluenediamine (TDA), also known as diaminotoluene, is an important chemical raw material and chemical intermediate, which is usually synthesized by hydrogenation of dinitrotoluene (DNT) in the presence of an external organic solvent and catalyst. At present, there are two main DNT hydrogenation technologies in the industry: the first is the American DuPont technology using supported Pd+Pt / C noble metal catalysts, which has the advantages of low reaction pressure (1MPa), high catalyst activity and no need for additional solvents. However, there are the disadvantages that the catalyst is difficult to separate,...

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Problems solved by technology

[0008] In order to achieve the above-mentioned purpose, the present invention breaks through the shackles of conventional technical cognition that nickel-based catalysts need to add solvents and reaction pressures up to 2MPa in the hydrogenation reaction of dinitrotoluene, and through a large number of catalyst modification experiments, activity evaluation experiments and mechanism research Analyzed and screened and compared various nickel-based catalysts, and successfully developed a Raney nickel catalyst with activity similar to noble metal catalysts at a low pressure of about 1MPa and without an external solvent; and according to the developed Raney nickel catalyst. Catalytic performance , strength and settling properties, through a large number of theoretical calculations and experimental research to further develop a new process of dinitrotoluene hydrogenation continuous production of tolenediamine; Raney nickel catalyst in the new process of dinitrotoluene hydrogenation The invention not only completely overcomes the shortcomings of the existing two industrial DNT hydrogenation technologies, but also fundamentally solves the problem that the catalysts in the two industrial dinitrotoluene hydrogenation technologies such as Sweden and the DuPont technology in the United States are expensive, deactivated and separated. Difficulties and problems in BASF technology that require additional solvent, high reaction pressure and large investment in equipment

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