A kind of catalyst and its preparation method for dns hydrogenation reduction preparation das

Abstract

The invention relates to the catalyst field, and in particular relates to a catalyst for preparing DAS by from DNS by hydrogenation reduction and a preparation method thereof. The catalyst comprises a palladium / carbon catalyst, a surfactant and a passivating agent, wherein the weight ratio of the palladium / carbon catalyst to the surfactant is 100:0.1 to 5; a solvent of the catalyst is pure water, and the weight of the pure water is 3-20 times, preferably 5-10 times, of the weight of the palladium / carbon catalyst. The catalyst has the advantages of high yield, high content of high performance liquid chromatography, low impurity, fast reaction speed, short production period, light product color, low iron ion content, low production energy consumption and the like. The catalyst not only solves the problem that the catalyst selectivity of DNS catalytic hydrogenation is not high in previous reports, and meanwhile the service life of the catalyst is greatly improved.

Description

technical field [0001] The invention relates to the field of catalysts, in particular to a catalyst for preparing DAS by hydrogenation reduction of DNS and a preparation method thereof. Background technique [0002] DAS acid (4,4'-diaminostilbene-2,2'-disulfonic acid) is an important raw material for the production of stilbene bistriazine amino-type brighteners, and is also an important intermediate for the manufacture of direct dyes and reactive dyes It can also be used to synthesize insecticides. For a long time, industrial production has adopted the Bechamp reduction method of nitroaromatics, that is, iron powder reduction method. Its principle is to reduce nitroaromatics to corresponding aromatic amines with iron powder, ferrous chloride and dilute acid. This method is simple in operation, low in production cost, and easy to control, but it will produce a large amount of solid waste iron sludge. Although there are comprehensive utilizations to produce iron red, the cur...

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Problems solved by technology

2011103425758 This application relates to a palladium-loaded mesoporous carbon catalyst to commercial TiO 2 As a carrier, prepared as Ni-Au-Pt / TiO 2 Nano multi-metal catalyst, although the preparation of the catalyst is simple, but precious metals such as gold and platinum are needed, so the cost of the catalyst is high

It has been verified by experiments that the selectivity cannot achieve satisfactory results, and the life of the catalyst is out of the question. Not only is the selectivity not up to standard, but it will also bring serious consequences of heavy metal pollution of the reaction solution.

[0006] At present, although many institutions in China are researching the preparation of DAS by catalytic hydrogenation of DNS, according to public reports, it is basically focused on how to improve the catalytic selectivity of hydrogenation, but the actual selectivity and the high Selectivity has not been reported in the literature

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