Tar-resisting nickel-based catalyst for synthesizing TDA (Toluenediamine) and preparation method thereof

Abstract

The invention relates to a tar-resisting nickel-based catalyst for synthesizing TDA (Toluenediamine) and a preparation method thereof. The tar-resisting nickel-based catalyst is characterized by being a supported type nickel-based nanometer catalyst, taking an HY molecular sieve as a carrier and comprising an active component of metallic nickel, wherein the mass percentage content of the metallicnickel is 30-50 percent, and the mass percentage content of the HY molecular sieve is 50-70 percent. The tar-resisting nickel-based catalyst disclosed by the invention has the advantages of simple and convenient preparation method, low cost, easiness for industrialization, convenience for use, high conversion rate and selectivity and recyclability, can be safely stored below 150 DEG C in an air atmosphere, presents a catalytic activity when directly added to a reaction system without being activated before use, and is beneficial to shortening of the production period of products.

Description

technical field [0001] The invention relates to a catalyst and a preparation method thereof, in particular to a catalyst and a preparation method for synthesizing toluenediamine by liquid-phase hydrogenation of dinitrotoluene. Background technique [0002] Toluene diamine (TDA), mainly used to produce toluene diisocyanate (TDI), is an important organic intermediate in the polyurethane industry. Polyurethane (PU) is widely used in foam plastics, elastomers, adhesives, coatings and fibers, and is currently one of the most promising synthetic materials. With the increasingly prominent position of TDI in the polyester industry, the green and efficient preparation method of TDA has become a research hotspot at home and abroad in recent years. Dinitrotoluene (DNT) is reduced to produce toluene diamine (TDA) by many methods, such as iron powder reduction method, catalytic hydrogenation method, sulfide reduction method, electrolytic reduction method and so on. Because catalytic hy...

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Problems solved by technology

[0003] At present, there are problems in the synthesis of TDA in the industry: (1) problems caused by side reactions: the catalyst has a low type-selective catalytic ability, which leads to further reaction of the product TDA; the by-product reduces the yield of the product TDA and brings difficulties to the separation and purification of the product The by-products block the surface of the catalyst and lead to catalyst deactivation; the generation of tar seriously affects the product yield and quality of meta-TDA, and the concentration of tar in the TDA separation process is too high to easily block the equipment, thereby affecting the continuity and stability of the operation

(2) Problems caused by the physical properties of the catalyst: the deactivation of the catalyst not only causes a large amount of catalyst consumption, but also reduces the reaction speed and selectivity, affects the reaction process and thus affects the yield and quality of the product; in the TDA production process, except for a small amount of deactivation The active catalyst needs to be discharged, most of the catalyst needs to be separated from the reaction liquid, and recycled; during the reaction process, the catalyst particles are gradually ground in the process of stirring with the reaction mixture in the kettle, and the fine catalyst particles The diameter can reach several microns, and it is not easy to separate; the inclined plate sedimentation is used in the current industrial production equipment, the utilization rate of the equipment is low, the concentration of the catalyst in the reactor fluctuates relatively large, and the consumption of the catalyst is high. Speed ​​up the generation of tar in the process

[0004] Analysis of the causes of the above problems is mainly due to the low mechanical strength of existing industrial catalysts, easy wear, too small particle size and difficult separation, low selectivity, high requirements for reaction temperature, and long reaction residence time.

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