Catalyst for use in preparation of paraphenyldimethylamine and preparation method thereof

Abstract

The invention discloses a catalyst for use in the preparation of paraphenyldimethylamine, which is a supported nickel catalyst. The carrier of the catalyst is gamma-Al2O3 type aluminum oxide, the specific surface area of the carrier is 170 to 200m<2> / g, the pore volume is 0.35 to 0.45cm<3> / g, and the aperture is 4.5 to 6.0nm, the carrier is loaded with nickel and an auxiliary catalyst which may be copper, cobalt, iron or zinc or one or two of copper, cobalt, iron or zinc, the loaded nickel accounts for 5 to 25 percent of the total mass of the catalyst, the auxiliary catalyst accounts for 3 to8 percent of the total mass, and the carrier aluminum oxide accounts for the balance. When the catalyst disclosed by the invention is used, paraphenyldimethylamine can be prepared by hydrogenation ofisophthalodinitrile under milder conditions, the conversion rate of isophthalonitrile is 100 percent, and the selectivity of the paraphenyldimethylamine can reach 98.8 percent. The invention also discloses the preparation method of the catalyst.

Description

technical field [0001] The invention relates to a nickel catalyst, in particular to a supported nickel catalyst, and also relates to the preparation of m-xylylenediamine. technical background [0002] m-xylylenediamine is not only an epoxy resin curing agent with excellent performance and wide application, but also an important fine chemical intermediate. Its main uses are: ① series epoxy resin curing agent; ② new engineering materials Additives; ③Rubber additives, pesticides, fiber finishing agents, rust inhibitors, chelating agents, lubricants, paper processing aids and electronic chemicals are high value-added fine chemicals with broad application prospects. [0003] At present, m-xylylenediamine is produced by the catalytic hydrogenation process of isophthalonitrile. The common catalysts used are Raney nickel, modified Raney nickel or amorphous nickel, etc. The metal nickel content of these catalysts reaches 60%. Above, the manufacturing cost is high. [0004] The exis...

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Problems solved by technology

[0003]At present, m-xylylenediamine is produced by the catalytic hydrogenation process of isophthalonitrile, and the catalysts used are common Raney nickel and modified Raney nickel Or amorphous nickel, etc., the nickel content of these catalysts reaches more than 60%, and the manufacturing cost is high

[0004]The existing catalysts have good initial activity, but poor stability. After being used in the reactor for a period of time, the hydrogenation activity of the catalyst decreases significantly. The possible reasons are: ① The existence of a small amount of impurities in isophthalonitrile may lead to partial deactivation of the catalyst; ② dimerization or polymer by-products generated by the hydrogenation reaction are deposited on the surface of the catalyst, resulting in a decrease in catalyst activity

[0005] In addition, the existing catalysts are suitable for batch reaction, the production scale is small, the catalyst particles are small, and they are easy to pulverize after repeated use under stirring conditions, resulting in poor separation effect , the catalyst loss is also large

As far as the batch reaction production process is concerned, the hydrogen utilization rate is only 50-60%, and there are problems such as high production cost and poor safety