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2023
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11
Latest progress in m-xylylenediamine production: advanced process and high quality catalyst
Classification:
【Summary】M-xylylenediamine (MXDA) is an epoxy resin curing agent with excellent performance. It has the advantages of low temperature curing, heat resistance, water resistance, good chemical corrosion resistance, low viscosity, easy operation, etc. It can also be used in polyurethane, Polyamide, rubber additives, pesticides, fiber finishing agents, rust removers, chelating agents, lubricants, paper processing aids and electronic chemicals. It is a fine chemical with wide application and high added value. M-xylylenediamine is generally produced by catalytic hydrogenation of m-phthalonitrile. Domestic industrial production of m-xylylenediamine is still dominated by batch kettle reaction, with small production scale, fine catalyst particles, easy pulverization, poor separation effect, high production cost, poor safety and low degree of automation. Moreover, batch kettle reaction generally uses magnetic force or mechanical stirring, which makes it difficult to ensure sufficient hydrogen supply on the surface of the catalyst, resulting in too many central amine intermediates in the reaction liquid and too many by-products. Major international producers, such as Mitsubishi Gas of Japan, use trickle bed continuous production process, and BASF of Germany also uses fixed bed catalytic method. Raney nickel or modified Raney nickel is mainly used in batch reactions, and supported nickel-based catalysts are mostly used in fixed-bed processes.
M-xylylenediamine (MXDA) is an epoxy resin curing agent with excellent performance. It has the advantages of low temperature curing, heat resistance, water resistance, good chemical corrosion resistance, low viscosity, easy operation, etc. It can also be used in polyurethane, Polyamide, rubber additives, pesticides, fiber finishing agents, rust removers, chelating agents, lubricants, paper processing aids and electronic chemicals. It is a fine chemical with wide application and high added value.
M-xylylenediamine is generally produced by catalytic hydrogenation of m-phthalonitrile. Domestic industrial production of m-xylylenediamine is still dominated by batch kettle reaction, with small production scale, fine catalyst particles, easy pulverization, poor separation effect, high production cost, poor safety and low degree of automation. Moreover, batch kettle reaction generally uses magnetic force or mechanical stirring, which makes it difficult to ensure sufficient hydrogen supply on the surface of the catalyst, resulting in too many central amine intermediates in the reaction liquid and too many by-products. Major international producers, such as Mitsubishi Gas of Japan, use trickle bed continuous production process, and BASF of Germany also uses fixed bed catalytic method. Raney nickel or modified Raney nickel is mainly used in batch reactions, and supported nickel-based catalysts are mostly used in fixed-bed processes.
The intermediate process of the isophthalonitrile hydrogenation reaction will produce an imine intermediate product with high reactivity, which is easy to undergo further polycondensation reaction with the reaction intermediate product and the target product to generate secondary amine, tertiary amine and other high boiling point polymerization by-products. These by-products are adsorbed and deposited on the surface of the catalyst, often causing catalyst poisoning and deactivation. An important way to suppress the side reaction of polycondensation is to use an excess of liquid ammonia or ammonia gas or an organic amine as an inhibitor. However, the recovery cost of using a large amount of liquid ammonia is high, and a large amount of ammonia-containing waste gas and waste water will be produced, and the pollution is serious. Another more effective method uses a catalyst with higher primary amine selectivity, which effectively reduces the production of secondary amines, tertiary amines and other high-boiling substances, which not only improves the poisoning of the catalyst, but also improves the product yield.
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