Polyether amine (PEA): It is a polymer with polyether structure as the main chain and amine as the terminal active functional group. Polyether amine is made of polyethylene glycol, polypropylene glycol or ethylene glycol/propylene glycol copolymer under high temperature and pressure. The reactivity, toughness, viscosity, hydrophilicity and other properties of polyether amine can be adjusted by selecting different polyalkyl oxide structures. Amino groups make it possible for polyether amine to react with a variety of compounds. Polyether amine has excellent comprehensive properties due to its special molecular structure. At present, commercial polyether amines include single function, dual function and triple function products with molecular weights ranging from 230 to 5000. It is widely used in polyurea spraying, large composite materials, epoxy resin curing agent, automobile gasoline cleaning agent and other fields.
At present, the main process for producing polyether amine at home and abroad is ammonolysis, also known as reductive amination: starting from the terminal hydroxyl of polyether polyol, the terminal hydroxyl is replaced by amino through amination reaction.
The reaction is carried out under high temperature and pressure. Early production is intermittent production in high-pressure mixing tank, which requires higher equipment. Because the reaction will produce water, which cannot be discharged in the system, and the reaction balance can be achieved at a low conversion rate, the reaction conversion rate is quite limited. The products with molecular weight above 2000 are less affected by the reaction balance due to the relatively low hydroxyl concentration, while the products with molecular weight below 800 have very obvious limitations. In order to improve the production efficiency of short chain polyether amine, the fixed bed is generally used for continuous production, so that the water can be discharged from the system as soon as possible, so that the reaction balance can move forward, and the conversion and yield can be improved.
At present, the relatively mature fixed bed catalysts for reduction and ammoniation can be roughly divided into three categories: copper catalysts, noble metal catalysts and nickel catalysts.
For the copper catalyst with low price, its selectivity is low, which reduces the product yield, and there will be metal residues, so the application of the product is greatly limited; Precious metals have obvious advantages in use performance, but their costs are too high. Unless it is irreplaceable in some fields with special requirements, the cost will be more unbearable for more manufacturers; Nickel catalyst has obvious advantages in comprehensive performance, which can be said to be the choice of most enterprises in the future.
