Study On Preparation Of Benzylamine By Selective Hydrogenation Of Benzonitrile

Benzylamine is an important organic synthesis intermediates and raw material of fine chemicals. With the fast development of chemical industry, the demand for benzylamine increasing. At present, most benzylamine rely on foreign imports from Germany, the United States, Japan. The production technology of benzylamine is backward, Therefore, the development of efficient production processes benzylamine will have good market prospects.The hydrogenation catalyst from benzonitrile to benzylamine with excellent performance, which use palladium as an active ingredient, was studied under the fixed bed reaction conditions in this paper. Compared with the literature, the palladium content is greatly reduced, and the reaction conditions are milder, which provides a very useful theoretical foundation for the continuous industrial production of benzylamine from hydrogenation of benzonitrile.The main contents and results of this paper are as follows:1. Different catalyst systems were screened, Supported catalysts Pd/γ-Al2O3 prepared by impregnation is the optimal catalyst system; The effects of different active metal loading on reaction performance were compared. Preferred, active metal loading is 0.5 wt%. Besides, the preparation conditions of impregnation were optimized.2. The effects of different reaction conditions on reaction performance were investigated, and the reaction conditions were optimized. Suitable reaction conditions are as follows:reaction temperature 70-90℃, reaction pressure 1.5 MPa, hydrogen benzonitrile ratio 10-40, WHSV≤0.5 h-1. Under these conditions, the highest yield of benzylamine is 88.8%.3. Catalyst stability was investigated, the results showed that the catalyst is able to run stably for 209 h. Then, the conversion rate of benzylamine is below 97% There isn’t a great active metal component loss. Palladium metal particle size doesn’t grows up. Many materials cover the surface of the catalyst, which leads to the surface area, pore volume and pore size of catalyst decrease. The surface materials is the main cause of catalyst deactivation.