Efficient and selective hydrogenation of benzonitrile to benzylamine: improvement on catalytic performance and stability in a trickle-bed reactor

An efficient and selective hydrogenation of benzonitrile to benzylamine has been accomplished over a Pd/gamma-Al2O3 catalyst, without any additives, in a trickle-bed reactor. Some unique features involving both a gas-liquid phase reaction and a gas phase reaction were found for the hydrogenation of benzonitrile, due to the application of the trickle-bed reactor. A comparison of the catalytic performances clearly showed that there was more excellent mass transmission and more substantial back-mixing restriction in the trickle-bed reactor than in the batch reactor. As a result, Pd/gamma-Al2O3 exhibited a higher activity and benzylamine selectivity for the hydrogenation of benzonitrile, generating benzylamine in a yield of similar to 86%. Furthermore, a long-term stability test of up to 120 h was conducted on Pd/gamma-Al2O3 for the hydrogenation of benzonitrile, with no significant loss of activity, exhibiting its potential in industrial application.