Effect of alkali metal promoters on catalytic performance of Co-based catalysts in selective hydrogenation of aniline to cyclohexylamine

In this study, a series of Co-based catalysts with alkali metal carbonate promoters were prepared to investigate the interrelation between promotion effect of these carbonates and catalytic performance for aniline hydrogenation to cyclohexylamine in vapour phase. The chemical promoters Li₂CO₃ and Na2CO₃ leading to decrease in catalytic activity of cobalt catalysts for aniline hydrogenation. Catalysts with K₂CO₃ and Cs2CO₃ loadings have practically no catalytic activity for hydrogenation of aniline. Results of TPD of aniline proved that presence of alkali metals carbonates restricts the adsorption of aniline on the surface of cobalt catalysts. Further, it was found that the addition of Na₂CO₃ greatly enhances the catalytic selectivity towards the cyclohexylamine and inhibits the consecutive reactions of cyclohexylamine leading to formation of by-products such as dicyclohexylamine and N-phenylcyclohexylamine.