Preparation, structural characterization of a novel egg-shell palladium sulfide catalyst and its application in selective reductive alkylation reaction

A novel egg-shell Pd–S catalyst with palladium metal as the core and a membrane of palladium sulfide as the surface has been prepared by sulphidizing Pd/C with H2S. This catalyst is effective for the reductive alkylation of p-amino diphenylamine (PADPA) and methylisobutyl ketone (MIBK) to afford N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenedianine (DBPPD) with conversion up to 99.42% and selectivity to 97.46%. Comparing with the other common palladium sulfide catalysts, the membrane of palladium sulfide on the surface and the core of palladium metal cause the Pd on the surface of the new catalyst in a lower sulfur coordination, which improves its activity. Our result indicates that this new egg-shell Pd–S/C is an efficient hydrogenation catalyst.