Promotional Effect of Ni in the Selective Gas-Phase Hydrogenation of Chloronitrobenzene over Cu-based Catalysts

We present 100?% selectivity to p-chloroaniline through the continuous gas-phase (atmospheric pressure; T=393523 K) catalytic hydrogenation of p-chloronitrobenzene over an activated Cu?Al (molar Cu/Al ratio 3:1) hydrotalcite. The synthesis by continuous co-precipitation and application of a Cu?Ni?Al (atomic Cu/Ni/Al ratio 2.75:0.25:1) catalyst is also described. Temperature-programmed reduction in hydrogen and XPS analyses of the ternary catalyst suggest Cu?Ni interaction with no evidence of (bulk) alloy formation (based on XRD). Under the same reaction conditions, Cu?Ni?Al exhibited a higher (by up to a two-fold) hydrogenation rate when compared to Cu?Al, while the exclusive nitro-group reduction was maintained.