Ultra-small Mo2N on SBA-15 as a highly efficient promoter of low-loading Pd for catalytic hydrogenation

Decreasing Pd usage whilst maintaining a superior performance is promising, but remains a challenge in the catalytic field. Herein, we have demonstrated the highly efficient promotion of Mo2N with a reduced amount of Pd for the liquid-phase hydrogenation reaction. The Mo2N (2-3 nm) was uniformly anchored onto mesoporous SBA-15 by using PMo12 as the Mo source. The small size and good dispersion of Mo2N is favourable for allowing their effective contact with post-loading Pd. This good contact is conducive to developing a synergistic catalyst, which was verified by studying the liquid-phase hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) with NaBH4 as the H source. The conversion ability of PNP to PAP on 1 wt% Pd-Mo2N/SBA-15 was vastly superior to 1 wt% Pd/SBA-15 and even better than 20 wt% Pd/SBA-15. The low-Pd, highly efficient catalysis is ascribed to the transfer of the electrons from Mo2N to Pd for the easy activation of H. The synergy can be affected by the type of support used. SBA-15 is superior to SiO2 and the other supports, which could be related to the large surface area and the plentiful number of pores on SBA-15, which is favourable to the dispersion of Pd and Mo2N, and the transfer/diffusion of the reactants. In particular, a highly efficient catalyst can be achieved at an even more reduced Pd loading (0.05 wt%). The current method describes the design of a highly efficient catalyst for the hydrogenation reaction using low amounts of noble metals.