Ultra-small MoN 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 MoN with a reduced amount of Pd for the liquid-phase hydrogenation reaction. The MoN (2-3 nm) was uniformly anchored onto mesoporous SBA-15 by using PMo as the Mo source. The small size and good dispersion of MoN 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 NaBH as the H source. The conversion ability of PNP to PAP on 1 wt% Pd-MoN/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 MoN to Pd for the easy activation of H. The synergy can be affected by the type of support used. SBA-15 is superior to SiO 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 MoN, 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.