Effects of metal promoters in bimetallic catalysts in hydrogenolysis of lignin derivatives into value-added chemicals

Bimetallic catalysts have been widely employed in the lignin hydrogenolysis research, which is attributed to that the interaction between the two metals can regulate the catalyst surface properties, thus improving the catalytic performance. The metal promoters can change the adsorption strength and orientation between the catalyst surface and the substrates, the active sites dispersion and the catalyst stability, so the activity, selectivity and stability of bimetallic catalysts are better than those of the corresponding monometallic catalysts in lignin hydrogenolysis. The effects between the two metals can be divided into the following four types: the electronic (ligand) effect, synergistic effect, stabilizing effect and geometric (ensemble) effect. Herein, these four different effects between the two metals and the reaction mechanisms over different bimetallic catalysts in lignin hydrogenolysis are discussed in this minireview, aiming to point out the challenges and further perspectives in the design of efficient bimetallic catalysts.