Effect of Zn doping on the hydrogenolysis of glycerol over ZnNiAl catalyst

• Doping of Zn caused remarkable improvements of activity and selectivity of ZnNiAl catalysts.
• The formation of ZnNi alloy altered the surface electronic structure of ZnNiAl catalysts.
• The adsorption mode of glycerol was changed on the surface of ZnNi alloy.
• A new reaction pathway of glycerol hydrogenolysis was proposed.

Nickel based catalyst is of interest in the industrial catalytic processes, and it is always modified by doping a second element to improve its catalytic properties. Understanding the role of dopant is extremely helpful in tailoring the active centers. In this work, Zn could induce a significant improvement of the catalytic performance of NiAl for the hydrogenolysis of glycerol. The Zn doped ZnNiAl catalysts exhibited high activity and the improved selectivity to 1,2-propanediol, it was about 2 times higher than the original ones. The ZnNi alloy formed in ZnNiAl was responsible for the noticeable catalytic performance. They preferred to coordinate with the end hydroxyl group of glycerol, promoted the cleavage of CO bond in glycerol, and resulted in the dominant formation of 1,2-propanediol. The findings described here will provide a useful knowledge for rational design of nickel-based catalysts, as well as reveal a new reaction model for the hydrogenolysis of glycerol.

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