Aqueous-phase hydrogenolysis of glycerol over NiCeZr catalysts using in-situ produced H2: Effect of Ce/Zr ratio

Abstract

Glycerol is a renewable carbon resource for producing high-value products via hydrogenolysis. Herein, we investigated the impact of Ce/Zr molar ratios of NiCeZr-x catalysts, synthesized using a single-step co-precipitation method, on their physico-chemical and catalytic properties during the hydrogenolysis of glycerol with in-situ generated H2. The catalytic performance of the NiCeZr-x catalysts depended significantly on the synergy between oxygen vacancies, acid-base properties, and metallic sites. Ce-rich catalysts increased hydrogen production, whereas Zr-rich catalysts showed higher selectivity in breaking C–O bonds, leading to significant 1,2-propylene glycol yields. The catalyst with a Ce/Zr molar ratio of 15/85 displayed superior performance, attaining a 75.3% glycerol conversion, 29.7% yield, and 52.8% selectivity for 1,2-propylene glycol at 235°C/35 bar and 12 h−1. After use, the Ce-rich catalysts underwent oxidation and coalescence of nickel, whereas the Zr-rich catalysts exhibited Ni leaching. The results indicated that Zr-rich NiCeZr-x catalysts possessed potential to sustainably produce deoxygenated products from glycerol, making it an eco-friendly alternative.