Reusable ReOx‐Pd/CeO2 Catalyst with Low Metal Surface Concentration for Efficient Consecutive Deoxydehydration and Hydrogenation of Vicinal OH Groups

Abstract

A strategy is proposed to enhance the stability and reusability of the ReOx‐Pd/CeO2 catalyst for the consecutive deoxydehydration and hydrogenation (DODH + HG) of biomass‐derived vicinal diols. A remarkable result involving a simultaneous enhancement of activity, stability, and regeneration ability of the catalyst is obtained by lowering the surface concentration of metals. Using erythritol as a model compound, DODH + HG over a low‐loading ReOx‐Pd/CeO2 can be completed much faster with a higher turnover number compared to the high‐loading standard catalyst. Moreover, a three‐fold decrease in deactivation rate is also obtained when shifting from a 2 wt% Re‐containing catalyst to a 0.5 wt% one, confirming the enhancement of stability. The regeneration of a low‐loading ReOx‐Pd/CeO2 (0.5 wt% Re) can be completely achieved via heat‐treatment under air in milder conditions at a temperature as low as 353 K. Based on Raman spectroscopy, no sign of polymeric ReOx could be detected on the surface of a spent ReOx‐Pd/CeO2 (0.5 wt% Re) after a simple oven drying under air, confirming the complete redispersion of the inactive species, which was previously traced as the main cause of catalyst deactivation in the catalyst with a higher metal loading.