Effect of rhenium on the activity of ZrO2-supported copper catalysts for hydrodeoxygenation of m-cresol

Abstract

This work studies the effect of adding different loadings of Re on the performance of ZrO₂-supported Cu catalysts for hydrodeoxygenation (HDO) of m-cresol. H₂-TPR and XPS show a synergistic effect between Cu and Re, decreasing the reduction temperature of both metals and promoting the reduction of Re oxide. Moreover, the addition of Re changes Cu dispersion and acid properties of all catalysts. High Re contents results in a coverage of Cu surface. Catalytic tests reveal that HDO reaction rate and product distribution vary considerably depending on the Re loading. Cu catalyst was inactive for HDO reaction, forming only hydrogenation products. In contrast, Re catalyst stood out for its high capacity to promote HDO reaction, with significant production of toluene. For the bimetallic catalysts, the addition of Re increases HDO reaction rate from 0 to 0.39 mmol g_metal⁻¹ min⁻¹ and the selectivity towards toluene (0–82.6 %), whereas the formation of hydrogenation and dehydration products decreases.