The promoting role of Ti modification on Cu/Al2O3 for enhanced selective hydrogenation of furfural

The selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL), catalyzed by the industrially important Cu/Al 2 O 3 catalysts, represents a significant research focus in biomass valorization. In this work, the significant promoting role of Ti modification on the performance of Cu/Al 2 O 3 for this reaction was systematically investigated using a series of Cu-xTi/Al 2 O 3 (x = 1–15 wt%) catalysts. The results revealed that at low Ti loadings (<9 wt%), Ti species were highly dispersed, formed Ti–O–Al interfacial structures with the Al 2 O 3 support, effectively increasing the number of weak acid sites and oxygen vacancies. Importantly, Ti modification optimized the metal-support interaction, enhanced the electron density of Cu species through electron transfer, significantly improved the reducibility of Cu species, and promoted the formation of metallic Cu 0 . However, excessive Ti loading (>9 wt%) led to the formation of crystalline TiO 2 particles that blocked surface active sites. The Cu-9Ti/Al 2 O 3 catalyst exhibited the best performance, achieving 100 % furfural conversion and 100 % furfuryl alcohol selectivity under reaction conditions of 85 °C, 1.0 MPa H 2 , and 4.5 h in isopropanol solvent. In situ DRIFTS experiments confirmed that the reaction followed the pathway of selective carbonyl adsorption and hydrogenation, and the formed furfuryl alcohol underwent rapid desorption, avoiding over-hydrogenation. This work elucidates the dual role of Ti modification in enhancing catalytic performance by tuning support acidity and optimizing the Cu electronic structure, providing insights for designing high-performance non-noble metal hydrogenation catalysts.