Correlating O-Vacancy and Hydrogen Spillover in Ru/TiO2-SiO2 Catalysts with Their Activity and Selectivity Towards Furfural Hydrogenation

The nanoengineering of efficient and stable catalysts is highly desired for sustainable biomass valorization towards the selective hydrogenation of furfural. Here, by a combination of DFT calculations and catalytic experimental data, we demonstrated that the presence of TiO 2 in Ru-SiO 2 catalysts might allow an association between oxygen vacancies and the hydrogen spillover effect, leading to Ru-TiO 2 -SiO 2 (Ru-TSdp and Ru-TSdc) and Ru-SiO 2 (Ru-Sdp and Ru-Sdc) nanocatalysts displaying improved activities and selectivities towards the reaction mentioned above. The catalysts were prepared by a simple, versatile, and single-step modified sol-gel process build-upon two different stabilizing agents (P123 and CTAB), which afforded entire-covered surfaces of TiO 2 -SiO 2 and SiO 2 supports with uniform Ru nanoparticles generated in situ . The Ru-TSdc catalyst displayed several interesting features for hydrogenation of furfural: (i) uniform distribution of Ru, Ti, and Si elements over the entire catalyst surface, (ii) deposition of small Ru NPs (3 nm) with no significant particle agglomeration; (iii) facilitated hydrogen spillover from Ru NPs to TiO 2 support, and (iv) a significant amount of oxygen vacancies at the surface. For these reasons, the Ru-TSdc sample afforded the optimal performance toward the selective hydrogenation of furfural (up to 99% of selectivity maintaining good conversions (%) and in some reaction conditions).