Correlating O-Vacancy and Hydrogen Spillover with Activity and Selectivity in Furfural Hydrogenation Using Nanocatalysts Comprised of Ru Nanoparticles Supported on TiO₂–SiO₂

Abstract

The nanoengineering of efficient and stable nanocatalysts is highly desired for sustainable biomass valorization toward the selective hydrogenation of furfural. The interaction of supports with metallic nanoparticles and oxygen vacancies has a significant role in the catalytic activity of oxide nanocatalysts. Here, by combining density functional theory (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. Specifically, Ru−TiO 2 −SiO 2 and Ru−SiO 2 nanocatalysts displayed improved activities and selectivities toward the reaction mentioned above. The nanomaterials were prepared by a simple, versatile, and single-step modified sol− gel process build upon two different stabilizing agents (P123 and CTAB), which afforded entirely covered surfaces of TiO 2 −SiO 2 and SiO 2 supports with uniform small Ru nanoparticles generated in situ. The Ru-TSdc nanocatalyst displayed several interesting promising nanoscale features for hydrogenation of furfural: (i) uniform distribution of Ru, Ti, and Si elements over the entire catalyst surface, (ii) deposition of small Ru nanoparticles with no significant particle agglomeration, (iii) facilitated hydrogen spillover from Ru NPs to the TiO 2 support, and (iv) a significant amount of oxygen vacancies at the nanoparticle 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 in certain reaction conditions. This work demonstrates how the catalytic activity of metallic nanoparticles could be improved by the structural addition of a reducible oxide, leading to more efficient inorganic supports and for preparing nanocatalysts.

Pt nanoparticles anchored by oxygen vacancies in MXenes for efficient electrocatalytic hydrogen evolution reaction

“…[24][25][26] Most of the previously reported carriers are transition metal oxides, sulfides, nitrides, carbides, and hydroxides. [27][28][29][30][31][32][33] Compared with the currently used carrier, such as carbides and metal oxides, MXenes are two-dimensional acid and alkali-resistant layered transition metal carbon/nitride materials with abundant surface groups and atomic vacancy defects. 34,35 They are widely used in energy storage and conversion because of their efficient electron transfer and excellent electronic conductivity.…”

Introduction of TiO2 enhancing the catalytic performance of Ti(SO4)2/SiO2 for dimethyl ether oxidation

“…Leandro et al have proved that the presence of TiO 2 in Ru–TiO 2 –SiO 2 created a large number of oxygen vacancies on the surface and led to the homogeneous dispersion of Ru particles. 15 Xie et al reported that the addition of SiO 2 not only increased the dispersion of Pd, but also facilitated the formation of more oxygen vacancies on the Pd–SiO 2 /TiO 2 catalyst. 16 From the above studies, it is clear that the TiO 2 coated on SiO 2 improves the dispersion of metals and the distribution of the active sites, which indicates that the TiO 2 /SiO 2 material has good modulation ability.…”

“…The introduction of Ti(SO 4 ) 2 enriches the Ti species on the catalyst surface, and the dispersion of Ti species is highly dependent on oxygen vacancies. 15 TS-400 °C has a smaller particle size and is the most uniformly dispersed, which results in a significant reduction in the enthalpy of formation of oxygen defects and ultimately increases the number of oxygen vacancies on the surface. 26 The presence of oxygen vacancies promotes the charge transfer between TiO 2 and Ti(SO 4 ) 2 , which may increase the electron density of the bridged oxygen and the proton affinity to form more –OH groups.…”