Oxygen-vacancy-mediated catalytic methanation of lignocellulose at temperatures below 200°C

Summary

Biomethane is a clean energy and a key platform chemical for modern chemical industries. The conversion of biomass, especially the most abundant lignocellulose, into biomethane is challenging and shows low selectivity either in chemical or biological processes. Herein, we report the direct methanation of biomass at temperatures below 200°C with >95% selectivity using interfacial oxygen-vacancy (V_O)-mediated catalysis over Ru/TiO₂. The biomass feedstock is oxidized by TiO₂ to form CO₂ and V_O, and CO₂ is then in situ reduced on Ru sites to CH₄, restoring the oxygen to V_O simultaneously. Various biomass resources were converted into methane with 82%–99% yields. Even lowering the temperature to 120°C, about 0.24 mmol g⁻¹ h⁻¹ of CH₄ with >99% selectivity was steadily produced from 50 wt % aqueous glycerol for 432 h. In situ X-ray photoelectron spectroscopy, infrared spectrometry, and DFT calculation confirm the V_O-mediated catalysis process over Ru/TiO₂.