Efficient hydrodeoxygenation of guaiacol to phenol over Ru/Ti–SiO 2 catalysts: the significance of defect-rich TiO x species

• Published in: Green chemistry : an international journal and green chemistry resource : GC 2022-08, Vol.24 (15), p.5822-5834
• Main Authors: Wang, Xinchao, Wang, Zhuangqing, Zhou, Leilei, Liu, Yanchun, Yang, Yinze, Zhang, Liyan, Shang, Zongling, Li, Hui, Xiao, Tingting, Zhang, Chao, Zhao, Fengyu
• Format: Article
• Language: English
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/D2GC01714H

Selective hydrodeoxygenation of lignin-derived phenolics to value-added aromatic products such as phenol with high efficiency and low energy consumption remains an important challenge in the field of biomass conversion. Herein, we fabricated a series of Ti-modified SiO 2 supported catalysts (Ru/Ti–SiO 2 ) with rich Ti 3+ defects and size-controllable Ru particles via a facile wet impregnation method for the conversion of guaiacol in an aqueous phase. Under relatively mild conditions (240 °C and 0.4 MPa H 2 ), Ru/Ti–SiO 2 exhibited higher activity for C–O bond cleavage compared with both Ru/SiO 2 and Ru/TiO 2 catalysts, and achieved high guaiacol conversion (83.6%) and phenol selectivity (70.4%). The catalytic activity was increased with the introduction of the Ti modifier, and the deoxygenation ability of the Ru/Ti–SiO 2 catalyst gradually increased with the Ti content. The presence of Ti–O–Si linkages in the Ti-modified SiO 2 support promoted the formation of defect-rich TiO x species, which further inhibited the aggregation of Ru particles and increased their dispersion, regardless of the high reduction temperature and high Ru loading. Besides, those small-sized TiO x interacted with Ru electronically and promoted the formation of Ru 0 species. The interface between Ru and TiO x species (Ru 0 –Ti 3+ ) of the Ru/Ti–SiO 2 catalyst was confirmed as the main active sites for the deoxygenation of guaiacol, benefiting the activation of the C–O bond.