Chuqiao Song,Wei Cheng,Xiaojie Wu,Shufang Zhao,Ying Tang,Xin Tang,Yao Xu,Lili Lin,Siyu Yao
The one-pot hydrodeoxygenation of lignin-derived (alkyl)-guaiacols to (alkyl)-cyclohexanols with high selectivity is an attractive process for biomass conversion. However, designing catalysts that preferentially cleave etheric CAr–O(R) bonds over hydrogenating aromatic rings under mild conditions remains a significant challenge. In this study, we explore the structure sensitivity of supported Ru catalysts with varying particle sizes (0.6–7.5 nm) and identify the optimal catalyst for selective hydrodeoxygenation. Using a catalyst with 1.5 nm Ru particles, we achieve a ∼95% yield of cyclohexanol from guaiacol under relatively mild conditions (190 °C, 5 bar H2). In situ DRIFTS analysis reveals that the cleavage of CAr–OCH3 bonds occurs preferentially over aromatic ring hydrogenation on the 1.5 nm Ru particles, minimizing side reactions and enhancing cyclohexanol selectivity.
The hydrodeoxygenation of lignin-derived syringol to phenol faces challenges in selectively cleaving C Aryl –O bonds while maintaining aromatic ring and a phenolic -OH group integrity. Herein, we developed a trimetallic CoFeAg/SiO 2 catalyst that achieves 100 % syringol conversion and 52.4 % phenol selectivity, surpassing bimetallic CoAg/SiO 2 (42.2 mol%) and monometallic Co/SiO 2 (7.6 mol%) catalysts. As promoters, Ag facilitates the low-temperature reduction of Co 3 O 4 to CoO and further to metallic Co, while Fe prevents excessive reduction of CoO to metallic Co. Through the synergistic effects of Fe and Ag on Co, the CoFeAg/SiO 2 catalyst undergoes in situ reduction under reaction conditions (1 MPa H 2 , 330 °C), forming a polycrystalline CoO-Co structure with abundant oxygen vacancy (O ᴠ ) and Lewis acid sites. The CoO-Co-O v active sites facilitate heterolytic H 2 cleavage while preferentially adsorbing and activating oxygen-containing functional groups over the aromatic ring of syringol. This dual functionality selectively promotes C Aryl –O bond dissociation while suppressing undesired ring hydrogenation, providing an effective catalyst design strategy for sustainable phenol production from biomass-derived syringol.
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