The targeted transformation of renewable biomass resources into high-value-added liquid fuels and chemicals through thermocatalysis is a promising strategy to mitigate the global energy crisis and reduce the environmental impact associated with fossil fuel consumption. Noble metals (Pt, Pd, Rh and Ru) exhibit good hydrogenation and substrate activation properties under mild thermocatalysis conditions, but suffer from high cost and limited availability, which hinders their large-scale development. Cu-based catalysts are especially promising because they effectively cleave the C–O bond while minimizing aromatic ring saturation. Experimental studies have demonstrated that Cu/C and Cu/SiO2 catalysts selectively convert guaiacol to phenol. However, the fundamental mechanistic origins underlying this selectivity, particularly the role of surface structure and Cu coordination environment, remain poorly understood.
Recently, a research team led by Prof. Yu Jing from Nanjing Forestry University, China reveals how copper surface orientations and grain boundaries govern the competing deoxygenation and partial aromatic‑ring hydrogenation pathways of guaiacol HDO, identifies the d‑band center as a selectivity descriptor, and proposes grain‑boundary engineering to boost aromatic‑product selectivity for lignin‑derived bio‑oil upgrading. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(26)65098-X ).
Across Cu(100), Cu(111), and Cu(211) surfaces, two competing routes dominate product distribution: (1) hydrogen-assisted deoxygenation (H-DO) via methoxy dissociation, producing phenol, and (2) partial hydrogenation (PHDO) of the aromatic ring, leading to cyclohexanone-type products.H-DO activity is largely insensitive to surface orientation due to weak Cu-C2 interactions, whereas PHDO activity depends strongly on surface structure through Cu-C3/C6 bonding. Among the studied surfaces, Cu(111) exhibits the highest activity and selectivity toward aromatic products, favoring methoxy cleavage to produce phenol and methanol, in agreement with experimental observations.
The Cu coordination environment strongly influences adsorption strength of guaiacol and hydrogenated intermediates, following the order Cu(211) > Cu(100) > Cu(111). Weaker adsorption strength correlates with lower deoxygenation energy barriers but higher hydrogenation energy barriers, a trend primarily governed by the d-band center of the catalysts.Cu(111), with its more negative d-band center and weaker adsorption, exhibits the highest aromatic selectivity.
Guided by this insight, grain boundary (GB) engineering is proposed and validated as an effective design strategy. Cu(111)/(111) GB selectively suppresses PHDO by destabilizing hydrogenation transition states, while retaining H-DO activity. These results establish a clear structure-activity-selectivity relationship for guaiacol HDO and demonstrate that electronic tuning through facet and GB control provides a general framework for designing metal catalysts for selective biomass upgrading.
About the Journal
Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.2. The Editors-in-Chief are Profs. Can Li and Tao Zhang.
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