Catalytic Hydrogenation of Lignin Ethers and Bio‐Oil Using Non‐Noble Cobalt Catalysts

The conversion of lignocellulosic biomass into lignin bio‐oil and its subsequent upgrading into saturated cyclic products holds considerable promise for applications in the aviation industry. This study reports the synthesis of a defect‐enriched monometallic CoOx/Co‐350‐30 catalyst, which was utilized for hydrogenating lignin‐derived molecules and lignin bio‐oil obtained via reductive catalytic fractionation (RCF) of wheat straw. Under optimized conditions (180 °C, 2 MPa H2, 2 h), benzyl phenyl ether (BPE) afforded complete conversion, yielding ~99% cyclohexanol and ~98% methylcyclohexane. RCF of wheat straw (conducted at 230 °C and 3 MPa H2 for 6 h) afforded lignin bio‐oil containing ~43% alkyl‐substituted phenols. Hydrogenation of the bio‐oil using the CoOx/Co‐350‐30 catalyst (at 250 °C for 2 h at 3 MPa H2) resulted in ~98% yield of cyclic aliphatic alcohols. Comparative studies with commercial 5%Ru/C revealed that the CoOx/Co‐350‐30 catalyst produced products with lower oxygen functionalities and fewer native lignin linkages. Comprehensive catalyst characterizations and activity tests were conducted to propose a plausible reaction mechanism for BPE hydrogenation. The cobalt‐based catalyst, devoid of noble metals, provides a sustainable and cost‐effective method for biomass conversion into fuel‐range products, addressing the growing industry demand for more efficient catalytic processes.