High-Selectivity Demethoxylation of Lignin Alkylmethoxyphenols Enhanced by Hydrogen Spillover on Ag/Fe-CoOx Nanocatalyst

This investigation focuses on the catalytic demethoxylation of alkylmethoxyphenols derived from lignin depolymerization, aiming to convert them with high selectivity into essential chemical intermediates, namely methoxy-free alkyl phenols. A silver-loaded iron-cobalt oxide (Ag/Fe-Co3O4) nanocomposite catalytic system was developed, featuring a dual-active-site catalytic mechanism driven by a hydrogen-spillover effect that involves the activation of hydrogen at the metallic active site, while the support's secondary site serves as the reaction locus for the substrates. It was revealed that by integrating iron into cobalt oxide nanosheet supports, catalyst activity and selectivity were finely tuned, particularly to enhance the production of demethoxylated phenols. With the optimized Ag/Fe-Co3O4 catalyst, a 99.7% conversion of 4-propylguaiacol and a 94.1% selectivity for 4-propylphenol were achieved, indicating effective reductive demethoxylation at 280°C and 0.4 MPa H2. The fine structure of the support significantly affects demethoxylation selectivity, guiding the development of selective catalyst design in biomass conversion.