Boosting activity of heterogeneous Ru catalysts via solid-phase infiltration and syngas-mediated redispersion

Development of highly active and stable heterogeneous catalysts is of paramount importance for the efficient and green industrial processes. Although considerable progress has been made in nanostructured catalysts for biomass upgrading, it remains challenging to achieve facile synthesis of highly active catalysts that offer precise control over the hydrodeoxygenation activity, stability and reactivation process with satisfactory performance. Herein, we present a simple method for incorporating ruthenium into the various porous supports (Al-SBA-15, MCM-22, MFI-type zeolite nanosheets) using solid-phase infiltration (SPI) technique. The synthesis protocol includes the mechanochemical activation of Ru₃(CO)₁₂ with a porous support, followed by stepwise thermal treatment under vacuum, resulting in the formation of highly dispersed, stabilized ruthenium sites within the porous architecture. Partial decarbonylation of Ru₃(CO)₁₂ facilitates the anchoring of resulting Ru(CO)₂ species to the support surface, yielding active sites with superior catalytic activity over those from conventional impregnation methods. It was found that the developed syngas-mediated redispersion (SMR) readily converts Ru NPs back to highly active Ru(CO)₂ species. This reactivation protocol demonstrates broad applicability to Ru-based heterogeneous catalysts, irrespective of their synthetic origin. Redispersed catalysts demonstrate enhanced hydrodeoxygenation activity over the original Ru-catalytic systems. In situ DRIFTS and Ru K-edge XAS analyses revealed the evolution of Ru sites during bio-oil compounds hydrogenation, demonstrating a transition from Ru(CO)₂ to subnanometric and nanoparticle (NP) agglomerates.