Valorization of biomass-derived CO2 residues with Cu-MnOx catalysts for RWGS reaction

This study delivers useful understanding towards the design of effective catalytic systems for upgrading real CO2–rich residual streams derived from biomass valorization. Within this perspective, a catalysts' series based on (5 wt%) Cu - (X wt%) Mn/Al2O3 with X = 0, 3, 8 and 10 is employed. The improved catalyst performance achieved through Mn incorporation is ascribed to enhanced Cu dispersions and promoted surface basic concentrations. Under standard RWGS conditions, the highest reaction rates achieved by (5 wt%) Cu - (8 wt%) Mn/Al2O3 catalyst were associated to improved Cu dispersions along with the constitution of highly active Cu-MnOx domains. Remarkably, variations on the optimal Cu to Mn ratios were detected as a function of the RWGS reaction conditions. Thus, under simulated CO2-rich residual feedstock's, i.e., in presence of CO and CH4, the further promotion on the Cu dispersion attained by the larger amounts of MnOx rendered the (5 wt%) Cu - (10 wt%) Mn/Al2O3 catalyst as the best performing sample. Overall, the presented outcomes underline operative strategies for developing catalytic systems with advanced implementation potentialities.