Catalytic wet air oxidation of d-glucose by perovskite type oxides (Fe, Co, Mn) for the synthesis of value-added chemicals

Abstract

The conversion of common biomasses derived, as d-glucose, into value-added chemicals has received highest attention in the last few years. Among all processes, the catalytic wet air oxidation (CWAO) of derived biomasses using noble metal-based heterogeneous catalytic systems has been investigated. Nevertheless, the redox effect of such catalysts on such bio-compounds has still to be investigated in detail. In the present work, the activity for the conversion of d-glucose into C₆ aldaric acid, lactic acid and levulinic acid of some perovskite type oxides (LaBO₃; B: Fe, Co, Mn) characterized by noticeable catalytic properties and stability under hydrothermal conditions, have been investigated. The influence of the reaction temperature and the effect of the catalytic properties on the distribution of the liquid products have been studied. In the best conditions, 50.3 mol.% and 69.5 mol.% of lactic and levulinic acid have been obtained by using LaCoO₃ and LaMnO₃, respectively. Apart from the oxidative effect, the affinity hydrogen allowed the catalytic conversion of some key intermediates, such as pyruvic aldehyde and hydroxymethylfurfural, into the desired products. LaMnO₃, which has resulted to be the most oxidizable/reducible catalyst at low temperatures, has shown the best catalytic activity among the studied catalysts, promoting the conversion of hydroxymethylfurfural to levulinic acid and giving overall the highest yield.

Keywords: CWAO; Lactic acid; Levulinic acid; Perovskites; d-glucose; d-saccharic acid.