Total Catalytic Oxidation of Ethanol over MnCoAl Mixed Oxides Derived from Layered Double Hydroxides: Effect of the Metal Ratio and the Synthesis Atmosphere Conditions

In this work, the LDH approach was used to prepare MnCoAl mixed oxides with various textural and structural frameworks for the purpose of enhancing the total oxidation of ethanol. Our results showed that the catalytic activity of the MnCoAl oxides was influenced by the Mn/Co ratio and the gas atmosphere used during synthesis and thermal treatment. Rietveld refinement was processed to estimate the proportion of phases presented in the prepared materials. Our findings indicated that the generation of Mn2CoO4 spinel and Mn5O8 lamellar phases improved the redox properties and enhanced the active sites in the MnCoAl oxides. Notably, we observed that the catalytic activity at low temperatures of the catalyst increased with the decrease in the cobalt amount. It was also demonstrated that using an N2 atmosphere during the preparation of the materials is a promising route to prevent the formation of undesirable phases in the LDHs and their corresponding oxides. The presence of an O2-free atmosphere during the LDH synthesis positively affects the total ethanol transformation to CO2 over the oxide catalysts.

Automated summary

In this study, MnCoAl mixed oxides were prepared using the LDH approach with various textural and structural frameworks, showing that the catalytic activity was influenced by the Mn/Co ratio and gas atmosphere. Rietveld refinement was utilized to estimate phase proportions, revealing that the spinel and lamellar phases improved redox properties and active sites in the oxides. Lowering cobalt content increased catalytic activity at low temperatures, while using an N2 atmosphere during synthesis helped prevent undesirable phase formation. The presence of an oxygen-free atmosphere during LDH synthesis positively affected ethanol transformation to CO2 over the oxide catalysts.