Effect of catalytic hydrodynamics over microagglomerates of Mn2O3 and PdO supported on γ-χ-Al2O3 for dimethyl ether production

Abstract

In this study, we synthesize microagglomerates of PdO and Mn2O3 supported over γ-χ-Al2O3 via the impregnation method, for their application in the methanol dehydration to dimethyl ether, under reaction conditions of 240 °C to 290 °C and 1 pressure atm. It was determined by XRD, TEM and XPS that when PdO (Pd2+) is present at 3% by weight over γ-χ-Al2O3, conversions of 57% and selectiveness of 100% towards dimethyl ether can be reached at 250 °C due to at a higher density of moderate acid sites (a moderate acidity difference of 0.5276 mmol/g with respect to Mn2O3/γ-χ-Al2O3). Additionally, our theoretical and experimental results between the correlation of the textural and morphological properties of the PdO/γ-χ-Al2O3 and Mn2O3/γ-χ-Al2O3 materials with the hydrodynamics and kinetics of the reaction, showed that when PdO agglomerates with a size of ∼79.2 µm are used, higher internal mass transfer rates predominate when compared to using Mn2O3 agglomerates of a larger size, ∼124 µm. Finally, the relative stability shown by the PdO/γ-χ-Al2O3 catalyst during 10 h of reaction was correlated with its low apparent activation energy (111 kJ/mol) and with its inactive phase change of PdO measured by XPS after the reaction.