Boosting Catalytic Combustion of Ethanol by Tuning Morphologies and Exposed Crystal Facets of -Mn₂O₃

Three types of a-Mn2O3 catalysts with different well-defined morphologies (cubic, truncated octahedra and octahedra) and exposed crystal facets have been successfully prepared via hydrothermal processes, and evaluated for ethanol total oxidation with low ethanol concentration at low temperatures. The a-Mn2O3-cubic catalyst shows a superior catalytic reaction rate than that of a-Mn2O3-truncated octahedra and a-Mn2O3-octahedra under high space velocity of 192,000 mL/(g.h). Based on the characterization results obtained from XRD, BET, FE-SEM, HR-TEM, FT-IR, H-2-TPR, XPS, ethanol-TPD, and CO-TPSR techniques, the observed morphology-dependent reactivity of a-Mn2O3 catalysts can be correlated to the good low-temperature reducibility, abundant surface Mn4+ and adsorbed reactive oxygen species, which was originated from the exposed (001) crystal planes. Through tuning the morphology and exposed (001) crystal facet of a-Mn2O3, a highly active ethanol oxidation catalyst with high selectivity and excellent stability is obtained. The developed approach may be applied broadly to the development of the design principles for high-performance low-cost and environmentally friendly Mn-based oxidation catalysts.