Non thermal plasma assisted catalysis of methanol oxidation on Mn, Ce and Cu oxides supported on γ-Al2O3

A non thermal plasma reactor coupled with different metal oxide based catalysts (MnO2, CeO2, CuO, MnO2-CeO2, MnO2-CuO supported on Al2O3) has been developed for the decomposition of methanol at low concentration (25-150 ppm) and low residence time (0.36 s) in an air flow. The geometry of the reactor developed in this study led to the formation of a surface plasma that presented high energetic efficiency since 75% methanol conversion was reached with a concentration of 25 ppm of methanol at an energy density of 20 J.L-1 in a single plasma configuration. The methanol conversion was improved when a catalyst was placed beyond the discharge. Apart from CO2, secondary products were identified as formaldehyde, methyl formate, methylal, CO and ozone. The influence of the methanol concentration, energy density and metal oxide catalyst composition on the methanol conversion, by-products selectivities and ozone formation were studied. The best methanol conversion and lower ozone residual concentration were obtained with bimetallic oxides MnO2/CuO/Al2O3 and MnO2/CeO2/Al2O3. A kinetic model and reaction mechanisms were proposed for methanol decomposition without catalyst, building on the work carried out in diverse publications. (C) 2016 Elsevier B.V. All rights reserved.