Evaluation of Different Dielectric Barrier Discharge Plasma Configurations As an Alternative Technology for Green C1 Chemistry in the Carbon Dioxide Reforming of Methane and the Direct Decomposition of Methanol

Carbon dioxide reforming of methane and direct decomposition of methanol have been investigated using dielectric barrier discharges (DBD) at atmospheric pressure and reduced working temperatures. Two different plasma reactor configurations are compared and especial attention is paid to the influence of the surface roughness of the electrodes on the conversion yields in the first plasma device. The influence of different filling gap dielectric materials (i.e., Al2O3 or BaTiO3) in the second packed configuration has been also evaluated. Depending on the experimental conditions of applied voltage, residence time of reactants, feed ratios, or reactor configuration, different conversion yields are achieved ranging from 20 to 80% in the case of methane and 7−45% for the carbon dioxide. The direct decomposition of methanol reaches 60−100% under similar experimental conditions. Interestingly, the selectivity toward the production of hydrogen and carbon monoxide is kept almost constant under all the experimental conditions, and the formation of longer hydrocarbon chains or coke as a byproduct is not detected. The maximum efficiency yields are observed for the packed-bed reactor configuration containing alumina for both reaction processes (∼1 mol H2 per kilowatt hour for dry reforming of methane and ∼4.5 mol H2 per kilowatt hour for direct decomposition of methanol).