Abstract:
The aim of this study is to determine the optimum operating parameters of the methane OSR unit of the Fuel Processor Prototype-FPP yielding high methane conversion activity with suppressed H2/CO product selectivity through a Box-Behnken experimental design using temperature, S/C and O/C ratios of the feed, and the catalyst weight (or residence time, W/F) as the experimental parameters. The ranges of 350-450 °C, 3-5, 0.74-1.33, and 1.50-2.00 mg.min/ml were used as the experimental design parameter ranges for temperature, S/C feed ratio, O/C feed ratio and W/F, respectively. Additionally, a thermodynamic analysis was also performed for the same operation conditions in order to form a comparison basis for evaluating the performance test results, and for better understanding of the nature of OSR as well. Experimental CH4 conversion was increased by a rise in each of the parameters of temperature, S/C and O/C feed ratios; and this trend was confirmed via the thermodynamic analysis for the conditions used in the experiments. On the other hand, the observed effect of W/F on experimental CH4 conversion was nonconventional, i.e. an increase in W/F mostly resulted in a decrease in CH4 conversion. This was confirmed further by comparative analysis with the thermodynamic simulation results yielding lower CH4 conversion levels compared to those obtained in the experiments for W/F ratios of 1.50-2.00 mg.min/ml. In addition to CH4 conversion, product distribution of OSR varied with the changes in the reaction conditions. Consequently, as the trends in H2 production and H2/CO product ratio obtained as a function of W/F were -in general- opposite, the results reveal the existence of a Pareto optimal for W/F value, and strongly suggested the necessity of scrutinizing the relation between space time/space velocity (W/F) and reactor performance to find the practical operating conditions for the OSR reactor.
