Effect of Oxidants on Syngas Synthesis from Biogas over 3 wt % Ni-Ce-MgO-ZrO2/Al2O3 Catalyst

Abstract

The utilization of fossil fuels has led to a gradual increase in greenhouse gas emissions, which have accelerated global climate change. Therefore, there is a growing interest in renewable energy sources and technologies. Biogas has gained considerable attention as an abundant renewable energy resource. Common biogases include anaerobic digestion gas and landfill gas, which can be used to synthesize high-value-added syngas through catalytic reforming. Because syngas (CO and H2) is synthesized at high reaction temperature, carbon is generated by the Boudouard reaction from CO and CH4 cracking; thus, C blocks the pores and surface of the catalyst, thereby causing catalyst deactivation. In this study, a simulation was performed to measure the CH4 and CO2 conversion rates and the syngas yield for different ratios of CO2/CH4 (0.5, 1, and 2). The simulation results showed that the optimum CO2/CH4 ratio is 0.5; therefore, biogas reforming over the 3 wt% Ni/Ce-MgO-ZrO2/Al2O3 catalyst was performed under these conditions. CH4 and CO2 conversion rates and the syngas yield were evaluated by varying the R values (R = (CO2 + O2)/CH4) on the effect of CO2 and O2 oxidants of CH4. In addition, steam was added during biogas reforming to elucidate the effect of steam addition on CO2 and CH4 conversion rates. The durability and activity of the catalyst after 200-h biogas reforming were evaluated under the optimal conditions of R = 0.7, 850 °C, and 1 atm.