Experimental Study of Model Biogas Catalytic Steam Reforming: 1. Thermodynamic Optimization

The general objective of this investigation is the development of a biogas steam reforming concept and to bring it to a state of readiness for industrial demonstration. Through biogas steam reforming, H2-rich synthesis gas will be produced from which gas engines benefit in terms of higher efficiency and lower NO x emissions compared to direct combustion of raw biogas. Furthermore, pure hydrogen can be produced out of a renewable source using this route. The aim of this experimental study is to determine the operational envelope of biogas steam reforming by optimizing the performance of an externally heated reformer in terms of CH4 conversion, H2 yield, and catalyst efficiency. Therefore, a clean model biogas, using a constant molar ratio of CH4/CO2 = 1.5, is contacted to different supported nickel catalysts in a fixed bed reactor. The influence of temperature, water vapor portion, and contact time is analyzed. The resulted reformate composition is plausible with respect to thermodynamic equilibrium calculations. On the basis of the results, the steam/carbon molar ratio in the range of 3−4 and operating temperature of 700 °C are found as the optimal operating conditions. In addition, the catalyst activity, thermal stability, and resistance to carbon formation have been observed as critical parameters on the application of different kinds of catalysts.