Experimental Study on Dry Reforming of Biogas for Syngas Production over Ni-Based Catalysts

Abstract

Syngas production from dry reforming of biogas (DRB) is studied experimentally in this work. Ni/Al2O3, Pt/Al2O3, and Pt-Ni/Al2O3 are used as catalysts to examine the effect of CO2 content in biogas and H2O addition on DRB performance for reaction temperatures in the 600-800 °C range. It is found that the bimetallic Pt-Ni catalyst exhibits the best activity and thermal stability among the three types of catalysts studied due to better carbon deposition resistance. Because CO2 functions as the oxidant in combustion, CH4 conversion is enhanced when the biogas contains more CO2. One hundred percent CO2 conversion can be reached for biogas containing a less amount of CO2 at high temperatures. With H2O addition in DRB, the steam reforming of methane (SRM) reaction is the dominant reaction, resulting in higher H2 and CO yields with biogas containing lesser amounts of CO2. However, lower CH4 conversion and negative CO2 conversion do result. With higher CO2 content in the biogas, higher CH4 and CO2 conversions can be obtained. Lower yields of H2 and CO are obtained due to less SRM dominance. With H2O addition in biogas, the H2/CO ratio with a value greater than 1 can be obtained from DRB. It is also found that the H2/CO ratio with a value of 2.1 can be obtained for reactant composition with a molar ratio of CH4/CO2/H2O = 1:0.25:1 and reaction temperature of 800 °C.