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

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.