NiMg/Ceria-Zirconia Cylindrical Pellet Catalysts for Tri-reforming of Surrogate Biogas

Cylindrical NiMg/Ce0.6Zr0.4O2 pellet catalysts with two different sizes (large, radius = 1.59 mm; small, radius = 0.75 mm) were produced by extrusion of powder catalysts. The small catalyst pellets had a higher specific surface area, pore volume, average pore size, radial crush strength, and resistance to breakage than the large pellets. Tri-reforming tests with surrogate biogas were conducted at 3 bar and 882 degrees C, with the feed molar ratios of CH4:CO2:air fixed at 1.0:0.7:0.95 and the H2O/CH4 molar feed ratio varied (0.35-1.16). The small catalyst pellets exhibited lower internal mass-transfer resistance and higher coking resistance compared to the large pellets. CO2 conversion decreased and H-2/CO molar ratio increased with the increase of H2O/CH4 molar feed ratio; which are consistent with the trends predicted by thermodynamic equilibrium calculations. The results indicate that the NiMg/Ce0.6Zr0.4O2 catalyst pellets, are promising for Commercial scale applications.