Hydrogen and/or syngas production by combined steam and dry reforming of methane on nickel catalysts

Abstract

Two alumina supported Ni catalysts with pore sizes of 5.4 nm and 9 nm were synthetized, characterized and tested in the Combined Steam and Dry Reforming of Methane (CSDRM) for the production of hydrogen rich gases or syngas. The reaction mixture was designed to simulate the composition of real clean biogas, the addition of water being made in order to have molar ratios of H2O:CO2 corresponding to 2.5:1, 7.5:1 and 12.5:1. Structural and functional characterization of catalysts revealed that Ni/Al2O3 with larger pore size shows better characteristics: higher surface area, lower Ni crystallite sizes, higher proportion of stronger catalytic sites for hydrogen adsorption, and higher capacity to adsorb CO2. At all studied temperatures, for a CH4:CO2:H2O molar ratio of 1:0.48:1.2, a (H2+CO) mixture with H2:CO ratio around 2.5 is obtained. For the production of hydrogen rich gases, the optimum conditions are: CH4:CO2:H2O = 1:0.48:6.1 and 600 °C. No catalyst deactivation was observed after 24 h time on stream for both studied catalysts, and no carbon deposition was revealed on the used catalysts surface regardless the reaction conditions.