Combined steam and dry reforming of methane for syngas production from biogas using bimodal pore catalysts

Three catalysts with bimodal pore structure: Ni/Al2O3, Ni/MgO-Al2O3, Ni/La2O3-Al2O3 were prepared by refluxed co-precipitation method and characterized by N-2 adsorption-desorption, XRD, TPR, H-2-TPD and CO2-TPD. For comparison, a Ni catalyst impregnated on commercial alumina was also prepared. The catalysts were tested in combined steam and dry reforming of methane (CSDRM) at atmospheric pressure, 600-700 degrees C and CH4: CO2:H2O = 1:0.48:0.8, for the preparation of synthesis gas with H-2:CO ratio proper for methanol synthesis. The presence of both magnesium and lanthanum oxides contributes to a better dispersion and stabilization of Ni nanoparticles on the catalyst surface. The catalytic activity for CSDRM increases in the order Ni/Al2O3(r) < Ni/Al2O3 < Ni/La2O3-Al2O3 approximate to Ni/MgO-Al2O3. TPD methods revealed that the good performance of Ni/La2O3-Al2O3 is a consequence of its good properties for hydrogen adsorption, while the improved catalytic properties of Ni/ MgO-Al2O3 reside in its good properties for CO2 adsorption. Synthesis gas with the H-2:CO ratio between 2.3 and 2.5 was obtained for all the reaction conditions used in this work. The bimodal pore catalysts showed no deactivation during 6 h TOS. The analysis of used catalysts established the catalyst with the best stability as being Ni/La2O3-Al2O3.