The effect of WO₃ modification of ZrO₂ support on the Ni-catalyzed dry reforming of biogas reaction for syngas production

The time-on-stream catalytic performance and stability of 8 wt. % Ni catalyst supported on two commercially available catalytic supports, ZrO₂ and 15 wt.% WO₃-ZrO₂, was investigated under the biogas dry reforming reaction for syngas production, at 750°C and a biogas quality equal to CH₄/CO₂ = 1.5, that represents a common concentration of real biogas. A number of analytical techniques such as N2 adsorption/desorption (BET method), XRD, H₂-TPR, NH₃- and CO₂-TPD, SEM, ICP, thermal analysis (TGA/DTG) and Raman spectroscopy were used in order to determine textural, structural and other physicochemical properties of the catalytic materials, and the type of carbon deposited on the catalytic surface of spent samples. These techniques were used in an attempt to understand better the effects of WO₃-induced modifications on the catalyst morphology, physicochemical properties and catalytic performance. Although Ni dispersion and reducibility characteristics were found superior on the modified Ni/WZr sample than that on Ni/Zr, its dry reforming of methane (DRM) performance was inferior a result attributed to the enhanced acidity and complete loss of the basicity recorded on this catalyst, an effect that competes and finally overshadows the benefits of the other superior properties. Raman studies revealed that the degree of graphitization decreases with the insertion of WO3 in the crystalline structure of the ZrO₂ support, as the I_D/I_G peak intensity ratio is 1.03 for the Ni/Zr and 1.29 for the Ni/WZr catalyst.