Catalysts applied in biogas reforming: phases behavior study during the H2 reduction and dry reforming by in situ X-ray diffraction

Dry reforming of methane is an important route to reuse the CO2 and CH4 to obtain the syngas (CO + H-2), which can be converted into several economically viable products. Generally, Ni-based catalysts are applied in dry reforming due to their low cost and high activity. Therefore, we propose the application of Ni-based catalysts dispersed in the mixed metal oxide (NiZnAl, Ni-ZnAlZr and Ni-ZnZr) obtained from the calcination of the precursor synthesized via the co-precipitation method. Herein, carbon dioxide (CO2) and methane (CH4) conversions were recorded over time-on-stream for all catalysts, simulating the biogas composition (60% CH4 and 40% CO2). As a complementary analysis, we also study the catalysts during the H-2 reduction and dry reforming by in situ X-ray diffraction (XRD). Carbon deposition on the surface of the catalysts was analyzed using X-ray diffraction, SEM images, Thermal analysis (TG) and Raman spectroscopy. In particular, the incorporation of Zr4+ into the materials provided the CH4 conversion, selectivity to hydrogen and stability of the phases during the reaction. On the other hand, the presence of a higher amount of basic sites in the Ni-ZnAl favored the CO2 conversion. In general, all samples showed the H-2 :CO product ratio less than a unit indicating the relevant contribution of parallel reactions. Thermal analysis showed that the amount of the deposited carbon post-reaction was lower on the surface of the Ni-ZnAl catalysts. [GRAPHICS] .