Dry Reforming of Biogas Over Li–Ni–Al Catalysts: Influence of Li Incorporation Method

Hydrogen is a promising source of energy, given the current context of depletion of fossil fuels and increased emissions of greenhouse gases. The technological route for obtaining this fuel from the dry reforming of biogas has received considerable attention from researchers, as it converts the polluting gases CH4 and CO2 into synthesis gas (H2 and CO). In this work, Ni–Al catalysts derived from hydrotalcite were modified with lithium through different methods and were tested in the biogas dry reforming. Coprecipitation, wet and dry impregnation methods were applied, as well as memory effect reconstruction. N2 adsorption–desorption, XRD, TPR, CO2‐TPD, SEM, and TPO techniques were used for the characterization of the catalysts. For the catalytic tests, a flow rate of 60% CH4 and 40% CO2 was used as synthetic biogas. The ramp tests were carried out in the range from 500 to 750°C while the stability tests were carried out at 700°C for 8 h. The results demonstrated that the different Li incorporation methods had a strong effect on the surface, structural and reduction properties of the obtained catalysts. The coprecipitated sample (CP) presented the best performance in the reaction, due to its smaller crystallite size, high basicity and presence of weak, medium and strong basic sites, while the worst results observed for the impregnated samples were attributed to the formation of the LiAlO2 phase in these samples, resulting in materials with low surface area and large crystallite size. The CP sample reached the highest CH4 conversion (54%) after 480 min of reaction and a low carbon formation rate.