Biogas reforming on hydrotalcite-derived Ni-Mg-Al catalysts: the effect of Ni loading and Ce promotion

Abstract

Due to the expected large growth of biogas production, particularly in Europe, biogas utilization technology could play an important role in the near future. Direct biogas reforming through dry reforming of methane (DRM) has great potential as an intermediate step in biogas upgrading to fuels and commodity chemicals. In this work, a series of Ce-promoted Ni-Mg-Al hydrotalcite (HT) derived catalysts with different Ni loadings was prepared to study their applicability for model biogas reforming at low CO2 concentrations. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H2-chemisorption, thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Reforming of model biogas was carried out at 600 °C, 1 bar and non-diluted CO2/CH4 = 1:3 and high GHSV. To further assess the effect of Ni loading on the Ce-promoted catalysts, DRM was studied in a temperature range of 500–800 °C. Furthermore, comprehensive post-mortem characterizations were conducted to elucidate the consequence of carbon formation and Ni sintering on the catalytic activity and stability. It was demonstrated that higher Ce/Ni ratio results in more active catalyst, which is also more resistant to sintering and coke deposition even at low concentrations of CO2 in the feed.