Biogas dry reforming for syngas production on La promoted hydrotalcite-derived Ni catalysts

Abstract

Biogas plays a key role in the emerging renewable energy market, and biogas utilization attracts increasing attention in the renewable energy industry. As biogas consists mainly of CH4 and CO2, one of the most suitable processes for its utilization is through dry reforming of methane (DRM) for synthesis gas (syngas) production. In this study, we demonstrate the feasibility of direct biogas reforming for syngas production over promoted hydrotalcite-derived (HT) Ni catalysts. A series of 20Ni-Mg-Al HT-like catalysts with different lanthanum (La) loadings were prepared to study the influence of La-promoter on the activity of the catalysts for biogas reforming through DRM. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H2-chemisorption and scanning electron microscopy (SEM). DRM experiments were performed at 600 and 750 °C, at a very high gas hourly space velocity (GHSV) of 240,000 ml/(gcat·h). Furthermore, a comprehensive range of CO2/CH4 ratios was studied at 600 °C to assess the catalyst under different biogas compositions. Methane decomposition reactions together with post-mortem catalyst characterization were also carried out to study the influence of carbon deposition on the deactivation of the catalysts. The catalysts exhibited different behavior under different DRM reaction conditions. The 20Ni-4La catalyst showed the highest activity and stability with the highest one-pass CO2 conversion of 80.8% at 750 °C. The stability of the 20Ni-8La catalyst at different model biogas compositions and very high GHSV demonstrated the feasibility of our La-promoted HT-derived Ni catalysts in direct biogas reforming at a low temperature of 600 °C.