CH4 and CO2 partial pressures influence and deactivation study on the Catalytic Decomposition of Biogas over a Ni catalyst

Abstract

A conceptually similar approach to dry reforming of CH4 (DRM) called Catalytic Decomposition of Biogas (CDB) is proposed. CDB is based on the direct decomposition of CH4 and CO2, which are the most abundant components in biogas (typically with CH4:CO2 molar ratios higher than 1). The main difference between DRM and CDB lies in the desired products obtained in each process. While in DRM carbon formation is not desired and thus avoided, in CDB carbon accumulation in form of filamentous structures is promoted. In this work, the effect of CH4 and CO2 partial pressures on the initial reaction rates of CDB was studied using a Ni/Al2O3 catalyst. Furthermore, a deactivation study was carried out in order to determine the experimental conditions (CH4 and CO2 partial pressures and temperature) at which carbon formation did not deactivate the catalyst. It was proved that after a certain time on stream, CDB can reach the steady state even though the CH4:CO2 molar ratio is higher than one (typical biogas conditions). In addition, temperature increased reaction rates since CDB is an endothermic process, but it had no effect on catalyst deactivation.