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

• Published in: Fuel (Guildford) 2013-09, Vol.111, p.778-783
• Main Authors: de Llobet, S., Pinilla, J.L., Lazaro, M.J., Moliner, R., Suelves, I.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biogas; Biomass; Carbon; Carbon dioxide; Catalysts; Catalytic Decomposition of Biogas; CH4–CO2 reaction; Deactivation; Deactivation study; Decomposition; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; Nanostructured carbon; Natural energy; Ni/Al2O3 catalyst; Nickel; Partial pressure
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2013.05.001

•CDB is based on the direct decomposition of CH4 and CO2.•CDB promotes carbon accumulation in form of filamentous structures.•Effect of CH4 and CO2 partial pressures on initial reaction rates of CDB is shown.•The steady state is reached even though the CH4:CO2 ratio is higher than one.•Temperature increases reaction rates, but it has no effect on catalyst deactivation. 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.