CO2 Impact on Methane Pyrolysis as a Key Issue of Using Biogas as an Educt: A Theoretical Study

Abstract

Dry reforming of methane (DRM) has attracted great interest for the production of syngas and/or hydrogen in a more environmentally friendly way. It is especially advantageous in this case to use biogas—as a mixture of methane, CO2, and traces of further gases—as a feedstock replacement for natural gas. Nevertheless, industrial implementation of DRM is currently limited because of its inherent process restrictions. The biggest challenge of dry reforming is the deposition of carbon on the catalyst, known as “coking.” The focus of this theoretical study is to evaluate the feasibility of a biogas dry reforming process in a liquid metal (Sn) bubble column reactor. This technology has already been proven suitable for methane pyrolysis to obtain hydrogen, preventing issues related to reactor clogging or catalyst deactivation caused by carbon deposition. Results show that at high operating temperatures and atmospheric pressure, a product gas primarily composed of H2 and CO would be obtained. CO2 and water vapor may also be present in the final product depending on the operating conditions. The molten tin inside the reactor would, according to the presented theoretical considerations, not be affected by the formation of carbides and oxides. Additionally, the syngas composition (the H2 : CO ratio) could be adjusted by using different CH4 : CO2 feed ratios.