AN EXPERIMENTAL AND THEORETICAL APPROACH FOR THE CARBON DEPOSITION PROBLEM DURING STEAM REFORMING OF MODEL BIOGAS

The conversion of biogas to electricity presents an attractive niche application for solid oxide
fuel cells (SOFCs). A number of attempts have been made to use biogas as a fuel for high
temperature fuel cell systems such as SOFCs. Biogas can be converted to a hydrogen-rich
fuel in a reforming process which can use steam or carbon dioxide as the reforming agent.
Conventionally, the reforming process is conducted at around 850◦C using several different
catalysts depending on application. Biogas naturally contains the reforming agent, carbon
dioxide, however, for typical biogas the content of carbon dioxide is insufficient to conduct
the reforming process safely. Fore those cases, steam is added to prevent carbon deposition.
Carbon formation occurs between the catalyst and the metal support, creating fibers which
damage the catalytic property of the reactor. A number of papers have dealt with the
problem of carbon deposition during both methane steam reforming and dry reforming.
However, from the standpoint of solid oxide fuel cells, not every carbon-free condition is
optimal for its operation. This paper treats this subject, explaining the mechanism of carbon
formation during the steam reforming of biogas and using a numerical analysis to determine
efficient and carbon-free working conditions.