Characteristics of Solid Fuel Oxidation in a Molten Carbonate Fuel Cell

Abstract

Oxidation behaviours of ash free coal (AFC), carbon, and H 2 fuels were investigated with a coin type molten carbonate fuel cell. Because AFC has no electrical conductivity, its oxidation occurs via gasification to H 2 and CO. An interesting behaviour of mass transfer resistance reduction at higher current density was observed. Since the anode reaction has the positive reaction order of H 2 , CO 2 and H 2 O, the lack of CO 2 and H 2 O from AFC results in a significant mass transfer resistance. However, the anode products of CO 2 and H 2 O at higher current densities raise their partial pressure and mitigate the resistance. The addition of CO 2 to AFC reduced the resistance sufficiently, thus the resistance reduction at higher current densities did not appear. Electrochemical impedance results also indicate that the addition of CO 2 reduces mass transfer resistance. Carbon and H 2 fuels without CO 2 and H 2 O also show similar behaviour to AFC: mass transfer resistance is diminished by raising current density and adding CO 2 .