Efficient conversion of low-concentration coal mine methane by solid oxide fuel cell with in-situ formed nanocomposite catalyst

Abstract

Solid oxide fuel cell is promising to efficiently convert the low-concentration coal mine methane (methane concentration c(CH4) <30%) from pollutant to clean energy. However, the low internal reforming performance and the coking at anode become the big challenges of SOFC using LC-CMM. Therefore, the Mo-doped NiTiO3 catalyst layer is fabricated over SOFC anode in this work. The catalyst can be in-situ reduced to nanoscale Ni and Mo-doped TiO2-δ composite catalyst with plentiful oxygen vacancies, thus adsorbing oxygen species to enhance CH4 internal reforming and remove carbon. It is demonstrated that the catalyst-modified SOFC using LC-CMM exhibits the much better electrochemical performance, anti-carbon effect and discharging stability than the un-modified SOFC. The modified SOFC also shows the good electrochemical and internal reforming performances under different LC-CMM with various methane concentration c(CH4) and oxygen concentration c(O2). The distribution of relaxation time (DRT) indicates that the catalyst can remove carbon and facilitates the adsorption, dissociation and transport of surface species through the enhanced oxygen-species mediated surface reactions. Besides, a 2D multi-physics coupling model is built to study the reforming-enhancing and anti-carbon mechanisms of the catalyst layer.