Direct Alkaline Anion Exchange Membrane Fuel Cell to Converting Methane into Methanol

摘要

Methane is the main constituent of natural gas and can be converted in higher value-added products for electricity cogeneration. It could be used as a solid membrane reactor (SMR) for application in Alkaline Anion-Exchange Membrane Fuel Cell (AAEMFC). The investigation for the conversion of methane was based on sodium borohydride (NaBH4) method using Pt/C Basf, Pd/C, Ni/C as catalysts. The electrocatalysts were prepared with 20 wt of metals loading on carbon. The X-ray diffraction (XRD) analysis revealed a face-centered cubic structure (FCC) for Pt/C and Pd/C catalysts, was observed Ni/NiO phases for Ni/C electrocatalyst. The Transmission Electron Microscopy (TEM) exhibited a good dispersion of nanoparticles and some agglomerations on the support, with a mean size of 6.4 nm for Pd/C, 5.7 nm for Ni/C and near to 2 nm size for Pt/C. The experiments with AAEMFC showed that all materials can carry out the reaction spontaneously. Pt/C catalyst presents energy density higher than the other materials. FTIR data suggest that methane was converted into small products organic molecules such as methanol and formate in different potentials for Pt/C, Pd/C, and Ni/C. The products were quantified by Raman spectroscopy. The high conversion efficiency obtained was about 20 at 0.3 V using Pt/C catalyst, the maximum conversion over Pd/C was 17.5 at 0.15 V, associated with the formation of a thin layer of PdO on the catalytic surface. The highest conversion rate (13) was observed in closed circuit potentials to the short circuit in the cell with Ni/C catalyst. The results suggest that for the selective conversion of methane to methanol are most promising using materials containing Pt or Pd.