Synthesis, characterization, and application of ruthenium-doped SrTiO3 perovskite catalysts for microwave-assisted methane dry reforming

A series of ruthenium-doped strontium titanate (SrTiO3) perovskite catalysts were synthesized by conventional and microwave-assisted hydrothermal methods. The structure was analyzed by X-Ray diffraction (XRD) confirming the formation of the perovskite phase with some TiO2 anatase phase in all the catalysts. Microwave irradiation decreases the temperature and time of synthesis from 220 degrees C for 24 h (conventional heating) to 180 degrees C for 1 h, without affecting the formation of perovskite. A 7 wt. % ruthenium-doped SrTiO3 catalyst showed the best dielectric properties, and thus its catalytic activity was evaluated for the methane dry reforming reaction under microwave heating in a custom fixed-bed quartz reactor. Microwave power, CH4:CO2 vol. % feed ratio and gas hourly space velocity (GHSV) were varied in order to determine the best conditions for performing dry reforming with high reactants conversions and H-2/CO ratio. Stable maximum CH4 and CO2 conversions of similar to 99.5% and similar to 94%, respectively, at H-2/CO similar to 0.9 were possible to reach with the 7 wt. % ruthenium-doped SrTiO3 catalyst exposed to maximum temperatures in the vicinity of 940 degrees C. A comparative theoretical scale-up study shows significant improvement in H-2 production capability in the case of the perovskite catalyst compared to carbon-based catalysts.