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 °C for 24 h (conventional heating) to 180 °C for 1h, 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 H₂/CO ratio. Stable maximum CH₄ and CO₂ conversions of ∼99.5% and ∼94%, respectively, at H₂/CO ∼0.9 were possible to reach with the 7 wt. % ruthenium-doped SrTiO₃ catalyst exposed to maximum temperatures in the vicinity of 940 °C. A comparative theoretical scale-up study shows significant improvement in H₂ production capability in the case of the perovskite catalyst compared to carbon-based catalysts.