Ruthenium(III) monosubstituted Keggin-type polyoxotungstate: Synthesis, characterization, and application in the catalytic methanation of carbon dioxide

Cs5[?-SiW11O39RuIII(H2O)]?8H2O heteropolysalt with a Keggin structure was successfully synthesized, and its physicochemical characteristics were determined via X-ray diffraction, UV?Vis spectroscopy, Fourier-transform infrared and Brunauer, Emmett and Teller surface area measurements. The acid? ?base properties were evaluated via isopropanol decomposition. The catalytic performance for the CO2 methanation reaction was evaluated in a fixed-bed reactor at atmospheric pressure by varying the process parameters, which included the reaction temperature (200?450?C), reactant mole ratio H2/CO2 (1, 2 and 4) and flow rate (1, 1.5 and 2 L/h). The experimental results showed that Cs5[?-SiW11O39RuIII(H2O)]?8H2O exhibited the best compromise between conversion and selectivity at 350?C, with a H2/CO2 mole ratio of 4 and a flow rate of 1 L/h.