Optimization of CO2 methanation reaction over M/Mn/Cu–Al2O3 (M: Pd, Rh and Ru) catalysts

•Trimetallic Ru/Mn/Cu–Al2O3 oxide catalyst was found to be a potential catalyst and was further optimized by response surface methodology–central composite design (RSM-CCD).•The experimental optimization value (98.8% CO2 conversion) obtained was in agreement with the predicted result from optimization by RSM-CCD (99.9% CO2 conversion). The catalytic activity of CO2 methanation with H2 over M*/Mn/Cu–Al2O3 (M*=Pd, Rh and Ru) oxide catalysts in simulated natural gas was investigated. Among them, Ru/Mn/Cu–Al2O3 catalyst was found to be the most promising catalyst. Response surface methodology involving central composite design was employed and Ru loading was found to be the most significant effective factor, followed by calcination temperature and catalyst loading. The optimum condition for CO2 conversion was at 10.9wt.% Ru loading, calcination temperature of 1035°C and catalyst loading of 5wt.g. Interestingly, the RMC10 catalyst demonstrated good activity, stability and robustness during entire testing period which is suitable for industrial application.