Investigation of Ru/Mn/Ce/Al2O3 catalyst for carbon dioxide methanation: Catalytic optimization, physicochemical studies and RSM

• The development of ceria based catalyst impregnated with Ru/Mn/Al2O3 was found to be considerably active for promoting the CO2 methanation reaction.
• The Ru/Mn/Ce-65/Al2O3 catalyst calcined at 1000 °C gave higher of 97.73% CO2 conversion with 91.31% of methane formation at reaction temperature of 200 °C.
• The investigation of Ru/Mn/Ce/Al2O3 catalysts on the ceria loading, calcination temperature and catalyst dosage can significantly affect the catalytic performance.
• The optimum conditions achieved from BBD model were 65 wt% of Ce loading with calcination temperature of 1025 °C and 10 g of catalyst dosage. The estimation of CO2 conversion was as high as 98.957%.
• The important degree of studied parameters which were suggested by RSM follows the order of calcination temperature > Ce loading > catalyst dosage.

The investigation of Ru/Mn/Ce/Al2O3 catalyst on the ceria loading, calcination temperature and catalyst dosage had significantly affected the catalytic performance. The optimum conditions were achieved over 10 g of Ru/Mn/Ce/Al2O3 catalysts calcined at 1000 °C with 65 wt% of Ce loading which gave 97.73% CO2 conversion and 91.31% of methane formation at reaction temperature of 200 °C. The physicochemical properties investigated by XRD diffractogram showed that the catalyst still having polycrystalline structure with the mixture of Mn4+ and Mn3+ although had being calcined at high temperature of 1000 °C. Meanwhile, FESEM analysis indicated a morphology which looks like staghorn coral morphology with the smallest particle size of 86 nm and the highest BET surface area of 47.65 m2/g. The impact of these three critical parameters was investigated via Box–Behnken experimental design and their optimum values obtained over 10 g of Ru/Mn/Ce/Al2O3 catalyst were calcined at 1025 °C with Ce loading of 65 wt%. The predicted value given was 98.95% of CO2 conversion which was closely agreed with our experimental result (98.25%) over similar conditions.