Characterization and modelling optimization on methanation activity using Box-Behnken design through cerium doped catalysts

Abstract

Catalytic methanation reaction has been a promising technique for the conversion of CO2 to valuable fuel product, CH4 and thus reduces the emission of CO2 to the environment. Many catalysts have been investigated by this method yet some carbon depositions have occurred during reaction which leading to low conversion rate of CO2 to CH4. Therefore, cerium catalyst has been applied in this study for the investigation of catalytic activity utilizing response surface methodology (RSM) method (Box-Behnken Design) in order to achieve the highest CO2 conversion. The potential trimetallic oxide catalyst of Ru/Mn/Ce (5:35:60)/Al2O3 was chosen and the experimental parameters used were calcination temperature of 600–800 °C, ratio based loadings of 60–80 wt%, and catalyst dosage of 3–7 g with CO2 conversion to CH4 as a respond. The RSM optimum parameter of calcination temperature of 697.47 °C, ratio of 60.38% and catalyst dosage 6.94 g was tested. At these conditions, the results were verified experimentally (99.98% CO2 conversion), which was accurately close to the predicted value (100% CO2 conversion). Ru/Mn/Ce (5:35:60)/Al2O3 catalyst revealed the active species of CeO2 in XRD analysis with oxidation state Ce 4+ as supported by ESR analysis. When the calcination temperature was increased, the surface area decreases as observed in nitrogen adsorption supported with larger particle size as shown in FESEM. The reducibility of cerium catalyst was started at lower temperature.