Optimization of praseodymium oxide based catalysts for methanation reaction of simulated natural gas using Box-Behnken design

Abstract

Malaysia energy demand on natural gas is increasing, leading to the purification of sour natural gas through the removal of carbon dioxide using catalytic conversion technique. Praseodymium oxide is preferred due to its properties which are suitable in the production of catalysers, polish glass and also as alloying agent. Therefore, a series of praseodymium oxide catalyst was prepared by incipient wetness impregnation method and was calcined at 400oC for 5 hours during screening reaction. The experimental Box-Behnken design was applied for optimizing the parameters in catalytic methanation reaction. The optimum parameters were found to be compatible with the experimental result which showed that Ru/Mn/Pr (5:35:60)/Al2O3 calcined at 800°C with 65% Pr loading and 7 g of catalyst dosage gave 96% of CO2 conversion, determined using FTIR, and yielded about 41% of CH4 at reaction temperature of 400°C. In the stability test, the catalyst’s performance showed an increase and was stable up to 7 hours with 96% of CO2 conversion. X-ray Diffraction (XRD) analysis showed an amorphous structure while Field Emission Scanning Electron Microscope (FESEM) illustrated the presence of small and dispersed particles with undefined shape covering the catalyst surface. EDX analysis revealed that when calcination temperature increased, the mass ratio of Ru increased. Meanwhile Nitrogen Adsorption (NA) analysis revealed that Ru/Mn/Pr (5:35:60)/Al2O3 catalyst attained surface area of 134.39 m2/g.