Catalytic methanation on conversion of carbon dioxide over alumina-supported manganese oxide catalysts

Abstract

In this study, the catalytic methanation conversion system is introduced to convert CO2 to methane (CH4). Hot mix asphalt (HMA) plants include of heating, drying and mixing processes contributed to carbon dioxide (CO2 ) emissions. The first stage of the study is the analysis of flue gases emissions from the chimney in HMA plant by on-site gas analysis and laboratory. The flue gas emission analysis shows that CO2 produced from HMA plant operating is between 1.30-7.33%. For second stage, the optimization and characterization of potential catalyst was conducted to determine the factor contributed to the catalytic activity. The results from optimization of catalyst revealed that the parameters catalyst loading with 65wt.% of manganese (Mn), 30wt.% of nickel (Ni), and 5wt.% of ruthenium (Ru) at calcination 500°C and aging of 90°C produced the optimum values in term of CO2 conversion and CH4 formation during the reaction. For characterization analysis, the X-ray diffractograms (XRD) has observed the well-defined sharp peaks for elements of alumina (Al2O3), manganese oxide (MnO), nickel oxide (NiO), and ruthenium oxide (RuO) in a crystalline shape. The Brunauer-Emmett-Teller (BET) theory of surface area of Ru/Ni/Mn (5:30:65)/Al2O3 catalyst are decreased along with the increasing of calcination temperature. The Nitrogen adsorption (NA) found that more characteristic of mesopores resembled the typical shape of Type IV isotherm. Field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX) revealed the morphology of catalyst was break into pieces with planes surfaces. Also, the presence of crystallite images in rhombic and diamond shape as the calcination temperature increased. At last stages, the effect of gas mixture of CO2/H2 methanation with compressed air (N2O2), nitrogen (N2), propane (C3Hg) and nitrous dioxide (NO2) that present in HMA plants towards the catalyst were not deactivate the catalytic activity. The results show that, less significant different (10%) of CO2 conversion produces compared to the optimum CO2 conversion. In addressing environmental issues, the introduction of catalyst technology in the HMA plants is therefore highly recommended to preserve sustainable environmental.