Nanocrystalline of Ruthenium-Iron Promoted Alkaline Oxides Based Catalysts for CO2/H2 Methanation Reaction

Abstract

New catalyst formulation of alkaline earths (M’ = Mg, Ca, Sr and Ba) based catalysts had been successfully prepared in this research by doping with iron (Fe) and noble metal ruthenium (Ru) in the ratio of 5:10:85 supported on alumina via impregnation method.  Two different ratios of catalyst Ru/Fe/M’ (5:30:65)/Al₂O₃ and Ru/Fe/M’ (5:10:85)/Al₂O₃ calcined at 1000°C had been prepared at the screening stage.  The best catalyst from this stage was further investigated in optimization process at different calcination temperatures between 900ºC – 1100 ºC and loadings between 80 - 90 wt.%.  An in-house-built micro reactor with Fourier transform infrared (FTIR) and TQ analysis software were used to study the percentage of CO₂ conversion and also the percentage of CH₄ formation.  From the catalytic study, Ru/Fe/Sr (5:10:85)/Al₂O₃ catalyst calcined at 1000ºC was categorized as a promising catalyst which gave 90.1% CO₂ conversion and 100% selectivity of CH₄ at reaction temperature of 300ºC.  This catalyst showed a polycrystalline structure with a mixture of SrO, Al₂O₃, Fe₂O₃ and RuO₂ species which was obtained by an X-Ray diffraction (XRD) analysis.  The characterization of surface morphology illustrated that the catalyst surface was covered with agglomerated and aggregated particles with staghorn coral shape. An energy dispersive X-Ray (EDX) analysis confirmed the presence Sr, Fe, Ru and Al on the catalyst surface.  The analysis from thermogravimetry analysis (TGA) revealed that 1000 °C of calcination temperature was good enough to produce pure metal oxide for the catalysts.