10:15 - 10:45
Thursday, 19 September 2019
T3.7 Recycling: CO2 Fixation into Methane using Ruthenium Base Catalysts
The implication of CO2 emissions to the climate change has become the focus of attention in the scientific and industrial communities. CO2 management is vital for ensuring the economic and environment viability especially for monetization of high CO2 field. In view of this outstanding challenges, CO2 is not seen anymore as a waste but as an alternative carbon feedstock to transform this stable molecule into useful chemicals and energy carriers. Methanation process might represent one of the most convenient ways for CO2 utilization with the easiness to integrate with current production facilities, thus it is desirous to convert more CO2 with high yield of methane. Synthesis of methane was achieved in this study using expediently synthesized Ru/Al2O3 and Ru/SiO2 catalysts. It was performed at temperatures between 280°C and 320°C under atmospheric pressure. The catalysts were prepared by wet impregnation technique with fixed Ru loadings. 0.1M of Ru precursor salt solution was added to 2.5 g oxide support, continuously stirred, and evaporated to dryness at 80°C. It was then dried in an oven, grinded and calcined at 400 °C. The synthesized catalysts were characterized using H2-TPR, N2-adsorption, XRD and FESEM. Catalytic tests were performed in a glass nano-sized reactor packed with 0.5 g of catalyst under atmospheric pressure. Reaction temperature and space velocity were taken into account as two important parameters with fixed H2/CO2 molar ratio. It can be seen that at low reaction temperature, highest CO2 conversion was achieved for Ru/Al2O3 by a factor of two as compared to Ru/SiO2 catalyst with conversion of 82.80% and 47.03% respectively. Ru/Al2O3 maintained high CO2 conversion as temperature varies in the range of 280°C to 320°C with no sign of deactivation, maintaining its catalytic activity. However, under the same reaction conditions, as temperature increased, Ru/SiO2 catalyst can reach the same performance as Ru/Al2O3 but suffer from catalyst deactivation. The conversion of CO2 at two different GHSV of 10000 and 15000 h-1 with respect to varying reaction temperature showed consistently high CO2 conversion for Ru/Al2O3 at 89.67% and 91.60% respectively. As for Ru/SiO2, the CO2 conversion are 80.39% and 84.07% respectively. By increasing GHSV, CO2 conversion increases, however CH4 selectivity remains high for both Ru catalysts. It is interesting to note that high GHSV gave higher CO2 conversion for both support systems, contrary to typical relationship which support conversion is inversely proportional to conversion. This behavior implies a competitive reaction takes place when reaction carried out at low GHSV. Hence, future work to carry out this gas phase CO2 methanation at a much higher GHSV to evaluate its effect and benefits.CO2 catalytic conversion to methane has been successfully performed with high catalyst activity at moderate reaction temperature. This is essential because high yield catalyst is a significant factor in ensuring economic feasibility of the conversion, complementing the availability of the sustainable hydrogen production. There is a prospect for further scaling up to complement the current commercial catalyst proven for handling low concentration on CO2.