From Carbon Dioxide to Fuel: KineticModelling of Methane Production in Carbon Dioxide Hydrogenation Processes

Abstract

Fuel production from carbon dioxide in the laboratory seems promising (e.g., Bhanage & Arai, 2014), however commercialization of the carbon dioxide-to-fuel processes at large scale is limited by high operating costs and technical challenges. Therefore, it is essential to develop mathematical models that would enable us to predict fuel production. This research is aiming at building kinetics model to predict catalytic carbon dioxide methanation at different operating parameters. The model was developed based on published experimental results with a total pressure of 17 bar, hydrogen and carbon dioxide molar ratio of 3, Gas hourly space velocity (GHSV) varies from 2.4 NLh-1gcat-1 to 8.4 NLh-1gcat-1, over a temperature range of 270°C to 310°C on iron catalyst with particle size between 14 nm and 38 nm (Pour et al., 2017). Possible rate equations were constructed by using Langmui-Hinshelwood-Hougen-Watson approach (1943) and discriminated by t-test and F-test at 95% confidence interval. It was found that CO2 methanation rate predicted by the following correlation exhibits excellent agreement with experimental data and satisfies thermodynamic consistency criteria. rCH4 = k[p(CO2)-(p(CH4) p(H2O)^2)/(Kp(H2)^4 )]/((1+ (K(CO2 ) p(CH4) p(H2O))/(Kp(H2)))) The kinetic model would help engineers and facilities owners to optimize methane production and reduce operating costs, thus encourage implementation of the carbon dioxide hydrogenation technology on a vast scale in various fields, such as power plant and transportation. Furthermore, it would allow policy makers to investigate the feasibility of installing carbon dioxide hydrogenation unit in the industrial plants to limit carbon dioxide emissions, as an alternative solution to carbon taxes.