Conversion of carbon dioxide emission using catalytic methanation method in hot mix asphalt

Abstract

The purpose of this study is to mitigate the carbon dioxide (CO2) emission from bitumen tank combustion unit in hot mix asphalt (HMA) plant. This study has been conducted by introducing the catalytic methanation method to reduce the CO2 emission which majorly contributed to the greenhouse gases emissions in atmosphere. The benefit of using the method is that a high amount of CO2 can be reduced without effecting the asphalt mixture properties which are very crucial to ensure high-quality asphalt pavement service life. This study suggested the conversion of CO2 from flue gases emission to utilize it into methane (CH4). The first stage of the study is the analysis of flue gases emissions from bitumen tank combustion unit in HMA plant by on-site gas analysis and laboratory analysis. The flue gas emission analysis shows that CO2 is the major emission produced by combustion activities in bitumen tank combustion unit in HMA plant which the emission is between 4.95 - 15.55%. For the mitigation stage, Fourier Transform Infrared (FTIR) analysis is done to determine the percentage of CO2 conversion and CH4 formation over the catalyst used. After preparation and optimization, Ru/Sr/Ce (5:30:65)/Al2O3 catalyst calcined at 700°C for 5 hours and pre-treated at 300°C for 30 minutes with compressed air has been proposed as the best catalyst for the application of catalytic methanation method. This is because the catalyst produced the optimum values in term of CO2 conversion and CH4 formation during the reaction. The final stage of the study is the characterization of the catalyst to determine the factors contributed to its catalytic activities. The results show that the higher catalytic activities are caused by the uneven surface of catalyst with well shape hexagonal like particle on it. Besides that, the higher amount of Ruthenium (Ru) element composition in the catalyst, moderate basicity properties of the catalyst, and the higher pore volume in the catalyst also significantly contributed to its higher catalytic activities.