Insights into CO2 removal mechanism via the carbonaceous surface in the exhaust gas of marine NG engines: A first-principles study

Abstract

Carbon-based materials adsorption method is a promising technology on CO2 removal in exhaust-gas environment for marine NG (Natural gas) engines. In the present study, the first-principles calculations are utilized to investigate CO2 adsorption capacity of the carbonaceous surface. The simulation results indicate that CO2 at different positions presents diverse adsorption characteristics. Simultaneously, the unsaturated carbon atoms on upper layer of the carbonaceous surface have better CO2 adsorption capacity. Moreover, a series of carbonaceous surface models have been calculated to examine CO2 adsorption behavior in the exhaust gas (containing CH4, O2, NO, NO2, H2O). It is found that CH4 can promote the adsorption capacity of CO2 on the carbonaceous surface and will not form competitive adsorption with CO2 when CH4 concentration is extremely low. Similarly, H2O and NO also have positive effect on CO2 adsorption. With the presence of O2 and NO2, the reverse appearance occurs. Noting that multiple oxygen atoms of the component are easier to gather electrons than the carbonaceous surface. The magnitude of charge transfer directly determines adsorption activity, so the carbonaceous surface with O2, NO2 assume weak CO2 adsorption capacity. This work provides a new insight into the field of CO2 adsorption.