(617d) Adsorption Separation of Methane and Carbon Dioxide for the Production of Renewable Natural Gas Using Activated Carbons
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Separations Division
Adsorption Applications for Sustainable Energy and Chemicals
Thursday, November 19, 2020 - 8:30am to 8:45am
Activated carbons are a widely used in industry for different applications due to their low cost and low energy requirements. This study investigated commercially available activated carbons and carbon aerogel for CO2 removal from biogas using adsorption, for the production of renewable natural gas. Pure component isotherms for methane were determined gravimetrically for temperatures of 10 to 90°C for pressures up to 6.5 atm. We also investigated the effect of some characteristics of the adsorbents such as pore size, surface, % oxidation, and ash content on this separation. It was observed that % oxidation had little effect on CH4 adsorption, while ash content had a negative effect on CH4 adsorption with these adsorbents. In the high-pressure region, pore size and surface area dominated the adsorption, whereas in the low pressure region, the heterogeneous nature of the carbon materials dominated adsorption, which has previously been observed for CO2 adsorption with similar materials. Using previously obtained pure component CO2 isotherms by the same materials, the Ideal Adsorbed Solution Theory (IAST) was used to predict binary isotherms for a CH4-CO2 mixture, and the Expected Working Capacity values (EWC) were calculated for different pressure swing adsorption applications. The most practical adsorbent used in this study for CO2 separation from biogas was found to be OLC carbon.