Ultra‐High Surface Area Activated Porous Asphalt for CO 2 Capture through Competitive Adsorption at High Pressures

This study reports an improved method for activating asphalt to produce ultra‐high surface area porous carbons. Pretreatment of asphalt (untreated Gilsonite, uGil ) at 400 °C for 3 h removes the more volatile organic compounds to form pretreated asphalt ( uGil‐P ) material with a larger fraction of higher molecular weight π‐conjugated asphaltenes. Subsequent activation of uGil‐P at 900 °C gives an ultra‐high surface area (4200 m 2 g −1 ) porous carbon material ( uGil‐900 ) with a mixed micro and mesoporous structure. uGil‐900 shows enhanced room temperature CO 2 uptake capacity at 54 bar of 154 wt% (35 mmol g −1 ). The CH 4 uptake capacity is 37.5 wt% (24 mmol g −1 ) at 300 bar. These are relevant pressures in natural gas production. The room temperature working CO 2 uptake capacity for uGil‐900 is 19.1 mmol g −1 (84 wt%) at 20 bar and 32.6 mmol g −1 (143 wt%) at 50 bar. In order to further assess the reliability of uGil‐900 for CO 2 capture at elevated pressures, the authors study competitive sorption of CO 2 and CH 4 on uGil‐900 at pressures from 1 to 20 bar at 25 °C. CO 2 /CH 4 displacement constants are measured at 2 to 40 bar, and found to increase significantly with pressure and surface area.