Preparation of potassium intercalated carbons by in-situ activation and speciation for CO2 capture from flue gas

Nitrogen and/or sulfur doped carbons were extensively investigated as CO 2 adsorbents, however their performance in CO 2 capture from combustion flue gas, which is the largest stationary emission source, was less promising. Herein, potassium was used as a dopant for carbon, and a new series of materials, namely potassium intercalated carbons (PICs), were prepared sequentially by oxidation of mesoporous carbon, potassium ion exchange, and calcination. Based on results from FT-IR, XPS, TG-MS, etc., it was found the pre-loaded potassium interacted with the carbon matrix during calcination, enabled great flexibility in: (1) porosity adjustment by “in-situ activation”, and (2) surface chemistry manipulation by potassium intercalation. Taking together, the optimized sample (PIC-700) showed fast and stable CO 2 uptake of 5.23 wt.% in flue gas conditions (40 °C, 1 bar, 15%CO 2 ), which is among the highest for carbon-based adsorbents. Such promising performance is directly related to the enhanced CO 2 affinity due to the presence of potassium dopants. Dynamic separation of CO 2 from 15%CO 2 /85%N 2 showed similar adsorption capacity, and no performance decay could be observed during temperature swing cycles, demonstrating the great potential for the PICs for practical CO 2 capture applications.