CO2 adsorption capacity and kinetics in nitrogen-enriched activated carbon fibers prepared by different methods

The effect of different N-doping treatments on the CO2 adsorption capacity and kinetics of activated carbons prepared from the same carbonaceous precursor was studied. Non-doped and N-doped activated carbon fibers with similar shape and diameter were considered in this study in order to discard the influence of particle size and morphology. The N-enriched fibers were obtained following different techniques, which led to activated fibers with different content, type and distribution of nitrogen. The porous texture was the main factor determining the CO2 adsorption capacity of the fibers, and treatment with ammonia at high temperature did not exert any positive influence. In contrast, fibers prepared from a pitch/nitrogenized resin blend showed a slightly enhanced CO2 adsorption capacity, which was ascribed to their homogenous distribution of nitrogen in the bulk material occupying internal positions of the carbon matrix. The kinetics of adsorption remarkably increased with the pH of the activated fibers, and the amount of CO2 adsorbed at short time (100 s) by the N-enriched fibers was, regardless the methodology used for their N-enrichment, twice higher than that observed for the N-free fibers. These findings prove the suitability of N-enriched activated carbons for use in swing adsorption systems operating at short time cycles. (C) 2015 Elsevier B.V. All rights reserved.