Effect of CO2 on the removal of NO over viscose-based activated carbon fibers

Abstract

Adsorption experiments under varied conditions were carried out in a laboratory-scale fixed bed reactor to investigate the effect of CO2 on the removal of NO over the viscose-based activated carbon fibers (ACFs). Pore volumes, average pore size, and specific surface area were separately determined by t-plot method, density functional theory, and Brunauer– Emmett–Teller theory. Surface functional groups were examined by X-ray photoelectron spectroscopy. Moreover, temperature programmed desorption was applied to investigate the NO adsorption behavior over the carbon surface. Based on the extensive information obtained, effect of CO2 on the removal of NO over the ACF surface was fully discussed. The results indicated that CO2 inhibited the adsorption and oxidation of NO over the ACF surface mainly because (1) CO2 and NO molecules compete for the limited active sites over the ACF surface; (2) CO2 could restrain the formation of oxygen groups derived of adsorbed O2 over the ACF surface; and (3) CO2 hinders direct reactions between NO and O2 molecules.