An investigation into the adverse effects of O2, SO2, and NOx on polyethyleneimine functional CO2 adsorbents
Kaimin Li, Jianguo Jiang
Abstract
Abstract In this study, we investigated the influence of O 2 , SO 2 , and NO x on branched and linear polyethyleneimine (PEI) functional silica CO 2 adsorbents (BPEI-SiO 2 and LPEI-SiO 2 , respectively). O 2 was much more likely to oxidize BPEI-SiO 2 , compared with LPEI-SiO 2 , to form C=O and C=N groups and led to a 23.0% decrease in the CO 2 adsorption capacity after 990 min of cumulative contact with 10% O 2 . In contrast, LPEI-SiO 2 lost only approximately 3.6% of its CO 2 adsorption capacity, although O 2 oxidized LPEI-SiO 2 to form C=O groups. SO 2 can cause severe degradation of BPEI-SiO 2 and LPEI-SiO 2 by forming heat-stable NH 3 + —and/or NH 2 + —containing adducts and by promoting the formation of urea linkages. After cumulative contact with 10, 50, and 200 ppm SO 2 for 990 min, BPEI-SiO 2 lost 18.2%, 61.4%, and 89.0% of its CO 2 adsorption capacity, and LPEI-SiO 2 lost 18.5%, 60.6%, and 78.5% of its CO 2 adsorption capacity, respectively. NO 2 at 10 ppm and NO at 200 ppm caused almost no loss in CO 2 adsorption capacity after cumulative contact for 990 min, but both led to degradation of adsorbents. NO 2 can cause irreversible formation of NH 3 + —and/or NH 2 + —containing adducts, acid products, N-nitro compounds (N–NO 2 ), C-nitroso compounds (C–N=O), and C-nitro (C–NO 2 ) compounds, and can promote the formation of urea linkages. NO can lead to the formation of NH 3 + —and/or NH 2 + —containing adducts and N-nitroso (N–N = O) compounds.