Stability and efficiency of CO2 capture using linear amine polymer modified carbon nanotubes

Abstract

Increasing atmospheric CO₂ concentration has become a cause for concern. The design of efficient and stable solid amine adsorbents for CO₂ capture, as well as for controlled release, is urgently needed. Polymeric amine modified multiwalled carbon nanotubes (CNT) are a promising material for meeting these goals. In this study, linear polyethylenimine (LPEI) was supported on CNT and was characterized and studied for reversible CO₂ adsorption. These results are compared to branched polythylenimine (BPEI) as well as other materials. Upon treatment with 3 M NaOH or 5 M HNO₃, the CO₂ adsorption was decreased by at least 15%. The CO₂ adsorption by LPEI (1.89 mmol g⁻¹) was lower than that of BPEI (2.43 mmol g⁻¹) when coated on CNT supports. The desorption temperature was noticeably lower on CNT–LPEI versus CNT–BPEI for complete CO₂ removal. CO₂ adsorption capacity was strongly dependent on the packing height of the material in the column reactor. The stability study showed that CO₂ adsorption of CNT–LPEI and CNT–BPEI decrease by 9.5% and 61.7%, respectively, after steam treatment, indicating that LPEI was more stable under humid conditions.