Performance study of activated multi-walled carbon nanotubes on catalyzing amine-based carbon capture

Abstract

Organic amine solution is currently the most commonly used chemical absorbent for carbon dioxide (CO₂) capture, but its drawback such as high energy consumption for regeneration of CO₂ loaded solution has seriously hindered its wide application in industry. Development of catalysts could reduce the regeneration energy consumption of the process. In this study, the catalytic effects of raw multi-walled carbon nanotubes (MWCNTs) and acid-treated MWCNTs in 30 wt% monoethanolamine solution on both absorption and desorption procedures were investigated. The results showed that the addition of raw MWCNTs and acid-treated MWCNTs as catalysts both promoted the CO₂ desorption rate and amount, among which the 700 ppm acid-treated MWCNTs increased the CO₂ desorption amount by 48.49 %. Furthermore, both MWCNTs shortened the desorption time of CO₂ as well. Stability of acid-treated MWCNTs has been examined by 20 cycles in the capture system. Characterization results indicate that the acid treatment increased the surface area of MWCNTs, and created more acid sites on their surfaces through the defected area. Both characteristics contribute to the enhanced CO₂ desorption performance. Therefore, acid-treated MWCNTs can be considered as promising catalysts for promoting CO₂ desorption and reducing energy consumption for CO₂ capture.