Polyethyleneimine Supported Mesoporous Silica for CO_2 Capture: Adsorption Kinetics and Degradation Problems

摘要

Polyethyleneimine supported mesoporous silica (PEI-MPS) has widely been investigated as solid sorbents for CO_2 adsorption in laboratory. However, the adsorption kinetics of CO_2 on this sorbent is still a disputed problem and the sorbent degradation could be a cause that hinders the sorbent from industrial application. In this study, the PEI-MPS sorbent was prepared by impregnating PEI onto mesoporous silica and then the adsorption kinetics was investigated using the pseudo-first order model, pseudo-second order model and intraparticle diffusion model. Results indicated that the CO_2 adsorption kinetics on the sorbent occurred in a 2 stage process. In early stage, it is well fitted by the pseudo-first order model, but in later stage, it is well fitted by the intraparticle diffusion model. The pseudo second-order model proved to be the most suitable one to describe the adsorption of CO_2 on the sorbent for the whole adsorption period with less than 5% absolute deviation. The sorbent with a CO_2 adsorption capacity of 144.9 mg/g was calculated based on the fitting of the pseudo-second order model. The major degradation issues and their potential effects on the CO_2 capture process were also discussed. The degradation significantly impacts on the performance and efficiency of CO_2 capture process. The chemical degradation, however, can be considerably minimized by humidification.