CO_2 Adsorption on Porous Materials: Experimental and Simulation Study

摘要

Removal and sequestration of CO_2 from flue gas has been proposed as one of the most reliable solutions to mitigate globe greenhouse emissions. Adsorption technology based on porous adsorbent is known to be one of the most efficient processes for the CO_2 capture from flue gas. The key issue of this technology is to find the adsorbent with high adsorption capacity and selectivity for CO_2. In this chapter, both the experimental and the computer simulation works about the CO_2 adsorption behavior on porous materials in our laboratory were introduced. In the experimental works, the mesoporous materials such as MCM-41 and SBA-15 were selected as the fundamental adsorbent. After surface modification by aminosilane, the amine groups became active centers and the CO_2 adsorption capacity was obviously increased due to the chemisorption. It is shown that the dual amine groups of AEAPMDS had better effect on CO_2 adsorption than the single amine group of APTS. The best CO_2 adsorption capacity of MCM-41-AEAPMDS was 2.20 mmol-g~(-1) at room temperature. Another effective way was incorporation metal Mg into the mesoporous materials. By various impregnating or doping methods, such as the co-condensation, the dispersion with the enhancement of Al~(3+) or amine, and the ionic exchange, a suitable amount of Mg~(2+) can be successfully introduced into MCM-41 and SBA-15, which effectively increased the CO_2 adsorption capacity. Different pore structures had their corresponding optimized methods, the real reason behind was the highly dispersed MgO state in the channels. The best CO_2 adsorption capacities of Mg-Al-SBA-15-D1 and Mg-EDA-MCM-41-D10 were about 1.35 mmol g~(-1). In the simulation works, some novel porous materials such as the micro/mesoporous composite, the covalent organic frameworks, the metal organic framework and the zeolitic imidazolate frameworks were selected as the potential adsorbents for the CO_2 capture. The CO_2 adsorption behavior of the zeoilte of MFI, the mesoporous MCM-41 and the micro/mesoporous composite of MFI/MCM-41 were simulated and compared. It is revealed that the micro/mesoporous composite had better performances on the CO_2 adsorption capacity and selectivity at high pressure, as well as the diffusion performance.