Synthesis, Characterization and Application of Amine-Functionalized Hierarchically Micro-Mesoporous Silicon Composites for CO(2) Capture in Flue Gas

An efficient CO(2) adsorbent with a hierarchically micro-mesoporous structure and a large number of amine groups was fabricated by a two-step synthesis technique. Its structural properties, surface groups, thermal stability and CO(2) adsorption performance were fully investigated. The analysis results show that the prepared CO(2) adsorbent has a specific hierarchically micro-mesoporous structure and highly uniformly dispersed amine groups that are favorable for the adsorption of CO(2). At the same time, the CO(2) adsorption capacity of the prepared adsorbent can reach a maximum of 3.32 mmol-CO(2)/g-adsorbent in the actual flue gas temperature range of 303–343 K. In addition, the kinetic analysis results indicate that both the adsorption process and the desorption process have rapid adsorption/desorption rates. Finally, the fitting of the CO(2) adsorption/desorption experimental data by Avrami’s fractional kinetic model shows that the CO(2) adsorption rate is mainly controlled by the intra-particle diffusion rate, and the temperature has little effect on the adsorption rate.