Effect of Immobilized Amines on the Sorption Properties of Solid Materials: Impregnation versus Grafting

The underlying mechanism of the adsorption process in functionalized materials is not yet fully understood. This incomplete understanding limits the possibility of designing optimal adsorbent materials for different applications. Hence, the availability of complementary methods to advance this field is of great interest. We present here results concerning the adsorption of CO2 in amine-functionalized silica materials by Monte Carlo simulations, providing new insights into the capture process. Two different mechanisms of functionalization are compared: impregnation (a physical mixture of the amine and the support) and grafting (a chemical bond is formed between the amine and the support). We evaluate in this work a model of MCM-41 for N2 and CO2 adsorption with varying degrees of density of the functionalized chains. The results indicate that the mobility of the impregnated chains allows the creation of a network of microcavities, which enhance the low-pressure adsorption capabilities of these materials. M...