Preparation and characterization of polyethylenimine-modified mesoporous silicas as CO2 sorbents.

Functionalization of MCM-48 and SBA-15 mesoporous silicas with polyethylenimine (PEI) has been achieved using the wet impregnation technique, and the obtained materials have been tested as media for CO(2) adsorption. Increasing PEI loading resulted in decreasing of the surface area and pore size of the potential adsorbents. PEI-modified mesoporous systems did not sorb any N(2) at 77 K, on the contrary both materials were able to sorb large amounts of CO2 at 348 K and at very low pressure. At PEI loading of 50 wt% in MCM-48 and 44 wt% in SBA-15 adsorption capacities over 6 wt% were obtained. CO(2) desorption from the mesoporous silica samples under vacuum was close to 100%. These materials could be successfully used as sorbents to capture CO(2) after combustion or as H(2) stream purification media.