CO2 Capture of Aminopolymer Loaded Porous Adsorbents

Amine loading of porous materials has given rise to a number of competitive alternatives for effective CO₂ absorbance. These materials offer not only high specific surface areas, but when integrated with amine containing groups often offer a high selectivity for carbon dioxide. However, recent studies have found that carbon dioxide capture performance is not directly related to the amine content for all solid materials. Our group recently investigated one of these materials, the silica pillared MCM-36 structure, in order to understand this phenomena. This material shows a decline in CO₂ capture kinetics and capacity after impregnation with amine polymer compared to the pure MCM-36. This deterioration was found to be due to the blockage of available pore channels by amine groups, which greatly hinders the diffusion of CO₂. The bare silica pillared MCM-36 is limited by two-dimensional pore connectivity, allowing for diffusion only along the a- and b- axis. To overcome this challenge, we have recently begun investigating a 3-dimensional porous silica support, known as 3-dimensional disordered silica (3dd-silica), composed of zeolite beta spheres connected into a meso-structured support. This material was tested for its use as a CO₂ capture platform when loaded with tetraethylenepentamine (TEPA) and polyethylenimine (PEI, ~800 average molecular weight). The results show that 3dd silica allows for amine loading without diffusion limitations, significantly improving carbon capture performance compared to the amine loaded MCM-36.