(353c) Design, Characterization, and Optimization of Hyperbranched Aminosilica (HAS) Adsorbents for CO2 Capture From Anthropogenic Point Sources
Recent concern over the effect of anthropogenic CO2 emissions on global climate change has driven research on the investigation of new technologies for capturing CO2 from large point sources, such as coal-fired power plants. Adsorption is one of these technologies being considered, because of their potential to be less energy-intensive than the current benchmark aqueous amine absorption technology. Of the many different classes of solid adsorbents, we have focused on the use of silica-supported amines for this purpose. We have developed a hyperbranched aminosilica (HAS) with a large amine content per weight of adsorbent, that translates to having a large CO2 capacity. This inorganic-organic hybrid material is prepared by the ring-opening polymerization of aziridine on mesoporous SBA-15 silica, yielding silica pores functionalized by low molecular weight aminopolymers. Early investigation of the HAS adsorbent revealed a relatively high adsorption capacity of 3.1 mmol CO2/g at 25 °C from humidified, simulated flue gas, that was fully regenerable over 10 adsorption/desorption cycles. This talk will discuss the effects of modification of certain synthesis parameters such as solvent, reactant concentration, and support structure and dimensions on the HAS adsorption properties. By tuning these parameters, we have observed capture capacities above 5 mmol CO2/g. The effects of these changes on the adsorbent structure, including surface area, pore volume, aminopolymer molecular weight, and ratio of 1°:2°:3° amines will be described. The interplay between adsorption capacity and adsorption kinetics will also be discussed in terms of the variation of the adsorbent structure and makeup. Based on these data, we will present optimized synthesis methods that enhance the equilibrium CO2 capacity and adsorption kinetics of the HAS adsorbent class.