(414e) Development of High Performance Carbon-Based Adsorbents for CO2 Adsorption

Thermal management of high-power systems is a pressing challenge for many USAF platforms.  These systems require rapid absorption and ultimately rejection of low-quality (low temperature) heat. Activated carbon is capable of adsorbing pressurized CO₂ gas with a high heat of adsorption, offering the possibility of rapidly absorbing and rejecting heat at low temperatures. The activated carbon adsorbent has to meet important performance criteria for high efficiency of the system. The performance criteria include high adsorption capacity, high adsorption kinetics, excellent stability and mechanical properties, and high thermal conductivity.  For activated carbon adsorbents to meet all of these criteria, the CO₂ adsorption capacity and the adsorption-desorption kinetics must be improved.  The adsorption of CO₂ on activated carbon can be significantly enhanced by the introduction of basic nitrogen functionalities on the surface. In this work, surface modification of a series of activated carbon adsorbents via gas phase amination under various conditions has been performed. The surface area, pore structure and pore volume were characterized using N₂ physisorption while the types of chemical functionalities present on the surface after amination were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and temperature programmed desorption (TPD). CO₂ adsorption on the modified activated carbon samples have been measured gravimetrically using a high-pressure TGA.