(617gw) Experimental and Theoretical Studies of CO2 Adsorption on Hydrotalcite

Lowd, J., University of California, Los Angeles
Manousiouthakis, V., University of California Los Angeles, Los Angeles
Tsotsis, T., University of Southern California
Ciora, R. J., Media and Process Technology Inc
This work investigates experimentally the adsorption kinetics of CO2 on hydrotalcite, and puts forward a simple two-step adsorption reaction mechanism that forms the modeling foundations of the process used to collect the experimental data. The experimental data collection process consists of pure CO2 gas being continuously fed to and removed from a semi-batch reactor in which a given amount of adsorbent material is enclosed within a Thermogravimetric Analysis (TGA) apparatus. The obtained experimental data consist of adsorbent weight gain measurements as function of time. A nonlinear, multi-parameter model describing the time evolution of the adsorption process is developed. At its core is a novel two-step mechanism, that involves CO2 adsorption onto multiple types of active sites. One to one and onto maps between the adsorption/desorption kinetic constants and parameters describing the time evolution curves are developed, which in turn allow the resulting nonlinear parameter regression problem to be solved for its global optimum. Uncertainty intervals containing the resulting kinetic constant values are also developed, corresponding to the variability of the experimental data.