New Kinetic Model That Describes the Reversible Adsorption and Desorption Behavior of CO2 in a Solid Amine Sorbent

Five, semi-empirical, temperature-dependent, kinetic models were developed and systematically studied to determine which one best described the reversible reaction/adsorption and desorption behavior' of CO2 in a solid amine sorbent over a broad range of experimental conditions. Each model varied in the number and type of reaction to account for different CO2 amine site reactions. The solid amine sorbent was composed of polyethylenimine (PEI) immobilized on a CARiACT G10 silica support. A total of 4 temperatures (40, 60, 80, and 100 degrees C) and 7 concentrations of CO2 in N-2 at 1 atm (1.2, 4.8, 14.5, 32.8, 56.1, 69.8, and 88.6 vol %) were studied by carrying out 4 consecutive adsorption/desorption cycles at each of the 28 conditions using a thermogravimetric analyzer (TGA). Each cycle consisted of 40 min of adsorption in CO2/N-2 followed by 40 min of desorption in N-2. The best model consisted of three parallel reactions, winch was consistent with PEI having three different amine sites. Considering the wide range of conditions studied, this is a first-of-its-kind, kinetic model that should prove to be very useful in an adsorption process simulator and, thus, for the development of new pressure and temperature swing adsorption processes using this commercially viable PEI solid amine sorbent for CO2 removal from a variety of gas streams.