in Wiley Online Library (wileyonlinelibrary.com).Thermogravimetric analysis is used to study the adsorption kinetics, equilibrium, and thermodynamics of CO 2 on immobilized polyethylenimine sorbent impregnated on a mesoporous silica over the range of 300-390 K and 5-100% CO 2 concentration. Adsorption isotherm models were fitted to the experimental data indicating that a change in adsorption mechanism occurred near 70 C. Below this temperature, the adsorption data followed the heterogeneous isotherms, while data taken at higher-temperatures followed isotherms for homogeneous surfaces. Heat of sorption was estimated to be 130 kJ/mole for the low-temperature regime, but this decreased to 48 kJ/mole above 70 C. The rate of CO 2 fractional uptake decreased as temperature increased. A phenomenological kinetic model was derived from the Weibull distribution function using a nucleation growth theory to describe the two-step process. The kinetic model was used to predict the uptake at different operating conditions and resulted in good agreement with experimental data. Published 2012 American Institute of Chemical Engineers AIChE J, 59: 923-935, 2013 Experiment MaterialsMethanol (reagent grade) and PEI (MW N 423) used in the preparation of the immobilized sorbents were purchased from Sigma-Aldrich Chemical and used without purification.

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