Kinetic and thermodynamic investigation of CO2 adsorption-desorption on polyethyleneimine - mesoporous silica

M.M. Khader, M.J. Al-Marri, Y.O. Kuti, E.P. Giannelis
Qatar University,
Qatar

Keywords: carbon, carbon capture, CO2 adsorption-desorption

Summary:

This study combines measurements of the kinetics and thermodynamics of carbon dioxide adsorption-desorption on polyethylene mesoporous silica (PEI/MPS) in the temperature range from 45 to 85℃. The study was performed on two CO2 solid sorbents: PEI-432 and PEI-10k each impregnated into MPS foam. Adsorption-desorption cycles were conducted using thermal gravimetric analyser (TGA). The adsorption kinetics in all cases follows a double exponential (DE) model, which is consistent with a surface and diffusion energy barriers. CO2 desorption follows first order kinetics. When the MPS foam was treated with the non-ionic surfactant, Span 80, prior to the PEI impregnation, the CO2 adsorption capacity at ambient pressure further increase due to significant increase in the rate of the diffusion process. CO2 adsorption–desorption isotherms were measured separately at temperatures within the range from 45 to 85℃ at various pressures using Rubotherm magnetic suspension balance (MSB). The adsorption isotherms follow the Freundlich relationship. Isosteric heats of adsorption were calculated from the adsorption isotherms using the Clausius–Clapeyron.