Adsorption of CO2 on Sodium-Exchanged Ferrierites: The Bridged CO2 Complexes Formed between Two Extraframework Cations
2009
Abstract
Isosteric heats of adsorption of CO2 on Na-FER with different Si/Al ratios were obtained from the adsorption isotherms. Large isosteric heats of adsorption were obtained for Na-FER when Si/Al = 8.7.
Based on calculations employing the periodic DFT model, these large isosteric heats are attributed to the formation of the linearly bridged CO2 adsorption complexes formed between a pair of Na+ cations located in cationic positions. The CO2 adsorption complexes formed on such dual cation sites are ca 10 kJ/mol more stable than the CO2 adsorption complexes where CO2 interacts only with a single Na cation