Determination of adsorption heats of individual adsorption complex by combination of microcalorimetry and FTIR spectroscopy

摘要

Adsorption of CO as a probe molecule on K-FER zeolites differing in Si/Al ratio was investigated. Successful determination of adsorption heats of individual adsorption complexes formed upon adsorption of CO molecules on K-FER zeolites at 300 K by combination of IR spectroscopy with adsorption microcalorimetry is reported. Adsorption heat of bridged carbonyl complexes, where CO molecule interacts with two nearby extraframework K+ cations, was experimentally determined for the first time. It was found that bridged complexes on dual cationic sites exhibit adsorption heat of 34.8 kJ mol~(-1), whereas monodentate carbonyls on single isolated K+ cation exhibit adsorption heat of only 26.2 kJ mol~(-1) and adsorption heat of isocarbonyls was 21.5 kJ mol~(-1).