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Variable‐Temperature Infrared Spectroscopy Studies on the Thermodynamics of CO Adsorption on the Zeolite Ca–Y
Author(s) -
Bonelli Barbara,
Areán Carlos Otero,
Armandi Marco,
Delgado Montserrat Rodríguez,
Garrone Edoardo
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800238
Subject(s) - chemistry , enthalpy , faujasite , isomerization , zeolite , infrared spectroscopy , adsorption , spectroscopy , standard enthalpy of formation , standard molar entropy , thermodynamics , catalysis , organic chemistry , physics , quantum mechanics
Variable temperature FT–IR spectroscopy (in the range of 298–380 K) is used to study the thermodynamics of formation of Ca 2+ ⋅⋅⋅CO carbonyl species upon CO adsorption on the faujasite‐type zeolite Ca–Y, and also the (temperature‐dependent) isomerization equilibrium between carbonyl and isocarbonyl (Ca 2+ ⋅⋅⋅OC) species. The standard enthalpy and entropy changes involved in formation of the monocarbonyl species resulted to be ΔH 0 =−50.3 (±0.5) kJ mol −1 and ΔS 0 =−186 (±5) J mol −1 K −1 , respectively. Isomerization of the (C‐bonded) Ca 2+ ⋅⋅⋅CO carbonyl to yield the (O‐bonded) Ca 2+ ⋅⋅⋅OC isocarbonyl involves an enthalpy change ${\Delta {\it H}_{{\rm{iso}}}^{\rm{0}} }$ =+11.4 (±1.0) kJ mol −1 . These results are compared with previously reported data for the CO/Sr–Y system; and also, a brief analysis of enthalpy–entropy correlation for CO adsorption on zeolites and metal oxides is given.