Variable-temperature infrared spectroscopy studies on the thermodynamics of CO adsorption on the zeolite Ca-Y.
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 DeltaH(0)=-50.3 (+/-0.5) kJ mol(-1) and DeltaS(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 DeltaH(iso)(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.
Bonelli
Barbara
B
Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino and INSTM Unit-Torino Politecnico, 10126 Turin, Italy.
Areán
Carlos Otero
CO
Armandi
Marco
M
Rodríguez Delgado
Montserrat
M
Garrone
Edoardo
E