title: Thermodynamics of carbon dioxide adsorption on the protonic zeolite H-ZSM-5.
abstract: Adsorption of carbon dioxide on H-ZSM-5 zeolite (Si:Al=11.5:1) was studied by means of variable-temperature FT-IR spectroscopy, in the temperature range of 310-365 K. The adsorbed CO(2) molecules interact with the zeolite Brønsted-acid OH groups bringing about a characteristic red-shift of the O-H stretching band from 3610 cm(-1) to 3480 cm(-1). Simultaneously, the nu(3) mode of adsorbed CO(2) is observed at 2345 cm(-1). From the variation of integrated intensity of the IR absorption bands at both 3610 and 2345 cm(-1), upon changing temperature (and CO(2) equilibrium pressure), the standard adsorption enthalpy of CO(2) on H-ZSM-5 is DeltaH(0)=-31.2(+/-1) kJ mol(-1) and the corresponding entropy change is DeltaS(0)=-140(+/-10) J mol(-1) K(-1). These results are discussed in the context of available data for carbon dioxide adsorption on other protonic, and also alkali-metal exchanged, zeolites.
authors.affiliation: Department of Materials Science and Chemical Engineering, Politecnico di Torino and INSTM Unit-Torino Politecnico, Corso Duca degli Abruzzi 24, I-10129 Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Armandi
authors.forename: Edoardo
authors.initials: E
authors.lastname: Garrone
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Areán
authors.forename: Barbara
authors.initials: B
authors.lastname: Bonelli