Issue 13, 2003
From the journal:

Physical Chemistry Chemical Physics

Two distinguishable lithium sites in the zeolite Li-ZSM-5 as revealed by adsorption of CO: an infrared spectroscopic and thermodynamic characterisation

B. Bonelli,a   E. Garrone,†*a   B. Fubini,b   B. Onida,a   M. Rodríguez Delgadoc  and  C. Otero Areánc  

* Corresponding authors

a Dipartimento di Ingegneria Chimica e Scienza dei Materiali, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy
E-mail: edoardo.garrone@polito.it
Fax: +39-(0)11-5644699
Tel: +39-(0)11-5644661

b Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Università di Torino, Via P. Giuria 7, Torino, Italy

c Departamento de Química, Universidad de las Islas Baleares, Palma de Mallorca, Spain

Abstract

By combining FTIR spectroscopic and microcalorimetric measurements on adsorbed CO, two lithium sites were found to be present in the zeolite Li-ZSM-5. Both of these sites, LiA and LiB, form Li(CO)+ monocarbonyl species with adsorbed CO; the corresponding C–O stretching frequencies are 2193 and 2187 cm−1, respectively. Formation of LiA(CO)+ involves an estimated adsorption enthalpy of ΔH° ≅ − 44 kJ mol−1, while for LiB(CO)+ the corresponding value is evaluated to be ΔH° ≅ −18 kJ mol−1. The large difference between these ΔH° values is explained in terms of an endothermic process occurring during formation of the LiB(CO)+ species, which involves a slight movement of the corresponding Li+ ion (away from its equilibrium position among oxygen anions of the zeolite framework). Formation of dicarbonyls is also discussed, as well as formation of O-bonded Li(OC)+ species.

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Article information

DOI
https://doi.org/10.1039/B303613H
Article type
Paper
Submitted
01 Apr 2003
Accepted
13 May 2003
First published
03 Jun 2003

Phys. Chem. Chem. Phys., 2003,5, 2900-2905

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Two distinguishable lithium sites in the zeolite Li-ZSM-5 as revealed by adsorption of CO: an infrared spectroscopic and thermodynamic characterisation

B. Bonelli, E. Garrone, B. Fubini, B. Onida, M. Rodríguez Delgado and C. Otero Areán, Phys. Chem. Chem. Phys., 2003, 5, 2900 DOI: 10.1039/B303613H

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