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Physicochemical and Catalytic Properties of a Modified Natural Clinoptilolite

Published online by Cambridge University Press:  09 July 2018

A. Arcoya
Affiliation:
Instituto de Catálisis y Petroleoquímica, CSIC, Campus Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
J. A. González
Affiliation:
Centro de Investigaciones Química, MINBAS, Washington 169, Cerro, La Habana, Cuba
N. Travieso
Affiliation:
Centro de Investigaciones Química, MINBAS, Washington 169, Cerro, La Habana, Cuba
X. L. Seoane
Affiliation:
Instituto de Catálisis y Petroleoquímica, CSIC, Campus Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain

Abstract

Samples of natural clinoptilolite modified by treatment with NH4Cl or HCl solutions, followed by thermal treatments, have been characterized, and their catalytic activity evaluated, in o-xylene isomerization and ethanol dehydration reactions. The substitution of the compensating cations by NH4+ does not produce structural changes in the original material, but it opens the channels and increases its acidity and thermal stability. The treatment with HCl increases both the acidity and the effective diameter of the channels and pores but it produces an important loss of zeolite phase. Calcination of the acidic forms above 973 K leads to the breakdown of the zeolite structure. Catalytic activity of the samples is related to the surface acidity. For the original and NH4Cl-treated samples, however, the conversion of o-xylene is limited by the access of the reactant inside the channels of the zeolite. A comparative study with modified sepiolite in dehydration of ethanol has also been performed.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

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