Structural and chemical disorder of cryptomelane promoted by alkali doping: Influence on catalytic properties

• Tipo: Artigo em Revista Científica Internacional
• Data: 2012

Autores

V.P. Santos (Autor) Outra; O.S.G.P. Soares (Autor) FEUP; J.J.W. Bakker (Autor) Outra; Manuel Fernando R Pereira (Autor) FEUP; José Melo Orfão (Autor) FEUP; J. Gascon (Autor) Outra; F. Kapteijn (Autor) Outra; José Luís Figueiredo (Autor) FEUP

Revista

Título: Journal of Catalysis

Vol. 293

Páginas: 165-174

ISSN: 0021-9517

Editora: Elsevier

Indexação

ISI Web of Knowledge - 75 Citações

ISI Web of Science

Scopus - 122 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia química

Outras Informações

ID Authenticus: P-002-61S

DOI: 10.1016/j.jcat.2012.06.020

Abstract (EN): Different amounts of cesium (0.8-1.3 at.%) and lithium (up to 0.5 at.%) were introduced in the tunnel structure of cryptomelane in order to tailor its physical and chemical properties. The mechanism by which cryptomelane accommodates these alkali cations is different; Li occupies mainly empty sites by a redox-type reaction, while Cs is ion-exchanged by H3O+ cations. The adsorption of these alkali metals into cryptomelane was highly selective and is dictated by the solvation energy and ionic radius. Extrinsic defects (e.g. positive holes and oxygen vacancies) are created upon doping, enhancing the redox-properties of cryptomelane. The basicity of the framework also increases when Cs and Li are incorporated. The catalytic properties of this material were tested in the oxidation of ethyl acetate, and greatly improved after doping. The observed activity increase is explained by the redox and basic properties of the modified materials. The amount of cesium loaded has no effect on the activity, as a result of pore mouth catalysis.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10