A case study: surface chemistry and surface structure of catalytic aluminas, as studied by vibrational spectroscopy of adsorbed species

Acid catalysts in industrial hydrocarbon chemistry.

Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities Christophe Copeŕet,*,† Aleix Comas-Vives,† Matthew P. Conley,† Deven P. Estes,† Alexey Fedorov,† Victor Mougel,† Haruki Nagae,†,‡ Francisco Nuñ́ez-Zarur,† and Pavel A. Zhizhko†,§ †Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1−5, CH-8093 Zürich, Switzerland ‡Department of Chemistry, Graduate School of Engineering Science, Osaka University, CREST, Toyonaka, Osaka 560-8531, Japan A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str. 28, 119991 Moscow, Russia

Surface Organometallic and Coordination Chemistry toward Single-Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities

Hydroxyl Groups on γ-Alumina Surfaces: A DFT Study

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In situ FTIR spectra of pyridine adsorbed on SiO2-Al2O3, TiO2, ZrO2 and CeO2: general considerations for the identification of acid sites on surfaces of finely divided metal oxides

Effects of crystallinity and morphology on the surface properties ofalumina

IR experiments involving carbon monoxide and pyridine adsorption as probe molecules showed that introduction of very small amounts of sodium (300 ppm Na2O) decreased the number and the strength of the strongest Lewis acid sites. It also decreased the catalytic activity of alumina towards isopropanol dehydration used as a test reaction. The effect is comparable to that of amorphisation. It was found that the number of affected sites is one order more than the quantity of Na+ cations introduced. A tentative model was proposed and results were explained involving inductive effects.

Comparative study of the effects of sodium impurity and amorphisation on the Lewis acidity of γ- alumina

Various samples of alumina were compared to study the effect of crystallinity and sodium impurity on alumina morphology and basicity. Carbon dioxide adsorption, followed by FT-IR and desorption (TPD), and COS hydrolysis test reaction were used. The decrease of surface area observed on rather amorphous samples after introduction of small amounts of sodium is ascribed to a better crystallinity due to migration of a part of Na+ into the bulk. The charge compensation phenomenon decreases the number of defects in the anion subnetwork. It also provokes a decrease of the number of OH groups which could explain the decrease of activity towards COS hydrolysis of the samples containing very small amounts of Na2O (< 1000 ppm). For larger amounts, COS conversion and carbon dioxide experiments showed an increase in basicity.

P. Nortier

Papers

Effects of crystallinity and morphology on the surface properties ofalumina

Comparative study of the effects of sodium impurity and amorphisation on the Lewis acidity of γ- alumina

Effect of sodium oxide on the morphology and basicity of alumina