Direct measurement of interaction energy between solids and gases. II. Microcalorimetric studies on the surface acidity and acid strength distribution of solid acid catalysts.
TLDR
In this paper, a twin conduction type microcalorimeter was used to measure the initial heat of adsorption of ammonia on several solid acids, including silica-alumina and zeolite.Abstract:
The differential heats of adsorption of ammonia on several solid acids were measured by means of a twin conduction type microcalorimeter, and surface acid strength distribution and acidity were evaluated. Silica–alumina showed very high initial heats which were not observed in decationated zeolite and silica–magnesia. The acidity of zeolite was about 6 times as high as that of silica–alumina, showing very charactristic acid site distribution at 100 kJ/mol of adsorption energy, and suggesting the existence of homogeneous acid sites. The surface water modified surface acidic nature transforming strong acid sites into weaker ones. The poisoning of acid sites of silica-alumina with alkali occurred preferentially at sites on which adsorption energy of ammonia was 96–105kJ/mol.read more
Citations
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Book ChapterDOI
Applications of Adsorption Microcalorimetry to the Study of Heterogeneous Catalysis
TL;DR: A survey of the theoretical and applied aspects of microcalorimetry to heterogeneous catalysis with particular emphasis on the determination of the acid-base properties of metal oxides and mixed-metal oxides can be found in this article.
Journal ArticleDOI
Deactivation of Zeolite Catalysts
TL;DR: In this paper, the role of the structure of a zeolite (dimension and forme) and the localisation des sites actifs affectant la selectivite pendant la desactivation is discussed.
Journal ArticleDOI
Catalytic activity of supported heteropoly acids for reactions requiring strong acid centres
TL;DR: The effect of supports such as silica, alumina, amorphous aluminosilicate and magnesia on the activity of heteropoly acids (HPA) for reactions requiring strong and very strong acid sites has been studied as discussed by the authors.
Journal ArticleDOI
Acid strength of silica-alumina and silica studied by microcalorimetric measurements of pyridine adsorption
TL;DR: In this paper, microcalorimetric measurements of the differential heat of pyridine adsorption at 473 K were used to probe the distribution of acid strength on silica and silica-supported alumina catalysts.
Journal ArticleDOI
Microcalorimetric studies of zeolite acidity
TL;DR: The acidity characteristics of H-ZSM-5, H-Mordenite and H-Y zeolite have been studied by microcalorimetric and gravimetric measurements of pyridine adsorption.
References
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Journal ArticleDOI
Acidity of Catalyst Surfaces. II. Amine Titration Using Hammett Indicators
Journal ArticleDOI
The measurement of catalyst acidity using indicators forming stable surface carbonium ions
TL;DR: In this article, it was shown that carbonium ion formation and catalytic activity correlate better with catalytic behavior than do the results employed by Hammett indicators, and evidence was presented for the view that Bronsted acidity is responsible for carbinar ion formation, and the nature of the blue species formed on reaction of 1,1-diphenylethylene with silica-alumina.
Journal ArticleDOI
Comparison of the Methods for the Determination of Surface Acidity of Solid Catalysts
TL;DR: The concept of surface acidity was originally introduced with the aim of justifying the presence of some substances formed in catalytic chemical reactions, not as a consequence of suppositions about the nature of surface active sites of solid catalysts.
Journal ArticleDOI
Hydrogen bond strengths and acidities of hydroxyl groups on silica–alumina surfaces and in molecules in solution
Paul Rouxhet,Raymond E. Sempels +1 more
TL;DR: The properties of hydroxyl groups on mixed silica-alumina gels (0-50 % Al2O3) have been studied by adsorbing weak H bond accepting molecules onto the gels and recording the OH stretching infrared band as discussed by the authors.
Journal ArticleDOI
The effect of faujasite cations on acid sites
TL;DR: In this paper, a model of the acid site is introduced in which the bond strengths of acidic hydroxyl groups are perturbed by the polarizing effects of neighboring cations.