Thermodynamic relations for the noncalorimetrical determination of the heat of adsorption in multicomponent systems

1993 ◽  
Vol 97 (29) ◽  
pp. 7730-7735 ◽  
Author(s):  
C. Wittrock ◽  
H. H. Kohler
Keyword(s):  
Heat Of Adsorption ◽  
Multicomponent Systems

Determination of the degree of adsorption and the heat of adsorption for 1-butylamine and ammonia on NaHY zeolites

1984 ◽  
Vol 49 (12) ◽  
pp. 2739-2743 ◽  
Author(s):  
Miloslav Křivánek ◽  
Pavel Jírů
Keyword(s):  
Lewis Acid ◽  
Adsorption Isotherms ◽  
Heat Of Adsorption ◽  
Brønsted And Lewis Acid

The degree and heat of adsorption of 1-butylamine and ammonia were measured on samples of NaHY zeolites activated at 400-600°C. The adsorption isotherms and calorimetric curves were compared for the two bases, and the amount of Bronsted and Lewis acid centres was determined from the calorimetric curves.

Determination of vapor—liquid equilibrium diagrams of multicomponent systems

2016 ◽  
Vol 70 (12) ◽  
Author(s):  
Leonid Serafimov ◽  
Anastasia Frolkova
Keyword(s):  
Phase Diagram ◽  
Multicomponent Systems ◽  
Liquid Equilibrium ◽  
Vapor Liquid Equilibrium ◽  
Equilibrium Modeling ◽  
Component Systems ◽  
Full Structure ◽  
Concentration Simplex ◽  
Vapor Liquid

AbstractA method for the determination of vapor–liquid phase diagram structure of five-component systems based on the analysis of types and Poincare indexes of singular points of the geometric scan and full structure of the concentration simplex is proposed. Validity of the proposed method was demonstrated by vapor–liquid equilibrium modeling in five-component mixtures: ethanol + water + toluene + butanol + chlorbenzene and acetone + chloroform + ethanol + cyclohexane + water.

Ein neues Verfahren zur Berechnung der Diffusionskoeffizienten in Multikomponentensystemen aus Meßdaten der quasistationären Diffusion / A new procedure for the determination of diffusion coefficients from quasi-stationary diffusion measurements in multicomponent systems

1975 ◽  
Vol 30 (4) ◽  
pp. 561-566
Author(s):  
W. Meiske ◽  
W. Schmidt ◽  
E. Kahrig
Keyword(s):  
Differential Equations ◽  
Diffusion Coefficients ◽  
Multicomponent Systems ◽  
Equivalent System ◽  
System Of Integral Equations ◽  
Component System ◽  
Flow Equations ◽  
Stationary Diffusion ◽  
Numerical Performance

Abstract Diffusion in an (n+1) -component system is described by Onsager's flow equations the integration of which leads in the case of quasi-stationarity to the differential equations d(Δc)/dt=-βD̅Δ c (Δc: vector of concentration differences between the compartments of the cell, D̅: matrix of integral diffusion coefficients, β: apparatus constant). Several procedures are known to determine these diffusion coefficients from such equations but all of them have certain disadvantages. In this paper a new method is described to compute the integral diffusion coefficients, which starts from the associated equivalent system of integral equations. The mathematical formalism is simple, and its numerical performance does not become more difficult with an increasing number of components of the system.

The calorimetric determination of the heats of adsorption of oxygen on evaporated metal films

1960 ◽  
Vol 256 (1284) ◽  
pp. 81-105 ◽  
Keyword(s):  
Empirical Relation ◽  
Adsorbed Layer ◽  
Oxygen Adsorption ◽  
Heat Of Adsorption ◽  
Oxide Formation ◽  
Heats Of Adsorption ◽  
Surface Areas ◽  
Before And After ◽  
Surface Metal

A Beeck-type calorimeter has been used to measure the integral heat of adsorption of oxygen on evaporated films of titanium, chromium, manganese, iron, cobalt, nickel, niobium, molybdenum, rhodium, palladium, tantalum, tungsten, platinum and aluminium. The variation of the heat with the extent of the adsorption has also been determined, except with palladium, platinum and aluminium, for which the amounts of oxygen adsorption were too small to allow this to be done. The heats of adsorption reported are based on a careful determination of the heat capacity of the calorimeter and the overall error is not more than ± 5 kcal/mole. Some investigations of calorimetric behaviour have been made. The surface areas of the films have been measured before and after an adsorption by the B.E.T. method; krypton isotherms at — 196 °C were used for this purpose. From these data, it has been possible to estimate the number of atoms of oxygen adsorbed per surface metal atom. In most cases, this quantity, together with the heat of adsorption, can be related to the oxygen/metal ratios and the heats of formation of certain oxides; this observation is remarkable in view of the limited extent of the adsorption. In the cases of rhodium, palladium and platinum the adsorption stops short of a monolayer and is probably true chemisorption rather than oxide formation. For those metals on which oxide formation occurs, the decrease in heat of adsorption with increasing coverage has been interpreted, in general, in terms of an increase in the oxidation number of surface metal ions by electron transfer within the adsorbed layer. Some theoretical correlations between the heat of adsorption and the atomic and the bulk properties of the species concerned have been examined and found of little value; an empirical relation with the metallic radius is given.

Numerical Determination of Intrinsic Diffusion in Fe-Cr-Al Systems

2010 ◽  
Vol 297-301 ◽  
pp. 948-953
Author(s):  
Bartłomiej Wierzba ◽  
Olivier Politano ◽  
Sébastien Chevalier ◽  
Marek Danielewski
Keyword(s):  
Concentration Profile ◽  
Diffusion Coefficients ◽  
Numerical Results ◽  
Multicomponent Systems ◽  
Numerical Determination ◽  
Intrinsic Diffusion ◽  
Aluminide Coatings ◽  
Interdiffusion Process

The intrinsic diffusion coefficients in diffusion aluminide coatings based on Fe-30Cr were determined at 1000oC. The diffusion fluxes were given by the Nernst Planck formulae and the Darken method for multicomponent systems was applied. This paper summarizes some numerical results to determine the composition dependent diffusivities in Fe-Cr-Al systems. The method presented in this study to obtain average intrinsic diffusion coefficients is as an alternative to the Dayananda method. Our method based on empirical parameters allowed us to predict the concentration profile during the interdiffusion process.

Determination of Heat of Adsorption on Clean Solid Surfaces

1969 ◽  
Vol 2 (1) ◽  
pp. 249-322 ◽  
Author(s):  
Slavoj Černý ◽  
Vladimír Ponec
Keyword(s):  
Heat Of Adsorption ◽  
Solid Surfaces

Determination of Isosteric Heat of Adsorption by Quenched Solid Density Functional Theory

Langmuir ◽  
2017 ◽  
Vol 33 (8) ◽  
pp. 1769-1779 ◽  
Author(s):  
Richard T. Cimino ◽  
Piotr Kowalczyk ◽  
Peter I. Ravikovitch ◽  
Alexander V. Neimark
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Functional Theory ◽  
Isosteric Heat Of Adsorption ◽  
Solid Density
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