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Université de Neuchâtel

Dubinin’s theory and its contribution to adsorption science

Stoeckli, Fritz

In: Russian Chemical Bulletin, 2001, vol. 50, no. 12, p. 2265-2272

Dubinin’s theory for the volume filling of micropores (TVFM), originally developed for the adsorption of single vapours by microporous solids such as activated carbons and zeolites, has gradually been extended to other areas. They include immersion calorimetry, the adsorption of water vapour and of mixtures, as well as adsorption from aqueous solutions. Recent studies in the field of adsorption...

Université de Neuchâtel

Recent Developments in the Context of the Dubinin-Astakhov Equation

Stoeckli, Fritz ; Lavanchy, A. ; Kraehenbuehl, F.

In: Adsorption at the Gas-Solid and Gas-Liquid Interface, 1982, p. 201-209

The present work deals with two important aspects of the Dubinin-Astakhov equation, the fundamental relation of the theory for the filling of micropores. First, the theoretical basis of this equation is examined in the framework of a possible model, which leads to a reasonable agreement with experimental results. Secondly, it is shown how the D-A equation leads to an exact relation for the...

Université de Neuchâtel

Physical adsorption of simple gases on the (111) face of sulfur; a model for the adsorption by heterogeneous surfaces, including lateral interactions

Morel, D. ; Stoeckli, Fritz ; Rudzinski, W.

In: Surface Science, 1982, vol. 114, no. 1, p. 85-95

As revealed by previous ab initio calculations, the surface of the (111) face of rhombic sulfur is characterized by heterogeneous but low adsorption energies. This implies relatively important contributions from lateral interactions in the adsorption mechanism. A theoretical model is presented for this case, also taking into account the random distribution of the sites. One assumes a local...

Université de Neuchâtel

The enthalpies of immersion of active carbons, in relation to the Dubinin theory for the volume filling of micropores

Stoeckli, Fritz ; Kraehenbuehl, F.

In: Carbon, 1981, vol. 19, no. 5, p. 353-356

It is shown that an exact expression can be derived from Dubinin's theory, for the enthalpy of immersion of active carbons. It appears that for a given liquid, the specific enthalpy of immersion is a function of the characteristic energy βE0 of the Dubinin-Astakhov equation. The new relation is illustrated by data obtained for 10 different carbons immersed into benzene and...

Université de Neuchâtel

The Excess Enthalpies and Volumes of Mixing of 3-Methylhexane with Carbon Tetrachloride

Quang Do, Kim ; Powell, Bernard ; Stoeckli, Fritz

In: Chimia, 1981, vol. 35, no. 4, p. 139-141

The functions HE and VE have been measured between 293.15 and 303.15 K for the mixtures of (±), (+) and (-) 3 methylhexane with carbon tetrachloride, using improved calorimetric and dilatometric systems. As expected, it is found that the excess functions are identical for the optical isomers, within experimental error.

Université de Neuchâtel

Changes in the micropore structure of strongly activated carbons, induced by large adsorbate molecules

Stoeckli, Fritz ; Perret, André ; Mena, Philippe

In: Carbon, 1980, vol. 18, no. 6, p. 443-445

Adsorption of molecules with increasing sizes, by strongly activated carbons, is characterized by a restricted accessibility of the micropore system for relative pressures p/p0−3 approx. The adsorption capacity at low pressures increases with successive adsorption-desorption cycles. The adsorption of relatively small molecular probes, considered in the light of...

Université de Neuchâtel

On the Physical Meaning of Parameters Eo and b in Dubinin's Theory

Morel, Daniel ; Stoeckli, Fritz

In: Chimia, 1980, vol. 34, no. 12, p. 503-504

A comparative study of limiting adsorption energies in microporous carbons and on graphitized carbon blacks shows that their difference is proportional to the quantity β Eo, which appears in Dubinin's theory. It follows that the characteristic energy Eo must be related to an average pore size, as found empirically. The affinity coefficient β, on the other...

Université de Neuchâtel

Homogeneous and heterogeneous micropore structures in carbonaceous adsorbents

Dubinin, M. M. ; Stoeckli, Fritz

In: Journal of Colloid and Interface Science, 1980, vol. 75, no. 1, p. 34-42

Microporous carbonaceous adsorbents obtained by moderate activation possess a rather narrow pore-size distribution, and their microporous structure may be considered to be practically homogeneous. In the case of high degrees of burn-off and of extreme activation, micropores of various sizes are formed, including large ones such as supermicropores. The distribution of the micropore volume with...

Université de Neuchâtel

Comparative study of gas adsorption and small angle X-ray scattering by active carbons, in relation to heterogeneity

Jánosi, A. ; Stoeckli, Fritz

In: Carbon, 1979, vol. 17, no. 6, p. 465-469

A comparative study of selected active carbons shows that the spread of the structural parameter B, implied by the generalized adsorption equation of Stoeckli, is compatible with the spread of the Guinier gyration radii suggested by the small-angle scattering of X-rays. In the case of a molecular-sieve carbon having a large micropore volume, there is no spread for either parameter. It is...

Université de Neuchâtel

A generalization of the Dubinin-Radushkevich equation for the filling of heterogeneous micropore systems in strongly activated carbons

Stoeckli, Fritz ; Houriet, Jean-Philippe

In: Journal of Colloid and Interface Science, 1978, vol. 67, no. 2, p. 195-203

A generalization of the Dubinin-Radushkevich equation, recently proposed by Stoeckli as an alternative to the Dubinin-Astakhov equation, is discussed theoretically and is tested with new experimental data. The extended equation applies to the filling of heterogeneous micropore systems in strongly activated carbons. It is based on the assumption that the original D---R equation only applies to...