Stoeckli, Fritz

1999, Wintgens, D., Lavanchy, André, Stoeckli, Fritz

1981, Quang Do, Kim, Powell, Bernard, Stoeckli, Fritz

The functions H^E and V^E 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.

1974, Stoeckli, Fritz

The problem of porosity in carbonaceous materials is briefly reviewed. Microporosity is investigated from the point of view of physical adsorption from the gas phase on graphite-like surfaces. Theoretical considerations show that the micropores can be treated as slots between the graphitic planes of the microcrystallites. The minima of the adsorption potentials are derived from the limiting heats of adsorption, measured by GSC.

1998, Stoeckli, Fritz, Lavanchy, A., Hugi-Cleary, Deirdre

Ce travail présente la théorie de Dubinin, ses conséquences en calorimétrie d'immersion ainsi que des développements recents. En particulier, la description des isothennes de type V par I'équation de Dubinin-Astakhov (vapeur d'eau sur les charbons actifs) et la combinaison avec la theorie de Myers et Prausnitz qui conduit à une description de l’adsorption multiple en régimes statique et dynamique. La théorie de Dubinin inclut également l’adsorption de vapeurs par certains solides non poreux., The paper presents the main features of Dubinin's theory for the volume-filling of micropores, its direct consequences in the field of immersion calorimelry and recent developments such as the possibility to describe type V isotherms (water on active carbons) with the Dubinin-Astakhov equation, and to deal with multiple adsorption under static and dynamic conditions. It also confirmed that in some cases Dubinin's theory applies to adsorption by non-porous surfaces.

1996, Lavanchy, André, Stöckli, M., Wirz, C., Stoeckli, Fritz

2003, Hugi-Cleary, Deirdre, Wermeille, Sandra, Stoeckli, Fritz

2008, Stoeckli, Fritz, Centeno, Teresa A.

This study shows that immersion calorimetry is a useful technique which simplifies considerably the analysis of porosity and chemical nature of activated carbons. The characterization of activated carbons in the general theoretical framework of Dubinin's theory with its extensions to calorimetry and adsorption from solutions allows the identification of some key parameters for the performance of these materials in electrochemical capacitors.

2005, Lavanchy, André, Liebi, R., Hugi-Cleary, Deirdre, Stoeckli, Fritz

The prediction of the protection efficiency of NBC-respiratory filters against organic vapours is often very difficult, especially when strong physical interactions or chemisorption processes are invoved. The presented statistical analysis is an attempt to develop a simple, but reliable, prediction model for breakthrough times. In over 70 experiments run under conditions of the EN 141 guidelines the breakthrough times of 39 organic compounds including alkanes, cyclo-alkanes, alkenes, alcohols, ketones and carboxylic acids have been measured for a given filter type. A linear regression model is then postulated to relate the breakthrough time to the adsorptive properties. For the model, each adsorptive molecule has been considered to be composed of a chemical functional group and a chain radical, resulting in a two dimensional structural code. The number of carbon atoms in the radical-chain and physical properties has been considered as an additional model parameter. General Linear Model (GLM) analysis was run to estimate model performances. We found out, that a simple linear model with only four regressors (two dimensional structural code, number of C atoms in the radical-chain and the saturation pressure) yields satisfactory breakthrough time predictions. Therefore, this study shows that, for a given filter type and well defined testing conditions, satisfactory predictions of breakthrough times of organic vapours are feasible.

1982, Stoeckli, Fritz, Lavanchy, A., Kraehenbuehl, F.

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 calculation of enthalpies of immersion of microporous carbons into organic liquids. So far, this relation has been tested with more than 35 systems (10 carbons and 8 liquids).

1969, Stoeckli, Fritz

It is shown that the formula for the gravitational red shift predicted by the theory of general relativity can also be derived by classical quantum mechanics combined with relativistic arguments. The agreement between the two derivations is a consequence of the separability of the time-dependent wave fonction, and of the first-order time differential in the wave equation.