Université de Neuchâtel

On the characterization of microporous carbons by immersion calorimetry alone

Stoeckli, Fritz ; Centeno, Teresa A.

In: Carbon, 1997, vol. 35, no. 8, p. 1097-1100

Immersion calorimetry is a useful tool for the characterization of solid surfaces in general, but in the case of microporous solids it usually requires complementary information, obtained from an adsorption isotherm. This article demonstrates the possibilities and the limitations of this technique when used alone. It appears that the use of a standard value for the enthalpy immersion does not...

Université de Neuchâtel

Dynamic adsorption of vapour mixtures in active carbon beds described by the Myers-Prausnitz and dubinin theories

Lavanchy, André ; Stoeckli, Fritz

In: Carbon, 1997, vol. 35, no. 10, p. 1573-1579

The adsorption of binary vapour mixtures from air by active carbon beds can be predicted with a good accuracy by adapting a model developed earlier for single vapours. This model is based on a semi-implicit finite difference scheme. Multiple adsorption of vapours is described by the combined theories of Myers-Prausnitz and of Dubinin (MPD), which have already been applied successfully to static...

Université de Neuchâtel

Dynamic adsorption, in active carbon beds, of vapour mixtures corresponding to miscible and immiscible liquids

Lavanchy, André ; Stoeckli, Fritz

In: Carbon, 1999, vol. 37, no. 2, p. 315-321

It is shown that the combined Myers–Prausnitz–Dubinin theory (MPD) can be extended to the adsorption of ternary mixtures from an air stream. When combined with a computer model developed for dynamic adsorption, it provides a satisfactory agreement with the experimental breakthrough curves in active carbon beds. On the other hand, as illustrated by a mixture of water and 2-chloropropane...

Université de Neuchâtel

On the characterization of acidic and basic surface sites on carbons by various techniques

López-Ramón, María Victoria ; Stoeckli, Fritz ; Moreno-Castilla, Carlos ; Carrasco-Marín, Francisco

In: Carbon, 1999, vol. 37, no. 8, p. 1215-1221

Active carbons of different origins have been oxidized with H2O2 and (NH4)2S2O8 and their oxygen surface complexes have been characterized by TPD, classical titration following Boehm's method and by neutralization calorimetry. The net enthalpies of neutralization, determined by immersion calorimetry into NaOH and HCl 2 N lead to...

Université de Neuchâtel

On the use of standard DRK isotherms in Dubinin’s t/F method

Hugi-Cleary, Deirdre ; Stoeckli, Fritz

In: Carbon, 2000, vol. 38, no. 9, p. 1309-1313

It is shown that the adsorption of benzene, carbon tetrachloride, dichloromethane and nitrogen by a typical non-porous carbon black follows the Dubinin–Radushkevich–Kaganer equation. The requirement for temperature invariance is fulfilled, with an average characteristic energy Eo=10.8 kJ mol−1. This expression is compared with the standard isotherms for benzene and...

Université de Neuchâtel

Reference isotherm for high pressure adsorption of CO2 by carbons at 273 K

Guillot, André ; Stoeckli, Fritz

In: Carbon, 2001, vol. 39, no. 13, p. 2059-2064

It is suggested that the adsorption of CO2 on Vulcan 3G at 273 K and up to 3.2 MPa can be used as a reference isotherm for the characterization of porous and non-porous carbons. The results obtained with the proposed reference are in good agreement with those of the nitrogen (77 K) and benzene (293 K) comparison plots. The external surface areas have also been compared with those...

Université de Neuchâtel

The comparison of experimental and calculated pore size distributions of activated carbons

Stoeckli, Fritz ; Guillot, André ; Slasli, Abdou ; Hugi-Cleary, Deirdre

In: Carbon, 2002, vol. 40, no. 3, p. 383-388

Activated carbons are disorganized materials with variable pore size distributions (PSD). If one assumes that the porosity consists mainly of locally slit-shaped micropores, model isotherms can be obtained by computer simulations and used to assess the PSD on the basis of experimental isotherms. In the present study, CO2 isotherms have been measured at 273 K on seven well-characterized...

Université de Neuchâtel

Water adsorption by activated carbons in relation to their microporous structure

Slasli, Abdou ; Jorge, M. ; Stoeckli, Fritz ; Seaton, N. A.

In: Carbon, 2003, vol. 41, no. 3, p. 479-486

The present paper examines the adsorption of water by microporous carbons in the absence of specific interactions. The modelling of water adsorption for 293 and 310 K, using variable pore size distributions (PSD), shows that the type V isotherms follow the Dubinin–Astakhov (DA) equation and fulfill the requirement for temperature invariance. Furthermore, the parameters of the DA equation can be...