Université de Neuchâtel

The physical and chemical characterization of a sulphur-impregnated active carbon, by combined adsorption and immersion techniques

Rebstein, Patrick ; Stoeckli, Fritz

In: Carbon, 1991, vol. 30, no. 5, p. 747-750

A commercially available active carbon, impregnated with sulphur, has been characterized and compared to the original carbon by using adsorption and immersion techniques. The specific reaction of liquid CS2 with sulphur, following the preadsorption of various amounts of n-nonane, shows that the accessibility of sulphur decreases rapidly. It is also found that the impregnated carbon...

Université de Neuchâtel

On the characterization of carbon blacks by various techniques

Stoeckli, Fritz ; Huguenin, Didier ; Laederach, A.

In: Carbon, 1994, vol. 32, no. 7, p. 1359-1362

It is shown how the use of various adsorption and calorimetric techniques can provide unambiguous information on the presence or the absence of porosity on the surface of carbon blacks. Dubinin's theory, its extension to immersion calorimetry, and gas-phase calorimetry can be applied successfully. As an example, the characterization of 6 porous and non-porous samples is described.

Université de Neuchâtel

On the activation of Asturian anthracite following various pretreatments

Centeno, Teresa A. ; Stoeckli, Fritz

In: Carbon, 1994, vol. 32, no. 8, p. 1463-1467

An Asturian anthracite has been subjected to different pretreatments and subsequently activated by steam at 850°C to a total burn-off of 55 percent. The physical properties (micropore sizes and distributions, external surface areas, etc.) of the solids are compared with those of the carbon obtained by direct activation. Although the yield is generally low, it appears that better results are...

Université de Neuchâtel

The oxidation of an Asturian bituminous coal in air and its influence on subsequent activation by steam

Centeno, Teresa A. ; Stoeckli, Fritz

In: Carbon, 1996, vol. 33, no. 5, p. 581-586

It is shown that the oxidation of an Asturian bituminous coal by air, at 150 ° and 270 °C, has a considerable influence on the microporous structure of the carbon obtained by subsequent carbonization and steam activation to 50% burn-off. The direct activation of the coal leads to an open micropore system of 0.2 cm3/g, with an average pore size near 0.8 nm. On the other hand, much larger systems...

Université de Neuchâtel

Evolution of microporosity during activation of carbon

Stoeckli, Fritz ; Ballerini, Luca

In: Fuel, 1991, vol. 70, no. 4, p. 557-559

Various adsorption and immersion techniques and a recent model for micropore distributions have been used to assess quantitatively the evolution of the main properties of active carbon. The precursors used in this study were of vegetable and polymeric origin. One activation series based on natural coal was also included.

Université de Neuchâtel

On the determination of surface areas in activated carbons

Stoeckli, Fritz ; Centeno, Teresa A.

In: Carbon, 2005, vol. 43, no. 7, p. 1184-1190

The paper examines the validity of two approaches frequently used to determine surface areas in activated carbons, namely the BET method and the use of immersion calorimetry. The study is based on 21 well characterized carbons, whose external and microporous surface areas, Se and Smi, have been determined by a variety of independent techniques. It appears...

Université de Neuchâtel

On the specific double-layer capacitance of activated carbons, in relation to their structural and chemical properties

Centeno, Teresa A. ; Stoeckli, Fritz

In: Journal of Power Sources, 2006, vol. 154, no. 1, p. 314-320

Twelve well-characterized activated carbons with average micropore widths between 0.7 and 2 nm, total surface areas of 378–1270 m2g−1 and specific capacitances C up to 320 F g−1 have been investigated, using H2SO4 2 M as electrolyte. Some of the carbons have also been oxidized with (NH4)2S2O8,...

Université de Neuchâtel

On the mechanisms of phenol adsorption by carbons

Stoeckli, Fritz ; Hugi-Cleary, D.

In: Russian Chemical Bulletin, 2001, vol. 50, no. 11, p. 2060-2063

The removal of phenol and related compounds from dilute aqueous solutions by activated carbons corresponds to the coating of the micropore walls and of the external surface by a monolayer. This process is described by an analog of the Dubinin—Radushkevich—Kaganer equation. On the other hand, as suggested by immersion calorimetry at 293 K, in the case of concentrated solutions, the mechanism...