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Stoeckli, Fritz

Nom
Stoeckli, Fritz
Affiliation principale
Fonction
Professeur.e émérite
Email
fritz.stoeckli@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/471

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  • Publication
    Accès libre
    Contributions of hemicellulose, cellulose and lignin to the mass and the porous properties of chars and steam activated carbons from various lignocellulosic precursors
    (2009)
    Cagnon, Benoît
    ;
    Py, Xavier
    ;
    Guillot, André
    ;
    Stoeckli, Fritz 
    ;
    Chambat, Gérard
    In this study, contributions of hemicellulose, cellulose and lignin to the mass and the porous properties of chars and activated carbons from various lignocellulosic materials were studied. A predictive calculation was established using the experimental results obtained for the three components separately to evaluate the carbonization and activation yields and their respective contributions to the chars and to the subsequent activated carbons of various precursors in term of weight fraction. These equations were validated. The results showed that lignin can be considering as being the major contributor of all chars and activated carbons. Besides, the evolution of the mean pore size versus the specific porous volume showed that each component contributes to the porosity of chars and activated carbons whatever is its weight contribution.
  • Publication
    Accès libre
    The oxidation of an Asturian bituminous coal in air and its influence on subsequent activation by steam
    (1996)
    Centeno, Teresa A.
    ;
    Stoeckli, Fritz 
    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 of micropores can be obtained in the final products, depending on the temperature of pretreatment in air. The oxidation at 270 °C eventually leads to supermicropores (W0 = 0.4 cm3/g) and to a small system of narrow micropores near 0.3–0.5 nm. Molecular sieving experiments indicate that these micropores are part of the constrictions leading into 50–60% of the larger pores.
  • Publication
    Accès libre
    On the activation of Asturian anthracite following various pretreatments
    (1994)
    Centeno, Teresa A.
    ;
    Stoeckli, Fritz 
    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 obtained by activation following preoxidation in air at 270°C for 3 days. In the case of pretreatments with a mixture of nitrogen, air, and water vapor at 450°C, the subsequent activation is less efficient. The micropore volumes and the pore size distributions are similar to those observed for soft precursors, but at a much lower degree of burn-off.
  • Publication
    Accès libre
    Pretreatment and physical activation of acetylene cokes
    (1994)
    Stoeckli, Fritz 
    ;
    Huguenin, Didier
    Pretreatment of acetylene cokes at 450 °C with a mixture of nitrogen, oxygen and water vapour creates a relatively large surface area and some initial microporosity, further developed by water activation at 800 °C. For the same degree of burn-off, but without pretreatment, large micropores (L > 2–3 nm) are obtained and the external surface area remains small.
  • Publication
    Accès libre