Using alkali metals to control reactivity and porosity during physical activation of demineralised kraft lignin |
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Authors: | Suhas M.M.L. Ribeiro Carrott |
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Affiliation: | Centro de Química de Évora e Departamento de Química, Universidade de Évora, Colégio Luís António Verney, 7000-671 Évora, Portugal |
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Abstract: | Demineralised kraft lignin was impregnated with between 6.2% and 50% NaCl or KCl and physically activated in CO2 at 750 °C. The results presented show that a considerable reduction in activation time even at a comparatively low activation temperature could be achieved, particularly when using KCl. Considering a fixed level of burn-off, the impregnation did not affect the pore volume and only increased the pore width by about 0.1-0.2 nm, depending on the concentration of NaCl or KCl used. By controlling the conditions it was possible to obtain predominantly ultramicroporous materials with mean pore widths over the range 0.53-0.77 nm. On the other hand, at high levels of burn-off there was evidence for micropore widening into the small mesopore range and also for the formation of a secondary mesopore structure. Under these conditions it was possible to obtain materials with pore volumes as high as 0.82 cm3 g−1. |
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