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  • Sulfonated foam catalysts f...
    Krzelj, Vladan; Ferrandez, Dulce Perez; Neira D’Angelo, M. Fernanda

    Catalysis today, 04/2021, Letnik: 365
    Journal Article

    Display omitted •Shift from sulfuric acid catalysts to novel solid acid foam catalyst for the continuous synthesis of furfural•Solid acid foams as catalyst and liquid-liquid contactor for synthesis and in-situ extraction of furfural: high yield, minimal residence time, and stable performance.•Novel and reproducible procedure to deposit stable sulfonic resins on foam structure. This paper demonstrates the use of sulfonated foam structures, acting both as catalyst and liquid-liquid contactor, during the continuous dehydration of xylose to furfural in biphasic media. First, we develop and optimize a coating procedure comprising a two-step polymerization technique (polypropylene and polystyrene-divinylbenzene), followed by swelling and sulfonation. The method was highly reproducible and led to a stable, well-adhered, 12–50 μm layer of sulfonic resin with an ion exchange capacity of 0.1 meq/cmfoam3. The catalytic foams showed the same activity than H2SO4 in terms of conversion and selectivity versus residence time and temperature. The enhanced mass transfer properties of the foam-based reactor facilitated rapid furfural extraction, thus allowing for higher temperature operations (ca. 20–50 °C higher) and shorter residence times (ca. 10 min vs. 4–5 h) than conventionally reported in the literature, while preserving high furfural selectivity (ca. 70–80%). Finally, the stability of the sulfonated foam catalyst during operation was demonstrated up to 170 °C, although higher temperatures led to a visible decay in activity. We conclude that the sulfonated foams show great potential for this application.