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    A Polystyrene supported Scandium (III) microencapsulated Lewis acid catalyst for hydrothermal carbonization of glucose
    (Pergamon-Elsevier Science Ltd, 2023) Ercan, Betul; Auersvald, Milos; Kejla, Lukas; Tekin, Kubilay; Simacek, Pavel; Karagoz, Selhan
    Hydrothermal carbonization of glucose in the absence and presence of recoverable solid polystyrene-supported microencapsulated Lewis acid catalyst has been carried out at 180 and 200 degrees C for 6, 12, and 24 h using either 0.25 g or 0.5 g of catalyst. The effects of temperature, residence time, and catalyst loading on the resulting hydrochars were investigated. At the lowest temperature (180 degrees C) and the shortest residence time (6 h) without the presence of a catalyst, the glucose conversion was the lowest as expected. No hydrochar was formed at 180 degrees C for 6 h without using any catalyst. In catalytic runs, the formation of hydrochar was observed under identical conditions although the yields of hydrochar were low. The use of the catalyst increased the yield of acid com-pounds (acetic, glycolic, lactic and levulinic) at the expense of 5-hydroxymethylfurfural under identical condi-tions. Except for 180 degrees C for 6 and 12 h, the use of the catalyst decreased the yield of hydrochar. The use of the catalyst led to increasing the diameter of carbon sphere particles under identical conditions. The presence of the catalyst resulted in the production of a notable amount, approximately 20 wt% of levulinic acid as a by-product.
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    Sulfonic Acid-Catalyzed Biocoal Production from Lignocellulosic Biomass
    (Amer Chemical Soc, 2024) Alper, Koray; Auersvald, Milos; Kejla, Lukas; Ercan, Betul; Ucar, Suat; Tekin, Kubilay; Simacek, Pavel
    In this study, hydrothermal carbonization (HTC) of spruce wood was studied at different temperatures (200-260 degrees C) and residence times (2-48 h). An increase in the temperature and residence time resulted in higher heating values of hydrochars. The effect of temperature on the hydrochar yield and carbon content was more pronounced than the residence time. Two sulfonic acid catalysts were explored for the first time in the HTC of spruce wood at 240 degrees C for 24 h. The impact of sulfonic acid type and concentration on hydrochar yields and characteristics was investigated. Among the tested acids, methanesulfonic acid (MSA) had a significant effect on HTC, producing hydrochar with increased fixed carbon content and a higher heating value compared to noncatalytic runs and runs with dodecyl benzenesulfonic acid (DBSA) under identical conditions. The highest fuel ratio obtained was 1.47 with MSA at a concentration of 0.01 M. A detailed quantitative analysis of the aqueous phase from HTC processing using gas chromatography helped to elucidate the differences between the tested acids and demonstrated promoted lignin depolymerization with increasing MSA concentration. The use of sulfonic acid significantly increased the yield of levulinic acid in the aqueous phase. Overall, these findings highlight the potential of sulfonic acid catalysts in enhancing the efficiency and product quality of HTC processes, providing insights into optimizing biomass conversion for sustainable energy production and biocoal synthesis.