A Polystyrene supported Scandium (III) microencapsulated Lewis acid catalyst for hydrothermal carbonization of glucose

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 °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 °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 °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 compounds (acetic, glycolic, lactic and levulinic) at the expense of 5-hydroxymethylfurfural under identical conditions. Except for 180 °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.