The Combined Role of Reaction Severity and Precursor Concentration in the Synthesis of Hydrothermal Carbon from D-xylose

Hydrothermal carbonization (HTC) is widely recognized as a promising thermochemical technology for the synthesis of bio-derived and tunable carbonaceous materials, which hold high potential in many emerging application fields. Despite the rapid progress made by academic exploration, significant gaps persist in the comprehension of the reaction mechanisms involved, posing ongoing challenges for the precise process control. In order to optimize the conversion, this study examines the influence of reaction severity and starting precursor concentration on the synthesis of HTC carbon from D-xylose. Results revealed that both the reaction parameters play a key role during the process, leading to the increase of char mass yield: from 10.7 to 35.4 wt%, with reaction severity, and from 17.3 to 31.0 wt%, with D-xylose starting concentration. In terms of elemental composition, the increase of process severity and feedstock concentration promote an enhanced carbonization degree, while the FTIR spectra highlighted the occurrence of a severe D-xylose dehydration and the formation of solid products by furfurals polycondensation.