The production of carbon materials by hydrothermal carbonization of cellulose

Highly functionalized carbonaceous materials were produced by means of the hydrothermal carbonization of cellulose at temperatures in the 220–250 °C range. The formation of this material follows essentially the path of a dehydration process, similar to that previously observed for the hydrothermal transformation of saccharides such as glucose, sucrose or starch. The materials so formed are composed of agglomerates of carbonaceous microspheres (size ∼2–5 μm), as evidenced by SEM. The combination of the results of the elemental analysis with that obtained by different spectroscopic techniques (infrared and Raman spectroscopy, and XPS) has allowed us to inferred that, from a chemical point of view, the solid product consists of small clusters of condensed benzene rings that form stable groups with oxygen in the core (i.e. ether, quinone, pyrone), whereas the shell possesses more reactive/hydrophilic oxygen functionalities (i.e. hydroxyl, carbonyl, carboxylic, ester).