Hydrothermal carbonization

In HTC process, the carbonization temperature is moderate ,ca. 180-250 °C in autogeneous pressure, and the carbonization is performed in the presence of water for 1-6 hours. The advantages with HTC is that different materials, e.g. wood, leaves, cellulose, hemicellulose, lignin, forest- and agro residues, microalgae, animal manure, municipal waste and different biosludges with very low dry content (5-10 wt-%) can be processed. The overall carbonization reactions might be exothermic, which makes the process energy-efficient.

Earlier research examples

We have used high temperature carbonization e.g. for production of carbon nanofibres from wet-spun cellulose fibres and electrospun polyacrylonitrile (1).

Figure. a) Carbon particles from kraft lignin by HTC and b) HTC carbonized unbleached softwood pulp.

[1] Wikberg, H, Grönberg, V. and Harlin, A. (2013) “Hydrothermal carbonisation (HTC) of wood components with high carbon content”, 17th International Symposium on Wood, Fibre and Pulping Chemistry (ISWFPC). Vancouver, Canada, June 12-14.
[2] Grönberg, V., Wikberg, H., Hentze, H.P., Harlin, A. and Jääskeläinen, A.-S. (2012) “Process for the hydrothermal treatment of high molar mass biomaterials” VTT Patent application PCT/FI2013/051180.