In Situ Observation of the Decomposition Process of Woodchips in Subcritical- and Supercritical Water by Neutron Imaging

Abstract

In situ observation of the decomposition process of woodchips (cedar and Quercus acutissima) in subcritical- and supercritical water was performed by neutron imaging experiment. The woodchips and D2O were sealed into a stainless tube, and the tube was heated up to 500 °C by a block heater designed for neutron imaging. The neutron imaging experiment was performed in energy-resolved neutron imaging system (RADEN) of Japan Proton Accelerator Research Complex Material and Life Science Experimental Facility (J-PARC MLF). The decomposition processes of the woodchips in D2O solvent were visualized clearly in time-lapse images. The outside of the woodchips was partially broken at 300 °C. The woodchips have a porous structure at 450 °C, and D2O penetrates the pores. The skeleton of the woodchips remains even at 500 °C. The present study clarified the optimal temperature in the decomposition process to observe the status of the woodchips during the decomposition process. It has an advantage compared with a time-consuming of the batch process. It will be useful for the development of biomass processing technology using high-temperature and high-pressure water.