Characterization of products from hydrothermal treatments of cellulose

The main aim of the present study was to investigate the characteristics of products from hydrothermal treatments of cellulose in an autoclave at various temperatures (200 °C–400 °C) and residence times (5 min–2 h). The gas products mainly consisted of CO2, CO, CH4, and H2 at 250 °C–400 °C for 30 min. Heavy oil mainly contained furans, phenols, carboxylic acids, aldehydes, ketones, and high molecular compounds at all hydrothermal temperatures. Aldehydes, phenols, ketones, acid groups and sugars were determined in the aqueous phase by gas chromatography-mass spectrometry and Fourier transform infrared (FTIR). The solid residues were analyzed by elemental analysis, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron microscopy, FTIR, and thermogravimetric analysis techniques. The results showed that the residues had core–shell structure and better physicochemical characterization at lower temperature (250 °C) and longer residence time (2 h). ► We choose cellulose as raw material. ► Analysis the liquid products to observe the formation of key compounds. ► Heavy oil contained furans, phenols, carboxylic acids, aldehydes, ketones, and high molecular compounds. ► Aqueous phase contained sugars and its degradation products (aldehydes, phenolic, ketones, acid groups) at 250 °C for 30 min. ► The solid residues have the better chemical and structural properties.