Fixed-bed pyrolysis of cotton stalk for liquid and solid products

The pyrolysis of cotton stalk was studied for determining the main characteristics and quantities of liquid and solid products. Particular variables investigated were temperature (from 400 °C to 700 °C), particle sizes (from 0.25 mm to 1.8 mm) and nitrogen gas flow rate (from 50 and 400 cm3/min). All experiments were performed at a heating rate of 7 °C/min. The results showed that particle size and nitrogen flow rate did not exert a significant influence, whereas temperature was very significant. The liquid products and the subfractions of pentane-soluble fraction were characterized by elemental analysis, FT-IR spectroscopy, 1H-NMR spectroscopy, and the pentane subfraction was analysed by gas chromatography. The characterization of char was performed in terms of its elemental composition, surface area and FT-IR spectroscopy. The H/C and O/C ratios of the chars decreased with the rise in the temperature. FT-IR showed that results the hydroxyl and carbonyl functionalities were lost at high temperatures. According to the experimental results the liquid products can be used as liquid fuels, whereas the solid products can be transformed to activated carbon for adsorption processes.