Research on Pyrolysis Characteristics of Cotton Straw

Pyrolysis of cotton straw (CS) was investigated using a thermogravimetirc analyzer and a lab-scale tubular reactor coupled with Fourier transform infrared (FTIR) spectrometer. The maximum pyrolysis rate increased with the rise in heating rate and the corresponding temperature also increased. The three-pseudocomponent model with first order kinetics could describe the pyrolysis behavior of cotton straw accurately. The main pyrolysis gas products were H₂O, CO₂, CO, CH₄, formaldehyde, formic acid and methanol, etc. The releasing of gas products mainly focused at 220-500°C. The H₂O formation process was separated into two stages corresponding to the evaporation of free water and the formation of primary volatiles. The formation of CO was mainly caused by the cracking and reforming of thermolabile carbonyl and ether groups. CH₄ evolution covered over a wider temperature range of 300-600°C, with a maximum at about 400°C. The formation of methane was mainly attributed to the cracking of the methoxyl (-O-CH₃) groups. The release of methanol occured at 250-450°C. The aliphatic -CH₂OH groups and aromatic methoxyl groups were the main source of methanol. Formaldehyde was mostly produced between 250 and 400°C.