Batch pyrolysis of cotton stalks for evaluation of biochar energy potential

Abstract

The thermal cracking of cotton stalks (CS) via pyrolysis was performed using a laboratory scale batch pyrolysis reactor. The effects of the final pyrolysis temperature varying from 300 to 800°C on the pyrolysis products distribution has been investigated. The maximum biochar yield of 46.5% was obtained at 400°C. As the pyrolysis process temperature increased, the solid char product yield decreased. The lowest biochar yield of 28% was obtained at 800°C. The largest higher heating value (HHV, 25.845 MJ kg-1) was obtained at 600°C. All biochar samples produced between 500 and 700°C had an energy densification ratio of 1.41, indicating a higher mass-energy density than the initial feedstock. A larger share of syngas and bio-oil were produced at higher temperatures, as estimated. Preferential selection of a char based on the energy yield would lead to a selection of the 400°C product, while selection based on the energy densification ratio would be for a product obtained between 500 to 700°C.