Study on the gas evolution and char structural change during pyrolysis of cotton stalk

► Evolution characteristics of main volatile products were given. ► The evolution of CO2 was approximately 26 °C earlier than that of CO and CH4 evolution mainly occurred 300-600 °C with a maximum at 394 °C. ► The amount of OH, aliphatic CH and olefinic CC bonds in the char decreased significantly above 250 °C. ► The aromatization process started at ≈350 °C and continued to higher temperatures, leaving the char enriched with condensed aromatic ring systems. ► SBET and Vmicro reached maxima of 4.68 m2/g and 0.0022 cm3/g at 500 °C, while Vmeso and Vtotal always increased.