Pyrolysis characteristics of hemicelluloses from bamboo stem

Water-soluble hemicelluloses H_W and four alkali-soluble hemicellulosic fractions H₁~H₄ were sequentially extracted from six-month-old bamboo stem by distilled water, 2% NaOH and 5% KOH. The thermal pyrolysis behavior of the five hemicellulosic fractions was characterized by using thermal gravimetric analysis (TGA) at the heating rate of 10°C/min, and the first-order reaction models were established in the fast pyrolysis temperature ranges. The fast decompositions of the five fractions happened in between 180~400°C with weight losses 33.91%~42.54%. The residue percentages were 34.52%~51.31% at the final temperature of 700°C. The activity energies of all the hemicelluloses fractions were quite low with the values of 26.068~51.938 kJ/mol. The activity energies of alkali-soluble fractions were higher than that of water-soluble fraction. The hemicellulosic fractions containing higher lignin residue exhibited higher activity energy and residue rate at the final temperature of pyrolysis.