Abstract: According to thermogravimetric analysis under different heating rates, the kinetic characteristics of pyrolysis of Chinese fir wood catalyzed by potassium salt was studied. In response to the separation of DTG peaks and the activation energy under different conversion rate calculated by distribution activation energy model, it was found that potassium salt had catalytic effect on decomposition of hemi-cellulose at low temperature, and on the whole pyrolysis process of cellulose. Besides, it weakened or even eliminated the shoulder peak of DTG curves(200-270℃) and promoted dehydration and cross-linking reaction, which improved the char yield, and the ordering of residue carbon, which was represented by the increase of char yield from 16.3% to 25.3% and the abrupt increase of activation energy at the residue carbon decomposition stage after 80% conversion rate. Based on the three-component parallel-reaction mechanism, a non-lineal regression method was adopted to fit and calculate the kinetic parameters for pyrolysis of Chinese fir wood. Results showed that decomposition of cellulose could be regarded as first-order reaction. Potassium salt enhanced the pyrolysis of cellulose and hemi-cellulose, decreased their activation energy from 148.12 and 235.43 kJ/mol to 108.84 and 171.41 kJ/mol respectively, while the catalytic effect on lignin was insignificant.

Key words: Chinese fir, pyrolysis, metallic salt, catalysis, kinetics