Based on the Gibbs free energy minimization method

HSC chemistry software was used to calculate the thermochemical equilibrium of wood pyrolysis. The effect of temperature on composition and proportion of products of wood pyrolysis was discussed and pyrolysis process was divided into four zones. According to the criterion of spontaneous reaction (the relationship between Gibbs free energy and temperature)

the reaction among products was discussed for the first time

and then the proper reactions at each zone were determined. At last

the effect of temperature on the wood pyrolysis products reported in literature is summarized

and the calculation results were found to be similar with experimental results of prior authors.