For understanding the dehydration mechanism in initial pyrolysis of cellulose, dehydration reaction mechanism of the glycerine as a model was investigated using UB3LYP/6-31＋＋G(d,p) methods in Gaussian 03 package. Six kinds of paths of dehydration reaction were designed, and the equilibrium geometries of the reactants, transition states and products were optimized, and the standard thermodynamic and kinetic parameters of every reaction path in different temperature ranges were calculated. The calculation results show that every reaction except the reactions of formation of the intermediates IM_a and IM_b is endothermic processes and dehydration reaction of the glycerine can take place when temperature of reaction exceeds 400 K. Compared to 1-2-dehydration reaction, 1-3-dehydration reaction is liable to take place, in which activation energy is about 233.75 kJ/mol. Addition of metal ions Li^＋ would be in favor of dehydration of the glycerine, and activation energy for 1-2-dehydration of the glycerine with addition of metal ions Li^＋ is about 201.95 kJ/mol, and that for 1-3-dehydration is about 202.14 kJ/mol.

Key words: glycerine, dehydration reaction, density functional theory