To ascertain the mechanism of hemicellulose pyrolysis and formation of the main products

xylan that containing 3 side groups and with polymerization degree of 10 was selected as the model compound for hemicelluloses to conduct molecular dynamic simulation on the pyrolysis process

by Hyperchem software.On the basis of AMBER force field

the simulation was in periodic boundary conditions and within temperature range from 300 K to 1 300 K.The results showed that

hydroxyl bonds began to fracture when temperature arrived at 450 K.As the temperature increasing to about 550 K

a time-dependent depolymerization occurred in the xylan molecule and all kinds of carbohydrate monomers were formed by glucoside bonds rupture

at the same time

pyranoid rings were opened and all kinds of molecular fragments formed.The simulation results agreed well with that of the experiment.In addition

the possible formation pathways of major products through reactions of all kinds of molecular fragments were analyzed.