Production Of Benzene And Its Derivatives From Selective Pyrolysis Of Poplar By Biological Pretreatment

There are many kinds of organic products in bio-oil from regular biomass pyrolysis,but their selectivity is low,which seriously restricts industrial applications.Appropriate pretreatment processes can help biomass pyrolysis to obtain certain high value-added products.Our research focuses on effect of biological pretreatment on preparation of benzene and its derivatives by selective pyrolysis of polar.1.Pyrolysis characteristic changes of poplar wood during natural decayTo explore the pyrolysis characteristic changes of wood during natural decay,4 decay degrees of poplar wood(PW)were chosen and pyrolysis behaviors were studied by TGA and Py-GC/MS.The results indicated that with an increase of decay degree from 0%to 60%,the contents of hemicellulose and cellulose decreased from 22.2%and 46.39%to 11.77%and 22.32%,and that of lignin and extractives increased from 23.9%and 7.51%to 39.85%and 26.06%,respectively.The pyrolysis processes mainly occurred in two stages.The effects of lower decay degree(for example 45%)on the wood pyrolysis progress were slight,and with an increase of decay degree,the pyrolysis behaviors were more and more close to that of the milled wood lignin.The changes of the physical and chemical structure resulted in a decrease of Activation Energy from 91.37 kJ/mol to 74.08 kJ/mol.In the bio-oil,the contents of the ketones,carbonyls,sugars and furans changed slightly from 15.67%,4.61%,8.31%and 7.86%to 12.52%,3.32%,7.90%and 6.46%,respectively.However,the content of the acids decreased from 19.03%to 11.25%,and the phenols content significantly increased from 22.52%to 35.97%.Rotten wood could be used as the feedstock of the selective pyrolysis to product the phenols.2.Effects of Anaerobic Fermentation on Pyrolysis Behaviors of PoplarThe poplar sawdust was biotreated by methanogens,and the pyrolysis characteristics of poplar sawdust with different fermentation days were investigated.The results showed that methanogens mainly destroyed cellulose and hemicellulose in the wood,the relative contents of which decreased from 54.05%and 17.96%to 51.29%and 13.21%,respectively.However,the relative contents of lignin increased from 26.58%to 28.19%.After the anaerobic fermentation,the main phenolic products were changed from phenol to catechol.In particular,the yield of catechol increased significantly when the pyrolysis temperature was 500℃,and the selectivity increased from 10.06%to 18.78%,which might be due to the destruction of the side chain of S-lignin in poplar.3.Effects of Anaerobic Fermentation on Selective Pyrolysis of PoplarThe poplar sawdust was biotreated by methanogens,and the effects of fermentation time on the catalytic pyrolysis characteristics of poplar sawdust were investigated.The results showed that the anaerobic fermentation could improve the liquid yield of poplar,especially the poplar pretreatmented for 5 days.The relative content of aromatic hydrocarbons of the poplar pretreatmented for 5 days reached 37.9%,and the relative content of monocyclic aromatic hydrocarbons was 26.5%.In addition,the relative contents of toluene and xylene were 10.4%and 10.1%,respectively.The research provided an idea for the preparation of aromatic hydrocarbons by selective pyrolysis of biomass from the perspective of bio-pretreatment.