VOC Emission During The Pyrolysis Of (Thermal Modification)Poplar And Chinese Fir

This study aims to analyze the composition and variation of the functional groups contained in the pyrolysis products of poplar?populus?and Chinese fir?Cunninghamia Lanceolata?wood powderaccording to thermal gravity infrared technology.Based on this,the pyrolysis gas chromatography-mass spectrometer was further used to determine the VOC composition and relative content of poplar and Chinese fir,and provide theoretical basis for the control technology and emission standards of organic volatiles in the process of thermal modification.The results show:?1?In the temperature of 30-300°C,due to the decomposition of some substances in the cell wall and cell cavity of poplar and Chinese fir,and the volatilization of VOC and water in poplar and Chinese fir itself,weight was reduced.The total weight loss of poplar was 38.88%,and the total weight loss of Chinese fir was 15.22%.The main absorption peaks of poplar and Chinese fir pyrolysis products occur in the temperature of 180-300°C.The pyrolysis products were mainly composed of small molecules H₂O,CO,CO₂,CH₄,and some ketones,aldehydes,alcohols,acids,phenolandesters.?2?The VOC components released from poplar and Chinese fir were relatively complex mixtures during the pyrolysis,mainly including alcohols,aldehydes,ketones,acids and phenols.The main aldehydes in poplar were 3-hydroxy-4-vanillin and4-dimethoxy-2-nitro-benzaldehyde;the ketones were mainly 1-hydroxy-2-pentanone and7-octene-2,4-dione;alcohols mainly include 2-furanmethanol,1-decen-3-ol;acid substances were mainly serine and n-hexadecanoic acid;phenols mainly include phenol and 2-methoxyl-Phenol;esters mainly include methyl hydroxybenzoate and methyl palmitate.The most important aldehydes in Chinese fir were furfural,5-acetoxymethyl-2-furaldehyde and 2,3-dihydroxybenzaldehyde.The ketones mainly include2-hydroxy-3-methyl-2-cyclopentene.1-ketone,1-?4-hydroxy-3-methoxyphenyl?-2-propanon e,alcohols mainly include trans-1,2-cyclopentanediol,4-hydroxy-3-methoxy Base-phenylpropanol,themainsubstanceswere10-hydroxydecanoicacid,4-hydroxy-3-methoxy-phenylaceticacid,andthephenolsweremainly?E?-4-?3-hydroxyprop-1-ene 1-yl?-2-methoxyphenol,4-?2-propenyl?-phenol;esters mainly include methyl 7-oxodehydroabietic acid,4-hydroxy-3-methoxyphenyl phenylacetate-Methyl ester.?3?The composition and content of VOC vary slightly with the pyrolysis temperature.As temperatures continue to rise,the variety of VOCs was becoming more complex.The main components of VOC are phenols from poplar during the pyrolysis,and the order of release of other volatiles from large to small was:ketones>acids>alcohols>aldehydes>esters.The main components of VOC were also phenols from Chinese fir during the pyrolysis.As to other volatiles,the order of release from large to small was:acid>aldehyde>alcohol>ketone>ester.?4?The VOC of poplar and Chinese fir during pyrolysis was compared and analyzed.It was found that the VOC composition released from poplar and Chinese fir were complex mixtures,and the types of VOC were the same,mainly phenols,aldehydes,ketones,acids,alcohols,estersand so on.Ketones were the main components except phenolic compounds,and acids were the main components of Chinese fir.