Study On The Preparetion Of Wood Vinegar From Biomass Residues By Pyrolysis Process

There are abundant biomass resources in China.Pyrolysis is one of the most competitive biomass energy conversion technologies.Wood vinegar is one of the liquid products from biomass pyrolysis.The compounds of the wood vinegar are complicate.Wood vinegar can be used as insect repellent,preservative and some other green products applied in agriculture,industry and other wide varieties of area.The studies of wood vinegar are still in the early stage and far from complete,mostly focused on the application in the agriculture and simple components analysis.Therefore,in the paper,the preparation experiment of wood vinegar was conducted on a vertical tubular carbonization reactor and the yields,physical properties and organic components changes of wood vinegars prepared under the different conditions from different biomass materials were investigated in detail.The aim of the research is to provide a theoretical basis for the further development and utilization of wood vinegar.The results of wood vinegar preparation experiment under the different pyrolysis temperature from Chinese fir sawdust(FS)were given as follow: The yield of crude wood vinegar increased gradually with the increasing temperature,while the yield of refined wood vinegar increased until the temperature reached 350 ℃ and then decreased.The highest yield of the refined wood vinegar produced under the temperature range of 350-450 ℃ reached 25%.The density and pH value of the refined wood vinegar changed a little.The organic acid content reached 13.211% at 250 ℃ and decreased with the increasing temperature.The main ingredients of the refined wood vinegar obtained at different temperature included acids,phenols and ketones.The relative contents of acids decreased and that of phenols increased and that of ketones still have a relatively high level with increasing temperature.Under the experimental conditions,most of the acids in the refined wood vinegar emited from the sawdust during the pyrolysis process at 250 ℃.The types and relative contents of the ketones changed a little when the temperature above 350 o C.Most of the phenols in the refined wood vinegar were produced below 450 ℃.The results of wood vinegar preparation experiment under the temperature of350 ℃ from Chinese fir sawdust(FS),cotton stalk(CS),bamboo sawdust(BS)were given as follow: The yields of the crude wood vinegar and the refined wood vinegar produced from three biomass materials were nearly the same.The physical and chemical properties of the three refined wood vinegars were different from each other.The pH value of FS wood vinegar was the lowest and its density was the highest.The content of the organic acids contained in BS and CS wood vinegars were higher than that of FS wood vinegar.Besides the main three ingredients of acids,phenols and ketones,the alcohols with high relative content were found in BS and CS wood vinegar.The relative content of the acids and phenols contained in the three wood vinegars was in the order of BS > CS > CFS and that of the ketones was FS > CS > BS.The guaiacols and their derivatives were the main phenols compounds contained in FS wood vinegar.Besides that,the higher content of the syringols were found in CS wood vinegar and BS wood vinegar.The acetic acid and propionic acid were the main compounds in the acids and acetic acid content was the highest of them.The results of wood vinegar preparation experiment under the temperature of 350 ℃ from KCl-treated Chinese fir sawdust(K-FS)were given as follow: The yields of the wood vinegars produced from K-FS decreased compared with that of FS wood vinegar and as the KCl concentration increased,the yield decreased.The relative contents of the phenols and ketones contained in the wood vinegar produced from K-FS decreased and that of the acids increased,especially the acetic acid.The relative content of the alcohols roughly doubled compared with that of FS wood vinegar.The increase of the ketones was the most obvious among them.It can be deduced that the presence of potassium has a certain inhibition effect on the formation of ketones in wood vinegar but can promote the decomposition of the unstable macromolecular compounds to form the compound of small molecular weight such as acetic acid,ethanol et al.