Study On Liquefaction Of Woody Biomass In Supercritical Fluid

The study on liquefaction of woody biomass in supercdtical water is the application of supercritical water as reaction media,in which the biomass is pyrolyzed,oxidated, disoxidated and other thermal chemical reactions.The main gas productions are hydrogen, carbon dioxide,carbon monoxide,methane and many flammable mixtures including C₂-C₄ paraffin gas The main liquid productions are polysaccharides and some Small organic molecules.Biomass energy is resourceful.Production of fuel by biomass liquefaction in supercritical water is a new and an effective energy transformation process.It has very high efficiency in biomass liquefaction and energy conversion,and has strong capabilities of treating organic matter to innocuity conversion.Combining renewable biomass with the water cycle can realize the conversion and reuse of energy as well as the benign cycle of the nature, so it is worth while further study.In this thesis,the experiments are carried out on the self-built equipment of supercritical biomass liquefaction with batch operation.Using real biomass as raw materials,aimed at decomposition ratio of compound,liquefaction yield and so on,the effects of reaction temperature,reaction pressure,the quality of reactant,residence time and catalyst on the reaction are studied.Using the GC-MS the qualitative and quantitative analyses to the liquid products are conducted.The formation and transformation process of the intermediates are understood.The reactionl path and reaction mechanism of biomass liquefaction in supercritical water are studied.The optimum technology conditions and parameters of the process of liquefaction are obtained.At first,experiments are nm in the supercritical water.The main effective factors and the availability of the process are studied with real biomass.GC/MS is employed to make qualitative analysis on the liquid phase with temperature programming,and the main components of the liquid phase under various reaction conditions are determined.Through these analyses,it is realized that a series of reactions have occurred and a lot of intermediates are produced.These intermediates are instable and finally form aldehyde,acid,gas with small molecule as the temperature and residence time increase.The knowledge of the reaction path and reaction mechanism of liquefaction of biomass in supercritical water is therefore deepened and widened. The experimental results show that the pressure is the main effective parameter on the process with real biomass.Within experimental range,with increasing of pressure the liquefaction effects increase.When the residence time is 10 minutes,the study has the best liquefaction effects,and the result has a little different with the different of biomass,but more time is no use to liquefaction result.The reaction temperature also has some effect on the liquefaction.Over critical point more high temperature is better.The effect of catylyst on the reaction is studied,and the results show that basic catalyst can improve liquefaction effects and promoting decyclization of cyclic compounds and isomerization reation.However,the environment pollution and other subsequent treatment resulting from using catalyst are problematic.