碱金属碱土金属对生物质热解特性及动力学研究-环境工程专业论文.docxVIP

ABSTRACTBiomass ABSTRACT Biomass absorbs various nutrients in the soll in the growth process．SO lt contains alkali metal salts and alkaline earth metal salts．Although the contents of metal salts not high，they still play important role on the pyrolysis process．Due to the various kinds of salts in biomass，the effect of each single metal salt the pyrolysis process was investigated after the biomass was acid demineralized．In this thesis，two plants(Pinus sylvestris and lauan)and their three main components(cellulose，hemicellulose and lignin) were selected the objective biomass． Firstly,the alkali metals and alkaline earth metals of the biomass were removed by acid demineralization，and then metal salts were added to the samples quantitatively．The content of K+，Ca2+，M92+analysised by atomic absorption experiment showed that pickling desalination efficiency was 90％，higher than that of water desalination．The scanning electron microscopy analysis revealed that demineralizing biomass by 5wt％hydrochloric acid for two hours slightly undermined the surface structure of the biomass．Due to the particle sizes of cellulose，hemicellulose and lignin were of 1 00阻n，adding salts by the mechanical dry mixing method able to contribute to the desired mixing results；The scanning electron microscope analysis showed that the salts added by impregnation method could be evenly distributed on the graded and pickled Pinus sylvestris and lauan samples． Then，different original and synthetic samples were analyzed by thermo gravimetric analyzer(TGA)．The influences of metallic salts of KCI，CaCl2 and MgCl2 on pyrolysis characteristics of biomass were investigated．Regarding with the thermal gravimetric analysis，it was found that the pyrolysis catalyst of CaCl2 could inhibit the condensation reaction during the thermal decomposition of biomass，resulting in the shoulder-like peak of the mass loss of hemicellulose and pickling sylvestris，and producing more low molecular weight compounds to promote the therm