STUDY ON MIGRATION AND TRANSFORMATION OF NITROGEN DURING PYROLYSIS PROCESS OF AGRICULTURAL AND FORESTRY BIOMASS
Three types of biomass,namely straw,pine wood,and peanut shell,were selected as raw materials to study the nitrogen occurrence forms.Pyrolysis experiments were conducted to compare the nitrogen migration and transformation patterns during the pyrolysis process of the three types of biomass.The research results indicate that nitrogen in agricultural and forestry biomass mainly exists in the form of proteins,with some in the form of inorganic nitrogen.As the pyrolysis temperature increases,the yields of NH3 and HCN continue to increase.About 75% of NH3 is generated at 400-500℃,which comes from the deamination reaction of tar nitrogen and protein nitrogen.About 80% of HCN is generated through the ring-opening reaction of heterocyclic nitrogen in tar and coke at 500-800℃.The yield of coke nitrogen continues to decrease,and stable protein nitrogen is stored in the coke through cross-linking and cyclization reactions to generate N-5 and N-6.Some of it will undergo cyclic condensation to form N-Q or oxygenation to form N-X.The yield of tar nitrogen first increases and then decreases,and unstable protein nitrogen decomposes to form tar nitrogen,which is then dehydrogenated to form nitrile nitrogen or cyclized to form heterocyclic nitrogen.In addition,the three major components and alkali metals in biomass also affect the distribution of three-phase nitrogen.
biomassnitrogenoccurrence modepyrolysismigration and transformationthree phase
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