选用秸秆、松木、花生壳3种生物质为原料,研究其氮的赋存形态,并进行热解实验,对比研究3种生物质热解过程氮的迁移转化规律。研究结果表明：农林生物质中氮主要以蛋白质的形式存在,部分以无机氮形式存在,随着热解温度的升高,NH3和HCN的产率不断增加,约75 %的NH3在400~500 ℃内产生,来自焦油氮和蛋白氮的脱氨反应,约80 %的HCN在500~800 ℃内通过焦油和焦炭中杂环氮的开环反应产生。焦炭氮的产率不断下降,稳定的蛋白氮通过交联环化反应贮存在焦炭中生成吡咯氮（N-5）和吡啶氮（N-6）,部分会环状缩合成季氮（N-Q）或加氧形成氧比氮（N-X）。焦油氮的产率先增后减,不稳定的蛋白氮分解形成焦油氮,并通过脱氢生成腈氮或环化形成杂环氮。此外,生物质中的三大组分和碱金属也会影响三相氮的分配。
Abstract
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.
关键词
生物质 /
氮 /
赋存形态 /
热解 /
迁移转化 /
三相
Key words
biomass /
nitrogen /
occurrence mode /
pyrolysis /
migration and transformation /
three phase
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基金
国家重点研发计划（2022YFE01967000）; “营口英才计划”项目
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