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通过建立多组分平行反应模型和开展非线性动力学解析,理论上探索植物焦炭氧化中的平行反应以及其对焦炭氧化反应活性影响的机制.运用高温管式炉并通入高纯氮气制备植物焦炭,热处理温度分别设定为450、520和800℃.运用同步热分析仪开展空气气氛中植物焦炭线性升温氧化实验,并通过对热重和质量损失速率实验数据进行拟合以获取焦炭氧化动力学参数值.解析结果证实,对于低中热处理温度(450和520℃)制得的焦炭,其质量损失速率及对应的热流率曲线的变化特征主要是由残留木质素、无定形碳及粗脂肪和粗蛋白等其它反应物质的平行氧化反应叠加而成;当热处理温度达到800℃时,焦炭中活性物质基本为无定形碳,氧化则可简化为无定形碳的单步反应.残留木质素氧化反应的活化能最低,范围为86~147 k J·mol-1,相应的温度作用区间为300~480℃;无定形碳的活化能为174~208kJ·mol-1,反应温度在370~520℃之间;其它物质的反应活化能为214~225 k J·mol-1,温度作用区间在420~510℃之间.焦炭的氧化活性主要由残留木质素含量决定.随着热处理温度升高,残留木质素含量降低,同时另两个反应组分的氧化活化能均有所增大,导致焦炭的氧化反应活性下降.
By establishing a multi-component parallel reaction model and carrying out nonlinear kinetic analysis, the parallel reaction of coke oxidation and its effect on the coke oxidation reaction activity are theoretically explored. The high temperature tube furnace is used to produce plant Coke and heat treatment temperature were set to 450,520 and 800 ℃ respectively.Using synchronous thermal analyzer to conduct linear temperature and oxidation experiments of plant coke in the air atmosphere and through the experimental data of the thermogravimetric and mass loss rate fitting to obtain the coke oxidation power The analytical results confirm that the mass loss rate and corresponding heat flux curve of coke obtained at low and medium heat treatment temperatures (450 and 520 ℃) are mainly characterized by residual lignin, amorphous carbon and crude fat And crude protein and other reactive substances by the parallel oxidation reaction stack; When the heat treatment temperature reaches 800 ℃, the coke active material is essentially amorphous carbon, oxidation can be simplified to amorphous carbon single-step reaction of residual lignin oxidation The activation energy of the reaction is the lowest, ranging from 86 to 147 kJ · mol-1. The corresponding temperature range is from 300 to 480 ℃. The activation energy of amorphous carbon is 17 4 ~ 208kJ · mol-1, the reaction temperature is between 370 ℃ and 520 ℃, the activation energy of other materials is 214 ~ 225 kJ · mol-1 and the temperature is between 420 ℃ and 510 ℃ .Oxidation activity of coke Mainly by the residual lignin content.With the heat treatment temperature, the residual lignin content decreased, while the other two reaction components of the oxidation activation energy are increased, resulting in decreased oxidation activity of coke.