为探索纤维素在铁基载氧体作用下的化学链解聚机理及过程。通过热重分析试验研究不同升温速率下纤维素的化学链燃烧特性；通过化学反应动力学计算纤维素化学链燃烧过程中的活化能并揭示其动力学机制；利用ReaxFF MD模拟综合技术从微观原子尺度阐释纤维素化学链燃烧过程微观反应网络。热分析结果表明，铁基载氧体的加入可降低纤维素化学链解聚的起始温度，其释放的晶格氧有助于促进纤维素的化学链解聚。纤维素化学链燃烧过程分为3个阶段：挥发分析出燃烧、半焦转化燃烧和焦炭燃烧阶段。反应动力学研究显示，纤维素在热转化过程中不同转化率下的活化能为220～405 kJ/mol，其中第3个阶段的反应活化能最高。ReaxFF MD模拟结果显示，纤维素化学链燃烧过程整体遵循自由基链反应理论。纤维素裂解产生的活性自由基与载氧体释放的晶格氧反应生成2-羟基丙酮等中间体，然后进一步发生自由基反应生成CO2。最终获得了载氧体作用下纤维素化学链解聚过程中CO2生成释放的复杂反应网络。

To explore the mechanism and process of chemical looping depolymerization for cellulose in the presence of iron-based oxygen carriers, the characteristics of chemical looping combustion for cellulose at different heating rates were investigated by thermogravimetric analysis tests. The activation energy of cellulose during chemical looping combustion was calculated using chemical reaction kinetics and its kinetic mechanism was revealed. The microscopic reaction network of cellulose during chemical looping combustion was elucidated from the microscopic atomic scale by using ReaxFF MD simulation synthesis technique.The thermal analysis results show that the addition of iron-based oxygen carriers can reduce the onset temperature of cellulose chemical looping depolymerization and that the lattice oxygen released by iron-based oxygen carriers can help promote the chemical looping depolymerization of cellulose. Chemical looping combustion process of cellulose are divided into three different stages: volatile analysis out combustion, semi-coke conversion combustion and coke combustion stages.The kinetic model shows that the activation energy of cellulose in the thermal conversion process at different conversion rates is about 220-405 kJ/mol, with the highest activation energy of the reaction occurring at stage 3. Finally,ReaxFF MD simulations show that the overall chemical looping combustion process of cellulose follows the free radical chain reaction theory. The reactive radicals generated by cellulose cleavage reacted with the lattice oxygen releasing the oxygen carrier form intermediates such as 2-hydroxyacetone, which then under go further radical reactions to produce CO2. A complex reaction network for the release of CO2 production during the chemical looping depolymerization of cellulose in the presence of oxygen carriers is finally obtained.

0 引言

1 试验

   1.1 样品制备

   1.2 TG测试

   1.3 分子模拟

2 结果与讨论

   2.1 不同升温速率下纤维素化学链解聚失重行为

   2.2 纤维素的化学链解聚动力学特性

   2.3 基于反应分子动力学模拟的纤维素化学链解聚过程及机理

3 结论