基于反应分子动力学的1-丁基-3-甲基咪唑硝酸盐与煤反应机理研究

使用FTT锥形量热仪对烟煤和烟煤-[Bmim][NO₃](1-丁基-3-甲基咪唑硝酸盐)混合物进行燃烧性能测试,并结合分子反应动力学方法(ReaxFF)分析1200K,1600K,1800K和2200K四个温度条件下[Bmim][NO₃]与煤的化学反应过程。实验结果表明:[Bmim][NO₃]的添加会使体系达到热释放速率(HRR)峰值的时间提前,即促进烟煤的氧化燃烧反应。模拟结果表明:当模拟温度为1200K时,仅产生了少量H₂O和NO₂;当模拟温度升高至1600K时,开始产生小分子烷烃、CO和CO₂,但数目较少且产生时间延后;当模拟温度继续升高至1800K时,开始产生少量的H₂等气体无机物,CO与CO₂的数目较1600K时增加一倍,且初次出现时间提前约100ps;当模拟温度为2200K时,反应物中的N元素转化为NH₃和HCN,CO数目继续增加,CO₂数目逐渐降低。总体来看,温度较低时反应过程主要受[NO₃]-影响,[NO₃]-通过与煤分子中羧基反应使煤分子脱氢形成得电子结构,从而易于发生分解反应;当温度继续升高,[Bmim]+开始显著参与反应过程,[Bmim]+热解产生的自由基与煤分子发生反应,生成大量NH₃和HCN,从而会对人体和环境造成危害。

Research on Reaction Mechanism of[Bmim][NO3]with Bituminous Coal Based on ReaxFF Molecular Dynamics

The FTT cone calorimeter was used to test the combustion performance of bituminous coal and the mixture of bituminous coal and[Bmim][NO₃](1-methyl-3-butylimidazole nitrate).In addition,combined with the molecular reaction dynamics method(Reactive Force Filed,ReaxFF),the chemical reactions between[Bmim][NO₃]and coal under four temperature conditions of 1200K,1600K,1800K,and 2200Kwere also analyzed.Experimental results show that[Bmim][NO₃]promotes the combustion of bituminous coal and shortens the time of reaching the peak of heat release rate(HRR).The simulation results show that only a small amount of H₂O and NO₂are produced at 1200K.When the temperature increases to 1600K,small molecular alkanes,CO,and CO₂are gradually formed in the reaction system,but the quantity is very low,and the production time is delayed.When the temperature further increases to 1800K,a small amount of H₂ and other inorganic gases start to form.The numbers of CO and CO₂molecules are double compared to the numbers at 1600K,and the initial appearing time is also 100ps earlier.At 2200K,the N element in the reactants is transformed into NH₃ and HCN.The amount of CO keeps increasing,but the amount of CO₂gradually decreases.In general,the chemical reaction is mainly affected by[NO₃]-at lower temperatures.[NO₃]-dehydrogenates coal to form an electronic structure,which is prone to decompose.When the temperature gradually increases,[Bmim]+begins to participate in the reaction process.The free radicals produced by[Bmim]+pyrolysis react with coal molecules and lead to a massive formation of NH₃ and HCN,which are harmful to the environment and human beings.