基于烟雾箱模拟的己烯醇与O 3气相反应的动力学研究

Kinetic Study of O 3 and Hexen-Ols Reaction Base on Smog Chamber

为了研究O 3与挥发性不饱和醇的动力学常数以及反应活性差异的原因,使用绝对速率法在烟雾箱中对5种己烯醇和O 3的反应动力学进行研究.结果表明:Z-2-己烯-1-醇、E-2-己烯-1-醇、Z-4-己烯-1-醇、E-4-己烯-1-醇、5-己烯-1-醇与O 3在298 K、101325 Pa下的反应动力学常数分别为(8.94×10^-17±0.80×10^-17)、(13.95×10^-17±0.48×10^-17)、(8.82×10^-17±0.31×10^-17)(10.01×10^-17±1.03×10^-17)和(0.82×10^-17±0.04×10^-17)cm 3(molecule·s),并通过理论计算结果来解释和讨论动力学常数的变化趋势,发现不同烯醇与O 3反应的活性会受到—OH和双键相对位置的影响.通过试验所得动力学数据与大气氧化剂平均浓度计算得到各种己烯醇的大气寿命,发现O 3、OH自由基和NO 3自由基在消除Z-2-己烯-1-醇、E-2-己烯-1-醇、Z-4-己烯-1-醇和E-4-己烯-1-醇的过程中均属于竞争反应,但在高O 3污染地区,这4种己烯醇的消除是由O 3所主导的,5-己烯-1-醇因结构的原因,其大气寿命较长,超过7 h.研究显示:O 3对这5种己烯醇的清除作用明显;研究数据为环境空气质量预测模式提供了相关的动力学参数;己烯醇中各官能团的不同位置对其与O 3反应活性的影响结果,可为类似烯醇与O 3的反应速率常数的测定和预测提供理论支持.

In order to study the kinetic rate constants and the discrepancy of reaction activities of O 3 with unsaturated alcohols,we studied the reaction kinetics of 5 kinds of hexen-ols and O 3 in smog chamber using the absolute rate method.The kinetic rate constant of Z-2-hexen-1-ol,E-2-hexen-1-ol,Z-4-hexen-1-ol,E-4-hexen-1-ol,and 5-hexen-1-ol with O 3 at 298 K,101,325 Pa was(8.94×10^-17±0.8×10^-17),(13.95×10^-17±0.48×10^-17),(8.82×10^-17±0.31×10^-17),(10.01×10^-17±1.03×10^-17),and(0.82×10^-17±0.04×10^-17)cm 3(molecule·s),respectively.Through the results of theoretical calculations,the different trends of kinetic rate constants were explained.The reaction activity of different hexen-ols with O 3 was efficiently influenced by the position of—OH and double bond.The atmospheric lifetime of hexen-ols was calculated through the kinetic rate constants and the normal concentration of atmospheric oxidants,which indicated the competitive reactions of O 3,OH,and NO 3 radicals in the elimination process of Z-2-hexen-1-ol,E-2-hexen-1-ol,Z-4-hexen-1-ol,and E-4-hexen-1-ol.However,these hexen-ols were mainly eliminated by O 3 in high photochemical pollution areas.The atmospheric lifetime of 5-hexen-1-ol was more than 7 h due to the conformation characteristics.Therefore,O 3 had an obvious impact on the removal of 5 hexen-ols.Our results provide the important kinetic parameters for the air quality prediction simulation of the dynamic models in the human-gathering areas,and provide theoretical support for the determination and prediction of the rate constants of the similar reactions between enols and O 3.