The Influence of Sulfur on NOx Formation in Combustion

该项目的目标是分离与燃烧系统中硫/氮相互作用相关的单个基元反应，并在宽温度范围内表征其反应动力学。 通过前体分子的脉冲紫外准分子激光或闪光灯光解产生包括氮、氧、氢和硫的原子以及诸如NH、NH 2、CN、SO、CS和SH的双原子自由基的短寿命反应性物种。 瞬态自由基物种的浓度监测与时间分辨荧光光谱-激光诱导荧光的分子自由基和真空紫外共振荧光的原子物种-以获得速率常数和产品识别作为温度和压力的函数。 反应进行了研究，在伪一阶条件下，大量过量的稳定反应物。 实验包括自由基与稳定分子如硫化氢，二氧化硫和一氧化氮的反应，以及涉及SO的自由基-自由基反应。火焰和废气中氮和硫化学的相互作用影响燃烧产生的氮氧化物，从而影响酸雨，光化学烟雾和对流层臭氧。 根据不同的条件，硫可以增加或减少氮氧化物的排放量。 本研究调查了这种相互作用的潜在化学作用。该项目通过德克萨斯州数学与科学学院和向上约束数学与科学项目为本科生和中学生的参与提供了一个工具。

The goal of this project is the isolation of individual elementary reactions relevant to the sulfur/nitrogen interaction in combustion systems and the characterization of their reaction kinetics over a wide range of temperature. Short-lived reactive species including atoms of nitrogen, oxygen, hydrogen, and sulfur and diatomic radicals such as NH, NH2, CN, SO, CS, and SH are generated by pulsed ultraviolet excimer-laser or flash-lamp photolysis of precursor molecules. The concentration of transient radical species are monitored with time-resolved fluorescence spectroscopy - laser-induced fluorescence for molecular radicals and vacuum-ultraviolet resonance fluorescence for atomic species - to obtain rate constants and product identification as functions of temperature and pressure. Reactions are studied under pseudo-first-order conditions with a large excess of the stable reactant. Experiments include reactions of radicals with stable molecules such as hydrogen sulfide, sulfur dioxide, and nitric oxide and also radical-radical reactions involving SO.The interaction of nitrogen and sulfur chemistry within flames and exhaust gases influences the generation of nitrogen oxides from combustion and thusly impacts acid rain, photochemical smog, and tropospheric ozone. Depending on conditions, sulfur may augment or reduce the amounts of nitrogen oxides emitted. This study investigates the underlying chemistry of this interaction.This project provides a vehicle for the participation of undergraduate and secondary-school students through the Texas Academy of Math and Science and the Upward Bound Math and Science Program.