Aubin Daniel G, Abbatt Jonathan P D
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
J Phys Chem A. 2007 Jul 19;111(28):6263-73. doi: 10.1021/jp068884h. Epub 2007 Jun 27.
Using a coated-wall flow tube connected to a mass spectrometer, the heterogeneous conversion of NO2 to HONO on dry hydrocarbon soot surfaces has been studied at room temperature and 243 K. Particular attention was given to the measurement of the HONO yield as a function of hydrocarbon fuel, NO2 partial pressure, extent of uptake, and surface oxidation state. In all cases, the yield is invariant of these parameters and close to unity, indicative of an irreversible oxidation mechanism by which the NO2 abstracts an H atom from the surface. XPS analysis shows that the surface N content does not measurably increase with NO2 exposure. There is minimal surface reactivity regeneration with time or via exposure to high relative humidity. A BET surface area measurement of the entire soot film exposed to NO2 was used to determine the amount of HONO that can be generated from the soot surface per unit surface area, prior to its deactivation. The reduction of NO2 to HONO on soot is unlikely to account for the observed nighttime buildup of HONO in polluted urban environments.
使用连接到质谱仪的涂壁流动管，在室温和243 K下研究了干燥烃类烟灰表面上NO₂向HONO的非均相转化。特别关注了HONO产率随烃类燃料、NO₂分压、摄取程度和表面氧化态的变化。在所有情况下，产率与这些参数无关且接近1，这表明存在一种不可逆的氧化机制，即NO₂从表面夺取一个H原子。XPS分析表明，表面N含量不会随着NO₂暴露而显著增加。随着时间推移或通过暴露于高相对湿度，表面反应性再生极小。在烟灰失活之前，对暴露于NO₂的整个烟灰膜进行BET表面积测量，以确定每单位表面积的烟灰表面可产生的HONO量。烟灰上NO₂还原为HONO不太可能解释在污染城市环境中观察到的夜间HONO积累。
