First online measurements of sulfuric acid gas in modern heavy-duty diesel engine exhaust: implications for nanoparticle formation.
First online measurements of sulfuric acid gas in modern heavy-duty diesel engine exhaust: implications for nanoparticle formation.
复制标题
DOI：
10.1021/es302432s
复制
发表时间：
2012-10
影响因子：
11.4
通讯作者：
F. Arnold;L. Pirjola;T. Rönkkö;U. Reichl;H. Schlager;T. Lähde;J. Heikkilä;J. Keskinen
中科院分区：
文献类型：
--
作者：
F. Arnold;L. Pirjola;T. Rönkkö;U. Reichl;H. Schlager;T. Lähde;J. Heikkilä;J. Keskinen
为了减轻柴油颗粒污染问题，柴油车辆配备了现代化的排气后处理系统（ATS），可有效去除发动机产生的初级颗粒（烟灰和灰烬）和气态碳氢化合物。不幸的是，ATS可以促进低蒸汽压气体的形成，其可以经历成核和冷凝，导致成核颗粒（NUP）的形成。这些颗粒的化学性质和形成机制只有很少的探索。使用一种新的质谱方法，低蒸汽压气体的在线测量进行了现代重型柴油发动机的排气与现代ATS和燃烧低和超低硫燃料和生物燃料。据观察，气态硫酸（GSA）的浓度变化很大，虽然发动机运行稳定。然而，排气GSA被观察到受燃料硫水平、排气后处理和驾驶条件的影响。当使用生物燃料时也测量到显著的GSA浓度，表明GSA也可以源自润滑油硫。此外，伴随NUP测量和NUP模型模拟进行。我们发现，排气GSA促进NUP形成，但有机（酸性）前体气体也可以有一定的作用。模型结果表明，单独测量的GSA浓度不足以使颗粒生长到检测到的尺寸。
To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes.