有机金属化合物降低柴油机炭烟排放及其机理的研究

Study on the soot reduction and the mechanism by organometallic compounds in a diesel engine

在直喷式柴油机上按自由加速法进行了柴油机炭烟排放试验,考察了8种有机金属化合物降低炭烟排放的效果,并对其作用机理进行了研究。实验表明,8种有机金属化合物均能有效降低炭烟排放,降烟效果顺序为二壬基萘磺酸钡>二茂铁>环烷酸铁>石油磺酸钡>环烷酸锰>环烷酸铜>环烷酸钡>环烷酸铈。在纯柴油中添加4‰二壬基萘磺酸钡时,降低炭烟排放40.7%;添加1‰二茂铁时,降低炭烟排放35.3%。试验还表明,有机结构影响有机金属化合物的降烟效果,同时影响着它在添加量上的感受性。炭烟的生成,主要与生成的乙炔(C2H2)和多环芳香烃(PAH)有关,而炭烟的氧化则与炭烟周围氧浓度和炭烟颗粒表面积有关。多数有机金属化合物本身携氧,能使燃油迅速分解生成CO,CO的增加使PAH明显减少,从而抑止炭烟的生成。茂型金属有机物能活化CO分子,进而有效抑止炭烟先导物的生成。

Experimental investigation was conducted to evaluate the effect of soot reduction by eight different organometallic compounds in a direct injection diesel engine by the free acceleration method. Meanwhile, the mechanism of these compounds was studied in the paper. All eight compounds were found to be effective in reducing soot emission with the sequence of barium dinonynalphthalene sulfonate 〉 ferrocene 〉 iron naphthenates 〉 petroleum barium sulfonate 〉 manganese naphthenates 〉 cuprum naphthenates 〉 barium naphthenates 〉 cerium naphthenates. When the proportion of barium dinonynalphthalene sulfonate in the fuel is 4‰, soot emission is reduced by 40.7 %, and the diesel fuel blended with 1‰ ferrocene could reduce soot emission by 35.3 %. The experimental results show that the organic structure of organometallic compounds makes effect on the reduction of the soot emission, as well as on the sensitivity to the content. The formation of the soot is related to the acetylene and polycyclic aromatic hydrocarbons （PAH）, while the oxidation of the soot is related to the concentration of the oxygen around and the surface area of the soot particles. Most of the organometallic compounds contain oxygen, and can break down the fuel into CO rapidly which greatly decreases the PAH. Cyclopentadienyl type organometallic comnound can activate CO which prohibits the formation of the precursor of the soot.