柴油机尾气颗粒和碳黑颗粒氧化特性的分析比较

Comparison of Oxidation Characteristics Analysis Between Diesel Soot and Carbon Black

利用热重分析仪（TGA）,对采集到的柴油机尾气颗粒和商用碳黑颗粒（Printex U）进行了不同升温速率下的热重分析、元素分析和显微测试实验;利用积分法（Coats-Redfern）计算出了两种颗粒的动力学参数,比较了两种颗粒的氧化特性.结果表明：相较于碳黑颗粒,由于无序活性碳结构和可溶性有机物的存在,柴油机尾气颗粒的燃烧呈现两个反应阶段,第1阶段（α=0.1~0.55）主要是颗粒的易氧化物质的氧化燃烧;第2阶段（α=0.6~0.9）主要是残余碳颗粒的反应.柴油机尾气颗粒的反应级数n为0.7,而碳黑颗粒的n则是1.颗粒内部微观结构和成分也会影响其氧化特性,柴油机尾气颗粒比碳黑颗粒起燃温度更低,更易氧化再生.

The thermogravimetric experiments on the samples of diesel soot and commercial carbon black（Printex U） were carried out on TGA under different heating rates.Elemental analysis and high resolution transmission electron microscopy were also applied to the analysis of the samples,respectively.Thermodynamic parameters of diesel soot and carbon black were calculated by integration（Coats-Redfern）method.Then the oxidation characteristics of the two types of particles were analyzed based on the thermodynamic parameters.The results showed that,compared with carbon black,diesel soot combustion showed two reaction stages due to the presence of disordered activated carbon structure and soluble organics fraction.The first phase（α=0—0.55）occurred due to the combustion of easily oxidized substance,while the second phase（α=0.6—0.9）occurred due to the reaction of residual carbon particles,thus the reaction order of diesel soot was 0.7 and that of carbon black was 1.Internal microscopic structure and composition of soot would also have important influences on its oxidation process.Therefore,compared with carbon black,diesel soot is more easily oxidized and regenerated under the same condition due to its lower ignition temperature.