气氛对柴油机碳烟热老化及其理化特性的影响

Effect of Different Atmospheres on the Thermal Aging and Physicochemical Characteristics of Diesel Carbon Black

为深入探讨不同气氛下的热老化对碳烟表面各类官能团以及碳烟氧化特性的影响,首先,对柴油机碳烟进行热老化预处理;其次,通过热重试验和化学反应动力学计算分析不同热老化后碳烟的氧化特征;最后,通过傅里叶红外光谱分析和X-射线光电子能谱研究不同热老化后碳烟表面官能团分布规律和元素组成。结果表明,热老化后碳烟起燃温度和活化能明显增加,其中O_(2)/NO_(2)/N_(2)气氛中热老化的碳烟起燃温度和活化能最低,分别为842.15 K和165.29 kJ·mol^(-1);热老化后碳烟表面碳氢官能团的支链化程度和含量下降,NO_(2)参与热老化的碳烟表面碳氢官能团相对含量最高;热老化后的碳烟表面O元素含量下降,在O_(2)/NO_(2)/N_(2)气氛下热老化的碳烟O/C摩尔比值最高为0.15;热老化后碳烟碳原子杂化程度降低且表面—C—OH和—C=O官能团含量均有所降低,热老化气氛中依次加入O_(2)和NO_(2)后的—C—OH官能团含量分别下降到0.21%及0.53%,而—C=O官能团含量分别增加至4.98%及5.98%。

To explore the effect of thermal aging on various functional groups and oxidation characteristics of carbon black under different atmospheres:Firstly,we performed thermal aging pretreatment of diesel carbon black;Secondly,we calculated and analyzed the oxidation characteristics of carbon black after different thermal aging through thermogravimetric test and chemical reaction kinetics;Finally,with method of Fourier infrared spectroscopy and X-ray photoelectron spectroscopy,we studied the functional group distribution and element composition of carbon black surface after different thermal aging.The results show that the ignition temperature and activation energy of carbon black after thermal aging increase significantly,and in O_(2)/NO_(2)/N_(2) atmosphere,the ignition temperature and activation energy are lowest for 842.15 K and 165.29 kJ·mol^(-1) respectively;after thermal aging,the branched degree and content of hydrocarbon functional groups on the carbon black surface lower,but the content in NO_(2) atmosphere is retained better;after thermal aging,the content of O element on carbon black surface also decreases,and the O/C molar ratio in O_(2)/NO_(2)/N_(2) atmosphere is highest for 0.15;after thermal aging,the carbon atom hybridization degree of carbon black,the—C—OH and—C=O functional group content on surface have decreased as well.After the addition of O_(2) and NO_(2) during thermal aging,the—C—OH functional group content decreases to 0.21%and 0.53%respectively,while the—C=O functional group content increases to 4.98%and 5.98%respectively.