废轮胎回转窑中试热解炭表面组分XPS分析

XPS analysis of surface component of carbon blacks from pyrolysis of used tires in pilot-scale rotary kiln

以X射线光电子能谱(XPS)对废轮胎回转窑中试热解炭表面组分进行实验分析,研究热解炭本体与表面的异同,热解温度、热解炭粒径的影响。与商用炭黒比较,废轮胎热解炭本体中含有更多的Zn、Si、S、Mg等杂质元素,各组分与热解温度没有大的相关性;热解炭表面在热解过程中形成了一吸附沉积层,表面层中杂元素的质量分数极低;低于500℃时,热解不完全,吸附沉积物较少。热解炭按粒径存在一定分布,粒度<0.074mm的粉末状热解炭来自表面磨损脱落的粉末,各种杂元素的质量分数很低;Zn元素的相对质量分数随热解炭粒径的减小而减少。对热解炭进行深度剖析发现,吸附层是极薄的,表面层对本体的影响是极小的;定量分析结果表明,以C质量分数为100,则O为4～6,S、N约为1,Zn小于0.6,而商用炭黑中S约为0.3,不含N、Zn。

The surface component of carbon black from pyrolysis of used tires in a pilot-scale rotary kiln was analyzed by X-ray photoelectron spectroscopy （XPS）, and the difference between surface and bulk of pyrolytic carbon black （PCB） depending on pyrolysis temperature and PCB particle diameter was studied. The surface component of PCB was compared with that of commercial carbon black （CCB）. Some X-ray photoelectron, auger electron and satellite peaks were found in the spectra of PCB or CCB. The bulk of PCB contains more ash elements such as Zn, Si, S and Mg than CCB. The type and distribution of ash elements are independence on pyrolysis temperature. Most ash elements in tires are left in PCB after pyrolysis. A layer consisting of adsorbates and deposits is found on the surface of PCB. The adsorbates and the deposits come from the condensed carbon formed by pyrolytic gases and hydrocarbons in gas phase during pyrolysis. The concentration of ash elements in the surface layer is very low. When pyrolysis is not completed below 500 ℃, there are a little adsorbates and deposits formation. The adsorbates layer is very thin and has little influence on the properties of bulk PCB. The finest PCB powder （ diameter 〈 0. 074 mm） from the abrasion of PCB surface during rotation in the rotary kiln contains few ash elements. The relative concentration of Zn decreases with the decrease of PCB particle diameter. The quantitative analysis results show that in PCB the relative concentration of O is 4-6, N and S is about 1,and Zn is less than 0.6, if C is set to 100. In CCB, the concentration of S is about 0.3 and without Zn and N.