废轮胎回转窑中试热解炭表面组分XPS分析

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.