Catalytic pyrolysis of waste tire using Cu- and Zn-modified catalysts

Abstract

This work studied the effects of Cu- and Zn-loaded catalysts on waste tire pyrolysis products. Several researchers succeeded in the uses of copper in selective hydrogenation applications and the uses of zinc in light alkane aromatization applications for producing petrochemicals. Furthermore, copper and zinc have been used to produce adsorbents for removing S-containing compounds in liquid fuels as well. So, if copper- and zinc-loaded catalysts are used for waste tire pyrolysis, the quality of tire-derived oils might be improved in the terms of sulfur reduction, and/or the valuable petrochemicals might be increasingly produced as well. From the experimental results, copper on different zeolite supports exhibited the same activities that it can increase cracking, hydrogenation and ring-opening activities of zeolite supports, but the change of product compositions were different because the interaction between copper and supports was relevant. Likewise, zinc exhibited the same ability on different zeolite supports that it promoted cracking, hydrogenation, ring-opening and aromatization activities. The change of product compositions was in the same trend. The produced oils were composed of a high concentration of mono-aromatics as compared with the oils in the pure zeolite cases. Moreover, the introduction of copper or zinc onto the zeolite supports can also reduce the sulfur distribution in oils (from 17.8-21.2 w t% S for pure zeolite cases to 12.2-18.8 w t% S for in copper- or zinc-loaded catalyst cases, based on S content in tire). Thermal and catalytic pyrolysis of waste tire can produce oils containing a high concentration of mono-aromatics (39.3-58.2 w t% in oil). The mono-aromatics produced in a high amount were benzene (except 5 w t% Cu/FIBETA), together with cumene and ethylbenzene in Cu- and Zn-loaded catalyst cases, respectively.