Role of the Catalyst in the Pyrolysis of Polyolefin Mixtures and Used Tires

Abstract

The role of polymeric structures and the presence of a catalyst in the pyrolysis of polyolefin mixtures and used tires was studied in a fixed bed reactor at 450 °C. Our results showed that while thermal pyrolysis of high density polyethylene (HDPE) produced 23.3%wt of condensable products, a mixture of polyolefins (HDPE, LDPE, and PP) showed an increase of more than 23%wt in this fraction. In both cases, a wide carbon number distribution was obtained for the condensable products, confirming that there was not any selectivity. By using HZSM-5 zeolites, the pyrolysis of pure HDPE was dramatically changed with both more gaseous products and a major selectivity toward C10–C16 hydrocarbons in the condensable fraction. It is noteworthy that, although the PP present in the mixture increases the production of lighter hydrocarbons as compared with pure HDPE, no major differences in product distribution were observed between HDPE and polyolefin mixture in catalytic pyrolysis. However, the zeolites used improved the...