Pyrolysis Oil from Scrap Tires as a Source of Fuel Components: Manufacturing, Fractionation, and Characterization

Abstract

One of the most efficient among the methods of managing waste tire rubber is the pyrolysis process which allows for obtaining pyrolysis oil. The as-received, raw tire pyrolysis oil (rTPO) is a complex mixture whose components exhibit a wide boiling temperature range, reflected in the physicochemical properties influencing injection, combustion, performance, and emission. The present contribution is aimed at producing TPO via steam-assisted pyrolysis followed by its fractionation by vacuum distillation. The resultant TPO fractions were analyzed in terms of composition as well as physicochemical parameters. The products are liquids with a relatively high density, poor volatility, and satisfactory low-temperature properties. They exhibit a mutually similar chemical composition reflected in a roughly the same Watson factor. The dominant components are cyclic and aromatic compounds, as was proven by gas chromatography coupled to mass spectrometry analysis and mid-infrared Fourier transform spectroscopy. Such a characteristic of the TPO fractions opens the way to utilize them either as additives to conventional automotive fuels or for heat and power generation. In particular, the two lightest fractions demonstrate high potential as fuel additives. Among the advantages of the fractionation of rTPO, one of the most important is the effect of the accumulation of sulfur-containing compounds in the highest boiling fractions, namely, vacuum fractionation allowed for reduction of the S content by 69.6 and 43.5 wt % (with regard to the rTPO) for the fractions boiling up to 180 and 180–250 °C, respectively. Thus, fractionation of pyrolysis oils could be used also as an ingenious and effective pretreatment method prior to exact desulfurization.