On Fractioning the Tire Pyrolysis Oil in a Pilot-Scale Distillation Plant under Industrially Relevant Conditions

Abstract

Tire pyrolysis oil (TPO) is one of the most interesting products derived from the pyrolysis of end-of-life tires. Among others, it contains valuable chemicals, such as benzene, toluene, ethylbenzene, and xylene (BTEX), as well as limonene. In order to recover these chemicals, a pilot-scale distillation plant has been designed, erected, and operated using TPO derived from an industrial-scale pyrolysis plant. The distillation facility consists of a packed column (20 kg/h) and is within the fifth technological readiness level. This work describes for the first time the fractioning of the TPO in a continuous operational mode under industrially relevant conditions. For this purpose, different reboiler temperatures (250–290 °C) and reflux ratios (up to 2.4) were preliminarily assessed on the yields and properties of the resulting products: light fraction (LF) and heavy fraction (HF). Thus, the distillation plant is capable of producing 27.0–36.7 and 63.3–73.0 wt % of LF and HF, respectively. The highest BTEX concentration in the LF (55.2 wt %) was found using a reboiler temperature of 250 °C and a reflux ratio of 2.4. Contrarily, the highest limonene concentration (4.9 wt %) in the LF was obtained at 290 °C in the reboiler without reflux. In this sense, the lower the reboiler temperature, the higher the BTEX, and the lower the limonene concentration in the LF. The main results herein obtained serve to gain key insights to operate packed distillation columns using complex and promising hydrocarbons as TPO in order to recover valuable products. In addition, this work provides significant information for optimizing the recovery efficiencies of both BTEX and limonene, as well as their potential applications including that for the resulting HF.

Pursuing the End-of-Life Tire Circularity: An Outlook toward the Production of Secondary Raw Materials from Tire Pyrolysis Oil

“…Alternatively, after being subjected to additional upgrading as hydrotreatment for heteroatoms reduction, they can be co-fed into other refinery units along with petroleum streams to be further treated. The aforementioned conclusions have been also corroborated in an industrially relevant packed distillation column . Two different fractions, namely, light and heavy fractions, were obtained depending on the reboiler temperature (250290 °C) and reflux ratio (up to 2.4).…”

“…Results for different TPOs have shown initial and final distillation points between 69 and 150 °C and between 514 and 600 °C, respectively (Figure ). ,, Recently, Martínez et al reported a relatively high distillation temperature at which 50% of TPO evaporates (T 50 ) of 243–350 °C, thus confirming the unrefined nature of raw TPO. The TPO was produced in an industrial-scale pyrolysis plant based on the auger technology using a nonisothermal profile (750–450 °C).…”

“…Based on the high final distillation temperature, the H/C ratio, and the concentration of heteroatoms, namely, sulfur- and nitrogen-containing compounds, it is also possible to deduce the presence of high molecular weight compounds in the raw TPO, including polycyclic aromatic hydrocarbons (PAH), polycyclic aromatic sulfur hydrocarbon (PASH), and nitrogen-containing polycyclic aromatic hydrocarbons, coupled with long paraffinic chains. − For instance, GC–MS results for the TPO obtained in an industrial-scale pyrolysis plant (400 kg/h) revealed a significant presence of single aromatic structures (59.93%), followed by PAH (27.2%) and naphthenic compounds (6.4%) …”

“…The fractionation of raw TPO into more uniform streams exhibiting similar chemical composition and properties to those derivatives from petroleum is regarded as a key stage for exploiting its potential in a more effective and sustainable approach. This can expand the range of possibilities, facilitating TPO deployment in commercial applications. , The resulting fractions can be used to produce SRMs that can partially replace their petroleum counterpart as precursors of chemical commodities. Such applications pave the path toward the defossilization of diverse economic sectors.…”

“…Also, the integration of TPO as co-feeding stream in refinery units could lead to specific fuels such as naphtha, light cycle oil (LCO), and liquefied petroleum gas (LPG), which continue having tremendous potential in the hydrocarbons market . After some refining operations, TPO also offers the possibility to be used as a feedstock for producing vCB which could be integrated into the manufacturing of new tires, thus increasing the degree of circularity. , …”