Influence of Specific Power on the Solid and Liquid Products Obtained in the Microwave-Assisted Pyrolysis of End-of-Life Tires

Abstract

In this work, chemical recycling as an alternative to conventional end-of-life treatments was studied. Two different types of end-of-life tires (ELT), truck tires and mix tires (50:50 mixture of passenger car and truck tires), were pyrolyzed in a batch microwave reactor. The influence of specific power (10, 20, and 30 W/g) on mass distribution was analyzed. The maximum liquid yield was attained at 10 W/g, while the maximum gas yield is obtained at 30 W/g. Liquid fractions were characterized by gas chromatography/quadrupole mass spectrometry (GC/qMS) to identify the main components, and major compounds were quantified. In all samples, limonene (3.76 ± 0.31–6.80 ± 2.37 wt. %) and BTEX (3.83 ± 0.20–1.19 ± 2.80 wt. %) were the main components. Major limonene concentration is obtained in oil produced from truck ELT while higher yields of aromatic compounds are obtained from mix ELT. The maximum BTEX concentration is obtained at 10 W/g being toluene the main compound with a concentration of 2.07 ± 0.42 and 4.63 ± 1.29 for truck and mix ELT, respectively. The separation and purification of these compounds will confer important value to these fractions. Higher yields of the solid fraction are produced when mix tires are pyrolyzed due to the higher concentration of ash in this type of ELT. Recovered carbon black was characterized by measuring the surface area.

Keywords

• end-of-life tires
• microwave-assisted pyrolysis
• specific power
• limonene
• aromatics compounds