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.

Characteristics and Applications of Waste Tire Pyrolysis Products: A Review

“…The C 6 -C 24 fraction can be an important source for obtaining individual aromatic hydrocarbons (a mixture of benzene, toluene, xylene, ethylbenzene, and limonene) 57,[60][61][62] . In addition, thanks to the high calorific value of 41-44 MJ/kg 63 , the C 6 -C 24 hydrocarbon fraction can be used as heating oils.…”

Recycling of Tire Waste Using Pyrolysis: An Environmental Perspective

“…Fixed-Bed 10 400-900 ~850 ~45 (Gas) [43] Rotary Bed 5-60 550 -67 (Gas) [44] Rotary Kiln * Nm 400-1050 550 44 (Oil) [45] Lab-scale 14 400-750 500 43.6 (Oil) [46] Rotary Bed 15 420-500 500 45 (Oil) [47] Photothermal As for the heating rate, increasing or decreasing the heating temperature can influence the overall production yield and the efficiency of the reactor. The thermal decomposition of the feedstock material can occur at a higher rate once the heating rate chosen increases, and vice versa, as it can also lead to secondary reactions and lessen the oil yield produced [48]. The heating rate also influences the time required to accomplish pyrolysis and the amount of energy required.…”

“…A large size of the sample would require a higher temperature and longer residence time inside the reactor to fully decompose and yield more char than gas and liquid, while a fine size of WT requires a lower temperature and more yield of oil and gas, which falls under fast pyrolysis [8]. If the objective is to maximize oil yield production, a small sample size of WT should be required for the reaction [48]. In the present case, as the objective is both maximizing the oil yield and maintaining the carbon footprint of the process, the WT is shredded to fine particles of 0.5-1.2 mm through a pulverization machine before injecting the material into the reactor.…”