Formation Mechanism of Monocyclic Aromatic Hydrocarbons during Pyrolysis of Styrene Butadiene Rubber in Waste Passenger Car Tires

Abstract

The production of aromatic hydrocarbons from the waste tire pyrolysis attracts more and more attention because of its tremendous potential. Based on styrene-butadiene rubber (SBR), which is the main rubber in the waste passenger car tires, this work studies the temperature influence on primary pyrolysis product distribution by experimental techniques (Py-GC/MS, TG−MS), and then, the formation mechanism of monocyclic aromatic hydrocarbons (MAHs) observed in the experiment was analyzed by first-principles calculations. The experimental results show that the MAHs during the pyrolysis mainly include styrene, toluene, and xylene, and subsequent calculations showed that these compounds were formed through a series of primary and secondary reactions. The formation pathways of these typical MAHs were studied via the reaction energy barrier analysis, respectively. It shows that the MAHs were not only derived from the benzene ring in the SBR chain but also generated from short-chain alkenes through the Diels−Alder reaction. The obtained pyrolysis reaction mechanism provides theoretical guidance for the regulation of the pyrolysis product distribution of MAHs.

A Comprehensive Study on the Effect of Highly Thermally Conductive Fillers on Improving the Properties of SBR/BR-Filled Nano-Silicon Nitride

“…Tires are complex products made of various rubbery sections, e.g., crown, tread, gum, beads, inner layers, and side walls, which are usually made of SBR, butadiene rubber (BR), NR, PIB, etc . It is estimated that 40–50% of a tire is rubber . Usually, the rubbers of SBR and BR form 60–70% of the rubbery parts of a tire .…”

“… 15 It is estimated that 40–50% of a tire is rubber. 16 Usually, the rubbers of SBR and BR form 60–70% of the rubbery parts of a tire. 17 This is due to their favorable properties, such as hardness and chemical and water resistance .…”