Limonene ethers from tire pyrolysis oil: Part 1: Batch experiments

Abstract

Tire pyrolysis oil was produced by EnerVision Inc., Halifax, Canada using the continuous ablative reactor (CAR) system. The tire oil was separated by distillation into several fractions. Naphtha and limonene enriched naphtha were reacted with methanol over different catalysts. Batch experiments were carried out to separate limonene as methyl limonene ethers. Whole tire pyrolysis oil was distilled and the resulting distillates were redistilled to separate the limonene (bp about 176 °C). Vacuum distillation yielded on average 25.5 wt% naphtha containing 16.3 wt% limonene (average). Redistillation increased the limonene concentration to approximately 32-37 wt%. The conversion of limonene (mono-terpene) to limonene ethers (terpenoides) shifted the boiling point of the limonene derivatives out of the naphtha boiling range (IBP -190 °C). This allowed the separation of fragrant limonene ethers from foul smelling naphtha. Alkoxylation reactions were performed mostly using methanol and acidic catalysts. The methyl ether [1-methyl-4-(α-methoxy-isopropyl)-1- cyclohexene] has a boiling point of about 198 °C which is higher than the end boiling point of the naphtha cut. Five heterogeneous catalysts (four zeolites and one ion exchange resin) were tested in a batch reactor. β-Zeolite produced excellent results. The reaction of R-(+)-limonene with methanol in the presence of activated β-zeolite yielded methyl ether, 87.5% at selectivity 89.7% with a maximum of 2 h reaction time. Limonene conversion from whole naphtha to ethers was also high. © 2005 Elsevier B.V. All rights reserved.