Synthesis of α-terpinyl methyl ether by catalytic alkoxylation of tire pyrolysis oil over heteropolyacid modified Hβ zeolite

Limonene is significant feedstock and how to abundantly acquire or convert into high-value chemicals is crucial. Waste tire pyrolysis oil (TPO) rich in limonene provides an alternative route. To address its difficult separation from other compounds in TPO, especially p -cymene, a new route to convert limonene into α-terpinyl methyl ether (TME) with high boiling point was proposed by alkoxylation over heteropolyacid-modified Hβ zeolite. Strong Brønsted acid centers can attain high efficiency in alkoxylation in limonene- p -cymene binary compounds. 89.24 % conversion was achieved after 5 h at 60 °C while TME yield is the highest (71.70 %) after 3 h with no reaction of p -cymene. Above 80 % limonene is transformed in real fraction of 160–180 °C of TPO and TME yield exceeds 60 %. Initial separation of TME and aromatic was achieved by vacuum distillation. The possible mechanism of limonene alkoxylation was proposed. This work provides a new approach to efficient utilization of limonene.