Limonene ethers from tire pyrolysis oil. Part 2: Continuous flow experiments

Abstract

The marketability of tire pyrolysis oil low is due to several demeritorious factors such as extreme odour and a high aromatic content. In order to enhance the marketability, we explored the production of fragrant oil from tire oil. In Part I of this study we reported the feasibility of reacting limonene-enriched tire oil with methanol to produce limonene ethers in a batch reactor. These ethers have higher boiling points than the starting limonene and thus their separation from the limonene-enriched fraction by distillation becomes an easy task. In this part of the investigation we report the etherification of limonene-enriched oil in a continuous microreactor. We examined the etherification of a model compound (dipentene) and limonene-enriched tire oil using various catalysts (β-zeolite, Amberlyst and Y-zeolite) under various process conditions. The relationships between reactants ratios, reactant/catalyst ratios and the catalyst life on stream were more complex in the microreactor runs than in the batch tests as reported in Part I. We also examined the effect of catalyst regeneration. The highest conversion to limonene methyl ether (1-methyl-4-[alpha-alkoxy-isopropyl]-1-cyclohexene) was 82% for pure limonene, 66% for dipentene, and 70% for limonene-enriched tire oil. Catalyst life on stream was short, a maximum of 2 h before regeneration was required. The catalyst can be regenerated in situ or outside the reactor. The catalyst maintained comparable activity for about five regenerations with no impact on its selectivity. Amberlyst-15 showed high activity but very poor selectivity for limonene ethers production. Crown Copyright © 2006.