Effect of macroreticular acidic ion-exchange resins on 2-methyl-1-butene and 2-methyl-2-butene mixture oligomerization

A screening of macroreticular ion exchange resins has been carried out in order to select the most suitable catalysts for liquid-phase oligomerization of an isoamylene mixture. The reaction was performed at mild temperature (343 K) to promote the dimerization and trimerization, and at higher temperature (383 K) to evaluate side reactions like cracking and copolymerization. No compounds higher than trimers were significantly detected at studied conditions. By plotting product yields versus conversion at 343 K, it was showed no significant differences between all catalysts tested. However, at 383 K, the ion exchange resins which mainly work in the external zone were more selective to dimerization and less to cracking and trimerization products, which suggests that trimerization and cracking mainly took place inside the gel-phase of the macroreticular resins.The most active catalysts were the oversulfonated resins with high cross-linking degree and high acid capacity. A heterogeneous Eley-Rideal kinetic model showed better fitting of dimerization rates than two pseudo-homogeneous models.

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► On the external catalyst surface mainly takes place the dimerization.
► Trimerization and cracking-copolimerization take place mainly inside the gel-phase.
► Conversion, yields and reactivity are related to superficial acid density of resins.
► A kinetic Eley-Rideal model shows a better fit than a pseudo-homogeneous model.