Dimerization of Linear Butenes on Zeolite-Supported Ni 2+

Andreas Ehrmaier, Yue Liu, Stephan Peitz, Andreas Jentys, Ya Huei Cathy Chin, Maricruz Sanchez-Sanchez, Ricardo Bermejo-Deval, Johannes Lercher

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Nickel- and alkali-earth-modified LTA based zeolites catalyze the dimerization of 1-butene in the absence of Brønsted acid sites. The catalyst reaches over 95% selectivity to n-octenes and methylheptenes. The ratio of these two dimers is markedly influenced by the parallel isomerization of 1-butene to 2-butene, shifting the methylheptene/octene ratio from 0.7 to 1.4 as the conversion increases to 35%. At this conversion, the thermodynamic equilibrium of 90% cis- and trans-2-butenes is reached. Conversion of 2-butene results in methylheptene and dimethylhexene with rates that are 1 order of magnitude lower than those with 1-butene. The catalyst is deactivated rapidly by strongly adsorbed products in the presence of 2-butene. The presence of π-allyl-bound butene and Ni-alkyl intermediates was observed by IR spectroscopy, suggesting both to be reaction intermediates in isomerization and dimerization. Product distribution and apparent activation barriers suggest 1-butene dimerization to occur via a 1′-adsorption of the first butene molecule and a subsequent 1′- or 2′-insertion of the second butene to form octene and methylheptene, respectively. The reaction order of 2 for 1-butene and its high surface coverage suggest that the rate-determining step involves two weakly adsorbed butene molecules in addition to the more strongly held butene.

Original languageEnglish
Pages (from-to)315-324
Number of pages10
JournalACS Catalysis
Volume9
Issue number1
DOIs
StatePublished - 4 Jan 2019

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