Dimerization and Cracking of [4-13C]But-l-ene with Deamminated Ammonium Exchanged Type Y Zeolite

Abstract

The use of highly enriched [4-13C]but-1-ene with an integrated gas chromatograph–mass spectrometer has enabled a better understanding of the mechanism of reaction between but-1-ene and deamminated ammonium exchanged type Y zeolite at 50 and 200°C. Of the octanes formed at 50°C, it is proposed that 2,4- and 3,4-dimethylhexane and 2,3,3- and 2,3,4-trimethylpentane are formed principally via a dimerization, isomerization, and hydrogen transfer mechanism, whereas 2,3- and 2,5-dimethylhexane and 2,2,4-trimethylpentane are formed principally via the breakdown of polymeric material. At 200°C the major products, isobutane, isobutene, and isopentane, are also formed by the breakdown of polymeric material and not by simple random nor bimolecular mechanisms. These products are enriched in carbon-13 relative to the starting material indicating that a strong one carbon bond is formed with the zeolite.