Isomerization of 2-methylpentane and ring opening of methylcyclopentane over PtCoNaY catalysts Original Research Article

The catalytic transformations of 2-methylpentane (2MP), and methylcyclopentane (MCP), over CoNaY, PtCoNaY, PtCoAl2O3 and NaY samples have been investigated. CoNaY was found to be an excellent isomerization catalyst, in contrast to CoAl2O3 on which the main route was observed to be cracking. This is attributed to the difference in cobalt reducibility over the two supports. The use of 13C-labelled 2-methyl pentanes made the elucidation of the mechanism of isomerization on these samples possible. A cyclic mechanism (CM) operates only on metal particles, while for both metal particles and support, a bond shift mechanism (BS) is the main route for isomerisation. On PtCoNaY samples, the contribution of the cyclic mechanism to isomerisation relative to isomerisation by bond shift route is significantly enhanced on the catalysts with cobalt loading higher than 22 at.%. The results are discussed in terms of small metal particles inserted into NaY supercage and the enhanced reduction of cobalt ions.