Olefin as an intermediate in n-butane isomerization on sulfated zirconia. An in situ 13C MAS NMR study of n-octene-1 conversion

Abstract

By using in situ 13C MAS NMR and ex situ GC-MS, the analysis of hydrocarbon products formed from n-octene-1 adsorbed on sulfated zirconia catalyst (SZ) has been performed. It is shown that a mixture of alkanes and stable alkyl substituted cyclopentenyl cations (CPC) is formed as the basic reaction products. Formation of both alkanes and CPC from n-octene-1, a precursor of C8 + cation, the key intermediate in n-butane isomerization via a “bimolecular pathway”, implies that formation of the isomerized alkane occurs by a complex process of “conjunct polymerization”, rather than isomerization itself. CPC deposited on the SZ surface can be in charge of the catalyst deactivation.