The influence of extraframework aluminum on H-FAU catalyzed cracking of light alkanes Original Research Article

The conversion of light linear and branched alkanes on two faujasite samples containing different concentrations of free Brønsted acid sites and extraframework alumina (EFAL) was studied between 733 K and 813 K. Protolytic cracking and bimolecular hydride transfer proceeded solely on Brønsted acid sites. For cracking of n-alkanes, the variation of the concentration of extraframework aluminum did not affect the catalytic activity per accessible Brønsted acid site. The activity to dehydrogenation is enhanced in the presence of EFAL and, unlike protolytic cracking, it decreased with time on stream. At high conversions relatively high concentrations of olefins change the selectivity and decrease the turnover frequencies. Compared to n-alkanes, the catalytic activity to convert iso-alkanes is enhanced in the presence of extralattice alumina.