Activation of light alkanes in the presence of benzene over acidic zeolites. A 13C MAS NMR study

I.I. Ivanova and F. Fajula

"Proc. 12th International Zeolite Conference", Materials Research Society, p. 2273, (1999)

ABSTRACT. 13C MAS NMR has been performed in situ to investigate the mechanism of alkane activation in the presence of benzene over H-ZSM-5 catalyst. Propane 2-13C and 2-methylpropane 2-13C were used as a labelled reactants. In order to clarify the main reaction pathways, conversion of the individual starting materials was also studied under similar conditions. NMR results suggest that two reaction routes of alkane activation are realized over H-ZSM-5 catalyst in the presence of benzene: i) low temperature carbenium ion type activation, initiated via hydride abstraction by protonated benzene molecule and leading to 13C label scrambling and isobutane isomerization into n-butane and ii) high temperature carbonium ion type activation leading to benzene alkylation with the fragments formed upon splitting of proponium and butonium ions.

Laboratory of Kinetics and Catalysis