Carbon-Carbon Bond Cleavage and Dehydrogenation of Isobutane Over HZSM-5 at Low Pressures and Temperatures

Abstract

Carbon-carbon bond cleavage and dehydrogenation are observed following low-pressure activation of isobutane over HZSM-5. Temperature-dependent rate parameters were determined by flexible least squares modelling of the propene and isobutene formation data. Apparent activation energies are 73.9 ± 2.4 kJ mol⁻¹ (C-C bond cleavage) and 62.8 ± 1.0 kJ mol⁻¹ (dehydrogenation). Such low energy barriers under molecular flow conditions suggest activation steps that are obscured by higher-pressure catalysis.