Indexed on: 01 Sep '07Published on: 01 Sep '07Published in: Kinetics and Catalysis
Diffuse reflectance IR spectroscopy was used to study adsorption and subsequent high-temperature hydrogen and ethane transformations on gallium ions in gallium-modified ZSM-5 zeolite. The results were correlated with the corresponding quantum-chemical calculations. From the experimental and calculated data, it follows that trivalent gallium oxo ions are reduced to the univalent state in a hydrogen or ethane atmosphere even at moderate temperatures. Therefore, gallium oxo ions can function as active sites only at the early stages of light-paraffin aromatization. At the later stages, the dehydrogenation of light paraffins involves univalent gallium ions through the formation of intermediate gallium and alkylgallium hydrides.