X-ray absorption fine structure measurements on Ru–Zn/ZSM-5 during heterogeneous catalysis using an in situ spectroscopic cell

Abstract

Abstract We introduce a design of a portable, multi-functional spectroscopic cell for in situ structural probe of materials using hard x-rays. This versatile reaction cell allows x-ray absorption fine structure (XAFS) and x-ray diffraction measurements in transmission mode on solids at a controlled temperature, pressure, and gas environment. A model heterogeneous catalysis system, co-aromatization of octane with methane catalyzed by Ru–Zn/ZSM-5, was employed to demonstrate the performance of the spectroscopic cell. Quick XAFS measurement at the Ru K-edge was performed during the catalyst activation and catalysis reaction. The chemical reduction of Ru from RuO2 to metallic-like Ru is found to occur rapidly once the temperature is above a threshold, and the reduction is completed in ∼75 s. Prolonged heating during catalysis reaction at constant operating temperature has a minimum effect on the electronic structure of the Ru species.