Coupled XAS-Raman Operando analysis of TiO2 supported oxomolyb-date catalysts in methanol conversion

Although heterogeneous catalysts are essential in numerous chemical processes, the exact structure of the active phase remains unsolved in many cases. In order to understand the structure-reactivity relationships, a relevant approach consists in examining the catalyst while operating. This so-called operando approach has recently attracted a fast growing attention and was applied to various spectroscopic techniques: IR, Raman, Electron Paramagnetic Resonance (EPR), UV-visible and X-ray Absorption Spectroscopy (XAS). However, it generally appears that one single spectroscopic technique does not make it possible to spell out the complexity of the catalytic process. Therefore, the direct coupling of complementary in situ or operando techniques offers a multiple and simultaneous characterization of a working catalyst for a much better understanding of the catalytic process. Such studies request the use of a single spectroscopic reactor fitting the combined peculiarities of catalysis and the involved spectroscopic techniques. The coupling of XAS and Raman spectroscopy was successfully performed in a commercially available operando chamber to supplement our previous Raman studies on TiO2 supported oxomolybdate catalysts. The investigated selective oxidation of methanol is both a major economic reaction for vaporization of biomass byproducts and a probe reaction broadly used to study redox and acido-basic properties of bulk and supported oxides.