XRD–Raman and Modulation Excitation Spectroscopy

Operando Raman Spectroscopy of the Microwave-Enhanced Catalytic Dehydration of 2-Propanol by WO3

“…New peaks at 1310 and 1550 cm –1 were formed during CH at 200 °C and MW heating at 150 and 200 °C. These peaks were attributed to the D band and G band of the deposited carbon . Although the intensities of these peaks did not differ significantly between the MW and CH spectra, the amount of carbon deposited during MW was 3 times greater than that during CH, suggesting the formation of local hot spots during MW heating even when the same reaction temperature was measured at the surface of the catalyst bed (Figure S3).…”

“…40 The reduction in the intensity of the Raman spectra also occurred due to carbon deposition, as has been observed in hydrocarbon-fed solid oxide fuel cell anodes. 41 In addition, the baseline rose during the reaction, which can be attributed to the emission of light from the WO 3 species 42 or intervalence charge transfer between neighboring W 6+ and W 5+ in conjunction with the generation of blue color by the reduction of the WO 3 catalyst surface. 43 New peaks at 1310 and 1550 cm −1 were formed during CH at 200 °C and MW heating at 150 and 200 °C.…”

Time Resolved Operando X-ray Techniques in Catalysis, a Case Study: CO Oxidation by O2 over Pt Surfaces and Alumina Supported Pt Catalysts

“…Therefore, these experiments are, to all intents, blind to the role that low Z adsorbates and any highly disordered phases might have in the catalysis being studied. In addition, surface molecular speciation is in general very difficult to be precise about when using most X-ray techniques, hence the evolution of experiments that couple Xray methods with techniques (e.g., IR, Raman, [73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91]) that can directly address such speciation.…”

“…As such they have become ideal resources for the development of operando philosophy that Banares and co-workers introduced in 2002 [71,72] as a method to properly establish relevant Quantitative Structure-Reactivity relationships (QSARS) in catalysis: structurally direct X-ray techniques being highly complementary partners to global assessments of catalytic performance (e.g., MS) or laboratory based spectroscopies sensitive to chemical speciation (e.g., infrared (DRIFTS [73][74][75][76][77][78][79], transmission IR [80,81]) or Raman spectroscopies [82][83][84][85][86][87], for reviews see [88][89][90][91]). …”

“…Equally, however, and with some caveats, these methods do not directly address the structure of the particles of surfaces upon which the adsorbates exist whereas techniques such as X-ray scattering and X-ray absorption do this in a very direct manner. As such, the combination of vibrational spectroscopies with X-ray techniques, when possible, is extremely desirable in studies of catalysis as it leads to an enhanced possibility to view the working system in a more holistic manner [88][89][90][91]. Further, as we shall see the evolution of these X-ray methods has, in some cases, led to the possibility of inducing surface sensitivity (for instance in the surface variants of X-ray scattering or by adopting specific methods of data collection and a posteriori data treatment methods) where ordinarily there is none.…”