The active role of the support in propane ODH over VOx/CeO2 catalysts studied using multiple operando spectroscopies

Research progress of CO2 oxidative dehydrogenation of propane to propylene over Cr-free metal catalysts

“…-O-V 3? sites and CO. A similar pathway was confirmed by Hess et al using operando UV Raman spectroscopy [84,85]. They observed distinct changes of the surface V species involving the breakage of V-O-V bonds, a partial reduction in vanadyl, as well as the formation of support hydroxyl groups.…”

Unraveling the Active Vanadium Sites and Adsorbate Dynamics in VOx/CeO2 Oxidation Catalysts Using Transient IR Spectroscopy

“…The empty reaction cell has no significant influence on the activity data (conversion <0.1%). 27 The onset of conversion is located at 230 °C for all catalysts and reaches a plateau at around 450 °C. For the following discussion, a temperature of 275 °C was chosen (dashed line), at which gas-phase processes can be excluded and conversions are <15% (differential conditions).…”

Ceria-Based Materials for Thermocatalytic and Photocatalytic Organic Synthesis

“…Even though these issues are present in the dehydrogenation of alkanes to value-added chemicals, several types of ceria-supported catalysts have been reported. Typical VO x /CeO 2 catalysts have been experimentally and theoretically investigated for the ODH of cyclohexane and propane , using molecular oxygen as oxidant. The work reported by Wu et al showed that the activation energy of VO x /CeO 2 catalysts on the (110)- and (100)-terminated nanorods was smaller than that on (111)-terminated octahedra in the ODH of isobutane mainly due to the lower surface oxygen vacancy formation energy and higher oxygen defect concentrations in ceria nanorods .…”

“…For example, in situ DRIFTS is often used to investigate the chemisorption and transformation of reactants with the surface active sites at various temperatures, especially for the gas-phase reactions on CeO 2 -based catalysts. , In the work from Wu et al, in situ INS and in situ DRIFTS were used to discriminate the role of surface cerium hydride (Ce-H) and hydroxyl (OH) groups in the acetylene semihydrogenation over CeO 2 , which explain the reaction mechanism including not only the surface chemistry but also the nature of the active hydrogen species for selective hydrogenation over ceria . In the work from Hess et al, a combination of operando multiwavelength Raman and operando UV–vis spectroscopy was applied to unravel the structural dynamics (e.g., the formation and breakage of V–O–Ce interface bonds) of VO x /CeO 2 catalysts during ethanol and propane ODH, demonstrating the participation of the ceria support in the redox catalysis. , The characterization equipment can also be connected with the flowing reactor effluent gases to monitor the concentration change of reactants and products, such as 1 H NMR . Considering the unreliability of the valence determination by traditional off-line XPS, the extended X-ray absorption fine structure (EXAFS and XANES) spectra have been applied to determine the valence precisely, to distinguish valence difference of metal species and to illustrate the interaction of CeO 2 support and metal species, ,,, especially for CeO 2 -supported metal single atoms. , In the work from Ishida et al, in situ Pd K-edge XAFS was used to elucidate the changes in chemical states or structures of single Pd atoms on CeO 2 during the decarbonylation of furfural to furan in the liquid phase, illustrating the aggregation of single Pd atoms to form Pd 13 clusters during heating and the reaction .…”

“…410 In the work from Hess et al, a combination of operando multiwavelength Raman and operando UV−vis spectroscopy was applied to unravel the structural dynamics (e.g., the formation and breakage of V− O−Ce interface bonds) of VO x /CeO 2 catalysts during ethanol and propane ODH, demonstrating the participation of the ceria support in the redox catalysis. 141,150 The characterization equipment can also be connected with the flowing reactor effluent gases to monitor the concentration change of reactants and products, such as 1 H NMR. 412 Considering the unreliability of the valence determination by traditional offline XPS, the extended X-ray absorption fine structure (EXAFS and XANES) spectra have been applied to determine the valence precisely, to distinguish valence difference of metal species and to illustrate the interaction of CeO 2 support and metal species, 177,256,257,267 especially for CeO 2 -supported metal single atoms.…”