A simultaneous operando FTIR & Raman study of propane ODH mechanism over V-Zr-O catalysts

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

“…The presence of oxygen increases the conversion of alkanes, but it can lower the LO selectivity due to the abundant release of unwanted carbon dioxide and carbon monoxide. 15 During the past two decades, the use of “soft” oxidants such as CO 2 , N 2 O, and even sulphur 108–112 has been considered most promising, since it does not lead to hydrocarbon overoxidation, implies the rational utilization of the most ecology-risked greenhouse gases and prevents the formation of explosive mixtures. 113 Somewhat lower LO selectivity of ODH relative to DDH is due to higher reactivity and higher probability of oxidation of LO compared to light alkanes in the presence of oxidizing agents.…”

“…117 Both types of sites are usually present on the surface simultaneously. Operando studies of propane O 2 -ODH showed 112 that the rate-determining step of propane ODH was iso-propoxide formation on the surface of the V–Zr–O catalyst. The decomposition of iso-propoxide resulted either in propylene or in oxidation to acetone, followed by oxidation to acetate/formate and, finally, to CO x .…”

“…7 DFT calculations for the structure of Pt 3 /graphene catalyst and energy profile of butane dehydrogenation to 2-butene of n-butane DDH over different platinum configurations (a) and the conversion rate of n-butane over the Pt catalysts with different Pt-Pt coordination number (b). 101 and even sulphur [108][109][110][111][112] has been considered most promising, since it does not lead to hydrocarbon overoxidation, implies the rational utilization of the most ecology-risked greenhouse gases and prevents the formation of explosive mixtures. 113 Somewhat lower LO selectivity of ODH relative to DDH is due to higher reactivity and higher probability of oxidation of LO compared to light alkanes in the presence of oxidizing agents.…”

Modulation of ODH Propane Selectivity by Zeolite Support Desilication: Vanadium Species Anchored to Al-Rich Shell as Crucial Active Sites

“…The sites represented by bands at 320, 360, and 375 nm are the only species that are consumed in the presence of propane and accompanied by the evolution of the V 4+ bands, as manifested by their negative correlations. According to the literature, higher reactivity of the bridging oxygens V-O-V than the oxo-group V=O [ 69 ] was agreed at lower temperatures. Based on the operando UV-vis results, the 320 and 360 nm were ascribed to the (SiO) 2 (HO)V=O and the highly dispersed polymeric tetrahedral vanadium(V) sites, respectively, while the 375 nm band was ascribed to the octahedral species, also active in the ODH process.…”

Redox Dynamics of Pt and Cu Nanoparticles on TiO2 during the Photocatalytic Oxidation of Methanol under Aerobic and Anaerobic Conditions Studied by In Situ Modulated Excitation X-ray Absorption Spectroscopy

“…11 In this context, information on the surface redox dynamics occurring in metal NPs on the photocatalyst surface under real working conditions is crucial for understanding any catalyst structure versus activity relationship and getting a deeper insight into the photocatalytic reaction mechanism, which are of outmost importance for the design and development of novel and more active materials. Several operando spectroscopic techniques can be exploited to pursue this goal, 13,14 including Fourier transform infrared spectroscopy (FTIR), 15−17 diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), 18−22 attenuated total reflectance (ATR), 23 nuclear magnetic resonance (NMR), 24 Raman spectroscopy, 17,25,26 X-ray absorption spectroscopy (XAS), 5,21,22,24,26−29 and X-ray diffraction (XRD). 26,30 However, the main challenge consists in discerning between the signal contributions of active sites from the static signal due to the background, the bulk, and the spectator species.…”