Titanium oxidation catalyst

Kato, A., Matsuda, S., Kamo, T., et al. (1981) Reaction between NOx and NH3 on Iron Oxide-Titanium Oxide Catalyst, J. Phys. Chem., 85, 4099. 

Anpo, M., Yamashita, H., Ichihashi, Y., and Ehara, S. (1995) Photocatalytic reduction of C02 with H20 on various titanium oxide catalysts. Journal of Electroanalytical Chemistry, 396 (1-2), 21-26. 

The main characteristics of the various titanium oxide catalysts used in this chapter are summarized in Table 1. Titanium oxide thin film photocatalysts were prepared using an ionized cluster beam (ICB) deposition method [13-16]. In ICB deposition method, the titanium metal target was heated to 2200 K in a crucible and Ti vapor was introduced into the high vacuum chamber to produce Ti clusters. These clusters then reacted with O2 in die chamber and stoichiometric titanium oxide clusters were formed. Tlie ionized titanium oxide clusters formed by electron beam irradiation were accelerated by a high electric field and bombarded onto the glass substrate to form titanium oxide thin films. 

The metal ion-implanted titanium oxide catalysts were calcined in O2 at around 725-823 K for 5 hr. Prior to various spectroscopic measurements such as UV-vis diffuse reflectance, SIMS, XRD, EXAFS, ESR, and ESCA, as well as investigations on the photocatalytic reactions, both the metal ion-implanted and unimplanted original pure titanium oxide photocatalysts were heated in O2 at 750 K and then degassed in cells at 725 K for 2 h, heated in O2 at the same temperature for 2 h, and, finally, outgassed at 473 K to 10 lorr [12-15]. 

The ESR spectra of the V-ion-implanted titanium oxide catalysts were measured before and after calcination of the samples in O2 at around 723-823 K, respectively (Fig. 11). Distinct and characteristic reticular V" ions were detected only after calcination at around 723-823 K. It was found that only when a shift in the absorption band toward visible-light regions was observed, the reticular V ions could be detected by ESR. No such reticular V ions or shift in the absorption band have ever been observed with titanium oxides chemically doped with V ions [16,18,19]. 

Figure 12 shows the XANES and FT-EXAFS spectra of the titanium oxide catalysts chemically doped with Cr ions (a and A) and physically implanted with Cr ions (b and B). Analyses of these XANES and FT-EXAFS spectra show that in the titanium oxide catalysts chemically doped with Cr ions by an impregnation or sol-gel method, the ions are present as aggregated Cr oxides having an octahedral coordination similar to CriOs and tetrahedral coordination similar to CrOs, respectively. On the other hand, in the catalysts physically implanted with Cr ions, the ions are present in a highly dispersed and isolated state in octahedral... 

Furthermore, as shown in Fig. 10.2, such red shifts in the absorption band of the metal ion-implanted titanium oxide photocatalysts can be observed for any kind of titanium oxide except amorphous types, the extent of the shift changing from sample to sample. It was also found that such shifts in the absorption band can be observed only after calcination of the metal ion-implanted titanium oxide samples in 02 at around 723-823 K. Therefore, calcination in 02 in combination with metal ion-implantation was found to be instrumental in the shift of the absoiption spectrum toward visible light regions. These results clearly show that shifts in the absorption band of the titanium oxides by metal ion-implantation is a general phenomenon and not a special feature of a certain kind of titanium oxide catalyst. 

Ti ion-implanted titanium oxides exhibited no shift, showing that such a shift is not caused by the high energy implantation process itself, but to some interaction of the transition metal ions with the titanium oxide catalyst. As can be seen in Fig. 10-1 ((b)—(d)), the absorption band of the Cr ion-implanted titanium oxide shifts smoothly to visible light regions, the extent of the red shift depending on the amount and type of metal ions implanted, with the absorption maximum and... 

Hamilton N, Wolfram T, Tzolova Muller G, Havecker M, Krohnert J, Carrero C, Schomacker R, Trunschke A, Schlogl R. Topology of silica supported vanadium-titanium oxide catalysts for oxidative dehydrogenation of propane. Catalysis Science Technology. 2012 2(7) 1346—1359. 

FIGURE 3 Selectivity for N2 formation as a function of the coordination number of Ti determined by EXAFS in the photocatalytic decomposition of NO into N2 and 02 on various titanium oxide catalysts including highly dispersed, chemical mixture and bulk Ti02 powder. (Reproduced with permission from Yamashita and Anpo (2004).)... 

Aromatic imides are another type of product which can be synthesized by catalytic ammoxidation. o-Xylene is converted over vanadium-titanium oxide catalysts to tolunitrile and then, depending on catalyst composition and reaction conditions, phthalimide or phthalonitrile can be selectively synthesized (Scheme 20.3) [94]. 

The addition of O2 onto the anchored titanium oxide catalyst led to an efficient quenching of the photoluminescence at 77 K. The addition of N2O also led to the quenching of the photoluminescence with an efficiency lower than that of O2. Such an efficient quenching of the photoluminescence by the addition of O2 or N2O is expected when the emitting sites are dispersed on the support surfaces due to the efficient interaction of the emitting sites with the quencher molecules 168, 212). 

N20 and O2 on the anchored titanium oxide catalyst (168, 212, 213). N2O dissociates into N2 and O on the activated oxide surfaces through an electron transfer from the oxide to N2O however, the N20 species has not been detected by EPR on oxide surfaces. 

P6-17g Review the oxidation of formaldehyde to formic acid leactions over a van-dium titanium oxide catalyst [Ind. Eng. Ch m. Res., 28, 387 (1989)] shown in the ODE solver algorithm in the Summary. 

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