Binary oxide catalysts

In spite of the accumulated mechanistic investigations, it still seems difficult to explain why multicomponent bismuth molybdate catalysts show much better performances in both the oxidation and the ammoxidation of propylene and isobutylene. The catalytic activity has been increased almost 100 times compared to the simple binary oxide catalysts to result in the lowering of the reaction temperatures 60 80°C. The selectivities to the partially oxidized products have been also improved remarkably, corresponding to the improvements of the catalyst composition and reaction conditions. The reaction mechanism shown in Figs. 1 and 2 have been partly examined on the multicomponent bismuth molybdate catalysts. However, there has been no evidence to suggest different mechanisms on the multicomponent bismuth molybdate catalysts. 

In the 1960s, a number of binary oxides, including molybdenum, tellurium, and antimony, were found to be active for the reactions and some of them were actually used in commercial reactors. Typical commercial catalysts are Fe-Sb-O by Nitto Chemical Ind. Co. (62 -64) and U-Sb-O by SOHIO (65-67), and the former is still industrially used for the ammoxidation of propylene after repeated improvements. Several investigations were reported for the iron-antimony (68-72) and antimony-uranium oxide catalysts (73-75), but more investigations were directed at the bismuth molybdate catalysts. The accumulated investigations for these simple binary oxide catalysts are summarized in the preceding reviews (5-8). 

Catalysts based on V2Os resemble the binary oxide catalysts such as... 

For several other binary oxide catalysts, this type of bifunctionality is indicated by the fact that both cations are partially reduced under reaction conditions, as observed by ESCA and y resonance techniques. An example of a catalyst investigated is FeMo04 [75]. 

D. Photolumlnkscknck of Various Oxidh-Bashd Catalysis 1. Silica-Supported Oxides and Binary Oxide Catalysts... 

I lG- 36. Photoluminescencc spectra of titanium-silicon binary oxide catalysts with different Ti/Si ratios at 77 K and the effect of the addition of O,. Excitation wavelength, 300 nm slit width for emission, 7.0 nm pressure of added O2, 13,3 Pa (a -e ) photoluminescence spectra in the absence of (a-e) [reproduced with pei mission from Anpo el al. (200)]. 

Binding Energies o f Ti(2p n2), Si(2pi/- ), and Si(2s) and the Ratio of the Signal Intensity of Ti(2p3i2) versus Si 2pn2) in Titanium-Silicon Binary Oxide Catalyst ... 

UV irradiation of the titanium-siheon binary oxide catalyst in 1-octanol acetonitrile solutions in the presence of O2 led to the oxidation of 1-octanol to produce 1-octanal as the main product, whereas no products were detected under dark conditions. The specific photocatalytic reactivities of the titanium oxide moieties in the bindar oxides can be determined since the... 

Photocatalytic reduction of CO2 with H2O on Ti/Si binary oxide catalysts prepared by the sol-gel method... 

Source of Activity in other Strongly Acidic Oxides.—While surface acidity is found to some degree in many oxides, relatively few show strong acidity comparable with that of the various siliceous materials considered above. Earlier work on these oxide systems has been reviewed by Tanabe and he later proposed a general model for acidic binary oxide catalysts. 

Moon S.-C., Fnjino M., Yamashita H. and Anpo M. (1997), Characterisation of zirconinm-silicon binary oxide catalysts prepared by the sol-gel method and their photocatalytic activity for the isomerization of 2-butene, J. Phys. Chem. B 101, 369-373. 

Binary oxide catalysts are of major industrial importance. Such compounds are combinations of the oxides of Fe, Co, Ni, Cu, and Zn with those of Cr, Mo, and W. 

BINARY OXIDE CATALYSTS SYNTHESIZED BY SEQUENTIAL PRECIPITATION C. S. BROOKS... 

FIG. 1 Hydrogen peroxide decomposition at 20°C over Cu/Al Binary oxide catalysts... 

FIG. 3 Oxidation of Benzaldehyde at 20° C to benzoic acid over Nl/Al and Cu/Al binary oxide catalysts... 

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