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1.
B. I. Popov A. V. Pashis L. N. Shkuratova 《Reaction Kinetics and Catalysis Letters》1986,30(1):129-135
XPS studies have revealed a decrease in the concentration of iron atoms on the surface of Mo–Fe catalysts with increasing calcination temperature. From a comparison of chemical analysis and XPS data the Mo/Fe ratios on the surface of catalyst samples at various calcination temperatures have been determined. Comparing the above data with changes in the catalytic activity of the samples examined in methanol oxidation, the conclusion has been made that the active component of the catalysts is a solid solution of molybdenum oxide in ferric molybdate.
. Mo/Fe . , .相似文献
2.
Smirnov M. Yu. Kalinkin A. V. Pashis A. V. Sorokin A. M. Noskov A. S. Bukhtiyarov V. I. Kharas K. C. Rodkin M. A. 《Kinetics and Catalysis》2003,44(4):575-583
The interactions of Al2O3, CeO2, Pt/Al2O3, and Pt/CeO2 films with SO2, SO2 + H2O, SO2 + O2, and SO2 + O2 + H2O in the temperature range 300–673 K at the partial pressures of SO2, O2, and H2O equal to 1.5 × 102, 1.5 × 102, and 3 × 102 Pa, respectively, were studied using X-ray photoelectron spectroscopy. The formation of surface sulfite at T 473 K (the S 2p
3/2 binding energy (E
b) is 167.5 eV) and surface sulfate at T 573 K (E
b = 169.2 eV) was observed in the reactions of Al2O3 and CeO2 with SO2. The formation of sulfates on the surface of CeO2 occurred much more effectively than in the case of Al2O3, and it was accompanied by the reduction of Ce(IV) to Ce(III). The formation of aluminum and cerium sulfates and sulfites on model Pt/Al2O3 and Pt/CeO2 catalysts occurred simultaneously with the formation of surface platinum sulfides (E
b of S 2p
3/2 is 162.2 eV). The effects of oxygen and water vapor on the nature and yield of sulfur-containing products were studied. 相似文献
3.
A.V. Kalinkin A.V. Pashis V.I. Bukhtiyarov 《Reaction Kinetics and Catalysis Letters》2002,77(2):255-261
The reaction of CO oxidation over thin films of rhodium and platinum prepared by vacuum evaporation of the metals on an inert support has been investigated at low pressures (P < 2×10-5 mbar). Rhodium has been found to be more active than platinum in this reaction. The reasons of the higher activity of Rh are discussed. 相似文献
4.
A.V. Kalinkin A.V. Pashis V.I. Bukhtiyarov 《Reaction Kinetics and Catalysis Letters》2003,78(1):121-127
The reaction of the CO oxidation over a Pt-Rh heterophase surface, which represents 10-20 nm platinum particles located on
a rhodium film, which in turn is deposited on an inert support, has been investigated at low pressures (P < 2'10-5 mbar). The results are compared with the data for the clean surfaces of Pt and Rh. In the high-temperature range, the rate
of CO2 formation on the heterophase surface is found to be higher than the sum of the rates on individual metals corrected by the
surface area of the different metals. The nature of the synergistic effect in the CO oxidation is discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
R Nirmala V Sankaranarayanan K Sethupathi AV Morozkin T Geethakumary Y Hariharan 《Pramana》2002,58(5-6):1101-1104
New R
2Ti3Ge4 (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac
magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize
in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series.
The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales
with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays
a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects. 相似文献
6.
M. Yu. Smirnov E. I. Vovk A. V. Kalinkin A. V. Pashis V. I. Bukhtiyarov 《Kinetics and Catalysis》2012,53(1):117-124
The interaction of the model catalysts Rh/Al2O3, Pd/Al2O3, Pt/Al2O3, and Pt/SiO2 with NO x (mixture of 10 Torr of NO and 10 Torr of O2) was studied by X-ray photoelectron spectroscopy (XPS). Samples of the model catalysts were prepared under vacuum conditions as oxide films ≥100 Å in thickness on tantalum foil with evaporated platinum-group metal particles. According to transmission electron microscopic data, the platinum-group metal particle size was several nanometers. It was found by XPS that the oxidation of Rh and Pd nanoparticles in their interaction with NO x occurs already at room temperature. The particles of platinum were more stable: their oxidation under the action of NO x was observed at elevated temperatures of ~300°C. At room temperature, the interaction of platinum nanoparticles with NO x hypothetically leads to the dissolution (insertion) of oxygen atoms in the bulk of the particles with the retention of their metallic nature. It was found that dissolved oxygen is much more readily reducible by hydrogen than the lattice oxygen of the platinum oxide particles. 相似文献
7.
8.
A.N. Startsev O.V. Klimov M.V. Sidyakin O.V. Voroshina N.A. Tchashkova I.I. Zakharov A.V. Pashis A.V. Kalinkin 《Reaction Kinetics and Catalysis Letters》2003,80(1):97-103
An X-ray photoelectron spectroscopy study of Mo/Al2O3 catalysts prepared via [MoV
2O4(C2O4)2(H2O)2]2- complexes showed that after heating the catalysts with hydrogen in the spectrometer chamber, the position of the Mo3d line
shifted to higher values of binding energy. This shift is interpreted as oxidative addition of hydrogen to the surface Mo
species. A similar phenomenon was observed for a CO treated catalyst. A temperature-programmed desorption study has shown
that hydrogen is strongly bounded to Mo and can only be removed from the catalysts at temperatures as high as 500°C.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
An approach to produce a bimetallic Pt-Rh model catalyst has been developed. It includes vacuum deposition of platinum on a Rh2O3 film, followed by the oxide reduction with hydrogen. The thermal stability range of the resulting bimetallic structure has been determined. 相似文献
10.
The reaction of CO oxidation on thin metal films of platinum, rhodium, and their alloy and on a heterophase bimetallic Pt/Rh surface that consisted of platinum particles of size 10–20 nm on the surface of rhodium was studied in the region of low reactant pressures (lower than 2 × 10?5 mbar). At low temperatures (T < 200°C), the activity of samples increased in the order Rh > Pt/Rh > Pt-Rh alloy > Pt. Above 200°C, the rate of reaction on the heterophase Pt/Rh surface was almost twice as high as the sum of the rates of reaction on the individual metals; this fact is indicative of a synergistic effect. The nature of this effect is considered. 相似文献