Yining Fan

Strong metal-support interaction and catalytic properties of anatase and rutile supported palladium catalyst Pd/TiO2

Abstract In situ EPR investigation by using CO as probe molecules shows that even pre-reduced by H 2 at lower temperature results in SMSI for anatase titania supported palladium catalyst, but not for rutile titania supported palladium catalyst. The reason of the different behavior between rutile and anatase titania supported palladium catalyst is discussed. The very different catalytic properties between anatase and rutile titania supported palladium catalyst pre-reduced at lower temperature, and the rapid change of conversion and selectivity of titania supported palladium catalyst with the elevation of pre-reduction temperature further confirm the above-mentioned results.

Carbon monoxide hydrogenation on Fe2O3/ZrO2 catalysts

Fe2O3/ZrO2 catalysts prepared by impregnation and coprecipitation methods were used for catalytic hydrogenation of CO. It was shown that the structure, reduction behavior of iron species, and catalytic properties of the catalysts were obviously affected by the preparation methods. For the Fe2O3/ZrO2 catalyst prepared by the impregnation method, the Fischer-Tropsch catalytic activity and the selectivity to light olefins were much higher than those of the corresponding catalyst prepared by the coprecipitation method, the formation of methane was suppressed and the selectivity to light olefins was enhanced. Various intermediates formed during the successive steps of reduction of the catalysts were studied by using temperature-programmed reduction combined with in situ Mössbauer spectroscopy. The role of zirconia in the catalysts was discussed.

Preparation and characterisation of ultrafine amorphous alloy particles

Chemical preparation, characterisation, and properties are briefly reviewed for transition metal-metalloid ultrafine amorphous alloy particles (UAAP). Special attention is paid to the new solid-state chemical reaction method and the new systems, i.e. P-bearing and B-and-P-bearing systems. These new kinds of materials have some unique properties resulting from the combination of ultrafine size with amorphous structure as well as the convenience of the composition regulation over a rather wide range, Their magnetic and catalytic properties are of particular interest for future applications.

Catalytic properties of ultrafine molybdenum-cerium oxide particles prepared by the sol-gel method

The structure and catalytic properties of ultrafine Mo-Ce oxide particles prepared by the sol-gel method have been studied by using X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, laser Raman spectroscopy and microreactor tests. It has been shown that for selective oxidation of toluene to benzaldehyde the ultrafine Mo-Ce oxide particles exhibit higher catalytic activity than the larger oxide particles prepared by a conventional coprecipitation method. The unique catalytic properties of ultrafine Mo-Ce oxide particles may be correlated not only to the interaction between molybdenum oxide and cerium oxide, but also to the higher reactivity of lattice oxygen species in the ultrafine oxide matrix.

The Preparation of Molybdenum Oxynitride by Hydrazine Reduction of MoO3 at Moderate Temperature and Its Application in the Selective Hydrogenation of Long-Chain Linear Alkadienes

Molybdenum oxynitride was prepared by hydrazine reduction of MoO3 at moderate temperatures. The anhydrous condition was favorable to production of amorphous molybdenum oxynitride, and the presence of hydrogen favored the reduction of Mo6+ and Mo4+ species to Moδ+ (0 < δ < 4) species. These molybdenum oxynitrides exhibited activity for hydrogenation which depended on the amount of Moδ+ (0 < δ < 4) species produced under reaction conditions. The amorphous molybdenum oxynitride MoO1.83N0.36 catalyst showed a good catalytic activity, selectivity, and resistance to poisoning of H2S for liquid-phase hydrogenation of longer-chain alkadienes.

A novel route to nanosized molybdenum boride and carbide and/or metallic molybdenum by thermo-synthesis method from MoO3, KBH4, and CCl4

Abstract Nanosized molybdenum boride and carbide were synthesized from MoO 3 , KBH 4 , and CCl 4 by thermo-synthesis method at lower temperature. The relative content of Mo, Mo 2 C, and molybdenum boride in the product was decided by the molar ratio between MoO 3 , KBH 4 , and CCl 4 . Increasing the molar ratio of CCl 4 to MoO 3 was favorable to the production of Mo 2 C. Increasing the molar ratio of KBH 4 to MoO 3 was favorable to the production of molybdenum boride. By carefully adjusting the reaction conditions and annealing in Ar at 900°C, a single phase of MoB could be obtained.

Ultrafine La-Mo and Ce-Mo complex oxide particle catalysts for selective oxidation of toluene

It has been found that by decreasing the particle size of La–Mo and Ce–Mo complex oxides to nanoscale, the reactivity of lattice oxygen ions and thus the selectivity for oxidation of toluene to benzaldehyde can be remarkably improved.

A study on FePB ultrafine amorphous alloy particles

Fe 100-x-y P x B y ultrafine amorphous alloy particles with 3.6≤x≤10.5 and 6.6≤y≤32.0 were systematically produced by chemical reduction. Information about the preparation mechanism, the particles sizes, the crystallization of the samples and the interaction between the elements was obtained by Mossbauer spectroscopy and several other means

Lattice oxygen properties of BiMo based catalysts for selective oxidation of propane to acrolein

Abstract The properties of BiMo based catalysts with varied composition and structure for the direct selective oxidation of propane to acrolein were investigated. It has been seen by XRD, XPS, in situ FT-LRS, and ESR that propane is selectively oxidized to acrolein via propylene intermediate species. The lattice oxygen of the catalysts is the active oxygen species for the selective oxidation of propane to acrolein via propylene; the selectivity and yield of acrolein associate closely with the redox properties of Mo=O species while the activity of Mo=O correlates tightly with its coordinated circumstance. The selective activity of Mo=O is improved in a sequence of locations as distorted octahedral MoO6, corner shared octahedral in koechlinite structure, edge shared octahedral and tetrahedral MoO4 in distorted scheelite structure. The selectivity and yield of acrolein approached 45mol% and 13.5mol%, respectively, and the amount of lattice oxygen with selective oxidative activity amounted to 258 mol/g on the optimum catalyst.

Study on the structure and reduction behaviour of the iron–zirconium oxide system

The structures and reduction behaviour of iron–zirconium oxides prepared by the coprecipitation method have been studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), BET surface-area measurements and Mossbauer spectroscopy. The structure of the iron-zirconium oxides is severely affected by the composition. For iron-zirconium oxides with different iron contents, the chemical states of the Fe3+ cations are quite different, and hence the reduction behaviour of these Fe3+ cations is quite different too. The various intermediates formed during the successive reduction steps of the iron–zirconium oxides were determined using TPR combined with in situ Mossbauer spectroscopy. For the samples with low iron content (⩽ 20 atom%), Fe3+ cations were doped in the lattice of cubic zirconia and were difficult to reduce to Fe°. By contrast, for the samples with high iron content (≫ 70 atom%), Zr4+ cations were doped in the lattice of α-Fe2O3 and the reduction of the Fe3+ cations to Fe° was easier than that of the samples with low iron content.