Nickel Molybdenum Oxide Research Articles

Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique

Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590 oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The process of solid transformation and properties of materials prepared from ammonium hydrogen phosphate (AMP)-impregnated samples were compared with those of phosphide made from phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2 was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous reagent

Tribological behavior and wear mechanism of film electrolytic nanocomposites based on nickel and mixed tungsten and molybdenum oxides

It is shown that the electrolytic co-deposition of nickel and ultradispersed particles of mixed tungsten and molybdenum oxides changes considerably the coating morphology at both the nano- and micro-level. Under boundary lubrication at the pressure of 1 MPa the pair Ni-MoO3·WO3 — hardened steel operates at the stationary regime which is characterized by the constant friction coefficient f = 0.28 ± 0.01 and the minimal wear of the pair. At dry friction abrasive wear dominates. Decrease in the pressure from 70 to 2.5 MPa during friction results in the equilibrium structure of the friction surface with the fractal dimension of the profile tending to 2.

Effect of Ni Promoter on Dibenzothiophene Hydrodesulfurization Performance of Molybdenum Carbide Catalyst

Molybdenum carbide and nickel-molybdenum carbide catalysts were prepared by the temperature-programmed reduction and carburization of molybdenum trioxide and nickel-molybdenum oxide, respectively, using a CH4/H2 gas mixture. X-ray diffraction patterns showed that the crystals were β-Mo2C and Ni-Mo2C, respectively. The effects of nickel promoter on the preparation of molybdenum carbide and its catalytic performance for the hydrodesulfurization of dibenzothiophene (DBT) were studied. The results indicated that the addition of proper amount of the nickel promoter could decrease the carburizing temperature, increase the BET surface area, and markedly promote the DBT hydrodesulfurization activity of the molybdenum carbide catalysts. When the Ni/Mo atom ratio was 0.3, the synergistic interaction between Ni and Mo reached the maximum. The hydrodesulfurization conversion of DBT over the Ni-Mo2C catalyst reached 96.25% under the reaction conditions of 330°C, 3.0 MPa, and space velocity 8 h−1, and the conversion was 1.57 times higher than that of Mo2C.

Bulk preparation and characterization of mesoporous carbon nanotubes by catalytic decomposition of cyclohexane on sol–gel prepared Ni–Mo–Mg oxide catalyst

Multiwalled carbon nanotubes were synthesized using Ni–Mo–Mg oxide catalyst prepared by sol–gel technique. Carbon nanotubes were formed in situ by the reduction of nickel oxide (NiO) and molybdenum oxide (MoO 3) to Ni and Mo by a gas mixture of nitrogen, hydrogen and cyclohexane at 750 °C. Scanning Electron Microscopy (SEM) was used to confirm the formation of carbon nanotubes (CNTs). The pore size distribution of carbon nanotubes (CNTs) was investigated by N 2 adsorption and desorption. It was found that the pore size fell into the mesopore range: 2 < d < 50 nm. Interpretation was also made using Raman spectroscopy, Diffuse reflectance spectroscopy, X-ray diffraction and ESR spectra. This method is found to produce a very high yield weighing over 20 times of the catalyst. Based on the experimental conditions and results obtained a possible growth mechanism of the carbon nanotubes is proposed.

EXAFS study of mixed nickel molybdenum oxide thin films at the Ni and Mo K-edges

Mixed nickel molybdenum oxide thin films were produced by DC magnetron co-sputtering technique with the nickel content about 8, 16 and 25at%. X-ray absorption spectroscopy at the Ni and Mo K-edges was used to study the local atomic structure in the films. The best-fit analysis of the EXAFS signals suggests that (i) the films are amorphous, except for the highest nickel content (25at%), at which a segregation of NiO phase was observed; (ii) nickel and molybdenum atoms are octahedrally coordinated by oxygen atoms. Opposite to the NiO6 octahedra, the MoO6 octahedra are strongly distorted, that results in an existence of two groups of oxygen atoms—four nearest at ∼1.76Å and two distant at ∼2.2Å. It was also found that the MoO6 octahedra are joined by edges, with the Mo–Mo distance about 3.26–3.31Å.

Nickel aluminide containing refractory-metal dispersoids: 1: Synthesis by reactive mechanical alloying

Nickel and aluminum powders were mechanically alloyed with 10 or 30 vol.% refractory metal powders (molybdenum or tungsten) for times up to 50 h. Intermetallic synthesis takes place after 10–20 h alloying, with concomitant dispersion of the inert refractory metal phase, resulting in an NiAl matrix containing fine refractory dispersoids. The reactive synthesis step is direct, without intermediate intermetallic products. In a separate processing route, the compound NiMo was first synthesized by hydrogen reduction of nickel oxide and molybdenum oxide. Subsequent reactive mechanical alloying of NiMo powders with metallic nickel and aluminum powders yielded the same phases as the direct route from elemental powders. However, the dispersion step is more efficient with brittle NiMo than with ductile molybdenum, leading to a finer molybdenum dispersion size in the reacted powders. All mechanically alloyed powders are stable on exposure for 1 h at 1000 °C in a reducing atmosphere, but oxidize rapidly in air between 425 °C and 1000 °C.

Interaction of zirconium and phosphorus with tungsten molybdenum or rhenium: Y.F. Lomnitskaya and Y.B. Kuzma, Poroshkovaya Metallurgiya, No 2, 1991, 82–86, (In Russian).

Molybdenum carbide and nickel-molybdenum carbide catalysts were prepared by the temperature-programmed reduction and carburization of molybdenum trioxide and nickel-molybdenum oxide, respectively, using a CH4/H2 gas mixture. X-ray diffraction patterns showed that the crystals were β-Mo2C and Ni-Mo2C, respectively. The effects of nickel promoter on the preparation of molybdenum carbide and its catalytic performance for the hydrodesulfurization of dibenzothiophene (DBT) were studied. The results indicated that the addition of proper amount of the nickel promoter could decrease the carburizing temperature, increase the BET surface area, and markedly promote the DBT hydrodesulfurization activity of the molybdenum carbide catalysts. When the Ni/Mo atom ratio was 0.3, the synergistic interaction between Ni and Mo reached the maximum. The hydrodesulfurization conversion of DBT over the Ni-Mo2C catalyst reached 96.25% under the reaction conditions of 330°C, 3.0 MPa, and space velocity 8 h−1, and the conversion was 1.57 times higher than that of Mo2C.

Destructive Hydrogenation of High-Molecular-Weight Polymers. Isobutene Polymer, Butadiene Polymer, and Natural Rubber

Abstract Destructive hydrogenation under pressure in the presence of nickel oxide and molybdenum oxide has been used to show the presence of naphthenic hydrocarbons in high-boiling olefin polymer. It was of interest to apply this tool to other hydrocarbons having large molecules, especially rubber and synthetic rubber like polymers. The destructive hydrogenation of isobutene polymer yielded only paraffinic hydrocarbons, including isobutane in the gases. Butadiene polymer, on the other hand, gave only naphthenic products, chiefly ethylcyclohexane and a dicyclic hydrocarbon. Similarly, natural rubber yielded only naphthenes, with p-methylisopropylcyclohexane as the major component of the lower boiling portion of the product. Isoprene, under the conditions used for the destructive hydrogenation of the rubber, yielded isopentane and an unsaturated naphthene, i. e., a hydropolymer of isoprene, which was converted into p-methylisopropylcyclohexane by further hydrogenation. Discussion of the relation of these results to the structures of the polymeric substances hydrogenated is reserved for a future publication of further work now in progress undertaken to aid in the proper interpretation of the above indicated experiments.