Zhai Yu-chun

Preparation of Mo60Cu40 Composite Nano-Powder by Hydrogen Reaction

Abstract Mo-Cu (Mo:Cu=60:40, mass ratio) predecessor powder was prepared by chemical co-precipitation taking (NH 4 ) 6 Mo 7 O 24 ·2H 2 O and CuSO 4 ·5H 2 O as starting materials. And then the Mo-Cu predecessor powder was reduced by hydrogen in closed circulation system to prepare the Mo-Cu composite nano-powder. The results reveal that conditions of the chemical co-precipitation are that reaction temperature is (50±5) °C, pH value (5.1±0.1), and ageing time (9±1) h. Under the conditions mentioned above, the average particle size of the prepared the Mo-Cu predecessor powder is 20 nm. The hydrogen reduction temperature during closed circulation is 650 °C. The particle size of obtained Mo-Cu composite powder is less than 100 nm.

Determination of naphthenic acids in crude oil by chemical ionization mass spectrometry

Naphthenic acids in petroleum are considered a class of biological markers. Their potential use in source correlation and as an indicator of biodegradation was reported in the past (Dzidic et al., 1988; Behar and Albrecht, 1984). Due to their highly complicated properties, detailed characterization of the acids is difficult.Naphthenic acids in petroleum are considered a class of biological markers. Their potential use in source correlation and as an indicator of biodegradation was reported in the past (Dzidic et al., 1988; Behar and Albrecht, 1984). Due to their highly complicated properties, detailed characterization of the acids is difficult.A method based on positive ion CI (chemical ionization) mass spectrometry using isobutane reagent gas to produce (M+15)+ ions was applied to the analysis of naphthenic acid esters. Since the complex mixture of naphthenic acids cannot be separated into individual components, only the determination of relative distribution of acids classified in terms of hydrogen deficiency was possible. The identities and relative distribution of fatty and mono-, di-, tri-, and higher polycyclic acids were obtained from the intensities of the (M+15)+ ions according to z-series formula CnH2n+zO2 of naphthenic acids. The components are characterized on the basis of group type and carbon number distributions. A comparison of the FAB and CI results showed that the group type distributions obtained by both methods agree surprisingly well. The results indicated this method is simple, rapid and easy to operate. The geochemical implication of naphthenic acids was investigated by using a set of well-characterized crude oil samples. It is found that the naphthenic acid distribution can be used as a fingerprint for oil-oil and oil-source correlations.

Preparation and UV Shielding Properties of Zn/Ce/Ti Oxide and Composite Oxide by Combustion Method

ZnO, CeO2, TiO2, ZnO-CeO2, CeO2-TiO2, ZnO-TiO2, and ZnO-CeO2-TiO2 powders have been fabricated using a combustion synthesis method for an application as UV Shielding agent for light stability of paraffin wax. Ascorbic acid (C6H8O6) was used as a new fuel and nitrate as raw materials. These powders are obtained when their processing parameters are optimized. The fuel (i.e., ascorbic acid) was used for producing the ZnO, CeO2, TiO2, ZnO-CeO2, CeO2-TiO2, ZnO-TiO2, and ZnO-CeO2-TiO2 powders. The produced particles have been characterized using SEM for the particle morphology, UV, and IR for absorbance properties, XRD for phase identification, and analysis of the particle size distribution and identification. In addition, these particles have shown good UV shielding properties, which provide an opportunity for these materials are used to improve light stability of paraffin wax.

Electrochemical Performance of Li4Ti5O12 Synthesized by a PVP Combustion Assisted Sol-gel Method

Abstract Li4Ti5O12 samples were synthesized via a PVP (polyvinylpyrrolidone) assisted gel-combustion method by varying the calcination temperature. The effect of different roasting temperatures on the structure, the morphology, and the electrochemical performance of the Li4Ti5O12 material was analyzed. The cycle performance, the structure and the morphology of the prepared material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge/discharge test system. The results show that the Li4Ti5O12 powder has a single-phase spinel structure with uniform particles size. The average particle size is 500 nm. The Li4Ti5O12 material synthesized at 800 oC for 8 h possesses excellent performance, and its first discharge capacity is 167.4 mAh/g.

Photocatalytic properties of TiO 2 thin films prepared by microarc oxidation

Titanium dioxide photocatalytic thin films were prepared using method of microarc oxidation. Effects of concentration of methylene blue (MB), object (congo red, MB, methyl orange, methyl red) intensity of illumination, accelerator concentration, reaction time and oxygen concentration on photocatalytic capability were studied. The results show that photocatalytic efficiency for MB solution is better than that of other organic tinctures. And Photocatalytic degradation ratio for MB solution increases with increase of intensity of illumination, accelerator concentration, reaction time and oxygen concentration. Dynamics of photocatalytic degradation for MB solution is studied with using UV light on titanium dioxide photocatalytic thin film. The results show that photocatalytic degradation double ratio for MB solution 2.5mg/L was improved with using the prepared titanium dioxide catalyzer. The photocatalytic process followed the first order kinetics on static condition system.

Study on the structure and electrochemical properties of melt-spun Zr0.9Ti0.1(Ni,Co,Mn,V)2.1 alloys

The structure and electrochemical properties of Zr0.9Ti0.1(Ni,Co,Mn,V)2.1 alloys prepared by both the melt-spinning method and conventional induction melting are investigated. XRD studies show that Zr0.9Ti0.1(Ni,Co,Mn,V)2.1 alloys at as-cast, melt-spinning and annealing are all face center cubic structures with a Laves C15 phase and the higher the melt-spinning rate, the greater the amorphous content. The electrochemical measurements show that melt-spun alloys have better active behavior and low discharge capacity (<270 mAh g−1). However, after annealing, the alloys are only activated completely after 30 cycles and the capacities (about 340 mAh g−1) are higher than those of as-cast and just melt-spun alloys; the annealed alloys have a better cycle stability than as-cast alloys, and the higher the melt-spinning rate, the more stable the alloy becomes.