Papers by Author: Xiang Yang Chen

Abstract: The flower-sphere molybdenum disulfide has been synthesized by reaction of Na₂MoO₄ and CS(NH₂)₂ with NH₂OH·HCl or H₂C₂O₄ as reductant. The microstructure and chemical composition of the product were characterized by means of X-ray diffraction and scanning electron microscope. XRD patterns showed that the molar ratio of Mo to S had a great effect on the purity of the product. When the molar ratio of Mo to S was 1:5, the product was nearly pure MoS₂. SEM images showed that the particle size increased as the molar ratio of Mo to S reduced. The MoS₂ microspheres had rough surfaces and were constructed with sheet-like structures in the two systems. But the product from the system of NH₂OH·HCl as reductant has the bigger particle size, clearer petal-sheets, coarser surface and weaker agglomeration than that from the system H₂C₂O₄ as reductant. The possible chemical reactions in hydrothermal systems were preliminarily discussed.

Abstract: Activated carbon was prepared from blue coke powder by physical activation. The results show that the specific surface area (BET) is 697.05m2/g, the total pore volume is 0.4569cm3/g and the average pore size is 2.6221nm. The adsorption properties of Cr( ) onto blue coke powder activated carbon are discussed from the kinetics and thermodynamics viewpoints. The pseudo-second-order kinetic model shows the best correlation with experimental data. Langmuir and Freundlich models are used to fit the equilibrium, and it is indicated that Freundlich best fits these data. The adsorption of Cr( ) onto blue coke powder activated carbon is found to be an endothermic process in nature.

Abstract: The principle and process of producing molybdenum powder via reduction reaction of molybdenum trioxide at lower temperature in a N2-H2 system were researched. The effects of hydrogen concentration, temperature, and volatilization rate of molybdenum trioxide on particle size were analyzed. The experimental results showed that the optimal process parameters were 770°C-790°C in 60min when the hydrogen flow rate was 700mL/min. Particle size of superfine molybdenum powder was less than 4μm. The concentrations of hydrogen, temperature and volatilization rate of molybdenum trioxide have great effect on the particle size of superfine molybdenum powder.