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Calcination Process (calcination + process)
Selected AbstractsEffect of Calcination on Crystallinity for Nanostructured Development of Wormhole-Like Mesoporous Tungsten OxideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007Wei Hao Lai The effects of calcination on the crystallinity and grain growth model for microstructure development of wormhole-like mesoporous tungsten oxide are investigated in this study. We found that residual mesopores of wormhole-like tungsten oxide can be seen calcined above 500°C, as evidenced by retention of a wormhole-like mesostructure of tungsten oxide. A model was proposed to combine grain growth with wormhole-like mesoporous behavior and to investigate whether the formation of wormhole-like mesoporous tungsten oxide can retard the collapse rate of mesopores during the calcination process. [source] Improving MCM-41 as a Nitrosamines Trap through a One-Pot SynthesisCHEMISTRY - AN ASIAN JOURNAL, Issue 8 2007Jia Hui Xu Abstract Copper oxide was incorporated into MCM-41 by a one-pot synthesis under acidic conditions to prepare a new mesoporous nitrosamines trap for protection of the environment. The resulting composites were characterized by XRD, N2 adsorption,desorption, and H2 temperature-programmed reduction techniques, and their adsorption capabilities were assessed in the gaseous adsorption of N -nitrosopyrrolidine (NPYR). The adsorption isotherms were consistent with the Freundlich equation. The copper salt was deposited onto MCM-41 during the evaporation stage and was fixed on the host in the calcination process that followed. MCM-41 was able to capture NPYR in air below 373,K but not at 453,K. Loading of copper oxide on MCM-41 greatly improved its adsorption capability at elevated temperatures. The influence of the incorporation of copper into MCM-41 samples and the adsorption behavior of these samples are discussed in detail. [source] Li4Ti5O12 Nanoparticles Prepared with Gel-hydrothermal Process as a High Performance Anode Material for Li-ion BatteriesCHINESE JOURNAL OF CHEMISTRY, Issue 6 2010Zheng Qiu Abstract Li4Ti5O12 (LTO) nanoparticles were prepared by gel-hydrothermal process and subsequent calcination treatment. Calcination treatment led to structural water removal, decomposition of organics and primary formation of LTO. The formation temperature of spinel LTO nanoparticles was lower than that of bulk materials counterpart prepared by solid-state reaction or by sol-gel processing. Based on the thermal gravimetric analysis (TG) and differential thermal gravimetric (DTG), samples calcined at different temperatures (350, 500 and 700°C) were characterized by X-ray diffraction (XRD), field emitting scanning electron microscopy (FESEM), transmission electron microscopy (TEM), cyclic voltammogram and charge-discharge cycling tests. A phase transition during the calcination process was observed from the XRD patterns. And the sample calcined at 500°C had a distribution of diameters around 20 nm and exhibited large capacity and good high rate capability. The well reversible cyclic voltammetric results of both electrodes indicated enhanced electrochemical kinetics for lithium insertion. It was found that the Li4Ti5O12 anode material prepared through gel-hydrothermal process, when being cycled at 8 C, could preserve 76.6% of the capacity at 0.3 C. Meanwhile, the discharge capacity can reach up to 160.3 mAh·g,1 even after 100 cycles at 1 C, close to the theoretical capacity of 175 mAh·g,1. The gel-hydrothermal method seemed to be a promising method to synthesize LTO nanoparticles with good application in lithium ion batteries and electrochemical cells. [source] Carbon combustion synthesis of complex oxides: Process demonstration and featuresAICHE JOURNAL, Issue 10 2005K. S. Martirosyan Abstract Carbon combustion synthesis of oxides (CCSO) is a novel process to rapidly produce high-purity, submicron, and porous powders of complex oxides. It is a modified form of self-propagating high temperature synthesis (SHS) that uses carbon as the fuel instead of a pure metal. The CO2 release increases the porosity and friability of the products. Like SHS, it is much faster (order of minutes) than the calcination processes (order of hours). CCSO has several advantages over SHS (the initial components are less expensive, porosity of the products is up to 70%). CCSO can produce complex oxides, such as LaGaO3, which cannot be produced by SHS. The feasibility and features of CCSO are illustrated by its use in producing barium titanate, lithium manganese, and lanthanum gallium oxides. The carbon concentration enabled control of the moving front temperature and average velocity and the particle size and surface area. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] | ||||||||||