Browsing by Author "Xu, Ming-Wei Paul"

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    Catalytic reaction in the process of carbon monoxide disintegration
    Xu, Ming-Wei Paul (Virginia Polytechnic Institute and State University, 1984)
    The catalytic effects of selected iron phases (metal, oxides, sulfides, and carbides) on the Boudouard reaction (2 CO = CO₂ + C) were studied, in an effort to more fully understand the disintegration of refractories when exposed to CO for long periods of time. Based on computer generated equilibrium phase maps (SOLGASMIX program), experimental kinetic data including activation energies and x-ray diffraction data of iron phases, the following conclusions were reached: (1) Ferric oxide (Fe₂O₃ ) is most catalytic; (2) Active iron atom generated by the reduction of Fe₂O₃ is a catalyst for carbon monoxide disintegration; (3) The catalytic process consists of the adsorption of CO, the formation of intermediates FeC, Fe₂C , and Fe₃C , and the decomposition of these intermediates.
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    Liquidus surface for the high cryolite/low alumina portion of the Na₃AlF₆-AlF₃-CaF₂-Al₂O₃ system
    Xu, Ming-Wei Paul (Virginia Polytechnic Institute and State University, 1983)
    The purpose of this work was to determine the liquidus surface of the cryolite-rich portion of the ternary system Na₃AlF₆-CaF₂-AlF₃ and to establish the effect of Al₂O₃ on the operation of the Hall cell electrolysis. A series of isotherm of the cryolite-rich portion were graphed. It was shown that pseudo-binary phase diagrams of Al₂O₃ and bulk composition in the cryolite-rich portion of the Na₃AlF₆-CaF₂-AlF₃ system were found to be simple eutectic. The temperatures and the alumina contents of the double solubility limit, two important parameters for the Hall cell, of the joins 95 Na₃AlF₆/5 AlF₃-Na₃AlF₆, 90 Na₃AlF₆/ 10 NaCaAlF₆ and 85 Na₃AlF₃/15 AlF₃-NaCaAlF₆ were determined. The cryolite liquidus temperature of the quaternary system Na₃AlF₆-CaF₂-AlF₃-Al₂O₃ was found to be expressed by: TLiq.. (C) = 1009.4 + 4.059(CaF₂) - 1.167(CaF₂)² + 0.968 x (CaF₂)(AlF₃) - 0.105(CaF₂)(AlF₃)² + 0.073 x (CaF₂)²(AlF₃) + 0.002(CaF₂)² (AlF₃)² - 4.165 x (AlF₃) - 0.054(AlF₃)² - 5.33(Al₂O₃) for CaF₂ 3.8~11.25%, AlF₃ 5~20%.