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Powders of two molybdenum carbides (Mo2C and MoC1-x) and tungsten carbide (WC) were prepared by means of temperature programmed reaction (TPR) method. Mo2C and MoC1-x were synthesized by reacting MoO3 with a preselected molar ratio of methane/hydrogen and carbon monoxide/hydrogen gas mixtures respectively. WC was prepared using tungsten oxide (WO3) and a methane/hydrogen gas mixture. These carbides were ultrasonically dispersed in de-ionized water. Samples were characterized using room temperature x-ray diffraction and scanning microscopy. A kinetic diffusion model is also studied to determine diffusivities in solids where the diffusing species desorbs or reacts at the external surfaces, and where the diffusivity does not vary appreciably with concentrations. The method involves measuring the flux of the diffusive species into the solid under the influence of a temperature program.
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Tom
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28--34
Opis fizyczny
Bibliogr. 30 poz., rys., tab.
Twórcy
autor
autor
autor
autor
- Department of Chemical Engineering, North Carolina A&T State University, awislam@crimson.ua.edu
Bibliografia
- 1. Oyama, T., (1996). “The chemistry of transition metal carbides and nitrides,” London, Chapman and Hall.
- 2. Storms, E.K., (1967). The Refractory Carbides, Academic Press, New York.
- 3. Toth, L.E., (1971). Transition Metal Carbides and Nitrides, Academic Press, New York.
- 4. Choi, J., Brenner, J. & Thompson, L.. (1995). Pyridine Hydroenitrogenation Over Molybdenum Carbide Catalysts, Journal of Catalysis, 154, 33–40. DOI:10.1006/jcat.1995.1143.
- 5. Oyama, S.T., Schlatter, J.C., Metclafe, J.E. & Lambert, J.M., (1988). Preparation and Characterization of Early Transition- Metal Carbides and Nitrides, Ind. Eng. Chem. Res., 27, 1639–1648. DOI: 10.1021/ie00081a013.
- 6. Gu, Y., Li, L., Chen, Z., Yang, Y. & Qian, Y., (2003). Synthesis of nanocrystalline MO2C via sodium co-reduction of MoCl5 and CBr4 in Benzene, Mater. Res. Bull., 38, 1119–1122. DOI:10.1016/S0025-5408(03)00132-6.
- 7. Hyeon, T., Fang, M. & Suslick, K., (1996). Nanostructured Molybdenum Carbide: Sonochemical Synthesis and Catalytic Properties, J. Am. Chem. Soc., 118, 5492–5493. DOI: 10.1021/ ja9538187.
- 8. Mcgee, R., Bej, S. & Thompson, L., (2005). Basic properties of molybdenum and tungsten nitride catalysts, Appl. Catal. A., 284, 139 146. DOI:10.1016/j.apcata.2005.01.029.
- 9. Weimer, A. (1997). Carbide, Nitride and Boride Materials Synthesis and Processing, New York, Chapman and Hall.
- 10. Giordano, C., Erpen, C., Yao, W. & Antoniettin, M., (2008). Synthesis of Mo and W Carbide and Nitride Nanoparticles via a Simple “Urea Glass” Route, Nano Lett., 8, 4659–4663. DOI: 10.1021/nl8018593.
- 11. Patel, M. & Subrahmanyam, J., (2008). Synthesis of nanocrystalline molybdenum carbide (MO2C) by solution route, Mater. Res. Bull., 43, 2036-2041. DOI:10.1016/j.materresbull. 2007.09.025.
- 12. Keller, N., Pietruszka, B. & Keller, V.. (2006). A new one-dimensional tungsten carbide nanostructured material, Mater. Lett., 60, 1774–1777. DOI:10.1016/j.matlet.2005.12.017.
- 13. Singh, R.P., (2008). Synthesis and characterization of tungsten carbide nanoparticles. School of Physics & Materials Science, MS Thesis., Thapar University, Patiala.
- 14. Yamada, K., (2000). Synthesis of tungsten carbide by dynamic shock compression of a tungsten-acetylene black powder mixture, J. Alloy Compd., 305, 253–258. DOI:10.1016/ S0925-8388(00)00700-3.
- 15. Kurishita, H., Matsuso, S., Arakawa, H., Hirai, T., Linke, J., Kawai, M. & Yoshida, N. (2009). Development of nanostructured W and Mo materials, Adv. Mater. Res., 59, 18–30. DOI: 10.4028/www.scientifi c.net/AMR.59.18.
- 16. de Medeiros, F.F.P., da Silva, A.G.P., de Souza, C.P. & Gomes, U.U., (2009). Carburization of Ammonium Paratungstate by Methane: The influence of Reaction Parameters, Int. J. Refract. Metals and Hard Materials., 27, 43–47. DOI:10.1016/j.ijrmhm.2008.03.001.
- 17. Reddy, K.M., Rao, T.N., Radha, K. & Joardan, J. (2010). Nanostructured Tungsten Carbides by Thermochemical Processing, J. Alloys and Compounds., 494, 404–409. DOI:10.1016/j.jallcom.2010.01.059.
- 18. Cetinkaya, S. & Eroglu, S. (2011). Comparative Kinetic & Structural Analysis of Nanocrystalline WC Powder Synthesis from Pre-reduced W under Pure and Diluted CH4 Atmospheres, Int. J. Refract. Metals and Hard Materials., 29, 214–220. DOI:10.1016/j.ijrmhm.2010.10.009.
- 19. Oyama, S.T. (1981). “Ammonia synthesis and decomposition on molybdenum and its interstitial alloys.” PhD Dissertation, Stanford University, Stanford, CA.
- 20. Kanervo, J. (2003). “Kinetic analysis of temperaturę programmed reactions.” PhD Dissertation, Helsinki University of Technology.
- 21. Knotzinger, H. (1997). “Temperature-programmed reduction, In Handbook of Heterogeneous Catalysis,” Eds. Etrl, G., Knozinger, H., Weitkamp, J., Vol 2, VCH, Weinheim, pp 676.
- 22. Bhatia, S., Beltramini, I. & Do, D.D. (1990). “Temperature- programmed analysis and its applications in catalytic systems.” Catal. Today, 7, 309–438.
- 23. Jones, A. & McNicol, B. (1986). “Temperature-programmed reduction for solid materials characterization.” Marcel Dekker Inc., New York.
- 24. Lemaitre, J.L. (1984). “Temperature-programmed methods, in characterization of heterogeneous catalysts.” Ed. Delannay, F., Marcel Dekker, Inc., New York, pp 29–70.
- 25. Hurst, N.M., Gentry, S.J. & Jones, A. (1982). “Temperature – programmed desorption and reduction.” Catal. Rev. -Sci. Eng., 24, 233–309.
- 26. Kanervo, J.M. & Krause, A.O.I. (2001) “Kinetic Analysis of temperature programmed reduction: behavior of a CrOx/ Al.2O3 Catalyst.” J. Phys. Chem. B, 105, 9778–9784.
- 27. Rudy, E., Windish, S., Stosick, A. & Hoffman, J. (1967). Revision of the Titanium-Tungsten System, Trans TMS-AIME., 239, 1247–1267.
- 28. Oyama, S.T., Schlatter, J., Metcalfe, J. & Lambert, J. (1988). Preparation and characterization of early transition metal carbides and nitrides, Ind. Eng. Chem. Res., 27, 1639–1648. DOI: 10.1021/ie00081a013.
- 29. Kapoor, R. & Oyama, S.T. (1997). Measurement of solid state diffusion coefficients by a temperature-programmed method, J. Mater. Res., 12, 467–473. DOI: 10.1557/JMR.1997.0068.
- 30. Redhead, P.A., (1962). Thermal Desorption of Gases, Vacuum., 12, 203–211. DOI:10.1016/0042-207X(62)90978-8.
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Bibliografia
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