Kinetics of chlorination of tantalum pentoxide in mixture with sucrose carbon by chlorine gas

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Vol. 35; no. 3; pp. 439 - 448
• Main Authors: GONZALEZ, J. A, RIVAROLA, J. B, RUIZ, M. Del C
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.06.2004; Springer Nature B.V
• Subjects: Applied sciences; Chemical elements; Exact sciences and technology; Metals. Metallurgy; Production of metals; Production of non ferrous metals. Process materials; Pyrometallurgy; Reaction kinetics; Scanning electron microscopy; BET method; Chlorination; Tantalum oxide; Chlorine; Thermogravimetry; Temperature effect; Experimental study; Reaction rate; Carbon; X ray diffraction; Pressure effect; Partial pressure; Thermodynamic analysis; Pyrometallurgy
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-004-0045-1

The mechanism and kinetics of [beta]-Ta^sub 2^O^sub 5^ chlorination, mixed with sucrose carbon, have been studied by a thermogravimetric technique. The investigated temperature range was 500 °C to 850 °C. The reactants and reaction residues were analyzed by scanning electronic microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller method for surface area (BET). The effect of various experimental parameters was studied, such as carbon percentage, temperature, chlorine partial pressure, and flow, use of the multiple sample method, and carbon previous oxidation. The carbon percentage and previous treatment have an effect on the system reactivity. The temperature has a marked effect on the reaction rate. In the 500 °C to 600 °C temperature interval, the apparent activation energy is 144 kJ/mol of oxide, while at higher temperatures, the activation energy decreases. With high chorine partial pressures, the order of reaction is near zero. The kinetic contractile plate model, X = kt, considering carbon oxidation as the controlling stage, is the one with the best fit to the experimental data. A probable mechanism for the carbochlorination of [beta]-Ta^sub 2^O^sub 5^ is proposed: (1) activation of chlorine on the carbon surface, (2) chlorination of Ta^sub 2^O^sub 5^, (3) oxidation of carbon, and (4) recrystallization of [beta]-Ta^sub 2^O^sub 5^. [PUBLICATION ABSTRACT]