Kinetics of chlorination of niobium pentoxide by carbon tetrachloride

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/s11663-997-0125-0· OSTI ID:464792

Jena, P K; Brocchi, E A; Garcia, R I ^[1]

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1. Catholic Univ. of Rio de Janeiro (Brazil). Dept. of Materials Science and Metallurgy

Kinetics of the chlorination of Nb{sub 2}O{sub 5} powder by CCl{sub 4} vapor in mixture with N{sub 2} in a static bed in the temperature range of 698 to 853 K were carried out at different partial pressures of CCl{sub 4} (p{sub CCl{sub 4}}), varying from 0.10 to 0.75 atm. The fraction of Nb{sub 2}O{sub 5} chlorinated R at p{sub CCl{sub 4}} of 0.6 atm in the temperature range of 698 to 773 K was found to be proportional to time t, and the activation energy E is calculated to be 112 kJ/mole. Results on the effect of p{sub CCl{sub 4}} (0.4, 0.6, and 0.75 atm) at 723 K suggest that the rate v (R/min) is proportional to p{sub CCl{sub 4}}{sup 1.5}. However, at p{sub CCl{sub 4}} of 0.2 atm, R is not linear with t, rather, R{sup 1/2} is linear with t. Based on these results, two mechanisms, one at low p{sub CCL{sub 4}} (0.2 atm) and another at higher p{sub CCL{sub 4}} values, in the temperature range of 698 to 773 K have been suggested. Similar studies in the higher temperature range (793 to 853 K), where p{sub CCl{sub 4}} used to decompose to elemental chlorine and carbon, were also carried out. At all temperatures and p{sub CCl{sub 4}} values, R is found to be directly proportional to t. At two higher p{sub CCl{sub 4}} (0.4 and 0.6 atm), {nu} is proportional to p{sub CCl{sub 4}}, whereas at two lower p{sub CCl{sub 4}} (0.1 and 0.2 atm) it is proportional to p{sub CCl{sub 4}}{sup 0.5}. The E values obtained in the temperature range of 793 to 853 K at p{sub CCl{sub 4}} of 0.6 and 0.2 atm are found to be 57 and 115 kJ/mole, respectively. In this higher temperature range, two different reaction mechanisms have been proposed.

• Sponsoring Organization: USDOE
• OSTI ID: 464792
• Journal Information: Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science Journal Issue: 1 Vol. 28; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ACTIVATION ENERGY
CARBON TETRACHLORIDE
CHLORINATION
EXPERIMENTAL DATA
KINETICS
NIOBIUM OXIDES
NITROGEN
PARTIAL PRESSURE
TEMPERATURE RANGE 0400-1000 K