Kinetics of chlorination and carbochlorination of molybdenum trioxide
- Inst. National Polytechnique de Lorraine, Vandoeuvre (France)
Molybdenum is principally used as an alloying agent in steels, cast irons, and superalloys to enhance hardness, strength, toughness, and wear corrosion resistance. The Mo compounds are also used in chemical applications such as catalysts (i.e., petroleum hydrorefining catalysts), lubricants, and pigments. Because of environmental regulations, cheap, efficient, and flexible techniques have to be investigated for the recovery of metals from industrial wastes such as spent catalysts. Chlorination could be one of these techniques. Kinetics of chlorination of MoO{sub 3} with Cl{sub 2}-air, Cl{sub 2n}N{sub 2}, and Cl{sub 2}-CO-N{sub 2} gas mixtures have been studied by nonisothermal and isothermal thermogravimetric measurements, between ambient temperature and 900 C. Between 500 C and 700 C, the chlorination reaction of MoO{sub 3} with Cl{sub 2}-N{sub 2} gas mixture has an apparent activation energy of about 165 kJ/mole, reflecting that a chemical reaction is the rate-controlling step. The reaction order with respect to Cl{sub 2} partial pressure is about 0.75. The apparent activation energy for carbochlorination with Cl{sub 2}-CO-N{sub 2} gas mixture is about 83 kJ/mole, between 400 and 650 C. The carbochlorination of MoO{sub 3} was controlled by the chemical reaction, probably affected by the pore diffusion regime. The maximum reaction rate is obtained by using a Cl{sub 2}-CO-N{sub 2} gas mixture, having a Cl{sub 2}/CO volume ratio equal to about 1. The total apparent reaction order with respect to Cl{sub 2} + CO in Cl{sub 2}-CO-N{sub 2} gas mixture is about 1.5 for a Cl{sub 2}/CO ratio equal to 1.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 94380
- Journal Information:
- Metallurgical Transactions, B, Journal Name: Metallurgical Transactions, B Journal Issue: 4 Vol. 26; ISSN MTTBCR; ISSN 0360-2141
- Country of Publication:
- United States
- Language:
- English
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