Synthesis of Mo–W carbide via propane carburization of the precursor sulfide: Kinetic analysis
✍ Scribed by Tuan-Huy Nguyen; Adesoji A Adesina; Ernest MT Yue; Yong-Joon Lee; Andrei Khodakov; Michael P Brungs
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2004
- Tongue
- English
- Weight
- 158 KB
- Volume
- 79
- Category
- Article
- ISSN
- 0268-2575
- DOI
- 10.1002/jctb.994
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✦ Synopsis
Abstract
Thermogravimetric analysis (TGA) has been used to investigate the carburization kinetics of Mo–W sulfide using an H~2~:C~3~H~8~ feed mixture. The effect of heating rate over the range 1–10 K min^−1^ showed that up to four different carburized products may be formed but the critical (peak) temperature for formation of these species and the amount (peak height) of each species formed are highly dependent on the heating rate employed. The critical temperature increased linearly with heating rate for each of the four products. The four TGA peaks corresponding to the four phase transformation species are consistent with XRD identifiable species, namely; α‐Mo~2~C, β‐Mo~2~C, W and MoC~1−x~. Isothermal conversion–time data at three different temperatures are described by a reaction‐controlled shrinking core model implicating a first‐order dependency on the H~2~:C~3~H~8~ ratio. The reaction exhibited fractional order dependence on the metal sulfide concentration, the associated global activation energy estimated as 227 kJ mol^−1^ is representative of a non‐catalytic gas–solid reaction. Copyright © 2004 Society of Chemical Industry