Estimation of the molybdena coverage in MoO3/alumina catalysts from residual OH groups
✍ Scribed by Vít, Zdeněk
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 78 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
A theoretical relation for calculation of the molybdena coverage in MoO 3 /alumina catalysts from OH amount, including the OH/Mo stoichiometry (OH removed per deposited Mo atom), was derived. Calculation of the coverage from OH amount of the catalysts, determined by reaction with dimethylzinc-tetrahydrofuranate, was compared both with theory and with literature data obtained by sorption methods and ISS. This comparison shows that calculation of the coverage from OH amount is possible at lower MoO 3 loadings up to ~2 Mo atoms nm -2 , where OH groups are eliminated by reaction with MoO 3 under almost constant OH/Mo stoichiometry. However, our data suggest limited validity of this approach at high MoO 3 loadings. The OH/Mo stoichiometry decreases due to the formation of polymolybdate species, and the molybdena coverage of highly loaded catalysts, when calculated from OH amount, is underestimated in comparison to the results of other methods.