Abstract
An ideal hydroisomerisation reaction is expected to take place over a bifunctional catalyst, in which a balance between the number of metal sites and acid sites might lead to an optimal performance. In order to assess this relationship and the implications for n-heptane hydroisomerisation, various loadings of molybdenum oxide (1–10 wt%) were impregnated on zirconia with a view to producing samples with a range of acid and metal-like properties. The nature and amounts of the acid sites were determined using quantitative FTIR of pyridine adsorption, while the metal-like properties were determined using CO chemisorption. It was observed that zirconia alone contained only Lewis acid sites (1440 cm−1), while addition of MoO3 generated Brønsted acidity (1536 cm−1). The ratio of Brønsted to Lewis acid sites increased with loadings. Similarly, the amounts of CO taken up by the samples increased with MoO3 loadings; hence, the addition of MoO3 resulted in an improved metal like behaviour. The ratio of Brønsted acid to metal-like sites were found to range between 0.009 and 1.180 on going from 1 to 10 wt% MoO3. The materials were used for n-heptane hydroconversion. The sample with the highest amount of Brønsted acid site, which also consumed the highest amount of CO showed the highest activity. Hence, it could be concluded that the addition of MoO3 improves the Brønsted acid to metal-like site ratio, which resulted in a pronounced improvement in the activity of the samples.
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Acknowledgements
This work was supported by the Tertiary Education Trust Fund (TETFUND) Research Grant through Adekunle Ajasin University, Akungba Akoko, Nigeria.
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Oloye, F.F., Ololade, I.A. Influence of Molybdenum Loadings on the Properties of MoO3/Zirconia Catalysts. Chemistry Africa 1, 119–126 (2018). https://doi.org/10.1007/s42250-018-0016-6
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DOI: https://doi.org/10.1007/s42250-018-0016-6