A series of MoS2 catalysts supported on hydrotalcite-derived mixed-metal oxide (MMO) supports promoted with K2CO3 is used for alcohol synthesis via CO hydrogenation. Alcohol selectivities are found to vary greatly when the Mg/Al mixed metal oxide material (MMO) is loaded with 5 % vs. 15 % Mo with a Mo:K molecular ratio of 1:1. The most striking difference is the low methanol and high C3+ alcohol selectivities over the 5 % Mo catalyst. This catalyst also produces more ethane than the 15% catalyst, which is shown to be associated with ethanol dehydration and hydrogenation over residual acid sites on this catalyst with lower K content. A series of catalysts with common composition (5% Mo and 3% K supported on MMO) prepared in different manners all yield similar catalytic selectivities, thus showing that selectivity is largely controlled by the MMO to Mo ratio, rather than the synthetic method or precursor Mo phase. The catalytic higher alcohol productivity is shown to correlate with the degree of stacking of the MoS2 layers, as assessed via X-ray diffraction and scanning transmission electron microscopy, with higher productivity correlating with higher MoS2 dispersion. Control reactions where K loading is increased or the positioning of the MMO in the catalyst bed is changed via creation of multiple or mixed catalyst beds show that MMO-Mo-K domains play a significant role in alcohol forming reactions. Higher alcohol forming pathways are believed to occur via CO insertion pathways or via coupling of adsorbed reaction intermediates at or near MoS2 domains. No evidence is observed for significant alcohol coupling pathways by adsorption of alcohols over downstream, bare MMO, although some coupling may occur over MMO/K domains. Other basic supports such as MgO are also shown to facilitate formation of higher alcohols, whereas more neutral supports such as alpha-alumina yield more methanol. Mo2C phases prepared on the same supports with similar 1:1 Mo:K ratios are less selective to alcohols than the corresponding MoS2 catalysts.

Magnesia, alumina and mixed MgAl oxide K promoted MoS<sub>2</sub> catalysts in higher alcohol synthesis

247th National Meeting (2014)

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Magnesia, alumina and mixed MgAl oxide K promoted MoS2 catalysts in higher alcohol synthesis

Magnesia, alumina and mixed MgAl oxide K promoted MoS₂ catalysts in higher alcohol synthesis