In situ infrared spectroscopic study of the reaction pathway of the direct synthesis of n-butanol from ethanol over MgAl mixed-oxide catalysts

• One-step process ethanol to butanol on hydrotalcite-derived catalysts studied by IR.
• Aldol condensation of ethanol to butanol on MgAl-oxides analyzed by in situ DRIFT.
• Effect of surface carboxylates on selectivity to butanol from ethanol on MgAl-oxides.
• Reaction pathway ethanol to butanol on hydrotalcite-derived catalysts from IR study.

The interaction of ethanol and its evolution to n-butanol over different MgAl mixed oxides derived from hydrotalcite precursors is studied by FTIR and in situ DRIFT-MS experiments. The evolution of different surface species is monitored as a function of thermal treatments. Acetaldehyde appears as a primary intermediate which converts over the mixed oxides to C4 products through the aldol condensation reaction. However, acetaldehyde also produces surface carboxylate species which compete for the active sites and make the condensation process less efficient.

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