Dehydrogenation and Diels–Alder reactions in a one-pot synthesis of benzaldehyde from n-butane over acid catalysts

VOx/ZrO2/SiO2 catalysts were synthesized via grafting of vanadium and zirconium alkoxides over Aerosil 380. With these materials the formation of benzaldehyde from butane was possible in a one-pot synthesis, where oxidative dehydrogenation (ODH) for the formation of butadiene is coupled with a Diels–Alder reaction for the formation of benzaldehyde. Experiments performed with a catalyst where the support was modified with Ce instead of Zr, give a material that under the reaction conditions studied does not yield benzaldehyde, showing that acidity plays an important role in the formation of this compound.

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► Benzaldehyde was produced from n-butane in a one-pot synthesis at 400 °C.
► The reaction occurred over vanadium supported on Ce or Zr modified SiO2.
► The formation of benzaldehyde occurred only on catalysts with acid sites.
► Catalysts with strong acid sites showed high selectivity to CO and CO2.
► The reaction network consists of Diels–Alder and oxidative dehydrogenation steps.