A γ-alumina
support functionalized with transition metals
is one of the most widely used industrial catalysts for the total
oxidation of volatile organic compounds (VOCs) as air pollutants at
higher temperatures (280–450 °C). By rational design of
a bimetal CuFe-γ-alumina catalyst, synthesized from a dawsonite
alumina precursor, the activity in total oxidation of toluene as a
model VOC at a lower temperature (200–380 °C) is achieved.
A fundamental understanding of the catalyst and the reaction mechanism
is elucidated by advanced microscopic and spectroscopic characterizations
as well as by temperature-programmed surface techniques. The nature
of the metal–support bonding and the optimal abundance between
Cu–O–Al and Fe–O–Al species in the catalysts
leads to synergistic catalytic activity promoted by small amounts
of iron (Fe/Al = 0.005). The change in the metal oxide–cluster
alumina interface is related to the nature of the surfaces to which
the Cu atoms attach. In the most active catalyst, the CuO6octahedra are attached to 4 Al atoms, while in the less active catalyst,
they are attached to only 3 Al atoms. The oxidation of toluene occurs
via the Langmuir–Hinshelwood mechanism. The presented material
introduces a prospective family of low-cost and scalable oxidation
catalysts with superior efficiency at lower temperatures.