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Cu–Mg–Al oxides
Evaporation-induced self-assembly
Mesoporous materials
Migration
CO oxidation
Abstract:
Ordered mesoporous Cu-Mg-Al composite oxides were synthesized via the
one-pot evaporation-induced self-assembly strategy. Using this method,
copper was first homogeneously incorporated into the ordered mesoporous
spinel matrix. After H2 reduction treatment, according to X-ray
diffraction (XRD) and transmission electron microscopy (TEM) results,
copper existed as metallic nanoparticles with the size of 6-10 nm that
well decorated the parent mesoporous skeleton. The metallic
nanoparticles were then re-oxidized to copper oxide when exposed to air
or during CO oxidation reaction at low temperatures. Thus, copper
migrated from bulk spinel phase to the surface after the
reduction-oxidation treatment. Moreover, the copper on the surface was
re-incorporated into the bulk spinel phase by further thermal treatment
at much higher temperature in the presence of air. The correlation
between the state of copper in the mesoporous composite oxides and the
catalytic performance toward CO oxidation was studied. It was found that
copper existed as oxide nanoparticles on the surface of mesoporous Mg-Al
skeleton is much more active than that existed as lattice Cu ions in
spinel phase.
