In the general context of environmental air remediation,
copper-oxide-based
self-standing porous catalysts (MUB-103(x)) and their
reduced homologues (Red MUB-103(x)) have been synthesized
and studied for the thermoconversion of CO to CO2. Catalytic
experiments under dry air conditions reveal that for nonreduced catalysts,
increasing the Cu content diminishes the light-off temperature T
50 (corresponding to 50% conversion). The catalytic
performances exhibited by the CuO phase dispersed in the silica pores
of MUB-103(x) samples are the highest reached to
date despite the limitations of the experimental conditions used.
After reduction with H2, the native Red MUB-103(x) catalysts offer CO conversion efficiencies significantly
more increased, leading to a lowering of the T
50 values equal to at least 100°C. As such, the CO conversion
reaches a T
50 value of 160 °C for
Red MUB-103(2) with 1.81 wt % Cu; this catalyst displays a specific
rate of 8.6 mmolCO gCu
–1 s–1 at 175 °C, largely higher than those observed
to date. The performances of the Red MUB-103(2) sample were evaluated
for CO oxidation under humid conditions with the addition of 5 vol
% water vapor in the feed during four cycles, leading to the same
efficiency when compared with that under dry experimental conditions,
revealing robustness. A drastic increase in the CO conversion temperature
was observed for the 4th cycle, i.e., after 8 h under humid conditions.
Analyses of the spent Red MUB-103(2) catalyst after four cycles reveal
a slight oxidation of copper, leading to Cu2O species.
Importantly, after four cycles, the deactivated catalyst was able
to partially recover its performance when reactivated through a 2
h reducing treatment under H2 at 400 °C.
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