Selective catalytic oxidation of ammonia into nitrogen and water vapor (NH3-SCO) is considered to be an efficient technique to eliminate the hazardous and pungent gaseous phase NH3, which mainly emitted...
The
selective catalytic oxidation of ammonia (NH3-SCO)
into N2 and H2O is a recognized effective protocol
to eliminate excessive NH3 emission. Nevertheless, it is
a great challenge for NH3-SCO catalysts to balance the
NH3 oxidation activity with N2 selectivity.
Herein, promotion effects of the dynamically constructed CuO
x
-OH interfacial sites for NH3 oxidation
activity without the scarification of N2 selectivity were
unraveled. The enrichment of coordination unsaturated Cu sites and
Cu-OH acid sites in CuO
x
-OH interfacial
sites optimized the adsorption and activation for NH3 and
O2, leading to the over 9-fold increase in NH3 oxidation rate and the 40 kJ/mol decrease in apparent activation
energy compared with the conventional CuO sites. Unexpectedly, the
fast internal-selective catalytic reduction (i-SCR) mechanism was
identified on CuO
x
-OH interfacial sites,
which is characterized by the presence of consumable NO2 adsorbed species. This work paves an innovative way for the development
of effective NH3-SCO catalysts and contributes to the deeper
understanding of the reaction mechanism.
Currently, SO2-induced
catalyst deactivation from the
sulfation of active sites turns to be an intractable issue for selective
catalytic reduction (SCR) of NO
x
with
NH3 at low temperatures. Herein, SO2-tolerant
NO
x
reduction has been originally demonstrated
via tailoring the electron transfer between surface iron sulfate and
subsurface ceria. Engineered from the atomic layer deposition followed
by the pre-sulfation method, the structure of surface iron sulfate
and subsurface ceria was successfully constructed on CeO2/TiO2 catalysts, which delivered improved SO2 resistance for NO
x
reduction at 250
°C. It was demonstrated that the surface iron sulfate inhibited
the sulfation of subsurface Ce species, while the electron transfer
from the surface Fe species to the subsurface Ce species was well
retained. Such an innovative structure of surface iron sulfate and
subsurface ceria notably improved the reactivity of NH
x
species, thus endowing the catalysts with a high
NO
x
reaction efficiency in the presence
of SO2. This work unraveled the specific structure effect
of surface iron sulfate and subsurface ceria on SO2-toleant
NO
x
reduction and supplied a new point
to design SO2-tolerant catalysts by modulating the unique
electron transfer between surface sulfate species and subsurface oxides.
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