Selective catalytic reduction (SCR) is the most effective
method
to remove NO
x
from flue gas. Since the
flue gas contains CO gas, using CO as a reducing agent to selectively
remove NO (CO-SCR) is greatly convenient. In this paper, we developed
an improved coprecipitation method combined with spray drying technology
to design and synthesize a CuCoAlO
x
CO-SCR
denitration catalyst having a three-dimensional micro/nanoporous spherical
morphology. The structural features of the catalyst offer the following
advantages: (1) the micron size of metal oxide materials provides
sufficient mechanical strength to avoid material wear and consumption;
(2) the porous structure increases the specific surface area, exposes
more active sites, and facilitates the contact of CO and NO with active
substances, thereby improving the reactivity; (3) the spherical morphology
provides the catalyst with excellent fluidity, dispersion, uniformity,
and compactness, which are beneficial characteristics for coating
formation and to achieve satisfactory process operation performance.
The surface reaction mechanism of the CuCoAlO
x
catalyst was elucidated on the basis of in situ Fourier-transform
infrared spectroscopy and density functional theory calculation results,
which revealed that the preferential adsorption of NO in the presence
of a CO + NO mixture enhances the subsequent adsorption of CO, with
the adsorption energy decreasing from −0.47 for single CO adsorption
to −1.51 eV, thus improving the CO-SCR denitration performance.
The as-prepared CuCoAlO
x
catalyst reached
an NO conversion of 46.1% at 50 °C and 90.1% at 200 °C.