posted on 2021-06-10, 20:13authored byYunpeng Long, Yuetan Su, Yehui Xue, Zhongbiao Wu, Xiaole Weng
Municipal solid waste incineration
and the iron and steel smelting
industry can simultaneously discharge NOx and chlorinated organics, particularly polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). Synergistic
control of these pollutants has been considered among the most cost-effective
methods. This work combined experimental and computational methods
to investigate the reaction characteristics of a catalytically synergistic
approach and gives the first insight into the effect of arsenic (As)
on the multipollutant conversion efficiency, synergistic reaction
mechanism, and toxic byproduct distribution over a commercial V2O5–WO3/TiO2 catalyst.
The loaded As2O3 species were shown to distinctly
decrease the formation energy of an oxygen vacancy at the V–O–V
site, which likely contributed to the extensive formation of more
toxic polychlorinated byproducts in the synergistic reaction. The
As2O5 species strongly attacked neighboring
VO sites forming the As–O–V bands. Such an interaction
deactivated the deNOx reaction, but led
to excessive NO being oxidized into NO2 that greatly promoted
the V5+–V4+ redox cycle and in turn facilitated
chlorobenzene (CB) oxidation. Subsequent density functional theory
(DFT) calculation further reveals that both the As2O3 and As2O5 loadings can facilitate H2O adsorption on the V2O5–WO3/TiO2 catalyst, leading to competitive adsorption
between H2O and CB, and thereby deactivate the CB oxidation
with water stream.