Traditional adsorbents
undershot the expectations for arsine (AsH
3
) removal under
low-temperature operation conditions in the
industry. In this study, the copper (Cu) precursor was used to modify
activated carbon and yield novel adsorbents by low-temperature roasting
for high-efficiency removal of AsH
3
. The best conditions
were determined as impregnation with 2 mol/L Cu(NO
3
)
2
adsorbent and roasting at 180 °C. At a reaction temperature
of 40 °C and an oxygen content of 1%, the AsH
3
removal
efficiency reached over 90% and lasted for 40 h and the best capacity
of 369.6 mg/g was obtained with the Cu/Ac adsorbent. The characterization
results showed the decomposition of Cu(NO
3
)
2
during the low-temperature roasting process to form surface functional
groups. The formation of the important intermediate Cu
2
(NO
3
)(OH)
3
in the decomposition of Cu(NO
3
)
2
into CuO plays a role in the good regeneration
performance of the Cu/Ac adsorbent using water washing and the gas
regeneration method. The results of in situ diffuse reflectance infrared
Fourier transform spectroscopy combined with X-ray photoelectron spectroscopy
demonstrated that the interaction of trace oxygen with Lewis (L) acid
sites increased chemisorbed oxygen by 17.34%, significantly promoting
the spontaneity of AsH
3
oxidation reaction. These results
provide a friendly economic method with industrial processes practical
for AsH
3
removal.
Ceria (CeO2) based materials are potential catalysts for the removal of the Hg0 and AsH3 present in reducing atmospheres. However, theoretical studies investigating the Hg0 and AsH3 removal capacity of ceria remain limited. In this study, the adsorption behavior and mechanistic pathways for the catalytic oxidation of Hg0 and AsH3 on the CeO2(111) surface, including the calculation of optimized adsorption configurations and energies, were investigated using density functional theory calculations. The results suggest that Hg0 and AsH3 are favorably adsorbed on the CeO2(111) surface, whereas CO is not, which is crucial for selective removal when CO is a desirable gas component. Further, AsH3 is adsorbed more favorably than Hg0. In addition, the calculations revealed that the Hg atom is initially adsorbed on the surface and then oxidized by lattice oxygen to form HgO. Concerning AsH3 decomposition, the stepwise dehydrogenation of AsH3 followed by bonding with lattice O atoms to form As-O bond seems the most plausible. Finally, the adsorbed As-O bond is further formed elemental As and As2O3. Therefore, CeO2 can adsorb and remove Hg0 and AsH3, making it a promising catalyst for the simultaneous catalytic oxidation of Hg0 and AsH3 in strongly reducing off-gas.
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