The highly efficient removal of HCN over Cu8Mn2/CeO2 catalytic material

Abstract

In this work, porous CeO₂ flower-like spheres loaded with bimetal oxides were prepared to achieve effective removal of HCN in the lower temperature region of 30–150 °C. Among all samples, the CeO₂ loaded with copper and manganese oxides at the mass ratio of 8/2 (Cu₈Mn₂/CeO₂) exhibited the highest catalytic activity: the HCN removal rate was nearly 100% at 90 °C at the conditions of 120 000 h⁻¹ and 5 vol% H₂O, the catalytic activity of which was higher than for other reported catalysts. The introduction of MnO_x could improve the dispersion of CuO particles and increase the total acid sites of the prepared samples. It was proved that the synergy between CuO and MnO_x, the chemisorption oxygen, the oxygen vacancies, the Cu²⁺ and Mn⁴⁺ all played an important role in determining the good catalytic activity of the prepared samples. NH₃-TPD analysis indicated the introduction of MnO_x promoted the conversion of NH₃ and N₂ selectivity by increasing the acid sites of the sample. According to the C, N balance data and FT-IR results, when the temperature was below 30 °C, the removal of HCN over Cu₈Mn₂/CeO₂ was mainly by chemisorption and the HCN breakthrough behaviors corresponded to the Yoon and Nelson's model. When temperature was above 120 °C, the HCN was totally removed by catalytic hydrolysis and catalytic oxidation.