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

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 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 , 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 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.