Adsorption Performance of Gaseous HCN on Ni/Al Hydrotalcite-Derived Oxides

抄録

Ni/Al hydrotalcite-derived oxides (Ni/Al LDOs) prepared with various Ni/Al ratios at 300°C were used to investigate the removal of gaseous hydrogen cyanide (HCN). The results showed that Ni/Al LDOs exhibited outstanding performance for HCN removal, especially LDO with a Ni/Al ratio of 4 due to the formation of Ni/Al metal oxides (NiO and Al₂O₃) and the disappearance of hydrotalcite after 300°C calcination. Comparison of LDO with other Ni/Al ratios, LDO with a Ni/Al ratio of 4 had a higher surface area of 178 mg²/g and smaller mesopores of 5.46 nm as determined by nitrogen adsorption/desorption isotherms. CO₂ temperature programmed desorption (CO₂-TPD) experiments revealed that the weak basic sites and Ni–O group of the LDO with a Ni/Al ratio of 4 dominated HCN removal. Fourier-transform infrared (FTIR) spectra analysis demonstrated that adsorbed CN⁻ was converted into [Ni(CN)₄]²⁻, implying the occurrence of chemical adsorption. Further experiments found that a relatively low concentration water vapor can promote the removal efficiency of HCN on Ni/Al LDOs, while the inhibiting effect on the removal efficiency of HCN was observed in the presence of water vapor with high concentration due to its competitive adsorption effect. These findings are helpful for the development of innovative technology for the removal of HCN, and also provide a new treatment strategy for HCN based on Ni/Al LDOs.