Yixing Ma

Coupling catalytic hydrolysis and oxidation on metal-modified activated carbon for HCN removal

A method of coupling catalytic hydrolysis and oxidation for HCN removal by metal-modified activated carbon (denoted as AC-M) was studied using a dynamic method in a fixed bed reactor. The results showed that impregnation of metal oxides on the activated carbon significantly enhanced the removal capacity for HCN. Among the different types of metal-modified catalysts, AC-Cu exhibited the highest catalytic activity. The AC-Cu catalyst showed >96% conversion of HCN at 200–350 °C. The selectivity of N2 in the conversion of HCN reached 48.8% at 300 °C. Oxygen concentration, relative humidity and calcination temperature can greatly influence the catalytic activity. In particular, the reaction temperature was determined to be a crucial factor. The detailed characterization of the catalyst was performed using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature programmed desorption (TPD). The Cu 2p XPS spectra and XRD patterns indicated that CuO was formed as an active species for the catalytic removal of HCN. We concluded that AC-Cu could be used as a catalyst for the removal of HCN by coupling catalytic hydrolysis and oxidation.

Removal of mercury (II), elemental mercury and arsenic from simulated flue gas by ammonium sulphide

A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg2+, Hg0 and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg2+, Hg0 and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas.