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In this work, porous CeO 2 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 CeO 2 loaded with copper and manganese oxides at the mass ratio of 8/2 (Cu 8 Mn 2 /CeO 2 ) 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% H 2 O, 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 Cu 2+ and Mn 4+ all played an important role in determining the good catalytic activity of the prepared samples. NH 3 -TPD analysis indicated the introduction of MnO x promoted the conversion of NH 3 and N 2 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 Cu 8 Mn 2 /CeO 2 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., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A heterogeneous composite catalyst Cu 2 O/{001}TiO 2 was successfully prepared by the impregnation-reduction method. With ammonia as the target pollutant, the degradation performance and degradation mechanism analysis of the prepared composite catalyst were investigated, providing technology for the application of photocatalysis technology in ammonia treatment reference. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), specific surface area (BET), fluorescence spectrum (PL) and UV-visible absorption (UV-Vis). The results showed: compared with single {001}TiO 2 , the addition of Cu 2 O to form a composite catalyst can reduce the recombination of electron-hole pairs, resulting in increased absorption intensity in the visible light range, decreased band gap width, and finally improved the degradation performance. When the composite ratio is 1 : 10, the specific surface area is the largest, which is 72.51 m 2 g -1 , and the degradation rate of ammonia is also the highest maintained at 85%. After repeated use for 5 times, the degradation rate of ammonia decreases gradually due to the loss of catalyst and photo-corrosion. In the whole reaction process, surface adsorbed water and associated hydroxyl radical participate in the ammonia degradation reaction, and finally form free hydroxyl radical and NO 3 - . It provides some theoretical support for ammonia gas treatment, which is of great significance to protect the environment., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)