Feng Ouyang

Reaction and Characterization of Co and Ce Doped Mn/TiO2 Catalysts for Low-Temperature SCR of NO with NH3

The catalysts of cobalt and cerium doped Mn/TiO2 were tested for low-temperature selective catalytic reduction of NO with NH3, and these samples were characterized by XRD, XPS, Raman, H2-TPR and NH3-TPD methods. The catalytic activity results showed that the NOx conversion was obviously improved by Co and Ce doping. Ternary metal oxide catalyst Mn–Co–Ce/TiO2 exhibited the highest catalytic activity of 99xa0% at 423xa0K. The XRD and Raman analysis indicated formation of MnO2 or CoMnO3 phases on Mn/TiO2 and Mn–Co/TiO2. The XPS results demonstrated that the metal cations existed mainly in the form of Mn4+, Co2+ and Ce4+, respectively. XPS and H2-TPR results supported the presence of Mn–Co mixed oxides. Doping of Ce could enhance dispersion of Mn–Co oxides on the surface. Addition of Co and Ce led to higher surface Mn4+/Mn3+ ratio, chemisorbed oxygen, acidity and dispersity, which enhanced NH3 adsorption and oxidation of NO to NO2, subsequently, the NOx reduction was accelerated through the Fast SCR reaction.Graphical Abstract

Photocatalytic decomposition of acrylonitrile with N-F codoped TiO2/SiO2 under simulant solar light irradiation.

The solid acid catalyst, N-F codoped TiO2/SiO2 composite oxide was prepared by a sol-gel method using NH4F as nitrogen and fluorine source. The prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectroscopy (UV-Vis), ammonia adsorption and temperature-programmed desorption (NH3-TPD), in situ Fourier transform infrared spectroscopy (FT-IR) and N2 physical adsorption isotherm. The photocatalytic activity of the catalyst for acrylonitrile degradation was investigated under simulant solar irradiation. The results showed that strong Lewis and Brønsted acid sites appear on the surface of the sample after N-F doping. Systematic investigation showed that the highest photocatalytic activity for acrylonitrile degradation was obtained for samples calcined at 450°C with molar ratio (NH4F to Ti) of 0.8. The degradation ratio of 71.5% was achieved with the prepared catalyst after 6-min irradiation, demonstrating the effectiveness of photocatalytic degradation of acrylonitrile with N-F codoped TiO2/SiO2 composite oxide. The photocatalyst is promising for application under solar light irradiation. Moreover, the intermediates generated after irradiation were verified by gas chromatography-mass spectrometry (GC-MS) analysis and UV-Vis spectroscopy to be simple organic acids with lower toxicity, and the degradation pathway was also proposed for acrylonitrile degradation with the prepared catalyst.

Producing biodiesel from waste animal oil by modified ZnO

ABSTRACT Biodiesel produced by transesterification of waste animal oil is a promising green fuel in the future. ZnO-Al2O3 and ZnO/Zn2Al composition oxides were prepared by co-precipitation method and impregnation method, respectively. The above catalysts were characterized by X-ray diffraction (XRD), Brunauer--Emmett--Teller (BET) and CO2 adsorption and temperature-programmed desorption (CO2-TPD) and show that the high activity for the catalyst is attributed to its high alkalinity. The reaction parameters were optimized and the results show that the transesterification ratio of waste animal oil can reach 98.7% with 10% ZnO/Zn2Al catalyst after 2 h. Moreover, 10%ZnO/Zn2Al compound oxides can be active for the successive cycles. The glycerol as a predominant by-product after transesterification is of high purity with high use value.