A series of Fe–Mn catalysts was prepared using different supports(kaolin, diatomite, and alumina) and used for NO abatement via low-temperature NH_3-selective catalytic reduction(SCR).The results showed that 12 Fe–10 Mn/Kaolin(with the concentration of Fe and Mn 12 and 10 wt.%, respectively) exhibited the highest activity, and more than 95.8% NO conversion could be obtained within the wide temperature range of 120–300℃.The properties of the catalysts were characterized by inductively coupled plasma-atomic emission spectrometry(ICP-AES), thermogravimetry(TG), Brunner–Emmet–Teller(BET)measurements, X-ray diffraction(XRD), H_2-temperature programmed reduction(H_2-TPR),NH_3-temperature programmed desorption(NH_3-TPD), X-ray photoelectron spectroscopy(XPS), scanning electron microprobe(SEM) and energy dispersive spectroscopy(EDS)techniques.The support effects resulted in significant differences in the components and structures of catalysts.The 12 Fe–10 Mn/Kaolin catalyst exhibited better dispersion of active species, optimum low-temperature reduction behavior, the largest amount of normalized Br?nsted acid sites, and the highest Mn~(4+)/Mn and Fe~(3+)/(Fe~(3+)+ Fe~(2+)), all of which may be major reasons for its superior catalytic activity. 相似文献
Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) are efficient processes to degrade organic pollutants in water. In this paper, we especially reviewed the WAO and CWAO processes for phenolic compounds degradation. It provides a comprehensive introduction to the CWAO processes that could be beneficial to the scientists entering this field of research. The influence of different reaction parameters, such as temperature, oxygen pressure, pH, stirring speed are analyzed in detail; Homogenous catalysts and heterogeneous catalysts including carbon materials, transitional metal oxides and noble metals are extensively discussed, among which Cu based catalysts and Ru catalysts were shown to be the most active. Three different kinds of the reactor implemented for the CWAO (autoclave, packed bed and membrane reactors) are illustrated and compared. To enhance the degradation efficiency and reduce the cost of the CWAO process, biological degradation can be combined to develop an integrated technology.
A series of single-phase T-structured NdSrCu1??xCoxO4?? with oxygen vacancies and T0-structured Sm1:8Ce0:2Cu1??xCoxO4?? (x:
0–0.4) with oxygen excess were prepared using ultrasound-assisted citric acid complexing method, and characterized by means of
techniques such as thermogravimetric analysis and NO temperature-programmed desorption (NO-TPD). The catalytic activities of these
materials were evaluated for the decomposition of NO. It was found that the NdSrCu1??xCoxO4?? catalysts were of oxygen vacancies
whereas the Sm1:8Ce0:2Cu1??xCoxO4?? ones possessed excessive oxygen (i.e., over-stoichiometric oxygen); with a rise in Co doping level,
the oxygen vacancy density of NdSrCu1??xCoxO4?? decreased while the over-stoichiometric oxygen amount of Sm1:8Ce0:2Cu1??xCoxO4??
increased. The NO-TPD results revealed that NO could be activated much easier over the oxygen-deficient perovskite-like oxides
than over the oxygen-excessive perovskite-like oxides, with the NdSrCuO3:702 catalyst showing the best e ciency in activating NO
molecules. Under the conditions of 1.0% NO/helium, 2800 hr??1, and 600–900°C, the catalytic activity of NO decomposition followed
the order of NdSrCuO3:702 > NdSrCu0:8Co0:2O3:736 > NdSrCu0:6Co0:4O3:789 > Sm1:8Ce0:2Cu0:6Co0:4O4:187 > Sm1:8Ce0:2Cu0:8Co0:2O4:104
> Sm1:8Ce0:2CuO4:045, in concord with the sequence of decreasing oxygen vacancy or oxygen excess density. Based on the results,
we concluded that the higher oxygen vacancy density and the stronger Cu3+/Cu2+ redox ability of NdSrCu1??xCoxO4?? account for the
easier activation of NO and consequently improve the catalytic activity of NO decomposition over the catalysts. 相似文献
