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Phosphorous has a deactivation effect on an SCR catalyst. In this study, the effect of Mo modification on the resistance to P species of a Mn–Ti catalyst for selective catalytic reduction of NOx with NH3 was investigated. It was found that the addition of Mo could greatly improve the P species tolerance of the Mn–Ti catalyst. From the characterizat...
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The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe pollution regulations being imposed around the world. Supported and mixed transition metal oxides have been widely investigated for LT-SCR technology. However, these catalytic materials have some drawbacks, especially in...
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Citations
... Some researchers have found that the doping of some metals could weaken the chemical deactivation of catalysts. Guo et al. [262] studied the effect of Mo modification on the P resistance of Mn-Ti catalyst. They found that the addition of Mo could significantly improve the P resistance of the Mn-Ti catalyst. ...
Selective catalytic reduction technology has been widely used to remove NO x. However, the development of low-temperature selective catalytic reduction catalysts with high removal efficiency still faces severe challenges. This paper reviews the progress of research on Mn-based catalysts for selective catalytic reduction of NO x at low temperatures. Catalysts were divided into three categories: single manganese oxide catalysts, polymetallic oxide catalysts, and supported Mn-based catalysts. In the part of single manganese oxide catalysts, the effects of oxidation state, crystallinity, specific surface area, and species morphology on catalytic activity were systematically reviewed. In the part of polymetallic oxides catalysts, Mn-based catalysts were studied from the aspects of preparation strategy, catalytic performance, resistance to H 2 O and SO 2 , and broadening the operating temperature window. In the part of supported metal oxides, Mn-based catalysts supported on Al 2 O 3 , TiO 2 , CeO 2 , activated carbon fibers, and carbon nanotubes were reviewed. In addition, the mechanisms of hydrothermal deactivation, chemical deactivation, sulfur poisoning, and hydrocarbon poisoning of Mn-based catalysts were studied. Finally, the prospects and future directions for the development of Mn-based low-temperature selective catalytic reduction catalysts are presented.
... At present, there are many reports on Mn-based catalysts, such as MnO x and Mn-based composite oxides [7] . Mn-based composite oxides mainly include the following types: SM-Mn [8] , Fe-Mn [9][10][11] , CE-Mn [12] , EU-Mn [13] , Co-Mn [14] , Mn-Ti [15] , Mn-W [16] and Ni-Mn [17,18] . These catalysts have excellent low-temperature SCR performance. ...
Nickel-manganese oxides were studied for selective catalytic reduction of NO by XRD，H2-TPR and N2 adsorption-desorption. The study was found that the catalyst Ni0.4 Mn0.6Ox showed the best SCR activity，the reasons may be as follows: Ni0.4Mn0.6Ox catalyst showed the optimal synergistic effect between nickel and manganese and appropriate redox ability, which were conducive to NH3 under the condition of low temperature catalytic reduction of NO．
... Liu et al. [35] have reported that the Mo doping enhanced the adsorption and activation of NH 3 for CeO 2 /TiO 2 catalyst. Guo et al. [36] found that the modification of Mn-TiO x by Mo species could improve its resistance to P species in NH 3 -SCR reaction. Recently, Sun et al. [37] reported that doping proper amount Mo could effectively enhance the SCR catalytic properties of Mn/TiO 2 and the tolerance of SO 2 , which was mainly attributed to the specific surface area and surface adsorbed oxygen species. ...
Mo a MnTi 10 O x (a= 0.2, 0.4, 0.6 and 0.8) catalysts have been prepared by sol-gel and applied in the NH 3 -SCR of NO reaction. These catalysts were characterized by XRD, H 2 -TPR, NH 3 -TPD, XPS and in situ DRIFTS. Among the Mo a MnTi 10 O x catalysts, Mo 0.6 MnTi 10 O x exhibits the excellent NH 3 -SCR performance with a broaden activity temperature window even in presence of 5 vol.% H 2 O, together with an excellent resistance of H 2 O and SO 2 . Compared with MnTi 10 O x , the Mo addition leads to the reduction of redox ability, improvement of the surface acid sites and inhibition of NO adsorption. A serial of characterizations confirms that the synergistic effect between redox property and surface acidity plays a key role in the much better NH 3 -SCR activity over Mo 0.6 MnTi 10 O x . Furthermore, the in situ DRIFTS studies reveal the NH 3 -SCR reaction is following the E-R mechanism over Mo 0.6 MnTi 10 O x at 210 °C. In addition, the effects of H 2 O on the NH 3 -SCR reaction are investigated by in situ DRIFTS.
NiCuFe layered double oxide (LDO) catalysts were synthesized using co-precipitation, impregnation, and urea hydrothermal methods. The NH3-SCR activity of NiCuFe-LDO catalysts was investigated to determine the effect of different synthesis methods. All NiCuFe-LDO samples exhibited good catalytic performance at low temperatures, with the sample synthesized using the urea hydrothermal method (NiCuFe-LDO-3) being the most efficient catalyst. The NiCuFe-LDO-3 catalyst achieved over 80% NO conversion in the temperature range of 180 °C to 280 °C, with a peak of 95.13% at 240 °C. The physicochemical properties of the samples were systematically characterized using XRD, SEM, BET, NH3-TPD, H2-TPR, XPS, and in-situ DRIFTS. The results showed that the NiCuFe-LDO-3 sample had the best crystallinity, as demonstrated by XRD and SEM. BET analysis revealed that the NiCuFe-LDO-3 sample had the largest specific surface area. The NiCuFe-LDO-3 sample was found to have more acidic sites and a better redox capacity than the other samples, according to the H2-TPR and NH3-TPD results. In-situ DRIFTS analysis showed that the catalyst operates through both E–R and L–H reaction mechanisms.
In this work, a flower-like TiO2 support was firstly synthesized via the hydrothermal method, and then Mn and Ce were loaded onto the synthesized flower-like TiO2 carrier by impregnation for the selective catalytic reduction of NO with NH3 (NH3-SCR). The activity test results manifested that the flower-like MnCe/TiO2 (MnCe/TiO2-FL) catalyst exhibited marvelous SCR performance (almost 100% NO conversion in the range of 150-250 °C) and satisfactory resistance to SO2 and H2O. Based on a series of characterization experiments, it could be found that the MnCe/TiO2-FL catalyst possessed a larger surface area, higher Ce³⁺ and Mn⁴⁺ content, superior surface acidity and redox performance, which greatly ameliorated to the SCR performance of the MnCe/TiO2-FL catalyst. Furthermore, the accelerated surface adsorbed oxygen mobility and the increased quantity of active species also promoted to the SCR activity of MnCe/TiO2-FL at low temperatures.
Widening the operation temperature window of selective catalytic reduction NO by NH3 (NH3-SCR) is a challenge to meet the increasingly stringent emission control regulations of NOx. Hence, MnFeOx with different...
The novel CeO2/TiO2 catalysts were modified by W in this work. It revealed that W modification could significantly facilitate the capacity of CeO2/TiO2 catalyst for resisting Pb poisoning. And various characterizations were applied to explore the underlying resistance mechanism. XPS and H2-TPR analysis revealed that the W modification promoted the transformation from surface Ce⁴⁺ to Ce³⁺. Then the increased surface Ce³⁺ along with highly dispersed W species provided more Brønsted acid sites for NH3 adsorption on the surface of CeO2/TiO2 catalyst (NH3-TPD and DFT). By XPS and NO+O2 co-adsorption results, the oxidation of NO to NO2 was motivated due to the increased surface chemisorbed oxygen. Furthermore, both E-R and L-H mechanisms were suitable for the NH3-SCR reaction over CWT and CT catalysts according to in situ DRIFT analysis. The deposition of PbO merely inhibited the NH3 and NOx adsorption, while the NH3-SCR mechanism wasn't changed.
A series of Sb-doped CeVO4 samples were synthetized by hydrothermal method and used in selective catalytic reduction of NO with NH3. Contrasted with other catalysts, Sb2CeVO4 possessed superior NH3-SCR activity and excellent SO2 tolerance. Besides, the characterization results testified that Sb species in Sb2CeVO4 could reduce the crystallization of CeVO4, and improve the surface acidity and reducibility. Moreover, the existence of Sb³⁺ was beneficial to generate more surface adsorbed oxygen species. Based on the in situ DRIFT spectra, more ad-NH3 and ad-NOx species with higher reactivity were obtainable on Sb2CeVO4 catalyst compared with that on CeVO4 catalyst, which also contributed to enhancing the SCR activity by Langmuir-Hinshelwood (L-H) mechanism effectively.
xMo/TiO2 catalysts (x = 1, 2, 3, and 4%) were prepared using the coprecipitation method in the present study. The coprecipitation method was used in the thermal catalytic decomposition of H2O2 steam to treat NO
x
at a low temperature range (80-160 °C). Several characterization techniques have been employed, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller measurements, transmission electron microscopy (TEM), scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM-EDXS), and Fourier transform infrared spectroscopy. The activity tests showed that the incorporation of molybdenum into TiO2 led to a significant increase in the catalytic oxidation of NO, and under the condition of H2O2/NO = 6:1 (molar ratio), the NO
x
removal rate of 2% Mo/TiO2 is the highest, reaching 92.56%. XRD, TEM, and SEM-EDXS analyses showed that Mo was well dispersed on the surface of an anatase-phase TiO2. XPS analysis indicated that Mo mixed with slag mainly existed in the form of Mo6+. Moreover, in comparison with the mostly reported SCO catalysts, used for the elimination of NO, the prepared Mo/TiO2 catalyst showed excellent stability and sulfur resistance.
