H2O and SO2 deactivation mechanism of MnOx/MWCNTs for low-temperature SCR of NOx with NH3

Pan, Siwei; Luo, Huimin; Li, Li; Wei, Zhengle; Huang, Bichun

doi:10.1016/j.molcata.2013.05.009

Cited by 117 publications

(44 citation statements)

References 46 publications

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“…It can be deduced from Figure 2 that the poisoning of SO2 on the SCR activity of the catalysts was most likely caused by the sulfation of the active sites. This coincides with the work of Pan [24]. The addition of Ce or Y on MnZr slowed the sulfation progress and resulted in the improvement of SO2 resistance.…”

Section: Scr Performancesupporting

confidence: 85%

Effect of Ce/Y Addition on Low-Temperature SCR Activity and SO2 and H2O Resistance of MnOx/ZrO2/MWCNTs Catalysts

et al. 2017

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Abstract:The effects of SO 2 and H 2 O on the low-temperature selective catalytic reduction (SCR) activity over MnO x /ZrO 2 /MWCNTs and MnO x /ZrO 2 /MWCNTs catalysts modified by Ce or Y was studied. MnCeZr and MnYZr catalysts reached nearly 100% and 93.9% NO x conversions at 200 • C and 240 • C, respectively. They displayed a better SO 2 tolerance, and the effect of H 2 O was negligible. The structural properties of the catalysts were characterized by XRD, H 2 -TPR, XPS, and FTIR before and after the reaction. The results showed that Ce could increase the mobility of the oxygen and improve the valence and the oxidizability of manganese, while the effect of Y was the opposite. This might be the main reason why the catalytic activity of MnCeZr was better than MnYZr in the presence or absence of SO 2 and H 2 O. Doping Ce or Y broadened the active temperature window. Ce or Y, which existed in the catalysts with a high dispersion or at the amorphous state, preferred to react with SO 2 to form sulfate species, and protected the manganese active sites from combing with SO 2 to some extent, which coincided with the theory of ionic polarization.

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Section: Scr Performancesupporting

confidence: 85%

Effect of Ce/Y Addition on Low-Temperature SCR Activity and SO2 and H2O Resistance of MnOx/ZrO2/MWCNTs Catalysts

et al. 2017

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“…The decrease of SCR activity with the increase of space velocity has also been reported by other researchers [26]. Pan et al [30] reported that H 2 O has a reversible negative effect on NH 3 -SCR using a MnO x /MWCNTs catalyst, while SO 2 was found to have an irreversible deactivation effect.…”

Section: Introductionsupporting

confidence: 76%

“…SO2 is known to have a negative effect on NO conversion due to catalyst poisoning [6,11,30]. As shown in Figure 8, for all of the tested three catalysts (Mn/AC, Ce/AC and Mn-Ce/AC), the CO2 From Figure 7, it seems that for the Mn/AC catalyst, higher NO conversion was observed under the CO 2 atmosphere compared with the N 2 atmosphere, under high space velocity (13,632 h´1).…”

Section: −1mentioning

confidence: 99%

“…Furthermore, it is known that SCR performance is significantly affected by the process conditions such as temperature, space velocity [26][27][28], concentrations of H 2 O [25,[29][30][31], and the presence of SO 2 [6,11,25,30,32,33]. For example, Magnusson et al [25] investigated SCR using a marine based catalyst; they reported that higher space velocity (18,300 h´1) resulted in a continuous decrease in catalytic activity, compared with space velocities of 6100 and 12,200 h´1; in addition, they also reported that at temperatures higher than 300˝C, the catalyst showed a stable catalytic reactivity at different SO 2 concentrations, but a significant reduction of SCR activity was observed at a temperature of 250˝C for gas streams containing 250 and 750 ppm SO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

Gou

Zhang

et al. 2015

Energies

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Selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) has been widely investigated to reduce NO x emissions from combustion processes, which cause environmental challenges. However, most of the current work on NO x reduction has focused on using feed gas without CO 2 or containing small amounts of CO 2 . In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO 2 in flue gas. Therefore, studies on the SCR process under concentrated CO 2 atmosphere conditions are important for future SCR deployment in oxy-fuel combustion processes. In this work, Mn-and Ce-based catalysts using activated carbon as support were used to investigate the effect of CO 2 on NO conversion. A N 2 atmosphere was used for comparison. Different process conditions such as temperature, SO 2 concentration, H 2 O content in the feed gas and space velocity were studied. Under Mn-Ce/AC conditions, the results suggested that Mn metal could reduce the inhibition effect of CO 2 on the NO conversion, while Ce metal increased the inhibition effect of CO 2 . High space velocity also resulted in a reduction of CO 2 inhibition on the NO conversion, although the overall performance of SCR was greatly reduced at high space velocity. Future investigations to design novel Mn-based catalysts are suggested to enhance the SCR performance under concentrated CO 2 atmosphere conditions.

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“…Consequently, the catalyst activity significantly decreased after SO 2 poisoning. The S 2p XPS of the sulphated Mn-Ce/Al 2 O 3 catalyst ( Figure 7d) had two sub-peaks at 168.7 eV and 169.7 eV, assigned to the SO 3 2-and SO 4 2− species, respectively [39,40]. This result confirmed that sulfate species were formed over the sulphated Mn-Ce/Al 2 O 3 .…”

Section: Xpssupporting

confidence: 54%

Poisoning Effect of SO2 on Honeycomb Cordierite-Based Mn–Ce/Al2O3Catalysts for NO Reduction with NH3 at Low Temperature

et al. 2018

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Honeycomb cordierite-based Mn-Ce/Al 2 O 3 catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR) of NO x with NH 3 , with and without SO 2 and/or H 2 O in a homemade fixed-bed tubular reactor. The catalyst reached nearly 80% NO x conversion at 100 • C in the absence of SO 2 . However, SO 2 reduces the catalytic activity (80% to 72%) of the honeycomb cordierite-based Mn-Ce/Al 2 O 3 catalysts under identical conditions. This finding demonstrated that the catalyst exhibited high activity at low temperature and excellent SO 2 resistance in the presence of 50 ppm SO 2 . The fresh and sulfated honeycomb cordierite-based Mn-Ce/Al 2 O 3 catalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N 2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG-DTA), and Fourier transform infrared (FT-IR) spectroscopy. Characterization results indicated that the deactivation by SO 2 was primarily the result of the deposition of ammonium hydrogen sulfate and sulfated CeO 2 on the catalyst surface during the SCR process. The formed sulfates depressed the catalytic activity via the blocking of pores and the occupation of active sites. Additionally, the competitive adsorption between SO 2 and NH 3 always decreased the catalytic activity.

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H2O and SO2 deactivation mechanism of MnOx/MWCNTs for low-temperature SCR of NOx with NH3

Cited by 117 publications

References 46 publications

Effect of Ce/Y Addition on Low-Temperature SCR Activity and SO2 and H2O Resistance of MnOx/ZrO2/MWCNTs Catalysts

Effect of Ce/Y Addition on Low-Temperature SCR Activity and SO2 and H2O Resistance of MnOx/ZrO2/MWCNTs Catalysts

Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

Poisoning Effect of SO2 on Honeycomb Cordierite-Based Mn–Ce/Al2O3Catalysts for NO Reduction with NH3 at Low Temperature

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