In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian

doi:10.1016/j.apsusc.2017.11.180

Cited by 100 publications

(54 citation statements)

References 47 publications

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“…Selective catalytic reduction (SCR) over V 2 O 5 -WO 3 (MoO 3 )/TiO 2 catalyst has been widely applied in power stations because of its high denitration efficiency [5][6][7]. However, there are still shortcomings such as the toxicity of the catalyst, and the high operation costs [8]. In particular, the reaction temperature of the current commercial catalysts is higher than the temperature of the sintering flue gas [9].…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Chen

Qin

et al. 2019

Catalysts

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A sulfated sintered ore catalyst (SSOC) was prepared to improve the denitration performance of the sintered ore catalyst (SOC). The catalysts were characterized by X-ray Fluorescence Spectrometry (XRF), Brunauer–Emmett–Teller (BET) analyzer, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared spectroscopy (DRIFTS) to understand the NH3-selective catalytic reduction (SCR) reaction mechanism. Moreover, the denitration performance and stability of SSOC were also investigated. The experimental results indicated that there were more Brønsted acid sites at the surface of SSOC after the treatment by sulfuric acid, which lead to the enhancement of the adsorption capacity of NH3 and NO. Meanwhile, Lewis acid sites were also observed at the SSOC surface. The reaction between −NH2, NH 4 + and NO (E-R mechanism) and the reaction of the coordinated ammonia with the adsorbed NO2 (L-H mechanism) were attributed to NOx reduction. The maximum denitration efficiency over the SSOC, which was about 92%, occurred at 300 °C, with a 1.0 NH3/NO ratio, and 5000 h−1 gas hourly space velocity (GHSV).

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Section: Introductionmentioning

confidence: 99%

Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Chen

Qin

et al. 2019

Catalysts

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“…Figure 12 showed the NH 3 adsorption results on V-0.2Ce/Ti–Zr in the presence of SO 2 . It could be found that original adsorption capacity of NH 3 was very weak, and only the band at 1182 cm −1 was observed [26]. Then NH 3 was switched off and SO 2 + O 2 was introduced.…”

Section: Resultsmentioning

confidence: 99%

Effect of SO2 on the Selective Catalytic Reduction of NOx over V2O5-CeO2/TiO2-ZrO2 Catalysts

Zhang

Zhuang

et al. 2019

Materials

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The effect of SO2 on the selective catalytic reduction of NOx by NH3 over V2O5-0.2CeO2/TiO2-ZrO2 catalysts was studied through catalytic activity tests and various characterization methods, like Brunner−Emmet−Teller (BET) surface measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence (XRF), hydrogen temperature-programmed desorption (H2-TPR), X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the catalyst exhibited superior SO2 resistance when the volume fraction of SO2 was below 0.02%. As the SO2 concentration further increased, the NOx conversion exhibited some degree of decline but could restore to the original level when stopping feeding SO2. The deactivation of the catalyst caused by water in the flue gas was reversible. However, when 10% H2O was introduced together with 0.06% SO2, the NOx conversion was rapidly reduced and became unrecoverable. Characterizations indicated that the specific surface area of the deactivated catalyst was significantly reduced and the redox ability was weakened, which was highly responsible for the decrease of the catalytic activity. XPS results showed that more Ce3+ was generated in the case of reacting with SO2. In situ DRIFTS results confirmed that the adsorption capacity of SO2 was enhanced obviously in the presence of O2, while the SO2 considerably refrained the adsorption of NH3. The adsorption of NOx was strengthened by SO2 to some extent. In addition, NH3 adsorption was improved after pre-adsorbed by SO2 + O2, indicating that the Ce3+ and more oxygen vacancy were produced.

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“…However, in the case of 0.6Ce/SPCC at 150 • C, the results were quite different. From Figure 7b, NO adsorbed on oxide surface for covalent bonds (M-N=O, 1696 cm −1 ) [36,40], NO 2 molecules adsorbed in active state on the surface (1602 cm −1 ) [9] and nitrite species (1468, 1402 and 1315 cm −1 ) [38,41] could be observed. The results provide evidence for NO-to-NO 2 conversion.…”

Section: Co-adsorption Of No + Omentioning

confidence: 90%

“…Among these bands, the ones located at 3368 and 3271 cm −1 could be linked to the adsorbed NH3 on Lewis acid sites, while the band centered at 1384 cm −1 could be ascribed to the NH4 + on Brønsted acid sites [34]. The two bands located at 1580 and 1295 cm −1 were associated to the -NH2 species [35,36]. Based on the above analysis, both 0.6Ce/CPCC and 0.6Ce/SPCC have Lewis and Brønsted acid sites on the surface.…”

Section: Adsorption Of Nh3mentioning

confidence: 99%

In Situ DRIFTS Investigation on CeOx Catalyst Supported by Fly-Ash-Made Porous Cordierite Ceramics for Low-Temperature NH3-SCR of NOX

Wang

Chen

et al. 2019

Catalysts

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A series of CeOx catalysts supported by commercial porous cordierite ceramics (CPCC) and synthesized porous cordierite ceramics (SPCC) from fly ash were prepared for selective catalytic reduction of NOx with ammonia (NH3-SCR). A greater than 90% NOx conversion rate was achieved by the SPCC supported catalyst at 250–300 °C when the concentration of loading precursor was 0.6 mol/L (denoted as 0.6Ce/SPCC), which is more advantageous than the CPCC supported ones. The EDS mapping results reveal the existence of evenly distributed impurities on the surface of SPCC, which hence might be able to provide more attachment sites for CeOx particles. Further measurements with temperature programmed reduction by hydrogen (H2-TPR) demonstrate more reducible species on the surface of 0.6Ce/SPCC, thus giving rise to better NH3-SCR performance at a low-temperature range. The X-ray photoelectron spectroscopy (XPS) analyses reveal that the Ce atom ratio is higher in 0.6Ce/SPCC, indicating that a higher concentration of catalytic active sites could be found on the surface of 0.6Ce/SPCC. The in situ diffused reflectance infrared fourier transform spectroscopy (DRIFTS) results indicate that the SCR reactions over 0.6Ce/SPCC follow both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. Hence, the SPCC might be a promising candidate to provide support for NH3-SCR catalysts, which also provide a valuable approach to recycling the fly ash.

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In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

Cited by 100 publications

References 47 publications

Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Effect of SO2 on the Selective Catalytic Reduction of NOx over V2O5-CeO2/TiO2-ZrO2 Catalysts

In Situ DRIFTS Investigation on CeOx Catalyst Supported by Fly-Ash-Made Porous Cordierite Ceramics for Low-Temperature NH3-SCR of NOX

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