The effect of Fe species distribution and acidity of Fe-ZSM-5 on the hydrothermal stability and SO2 and hydrocarbons durability in NH3-SCR reaction

Shi, Xun; Xie, Lijuan

doi:10.1016/s1872-2067(14)60268-0

Cited by 43 publications

(15 citation statements)

References 39 publications

(68 reference statements)

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“…For three fresh samples, it was observed that all of the identified diffraction peaks could be ascribed to the mixed phase of HZSM-5 and the related doped oxides (Cr 2 O 3 , Fe 2 O 3 , and CuO). 7,24,25 For used Cr−O/HZSM-5 catalysts and Fe−O/ HZSM-5, no phase transformations were observed in XRD patterns compared to the fresh samples. It was worth noting that there were several new diffraction peaks (2θ = 16.0, 32.4, 39.9, 40.2, 57.2°) that emerged for Cu−O/HZSM-5(s) after 300 min reaction, as marked in Figure 7(c).…”

Section: Methodsmentioning

confidence: 99%

Catalytic Combustion of Dichloromethane over HZSM-5-Supported Typical Transition Metal (Cr, Fe, and Cu) Oxide Catalysts: A Stability Study

Liu

Yao

et al. 2016

J. Phys. Chem. C

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In this paper, three kinds of HZSM-5-supported transition metal (Cr, Fe, and Cu) oxide catalysts were prepared by the wet impregnation method, and their stability performances for catalytic combustion of dichloromethane (DCM) were investigated. Different behaviors were observed for these three catalysts during a 300 min catalytic reaction running at 320 °C. It was found that the Cr−O/HZSM-5 catalyst showed good catalytic stability, while both Fe−O/ HZSM-5 and Cu−O/HZSM-5 suffered obvious deactivation. Characterizations using XRD, BET, XPS, O 2 -TG, O 2 -TP-MS, NH 3 −IR, and temperatureprogrammed surface reaction (TPSR) techniques were then carried out to disclose the deactivation mechanisms. The results revealed that the main cause of the deactivation over the Fe−O/HZSM-5 catalyst was coke formation, which could be mainly attributed to its lower deep oxidation capacity of the intermediate products, i.e., the methoxy groups, and it could also be obtained that the Cu−O/ HZSM-5 catalyst was severely poisoned by chlorine species owing to the formation of stable Cu(OH)Cl species. Based on the results above, it could be concluded that the close proximity and synergy between acidic sites and active oxygen species were crucial to avoid coke deposition during the chlorinated volatile organic compound catalytic oxidation process.

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Section: Methodsmentioning

confidence: 99%

Catalytic Combustion of Dichloromethane over HZSM-5-Supported Typical Transition Metal (Cr, Fe, and Cu) Oxide Catalysts: A Stability Study

Liu

Yao

et al. 2016

J. Phys. Chem. C

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“…Wang [11] also stated that the Fe 2 O 3 particles had a good performance during NO x elimination, where the highest NO x conversion reached 95%. Yang et al [12] claimed that α-Fe 2 O 3 had a poor SCR activity, while γ-Fe 2 O 3 had an excellent SCR activity at 200-350 • C. Meanwhile, it was also found that the further increase reaction temperature from 350 to 500 • C would suppress NOx conversion over γ-Fe 2 O 3 [13].…”

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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“…The spectral series can be divided in three regions: the NH 4 + -chemisorption and Lewis acid sites region (1400-2000 cm −1 ), the N-H stretching region (2000-3500 cm −1 ) and the -OH stretching region (3500-4000 cm −1 ). In the first region, the absorption peaks at 1488 [28], 1745 [29,30] and 1946 cm −1 [30] show similar intensities among all samples and they are assigned to NH 4 + adsorbed on BASs. The peak at 1592 cm −1 , assigned to NH 3 adsorbed on Lewis sites [29], is more pronounced in the spectrum of the Al-silicalite sample and almost disappears in the spectrum of the Fe-silicalite sample.…”

Section: Nh 3 Adsorptionmentioning

confidence: 87%

Tuned Acidity for Catalytic Reactions: Synthesis and Characterization of Fe- and Al-MFI Zeotypes

et al. 2019

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The addition of elements other than Al in the framework structures of zeotype materials gives the opportunity to tune the acidity of the zeotype and thus might expand the possibilities in the field of acid-catalyzed reactions. Here, we have synthesized silicalite (MFI) with and without Fe and/or Al in the framework structure. To understand the mechanism of the removal of the structure directing agent (SDA) from the as synthesized samples we combine X-ray diffraction, nitrogen sorption and in situ IR spectroscopy experiments. IR spectroscopy is also used to examine the acid species with and without NH 3 as probe molecule. Furthermore, NO adsorption is performed to characterize the different metal species. The results of the IR experiments during calcination of the SDA suggest that the SDA first loses contact with the internal surface of the zeotype and then at higher temperature is oxidized to CO 2. The IR spectra of the zeotype samples in the H +-form show that the sample containing both Fe and Al shows a broader and less intense peak at 3620 cm −1 indicating the presence of two distinct Brønsted acid sites, one associated to Fe and one to Al. The IR experiments after NH 3 adsorption confirm these results and thus the following series of increasing acidity could be outlined: 0 = pure silicalite < Fe-silicalite < Fe/Al-silicalite < Al-silicalite. Finally, the IR experiments after NO adsorption shows the presence of nitrates in the Fe-containing samples suggesting the formation of extra framework Fe species.

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The effect of Fe species distribution and acidity of Fe-ZSM-5 on the hydrothermal stability and SO2 and hydrocarbons durability in NH3-SCR reaction

Cited by 43 publications

References 39 publications

Catalytic Combustion of Dichloromethane over HZSM-5-Supported Typical Transition Metal (Cr, Fe, and Cu) Oxide Catalysts: A Stability Study

Catalytic Combustion of Dichloromethane over HZSM-5-Supported Typical Transition Metal (Cr, Fe, and Cu) Oxide Catalysts: A Stability Study

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

Tuned Acidity for Catalytic Reactions: Synthesis and Characterization of Fe- and Al-MFI Zeotypes

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