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Li J, Ma S, Ren K, Xu N. Studies on the preparation of fly ash-derived Fe-SSZ-13 catalysts and their performance in the catalytic oxidation of NO by H2O2. MOLECULAR CATALYSIS 2023. [DOI: 10.1016/j.mcat.2023.112920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Catalytic Performance and Sulfur Dioxide Resistance of One-Pot Synthesized Fe-MCM-22 in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia (NH3-SCR)—The Effect of Iron Content. Int J Mol Sci 2022; 23:ijms231810754. [PMID: 36142666 PMCID: PMC9501588 DOI: 10.3390/ijms231810754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/07/2022] [Accepted: 09/11/2022] [Indexed: 11/17/2022] Open
Abstract
The catalytic performance of Fe-catalysts in selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) strongly depends on the nature of iron sites. Therefore, we aimed to prepare and investigate the catalytic potential of Fe-MCM-22 with various Si/Fe molar ratios in NH3-SCR. The samples were prepared by the one-pot synthesis method to provide high dispersion of iron and reduce the number of synthesis steps. We have found that the sample with the lowest concentration of Fe exhibited the highest catalytic activity of ca. 100% at 175 °C, due to the abundance of well-dispersed isolated iron species. The decrease of Si/Fe limited the formation of microporous structure and resulted in partial amorphization, formation of iron oxide clusters, and emission of N2O during the catalytic reaction. However, an optimal concentration of FexOy oligomers contributed to the decomposition of nitrous oxide within 250–400 °C. Moreover, the acidic character of the catalysts was not a key factor determining the high conversion of NO. Additionally, we conducted NH3-SCR catalytic tests over the samples after poisoning with sulfur dioxide (SO2). We observed that SO2 affected the catalytic performance mainly in the low-temperature region, due to the deposition of thermally unstable ammonium sulfates.
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Lew CM, Chen CY, Long GJ, Grandjean F, Ichimura AS, Xie D, Grosso-Giordano NA, Chakarawet K, Lacheen HS, Jensen KO, Martinez A, Katz A, Zhan BZ, Zones SI. Synthesis, Physicochemical Characterization, and Catalytic Evaluation of Fe 3+-Containing SSZ-70 Zeolite. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Cong-Yan Chen
- Chevron Technical Center, Richmond, California 94801, United States
| | - Gary J. Long
- Missouri University of Science and Technology, University of Missouri, Rolla, Missouri 65409-0010, United States
| | - Fernande Grandjean
- Missouri University of Science and Technology, University of Missouri, Rolla, Missouri 65409-0010, United States
| | - Andrew S. Ichimura
- San Francisco State University, San Francisco, California 94132, United States
| | - Dan Xie
- Chevron Technical Center, Richmond, California 94801, United States
| | | | | | | | - Kurt O. Jensen
- Chevron Technical Center, Richmond, California 94801, United States
| | - Abraham Martinez
- University of California Berkeley, Berkeley, California 94720, United States
| | - Alexander Katz
- University of California Berkeley, Berkeley, California 94720, United States
| | - Bi-Zeng Zhan
- Chevron Technical Center, Richmond, California 94801, United States
| | - Stacey I. Zones
- Chevron Technical Center, Richmond, California 94801, United States
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Catalytic Performance of One-Pot Synthesized Fe-MWW Layered Zeolites (MCM-22, MCM-36, and ITQ-2) in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia. Molecules 2022; 27:molecules27092983. [PMID: 35566333 PMCID: PMC9104601 DOI: 10.3390/molecules27092983] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/28/2022] [Accepted: 05/01/2022] [Indexed: 01/17/2023] Open
Abstract
The application of layered zeolites of MWW topology in environmental catalysis has attracted growing attention in recent years; however, only a few studies have explored their performance in selective catalytic reduction with ammonia (NH3-SCR). Thus, our work describes, for the first time, the one-pot synthesis of Fe-modified NH3-SCR catalysts supported on MCM-22, MCM-36, and ITQ-2. The calculated chemical composition of the materials was Si/Al of 30 and 5 wt.% of Fe. The reported results indicated a correlation between the arrangement of MWW layers and the form of iron in the zeolitic structure. We have observed that one-pot synthesis resulted in high dispersion of Fe3+ sites, which significantly enhanced low-temperature activity and prevented N2O generation during the reaction. All of the investigated samples exhibited almost 100% NO conversion at 250 °C. The most satisfactory activity was exhibited by Fe-modified MCM-36, since 50% of NO reduction was obtained at 150 °C for this catalyst. This effect can be explained by the abundance of isolated Fe3+ species, which are active in low-temperature NH3-SCR. Additionally, SiO2 pillars present in MCM-36 provided an additional surface for the deposition of the active phase.
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