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Title: Design of MoFe/Beta@CeO 2 catalysts with a core$-$shell structure and their catalytic performances for the selective catalytic reduction of NO with NH 3

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
FOREIGN
OSTI Identifier:
1339740
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis. B, Environmental; Journal Volume: 203
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Liu, Jixing, Du, Yuhao, Liu, Jian, Zhao, Zhen, Cheng, Kai, Chen, Yongsheng, Wei, Yuechang, Song, Weiyu, and Zhang, Xiao. Design of MoFe/Beta@CeO2 catalysts with a core$-$shell structure and their catalytic performances for the selective catalytic reduction of NO with NH3. United States: N. p., 2017. Web. doi:10.1016/j.apcatb.2016.10.039.
Liu, Jixing, Du, Yuhao, Liu, Jian, Zhao, Zhen, Cheng, Kai, Chen, Yongsheng, Wei, Yuechang, Song, Weiyu, & Zhang, Xiao. Design of MoFe/Beta@CeO2 catalysts with a core$-$shell structure and their catalytic performances for the selective catalytic reduction of NO with NH3. United States. doi:10.1016/j.apcatb.2016.10.039.
Liu, Jixing, Du, Yuhao, Liu, Jian, Zhao, Zhen, Cheng, Kai, Chen, Yongsheng, Wei, Yuechang, Song, Weiyu, and Zhang, Xiao. Sat . "Design of MoFe/Beta@CeO2 catalysts with a core$-$shell structure and their catalytic performances for the selective catalytic reduction of NO with NH3". United States. doi:10.1016/j.apcatb.2016.10.039.
@article{osti_1339740,
title = {Design of MoFe/Beta@CeO2 catalysts with a core$-$shell structure and their catalytic performances for the selective catalytic reduction of NO with NH3},
author = {Liu, Jixing and Du, Yuhao and Liu, Jian and Zhao, Zhen and Cheng, Kai and Chen, Yongsheng and Wei, Yuechang and Song, Weiyu and Zhang, Xiao},
abstractNote = {},
doi = {10.1016/j.apcatb.2016.10.039},
journal = {Applied Catalysis. B, Environmental},
number = ,
volume = 203,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • Isotopic tracer studies were performed to investigate the reaction network of selective catalytic reduction of nitric oxide over vanadia catalysts having preferential exposure of different crystal planes. The catalysts were characterized using BET surface area analysis, X-ray diffraction, laser Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, 3-D imaging, and thermal analysis techniques. The product analysis was carried out by a combination of chemiluminescence NO{sub x} analysis, gas chromatography-mass spectrometry, and chemical titration methods. The isotropic labeling experiments were performed under steady state reaction conditions by using NH{sub 3} + NO + {sup 16}O{sub 2} {r_arrow} NH{sub 3} + NOmore » + {sup 18}O{sub 2}, {sup 14}NH{sub 3} + NO + O{sub 2} {r_arrow} {sup 15}NH{sub 3} + NO + O{sub 2}, NH{sub 3} + {sup 14}NO + O{sub 2} {r_arrow} NH{sub 3} + {sup 15}NO + O{sub 2}, and NH{sub 3} + {sup 14}N{sup 16}O + {sup 16}O{sub 2} {r_arrow} NH{sub 3} + {sup 15}N{sub 18}O + {sup 18}O{sub 2} switches. Interaction of NO with the vanadia surface was also studied using a {sup 14}N{sup 16}O {r_arrow} {sup 15}N{sup 18}O switch. The results obtained in these experiments were combined with the tracer studies performed in ammonia oxidation reactions over the same catalysts to elucidate the reaction pathways involved in SCR reactions, to compare the surface residence times of nitrogen containing species, as well as to quantify the role of ammonia oxidation in SCR reactions. 35 refs., 14 figs., 3 tabs.« less
  • The products of the reaction between [sup 15]NO and [sup 14]NH[sub 3] over V[sub 2]O[sub 5]/TiO[sub 2]and [alpha]-Cr[sub 2]O[sub 3] catalysts in the absence of oxygen have been determined by mass spectrometry and Fourier transform infrared spectroscopy. With both catalysts [sup 14]N[sup 15]N comprises approximately two-thirds of the nitrogen-containing products. Very surprisingly, [sup 15]NH[sub 3] makes up about one-half the remainder. This has significant implications for the likely mechanism of the SCR reaction in the absence of oxygen. Formation of [sup 15]NH[sub 3] by direct exchange of both hydrogen and oxygen between [sup 14]NH[sub 3] and [sup 15]NO molecules canmore » be ruled out since no [sup 14]NO is produced. It seems that [sup 15]NO is broken down to separate [sup 15]N and oxygen species on reduced sites and that [sup 15]NH[sub 3] can then be made by reaction of the [sup 15]N species with water. It is possible that the nitrogen-containing species is an NH group. With V[sub 2]O[sub 5]/TiO[sub 2] the only remaining product is [sup 14]N[sup 15]NO. However, this is largely replaced by doubly labeled products, [sup 14]N[sub 2], [sup 15]N[sub 2], and [sup 15]N[sub 2]O, when using [alpha]-Cr[sub 2]O[sub 3]. 22 refs., 1 fig., 2 tabs.« less
  • We compared the molecular structures, surface acidity and catalytic activity for NO/NH 3/O 2 SCR of V 2O 5-WO 3/TiO 2 catalysts for two different synthesis methods: co-precipitation of aqueous vanadium and tungsten oxide precursors with TiO(OH) 2 and by incipient wetness impregnation of the aqueous precursors on a reference crystalline TiO 2 support (P25; primarily anatase phase). Bulk analysis by XRD showed that co-precipitation results in small and/or poorly ordered TiO 2(anatase) particles and that VO x and WO x do not form solid solutions with the bulk titania lattice. Surface analysis of the co-precipitated catalyst by High Sensitivity-Lowmore » Energy Ion Scattering (HS-LEIS) confirms that the VO x and WO x are surface segregated for the co-precipitated catalysts. In situ Raman and IR spectroscopy revealed that the vanadium and tungsten oxide components are present as surface mono-oxo O = VO 3 and O = WO 4 sites on the TiO 2 supports. Co-precipitation was shown for the first time to also form new mono-oxo surface VO 4 and WO 4 sites that appear to be anchored at surface defects of the TiO 2 support. IR analysis of chemisorbed ammonia showed the presence of both surface NH 3 * on Lewis acid sites and surface NH 4 +* on Brønsted acid sites. TPSR spectroscopy demonstrated that the specific SCR kinetics was controlled by the redox surface VO 4 species and that the surface kinetics was independent of TiO 2 synthesis method or presence of surface WO 5 sites. SCR reaction studies revealed that the surface WO5 sites possess minimal activity below ~325 °C and their primary function is to increase the adsorption capacity of ammonia. A relationship between the SCR activity and surface acidity was not found. The SCR reaction is controlled by the surface VO 4 sites that initiate the reaction at ~200 °C. The co-precipitated catalysts were always more active than the corresponding impregnated catalysts. Finally, we ascribe the higher activity of the co-precipitated catalysts to the presence of the new surface WO x sites associated surface defects on the TiO 2 support that increase the ammonia adsorption capacity.« less
  • A series of supported WO 3/TiO 2 catalysts was prepared by a new synthesis procedure involving co-precipitation of an aqueous TiO(OH) 2 and (NH 4) 10W 12O 41*5H 2O slurry under controlled pH conditions. The morphological properties, molecular structures, surface acidity and surface chemistry of the supported WO 3/TiO 2 catalysts were determined with BET, in situ Raman, in situ IR and temperature-programmed surface reaction (TPSR) spectroscopy, respectively. Isotopic 18O- 16O exchange demonstrated that tungsten oxide was exclusively present as surface WO x species on the TiO 2 support with mono-oxo W=O coordination. In contrast to previous studies employing impregnationmore » synthesis that found only surface one mono-oxo O=WO 4 site on TiO 2, the co-precipitation procedure resulted in the formation of two distinct surface WO x species: mono-oxo O=WO 4 (~1010-1017 cm -1) on low defect density patches of TiO 2 and a second mono-oxo O=WO 4 (~983-986 cm -1) on high defect density patches of TiO 2. The concentration of the second WO x surface species increases as a function of solution pH. Both surface WOx sites, however, exhibited the same NO/NH 3 SCR reactivity. The co-precipitated WO 3-TiO 2 catalysts synthesized in alkaline solutions exhibited enhanced performance for the NO/NH 3 SCR reaction that is ascribed to the greater number of surface defects on the resulting TiO2 support. For the co-precipitated catalyst prepared at pH10, surface NH 4 + species on Br nsted acid sites were found to be more reactive than surface NH 3* species on Lewis acid sites for SCR of NO with NH 3.« less