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Title: Selective catalytic reduction of NO by NH 3 with WO 3 -TiO 2 catalysts: Influence of catalyst synthesis method

Authors:
; ; ORCiD logo; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Understanding and Control of Acid Gas-induced Evolution of Materials for Energy (UNCAGE-ME)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1387434
DOE Contract Number:
SC0012577
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis. B, Environmental; Journal Volume: 188; Journal Issue: C; Related Information: UNCAGE-ME partners with Georgia Institute of Technology (lead); Lehigh University; Oak Ridge National Laboratory; University of Alabama; University of Florida; University of Wisconsin; Washington University in St. Louis
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), defects, membrane, carbon capture, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing)

Citation Formats

He, Yuanyuan, Ford, Michael E., Zhu, Minghui, Liu, Qingcai, Wu, Zili, and Wachs, Israel E.. Selective catalytic reduction of NO by NH 3 with WO 3 -TiO 2 catalysts: Influence of catalyst synthesis method. United States: N. p., 2016. Web. doi:10.1016/j.apcatb.2016.01.072.
He, Yuanyuan, Ford, Michael E., Zhu, Minghui, Liu, Qingcai, Wu, Zili, & Wachs, Israel E.. Selective catalytic reduction of NO by NH 3 with WO 3 -TiO 2 catalysts: Influence of catalyst synthesis method. United States. doi:10.1016/j.apcatb.2016.01.072.
He, Yuanyuan, Ford, Michael E., Zhu, Minghui, Liu, Qingcai, Wu, Zili, and Wachs, Israel E.. 2016. "Selective catalytic reduction of NO by NH 3 with WO 3 -TiO 2 catalysts: Influence of catalyst synthesis method". United States. doi:10.1016/j.apcatb.2016.01.072.
@article{osti_1387434,
title = {Selective catalytic reduction of NO by NH 3 with WO 3 -TiO 2 catalysts: Influence of catalyst synthesis method},
author = {He, Yuanyuan and Ford, Michael E. and Zhu, Minghui and Liu, Qingcai and Wu, Zili and Wachs, Israel E.},
abstractNote = {},
doi = {10.1016/j.apcatb.2016.01.072},
journal = {Applied Catalysis. B, Environmental},
number = C,
volume = 188,
place = {United States},
year = 2016,
month = 7
}
  • 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
  • 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