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Title: Selective Catalytic Reduction of NO by NH 3 with WO 3-TiO 2 Catalysts: Influence of Catalyst Synthesis Method

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 impregnation 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 formore » 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
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Lehigh Univ., Bethlehem, PA (United States). Operando Molecular Spectroscopy & Catalysis Lab., Dept. of Chemical & Biomolecular Engineering; Chongqing Univ., Chongqing (China). College of Materials Science and Engineering
  2. Lehigh Univ., Bethlehem, PA (United States). Operando Molecular Spectroscopy & Catalysis Lab., Dept. of Chemical & Biomolecular Engineering
  3. Chongqing Univ., Chongqing (China). College of Materials Science and Engineering
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC0012577; 51274263; 51204220
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. B, Environmental
Additional Journal Information:
Journal Volume: 188; Journal ID: ISSN 0926-3373
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Catalysts; Co-precipitated; TiO2; WO3; Spectroscopy; Raman; IR; Temperature programmed surface reaction (TPSR); Reaction; NO; NH3; Selective catalytic reduction (SCR)
OSTI Identifier:
1295096
Alternate Identifier(s):
OSTI ID: 1358764