Selective catalytic reduction of NO by NH3 with WO3-TiO2 catalysts: Influence of catalyst synthesis method

Yuanyuan He; Michael E. Ford; Minghui Zhu; Qingcai Liu; Zili Wu; Israel E. Wachs

doi:10.1016/j.apcatb.2016.01.072

Selective catalytic reduction of NO by NH₃ with WO₃-TiO₂ catalysts: Influence of catalyst synthesis method

Yuanyuan He, Michael E. Ford, Minghui Zhu, Qingcai Liu, Zili Wu, Israel E. Wachs

Surface Chemistry & Catalysis Group

Research output: Contribution to journal › Article › peer-review

58 Scopus citations

Abstract

A series of supported WO₃/TiO₂ catalysts was prepared by a new synthesis procedure involving co-precipitation of an aqueous TiO(OH)₂ and (NH₄)₁₀W₁₂O₄₁*5H₂O slurry under controlled pH conditions. The morphological properties, surface WO_x molecular structures, surface acidity and surface chemistry of the co-precipitated WO₃/TiO₂ catalysts were determined with BET, in situ Raman, in situ IR, steady-state NO/NH₃/O₂ SCR and NO/NH₃-temperature-programmed surface reaction (TPSR) spectroscopy, respectively. Time-resolved isotopic ¹⁸O-¹⁶O exchange with IR spectroscopy demonstrated that tungsten oxide was present as surface WO_x sites on the TiO₂ support with mono-oxo O = WO₄ coordination. In contrast to previous studies employing impregnation synthesis that found only surface one mono-oxo O = WO₄ site (1010-1016 cm^-1) on TiO₂, the co-precipitation procedure resulted in the formation of two distinct surface WO_x sites: mono-oxo O = WO₄ (~1012-1014 cm^-1) and a second mono-oxo O = WO₄ (~983-985 cm^-1). The new surface mono-oxo O = WO₄ (~983-985 cm^-1) site is thought to be associated with surface defects on the co-precipitated titania support. The co-precipitated catalysts exhibited slightly enhanced SCR reactivity that is thought to be related to the presence of the new surface O = WO₄ sites. Additional factors, however, may also be contributing. This is the first study that attempts to relate the molecular level structural properties of co-precipitated WO₃-TiO₂ catalysts with their surface reactivity for SCR.

Original language	English
Pages (from-to)	123-133
Number of pages	11
Journal	Applied Catalysis B: Environmental
Volume	188
DOIs	https://doi.org/10.1016/j.apcatb.2016.01.072
State	Published - Jul 5 2016

Funding

Ms. Yuanyuan He is grateful for financial support from the China Scholarship Council (CSC) for the State Scholarship and National Natural Science Funds of China (Nos. 51274263 and 51204220 ). Prof. I.E. Wachs (Lehigh University), M. Zhu (Lehigh) and Dr. Zili Wu (Oak Ridge National Laboratory) were supported by the Center for Understanding & Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME) , an Energy Frontier Research Center funded by DOE, Office of Science, Office of Basic Energy Sciences under grant DE-SC0012577 . A portion of this research including the isotopic exchange was conducted at the Center for Nanophase Materials Sciences, which is a DOE office of the Science User Facility. The authors thank D. G. Gregory and Ms. Q. Guo of Lehigh University for experimental assistance in obtaining BET and BJH data. DGG is also thanked for assistance in obtaining the XRD spectra. Dr. Henry Luftman of Lehigh University is thanked for collecting the HS-LEIS data.

Keywords

Catalysts
Co-precipitated
IR
NH
NO
Raman
Reaction
Selective catalytic reduction (SCR)
Spectroscopy
Temperature programmed surface reaction (TPSR)
TiO
WO

Access to Document

10.1016/j.apcatb.2016.01.072

Cite this

@article{c1a48e1e8a054e9db5796b6c478f83ff,

title = "Selective catalytic reduction of NO by NH3 with WO3-TiO2 catalysts: Influence of catalyst synthesis method",

abstract = "A series of supported WO3/TiO2 catalysts was prepared by a new synthesis procedure involving co-precipitation of an aqueous TiO(OH)2 and (NH4)10W12O41*5H2O slurry under controlled pH conditions. The morphological properties, surface WOx molecular structures, surface acidity and surface chemistry of the co-precipitated WO3/TiO2 catalysts were determined with BET, in situ Raman, in situ IR, steady-state NO/NH3/O2 SCR and NO/NH3-temperature-programmed surface reaction (TPSR) spectroscopy, respectively. Time-resolved isotopic 18O-16O exchange with IR spectroscopy demonstrated that tungsten oxide was present as surface WOx sites on the TiO2 support with mono-oxo O = WO4 coordination. In contrast to previous studies employing impregnation synthesis that found only surface one mono-oxo O = WO4 site (1010-1016 cm-1) on TiO2, the co-precipitation procedure resulted in the formation of two distinct surface WOx sites: mono-oxo O = WO4 (~1012-1014 cm-1) and a second mono-oxo O = WO4 (~983-985 cm-1). The new surface mono-oxo O = WO4 (~983-985 cm-1) site is thought to be associated with surface defects on the co-precipitated titania support. The co-precipitated catalysts exhibited slightly enhanced SCR reactivity that is thought to be related to the presence of the new surface O = WO4 sites. Additional factors, however, may also be contributing. This is the first study that attempts to relate the molecular level structural properties of co-precipitated WO3-TiO2 catalysts with their surface reactivity for SCR.",

keywords = "Catalysts, Co-precipitated, IR, NH, NO, Raman, Reaction, Selective catalytic reduction (SCR), Spectroscopy, Temperature programmed surface reaction (TPSR), TiO, WO",

author = "Yuanyuan He and Ford, {Michael E.} and Minghui Zhu and Qingcai Liu and Zili Wu and Wachs, {Israel E.}",

note = "Publisher Copyright: {\textcopyright} 2016 Elsevier B.V.",

year = "2016",

month = jul,

day = "5",

doi = "10.1016/j.apcatb.2016.01.072",

language = "English",

volume = "188",

pages = "123--133",

journal = "Applied Catalysis B: Environmental",

issn = "0926-3373",

publisher = "Elsevier",

}

TY - JOUR

T1 - Selective catalytic reduction of NO by NH3 with WO3-TiO2 catalysts

T2 - Influence of catalyst synthesis method

AU - He, Yuanyuan

AU - Ford, Michael E.

AU - Zhu, Minghui

AU - Liu, Qingcai

AU - Wu, Zili

AU - Wachs, Israel E.

PY - 2016/7/5

Y1 - 2016/7/5

N2 - A series of supported WO3/TiO2 catalysts was prepared by a new synthesis procedure involving co-precipitation of an aqueous TiO(OH)2 and (NH4)10W12O41*5H2O slurry under controlled pH conditions. The morphological properties, surface WOx molecular structures, surface acidity and surface chemistry of the co-precipitated WO3/TiO2 catalysts were determined with BET, in situ Raman, in situ IR, steady-state NO/NH3/O2 SCR and NO/NH3-temperature-programmed surface reaction (TPSR) spectroscopy, respectively. Time-resolved isotopic 18O-16O exchange with IR spectroscopy demonstrated that tungsten oxide was present as surface WOx sites on the TiO2 support with mono-oxo O = WO4 coordination. In contrast to previous studies employing impregnation synthesis that found only surface one mono-oxo O = WO4 site (1010-1016 cm-1) on TiO2, the co-precipitation procedure resulted in the formation of two distinct surface WOx sites: mono-oxo O = WO4 (~1012-1014 cm-1) and a second mono-oxo O = WO4 (~983-985 cm-1). The new surface mono-oxo O = WO4 (~983-985 cm-1) site is thought to be associated with surface defects on the co-precipitated titania support. The co-precipitated catalysts exhibited slightly enhanced SCR reactivity that is thought to be related to the presence of the new surface O = WO4 sites. Additional factors, however, may also be contributing. This is the first study that attempts to relate the molecular level structural properties of co-precipitated WO3-TiO2 catalysts with their surface reactivity for SCR.

AB - A series of supported WO3/TiO2 catalysts was prepared by a new synthesis procedure involving co-precipitation of an aqueous TiO(OH)2 and (NH4)10W12O41*5H2O slurry under controlled pH conditions. The morphological properties, surface WOx molecular structures, surface acidity and surface chemistry of the co-precipitated WO3/TiO2 catalysts were determined with BET, in situ Raman, in situ IR, steady-state NO/NH3/O2 SCR and NO/NH3-temperature-programmed surface reaction (TPSR) spectroscopy, respectively. Time-resolved isotopic 18O-16O exchange with IR spectroscopy demonstrated that tungsten oxide was present as surface WOx sites on the TiO2 support with mono-oxo O = WO4 coordination. In contrast to previous studies employing impregnation synthesis that found only surface one mono-oxo O = WO4 site (1010-1016 cm-1) on TiO2, the co-precipitation procedure resulted in the formation of two distinct surface WOx sites: mono-oxo O = WO4 (~1012-1014 cm-1) and a second mono-oxo O = WO4 (~983-985 cm-1). The new surface mono-oxo O = WO4 (~983-985 cm-1) site is thought to be associated with surface defects on the co-precipitated titania support. The co-precipitated catalysts exhibited slightly enhanced SCR reactivity that is thought to be related to the presence of the new surface O = WO4 sites. Additional factors, however, may also be contributing. This is the first study that attempts to relate the molecular level structural properties of co-precipitated WO3-TiO2 catalysts with their surface reactivity for SCR.

KW - Catalysts

KW - Co-precipitated

KW - IR

KW - NH

KW - NO

KW - Raman

KW - Reaction

KW - Selective catalytic reduction (SCR)

KW - Spectroscopy

KW - Temperature programmed surface reaction (TPSR)

KW - TiO

KW - WO

UR - http://www.scopus.com/inward/record.url?scp=84957685012&partnerID=8YFLogxK

U2 - 10.1016/j.apcatb.2016.01.072

DO - 10.1016/j.apcatb.2016.01.072

M3 - Article

AN - SCOPUS:84957685012

SN - 0926-3373

VL - 188

SP - 123

EP - 133

JO - Applied Catalysis B: Environmental

JF - Applied Catalysis B: Environmental

ER -