Low-Temperature Synthesis of Tunable Mesoporous Crystalline Transition Metal Oxides and Applications as Au Catalyst Supports
Mesoporous transition metal oxides are of great potential as catalyst supports, shape-selective catalysts, photocatalysts, and sensor materials. Previously stable crystalline mesoporous oxides were mostly obtained by thermally induced crystallization or by segregating the nanocrystals with an amorphous phase. Here we report a novel direct approach to crystalline mesoporous frameworks via the spontaneous growth and assembly of transition metal oxide nanocrystals (i.e., rutile TiO2, fluorite CeO2, cassiterite SnO2, and anatase SnxTi1-xO2) by oxidative hydrolysis and condensation in the presence of anionic surfactants. The influences of synthesis time, surfactants with different chain lengths, concentrations of the oxidant (i.e., hydrogen peroxide), and synthesis temperatures on the composition and morphologies of the resulting materials were investigated by X-ray diffraction (XRD), N2-sorption, transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). A mechanism for the templated synthesis of crystalline mesoporous metal oxides was tentatively proposed. To demonstrate the catalytic applications of these materials, gold nanoparticles were loaded on mesoporous rutile TiO2 and fluorite CeO2 supports, and their catalytic performance in CO oxidation and water-gas shift was surveyed. Au nanoparticles supported on the mesoporous crystalline metal oxides exhibit higher reactivity and excellent on-stream stability towards CO oxidation and water-gas shift reaction compared with commercial TiO2 and CeO2.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 939023
- Report Number(s):
- PNNL-SA-61302; 22390; KC0302010; TRN: US200820%%448
- Journal Information:
- Journal of Physical Chemistry C, 112(35):13499-13509, Vol. 112, Issue 35
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CATALYST SUPPORTS
CATALYSTS
CRYSTALLIZATION
ELECTRON DIFFRACTION
FLUORITE
GOLD
HYDROGEN
HYDROLYSIS
OXIDATION
OXIDES
OXIDIZERS
RUTILE
SCANNING ELECTRON MICROSCOPY
STABILITY
SURFACTANTS
SYNTHESIS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
WATER GAS
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
Environmental Molecular Sciences Laboratory