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Gold nanoparticles supported on conventional silica as catalysts for the low-temperature CO oxidation.
Gold nanoparticles supported on conventional silica as catalysts for the low-temperature CO oxidation.
- Source :
-
Journal of Molecular Catalysis A: Chemistry . Aug2015, Vol. 404, p83-91. 9p. - Publication Year :
- 2015
-
Abstract
- A catalytic system where gold nanoparticles are dispersed on the surface of a conventional mesoporous silica was investigated. The sample (2.25 wt% Au) was prepared by functionalizing the silica surface with 3-mercaptopropyltrimethoxysilane, anchoring gold from an HAuCl 4 solution and then reducing it with sodium citrate. Prior to the catalytic runs, the Au/SiO 2 –SH system was submitted to different thermal treatments. The catalyst, either as-made or after each thermal treatment, was characterized by N 2 adsorption–desorption at −196 °C, CHS elemental analysis, solid state 29 Si CPMAS NMR spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy of CO at −196 °C. The bare and functionalized supports were also characterized. Large Au nanoparticles ( ca. 30 nm) form readily by adding the HAuCl 4 solution to the functionalized support and, besides such particles, a second family of small ones originates upon thermal treatment (2–5 nm, depending on the temperature and the atmosphere), leading to a bimodal gold particle size distribution. Remarkable CO conversion is obtained when the catalyst is calcined in air at 560 °C and subsequently treated in H 2 /He at 600 °C or directly treated in H 2 /He at 600 °C. Based on the treatment-induced modifications in the physico-chemical properties of both the carrier and the supported phase, a reaction mechanism is outlined. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13811169
- Volume :
- 404
- Database :
- Academic Search Index
- Journal :
- Journal of Molecular Catalysis A: Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 102980001
- Full Text :
- https://doi.org/10.1016/j.molcata.2015.04.013