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Title: Investigation of the Origin of Catalytic Activity in Oxide-Supported Nanoparticle Gold

Abstract

Since Haruta’s discovery in 1987 of the surprising catalytic activity of supported Au nanoparticles, we have seen a very large number of experimental and theoretical efforts to explain this activity and to fully understand the nature of the behavior of the responsible active sites. In 2011, we discovered that a dual catalytic site at the perimeter of ~3nm diameter Au particles supported on TiO 2 is responsible for oxidative catalytic activity. O 2 molecules bind with Au atoms and Ti4+ ions in the TiO 2 support and the weakened O-O bond dissociates at low temperatures, proceeding to produce O atoms which act as oxidizing agents for the test molecule, CO. The papers supported by DOE have built on this finding and have been concerned with two aspects of the behavior of Au/TiO 2 catalysts: (1). Mechanistic behavior of dual catalytic sites in the oxidation of organic molecules such as ethylene and acetic acid; (2). Studies of the electronic properties of the TiO 2 (110) single crystal in relation to its participation in charge transfer at the occupied dual catalytic site. A total of 20 papers have been produced through DOE support of this work. The papers combine IR spectroscopic investigationsmore » of Au/TiO 2 catalysts with surface science on the TiO 2(110) and TiO 2 nanoparticle surfaces with modern density functional modeling. The primary goals of the work were to investigate the behavior of the dual Au/Ti 4+ site for the partial oxidation of alcohols to acids, the hydrogenation of aldehydes and ketones to alcohols, and the condensation of oxygenate intermediates- all processes related to the utilization of biomass in the production of useful chemical energy sources.« less

Authors:
 [1]
  1. Univ. of Virginia, Charlottesville, VA (United States)
Publication Date:
Research Org.:
Univ. of Virginia, Charlottesville, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1358579
Report Number(s):
DOE-UVA-0002365
DOE Contract Number:
SC0002365
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 09 BIOMASS FUELS; 74 ATOMIC AND MOLECULAR PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; catalysis; heterogenous catalysis; TiO2; gold catalysis; nanoparticles; reaction mechanism; active sites

Citation Formats

Harrison, Ian. Investigation of the Origin of Catalytic Activity in Oxide-Supported Nanoparticle Gold. United States: N. p., 2017. Web. doi:10.2172/1358579.
Harrison, Ian. Investigation of the Origin of Catalytic Activity in Oxide-Supported Nanoparticle Gold. United States. doi:10.2172/1358579.
Harrison, Ian. Fri . "Investigation of the Origin of Catalytic Activity in Oxide-Supported Nanoparticle Gold". United States. doi:10.2172/1358579. https://www.osti.gov/servlets/purl/1358579.
@article{osti_1358579,
title = {Investigation of the Origin of Catalytic Activity in Oxide-Supported Nanoparticle Gold},
author = {Harrison, Ian},
abstractNote = {Since Haruta’s discovery in 1987 of the surprising catalytic activity of supported Au nanoparticles, we have seen a very large number of experimental and theoretical efforts to explain this activity and to fully understand the nature of the behavior of the responsible active sites. In 2011, we discovered that a dual catalytic site at the perimeter of ~3nm diameter Au particles supported on TiO2 is responsible for oxidative catalytic activity. O2 molecules bind with Au atoms and Ti4+ ions in the TiO2 support and the weakened O-O bond dissociates at low temperatures, proceeding to produce O atoms which act as oxidizing agents for the test molecule, CO. The papers supported by DOE have built on this finding and have been concerned with two aspects of the behavior of Au/TiO2 catalysts: (1). Mechanistic behavior of dual catalytic sites in the oxidation of organic molecules such as ethylene and acetic acid; (2). Studies of the electronic properties of the TiO2 (110) single crystal in relation to its participation in charge transfer at the occupied dual catalytic site. A total of 20 papers have been produced through DOE support of this work. The papers combine IR spectroscopic investigations of Au/TiO2 catalysts with surface science on the TiO2(110) and TiO2 nanoparticle surfaces with modern density functional modeling. The primary goals of the work were to investigate the behavior of the dual Au/Ti4+ site for the partial oxidation of alcohols to acids, the hydrogenation of aldehydes and ketones to alcohols, and the condensation of oxygenate intermediates- all processes related to the utilization of biomass in the production of useful chemical energy sources.},
doi = {10.2172/1358579},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri May 26 00:00:00 EDT 2017},
month = {Fri May 26 00:00:00 EDT 2017}
}

Technical Report:

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  • This report describes research leading to the development of new catalytic materials based on hydrous metal oxide (HMO) ion exchangers. Present in this part, the second of two parts, are results of catalyst-related research and application of the materials to catalytic reactions for direct coal liquefaction processes. HMO materials are inorganic ion exchangers, derived from the alkoxides of Ti, Zr, Nb, or Ta, that exhibit a number of properties applicable to the preparation of catalysts. Research on the catalytic properties of HMO's has focused on the hydrous titanium oxide (HTO) system. However, exploratory coal liquefaction experiments with hydrous niobium oxidesmore » (HNO's) and hydrous zirconium oxides (HZO's) have demonstrated that these HMO's also exhibit potential as coal liquefaction catalysts. Studies performed during the course of this research include (1) preliminary coal liquefaction and hydrotreating tests, (2) tests of hydrogenation, hydrodesulfurization, hydrodeoxygenation and hydrodenitrogenation activity using model compounds, (3) development of catalyst pretreatment and activation procedures, (4) modification of HTO supports with silicon, (5) preparation and testing of thin film HTO catalysts, (6) synthesis, characterization and evaluation of base and noble metal catalyst deactivation tests, and (9) exploratory tests of applications other than direct liquefaction. The versatility of the HTO system for synthesis of catalysts allows great potential for further improvements in activity and selectivity as well as tailoring of catalysts for specific processes. Research is continuing in these areas. 54 refs., 63 figs., 25 tabs.« less
  • No abstract prepared.
  • Gold nanoparticles supported on hydrous tin-oxide (Au-SnO{sub x}) are active for the four-electron oxygen reduction reaction in an acid electrolyte. The unique electrocatalytic of the Au-SnO is confirmed by the low amount of peroxide detected with rotating ring-disk electrode voltammetry and Koutecky-Levich analysis. In comparison, 10 wt % Au supported on Vulcan carbon and SnO{sub x} catalysts both produce significant peroxide in the acid electrolyte, indicating only a two-electron reduction reaction. Characterization of the Au-SnO{sub x} catalyst reveals a high-surface area, amorphous support with 1.7 nm gold metal particles. The high catalytic activity of the Au-SnO is attributed to metalmore » support interactions. The results demonstrate a possible path to non-Pt catalysts for proton exchange membrane fuel cell cathodes.« less
  • We report the investigation of titania supported gold catalysts prepared by magnetron sputtering. Catalysts grown on natural fumed titania were structurally unstable resulting in the rapid coarsening of 2.3 nm gold clusters into large ~20 nm gold clusters in a few days at room temperature under normal atmospheric conditions. However, treating the titania support powder to a mock-deposition-precipitation process, at pH 4 or pH 10, followed by the subsequent deposition of gold onto this treated powder produced a remarkable enhancement in gold particle stability and a 20-40 fold enhancement of catalytic activity respectively. This enhancement can not be attributed tomore » the formation of oxygen vacancies on the TiO2 surface. Instead, it appears to be associated with the formation of strongly bound hydroxyl species on the TiO2 surface. The formation of surface hydroxyls during the deposition-precipitation method is coincidental and contributes significantly to the properties of Au/TiO2 catalysts.« less
  • 2.5 nm gold nanoparticles were grown on a fumed silica support, using the physical vapor deposition technique of magnetron sputtering, that are thermally stable when annealed in an oxygen containing environment up to at least 500 C. Traditional Au/TiO{sub 2} catalysts rapidly sinter to form large 13.9 nm gold clusters under these annealing conditions. This surprising stability of Au/SiO{sub 2} is attributed to the absence of residual impurities (ensured by the halide-free production method) and a strong bond between gold and defects at the silica surface (about 3 eV per bond) estimated from density functional theory (DFT) calculations. The Au/SiO{submore » 2} catalysts are less active for CO oxidation than the prototypical Au/TiO2 catalysts, however they can be regenerated far more easily, allowing the activity of a catalyst to be fully recovered after deactivation.« less