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Title: Effects of TiO 2 in Low Temperature Propylene Epoxidation Using Gold Catalysts

Propylene epoxidation with molecular oxygen has been proposed as a green and alternative process to produce propylene oxide (PO). In order to develop catalysts with high selectivity, high conversion, and long stability for the direct propylene epoxidation with molecular oxygen, understanding of catalyst structure and reactivity relationships is needed. Here in this study, we combined atomic layer deposition and deposition precipitation to synthesize series of well-defined Au-based catalysts to study the catalyst structure and reactivity relationships for propylene epoxidation at 373 K. We showed that by decorating TiO 2 on gold surface the inverse TiO 2/Au/SiO 2 catalysts maintained ~90% selectivity to PO regardless of the weight loading of the TiO 2. The inverse TiO 2/Au/SiO 2 catalysts exhibited improved regeneration compared to Au/TiO 2/SiO 2. The inverse TiO 2/Au/SiO 2 catalysts can be regenerated in 10% oxygen at 373 K, while the Au/TiO 2/SiO 2 catalysts failed to regenerate at as high as 473 K. Combined characterizations of the Au-based catalysts by X-ray absorption spectroscopy, scanning transmission electron microscopy, and UV–vis spectroscopy suggested that the unique selectivity and regeneration of TiO 2/Au/SiO 2 are derived from the site-isolated Ti sites on Au surface and Au–SiO 2 interfaces which aremore » critical to achieve high PO selectivity and generate only coke-like species with high oxygen content. The high oxygen content coke-like species can therefore be easily removed. Lastly, these results indicate that inverse TiO 2/Au/SiO 2 catalyst represents a system capable of realizing sustainable gas phase propylene epoxidation with molecular oxygen at low temperature.« less
Authors:
 [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [1]
  1. University of Alabama, Huntsville, AL (United States). Department of Chemical and Materials Engineering
  2. University of Alabama, Tuscaloosa, AL (United States). Department of Chemical and Biological Engineering
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Science Division and Center for Nanophase Materials Sciences
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 3; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
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
OSTI Identifier:
1468076

Lu, Zheng, Piernavieja-Hermida, Mar, Turner, C. Heath, Wu, Zili, and Lei, Yu. Effects of TiO2 in Low Temperature Propylene Epoxidation Using Gold Catalysts. United States: N. p., Web. doi:10.1021/acs.jpcc.7b10902.
Lu, Zheng, Piernavieja-Hermida, Mar, Turner, C. Heath, Wu, Zili, & Lei, Yu. Effects of TiO2 in Low Temperature Propylene Epoxidation Using Gold Catalysts. United States. doi:10.1021/acs.jpcc.7b10902.
Lu, Zheng, Piernavieja-Hermida, Mar, Turner, C. Heath, Wu, Zili, and Lei, Yu. 2017. "Effects of TiO2 in Low Temperature Propylene Epoxidation Using Gold Catalysts". United States. doi:10.1021/acs.jpcc.7b10902. https://www.osti.gov/servlets/purl/1468076.
@article{osti_1468076,
title = {Effects of TiO2 in Low Temperature Propylene Epoxidation Using Gold Catalysts},
author = {Lu, Zheng and Piernavieja-Hermida, Mar and Turner, C. Heath and Wu, Zili and Lei, Yu},
abstractNote = {Propylene epoxidation with molecular oxygen has been proposed as a green and alternative process to produce propylene oxide (PO). In order to develop catalysts with high selectivity, high conversion, and long stability for the direct propylene epoxidation with molecular oxygen, understanding of catalyst structure and reactivity relationships is needed. Here in this study, we combined atomic layer deposition and deposition precipitation to synthesize series of well-defined Au-based catalysts to study the catalyst structure and reactivity relationships for propylene epoxidation at 373 K. We showed that by decorating TiO2 on gold surface the inverse TiO2/Au/SiO2 catalysts maintained ~90% selectivity to PO regardless of the weight loading of the TiO2. The inverse TiO2/Au/SiO2 catalysts exhibited improved regeneration compared to Au/TiO2/SiO2. The inverse TiO2/Au/SiO2 catalysts can be regenerated in 10% oxygen at 373 K, while the Au/TiO2/SiO2 catalysts failed to regenerate at as high as 473 K. Combined characterizations of the Au-based catalysts by X-ray absorption spectroscopy, scanning transmission electron microscopy, and UV–vis spectroscopy suggested that the unique selectivity and regeneration of TiO2/Au/SiO2 are derived from the site-isolated Ti sites on Au surface and Au–SiO2 interfaces which are critical to achieve high PO selectivity and generate only coke-like species with high oxygen content. The high oxygen content coke-like species can therefore be easily removed. Lastly, these results indicate that inverse TiO2/Au/SiO2 catalyst represents a system capable of realizing sustainable gas phase propylene epoxidation with molecular oxygen at low temperature.},
doi = {10.1021/acs.jpcc.7b10902},
journal = {Journal of Physical Chemistry. C},
number = 3,
volume = 122,
place = {United States},
year = {2017},
month = {12}
}