期刊
JOURNAL OF CATALYSIS
卷 377, 期 -, 页码 419-428出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2019.07.051
关键词
Atomic layer deposition; Single-atom catalysis; Coordination number; Titania; Gold
资金
- National Science Foundation [CBET-1511820, CBET-1510485]
- DOE Office of Science [DE-ACO2-06CH11357]
Propylene epoxidation using molecular oxygen and hydrogen mixture on Au-based catalysts has attracted attention because of high propylene oxide selectivity and the use of an inexpensive and environmental friendly oxidant. Single-site titanium on metal oxide supports plays an important role in achieving high reactivity and selectivity in propylene epoxidation. Here we used TiO2 atomic layer deposition (ALD) to synthesize single-site titanium imbedded in the SiO2 framework for propylene epoxidation. High temperature calcination was used as post-treatment to control the titania structure and Ti-O coordination number. Using UV-vis spectroscopy and X-ray absorption spectroscopy, we successfully established that under similar propylene conversion the selectivity to propylene oxide (PO) is strongly correlated to the Ti-O coordination number and bond length. Using a cluster model, density functional theory (DFT) calculations indicate that the partial charges of single Ti-SiO2 sites scale linearly as a function of the coordination number. Also, the predicted Ti-O bond lengths follow the same trend as found in the experiments, providing additional support for the observed experimental activity relationships. (C) 2019 Elsevier Inc. All rights reserved.
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