Abstract
Selective oxidation of cyclohexene to 2-cyclohexen-1-one over titania supported vanadia (VOx/TiO2) has been studied using temperature dependent in situ FTIR spectroscopy in both the presence and absence of oxygen. The VOx/TiO2 samples were prepared using one atomic layer deposition (ALD) cycle and characterized by Raman spectroscopy. In situ FTIR data for the oxidation of cyclohexene and perdeuterocyclohexene allow for the formulation of a molecular level reaction mechanism, which is initiated by the transfer of an allyl hydrogen. Oxidation of perdeuterocyclohexene provides a direct probe of the formation of OD and HDO moieties that support the involvement of specific steps in the proposed mechanism. The presence of gas phase oxygen does not lead to a change in the products versus anaerobic conditions. However, gas phase oxygen is significantly incorporated in the CO2 overoxidation product above ∼250 °C. Data were also obtained with cyclohexene epoxide as the reactant in an effort to determine whether there is a parallel reaction pathway, which is initiated by C≠C activation in cyclohexene, that involves cyclohexene epoxide as an intermediate. Though a minor pathway involving a cyclohexene epoxide intermediate cannot be ruled out, these data demonstrate that, under experimental conditions, the dominant pathway from cyclohexene to cyclohexene-1-one is initiated by an allyl-H activation step and does not involve an epoxide intermediate.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 11844-11862 |
| Number of pages | 19 |
| Journal | Journal of Physical Chemistry C |
| Volume | 124 |
| Issue number | 22 |
| DOIs | |
| State | Published - Jun 4 2020 |
Funding
This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (Award No. DE-FG02-03-ER15457). The in situ DRIFTS measurements were performed in the Clean Catalysis Facility of the Northwestern University Center for Catalysis and Surface Science supported by a grant from the Department of Energy (DE-FG02-03ER15457 and DE-AC02-06CH11357). ICP measurements were performed in the Quantitative Bioelement Imaging Center (QBIC). We thank Professor SonBinh Nguyen for suggesting we perform the reported experiment with cyclohexane. We thank Professors Randy Snurr and Kenneth R. Poeppelmeier for discussions with regard to ALD sample preparation. We also thank Prof. Neil Schweitzer and Dr. Selim Alayoglu from Clean Catalysis Facility of the Northwestern University for making available the apparatus for DRIFTs experiments. This work was supported by the Chemical Sciences Geosciences, and Biosciences Division, Office of Basic Energy Sciences Office of Science, U.S. Department of Energy (Award No. DE-FG02-03-ER15457). The in situ DRIFTS measurements were performed in the Clean Catalysis Facility of the Northwestern University Center for Catalysis and Surface Science supported by a grant from the Department of Energy (DE-FG02-03ER15457 and DE-AC02-06CH11357). ICP measurements were performed in the Quantitative Bioelement Imaging Center (QBIC). We thank Professor SonBinh Nguyen for suggesting we perform the reported experiment with cyclohexane. We thank Professors Randy Snurr and Kenneth R. Poeppelmeier for discussions with regard to ALD sample preparation. We also thank Prof. Neil Schweitzer and Dr. Selim Alayoglu from Clean Catalysis Facility of the Northwestern University for making available the apparatus for DRIFTs experiments.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films