456473 Interfacial Perimeter Sites of Au-TiOx in Isopropanol Decomposition

Friday, November 18, 2016: 9:00 AM
Franciscan C (Hilton San Francisco Union Square)
Yi Y. (Chloe) Wu and Harold H. Kung, Chemical and Biological Engineering, Northwestern University, Evanston, IL

Au-TiOx interfacial perimeter sites was found to be very active for dehydrogenation to acetone by comparing Au/SiO2, TiOx/SiO2 and TiOx/[Au/SiO2] in isopropanol decomposition. Although metal-support perimeter sites have been regarded active in different catalytic reactions,1 dehydrogenation of isopropanol at these sites has only been addressed recently.2, 3 Two TiOx coverage, corresponding to 0.5 and 3 monolayer equivalent of TiO2 and loadings of Ti 0.8-1.1 and 4.1-5.3 wt.%, respectively, were prepared on SiO2 or Au/SiO2. TiOx/SiO2, which possessed only Lewis acid sites as determined by FTIR spectroscopy and pyridine adsorption, catalyzed only dehydration of isopropanol to propene. The ratio of propene formation rate on 3MonoTiO2/SiO2 to that on Ti/SiO2 was 8. Unlike TiOx/SiO2, acetone as well as propene was produced over Au/SiO2 and TiOx/[Au/SiO2] with a high acetone selectivity of 50-85%. However, Au/SiO2 was much less active than TiOx/[Au/SiO2]. The rates of propene and acetone formation on TiOx/[Au/SiO2] were 3-16 and 8-9 times, respectively, higher than on Au/SiO2. In addition, relative to TiOx/SiO2, the propene formation rates on TiOx/[Au/SiO2] was 35-57% lower. These results suggested that the active sites for dehydrogenation of isopropanol were at the Au-TiOx interfacial perimeters. The decreases in propene formation rates may be contributed to the creation of Au-TiOx interfacial perimeters at the expense of TiOfree from Au. The kinetic results of reaction order and activation energies will also be presented.

1. Y. Y. Wu, N. A. Mashayekhi and H. H. Kung, Catal. Sci. Technol., 2013, 3, 2881-2891.

2. Z. Martinez-Ramirez, J. A. Gonzalez-Calderon, A. Almendarez-Camarillo and J. C. Fierro-Gonzalez, Surf. Sci., 2012, 606, 1167-1172.

3. M. C. Holz, K. Kahler, K. Tolle, A. C. van Veen and M. Muhler, Phys. Status Solidi B, 2013, 250, 1094-1106.

Extended Abstract: File Not Uploaded