Au-TiO
x interfacial perimeter sites was found to be very active for dehydrogenation to acetone by comparing Au/SiO
2, TiO
x/SiO
2 and TiO
x/[Au/SiO
2] 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 TiO
x coverage, corresponding to 0.5 and 3 monolayer equivalent of TiO
2 and loadings of Ti 0.8-1.1 and 4.1-5.3 wt.%, respectively, were prepared on SiO
2 or Au/SiO
2. TiO
x/SiO
2, 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 3MonoTiO
2/SiO
2 to that on Ti/SiO
2 was 8. Unlike TiO
x/SiO
2, acetone as well as propene was produced over Au/SiO
2 and TiO
x/[Au/SiO
2] with a high acetone selectivity of 50-85%. However, Au/SiO
2 was much less active than TiO
x/[Au/SiO
2]. The rates of propene and acetone formation on TiO
x/[Au/SiO
2] were 3-16 and 8-9 times, respectively, higher than on Au/SiO
2. In addition, relative to TiO
x/SiO
2, the propene formation rates on TiO
x/[Au/SiO
2] was 35-57% lower. These results suggested that the active sites for dehydrogenation of isopropanol were at the Au-TiO
x interfacial perimeters. The decreases in propene formation rates may be contributed to the creation of Au-TiO
x interfacial perimeters at the expense of TiO
x free 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.
