Metallic corner atoms in gold clusters supported on rutile are the dominant active site during water-gas shift catalysis.
Au/TiO(2) catalysts used in the water-gas shift (WGS) reaction at 120 °C, 7% CO, 22% H(2)O, 9% CO(2), and 37% H(2) had rates up to 0.1 moles of CO converted per mole of Au per second. However, the rate per mole of Au depends strongly on the Au particle size. The use of a nonporous, model support allowed for imaging of the active catalyst and a precise determination of the gold size distribution using transmission electron microscopy (TEM) because all the gold is exposed on the surface. A physical model of Au/TiO(2) is used to show that corner atoms with fewer than seven neighboring gold atoms are the dominant active sites. The number of corner sites does not vary as particle size increases above 1 nm, giving the surprising result that the rate per gold cluster is independent of size.
Williams
W Damion
WD
School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Shekhar
Mayank
M
Lee
Wen-Sheng
WS
Kispersky
Vincent
V
Delgass
W Nicholas
WN
Ribeiro
Fabio H
FH
Kim
Seung Min
SM
Stach
Eric A
EA
Miller
Jeffrey T
JT
Allard
Lawrence F
LF