(307c) Nanogold Particle-Oxide Interaction for the Water Gas Shift Reaction

The importance
of nanogold?oxide interaction for CO oxidation reactions has been discussed
extensively in the literature.  For the
water-gas shift (WGS) reaction, our group has shown that there is a strong
interaction between gold and cerium oxide. 
The presence of gold ions on the defect sites of ceria is a key feature
of Au-ceria catalysts [1-3].  The
importance of metallic gold nanoparticles has also been argued in the
literature [4].  Conventional techniques
such as co-precipitation, deposition-precipitation, and cogelation are
typically used to prepare these catalysts. 

Recently the use
of reverse micellar systems has been reexamined due to their ability to make
highly structured uniform catalysts [5]. 
The technique has already been used to make both encapsulated Pt and Pd
catalysts for butane combustion [6].  In
this work, we look at several nano gold-oxide materials; namely Au/SiO₂,
Au/CeO₂-doped SiO₂, and Au/Fe₂O₃
for the WGS reaction.  Materials
included encapsulated gold within a shell of oxide (via the reverse micelle
technique) and traditionally structured catalysts.  The catalysts were characterized by high-resolution transmission
electron microscopy (HRTEM), X-ray diffraction (XRD), BET surface area and H₂S
temperature-programmed desorption (TPD) measurements, as well as by H₂
and CO temperature-programmed reduction (TPR). Catalyst activities were
evaluated for the WGS reaction under various conditions that included
product-free and full reformate gas mixtures, as well as in the presence and absence
of ppm levels of H₂S to investigate the effects of poisons.

References:

1.              
Q. Fu, H. Saltsburg, and M. Flytzani-Stephanopoulos, Science
301 (2003) 935-938

2.              
Q. Fu, W. Deng, H. Saltsburg, and M. Flytzani-Stephanopoulos, Applied
Catalysis B 56 (2005) 57-68.

3.              
ZP Liu, SJ Jenkins, and DA King,  Physical Review Letters 94 (2005)

4.              
H. Sakuraia, T. Akitaa, S. Tsubota, M. Kiuchia and M.
Haruta,  Applied Catalysis A
(2005), in press

5.              
S. Eriksson, U. Nylén, S. Rojas and M. Boutonnet,  Applied Catalysis A 265 (2004) 207-219.

6.              
K. Yu, C. Yeung, D. Thompsett, and S. Tsang, J. Phys. Chem.
B 107 (2003) 4515-4526