Hydrogen chemisorption on Al2O3-supported gold catalysts.
Hydrogen is dissociatively adsorbed on the gold particles in Au/Al(2)O(3) catalysts, as demonstrated by a combination of in-situ X-ray absorption spectroscopy, chemisorption, and H/D exchange experiments. This chemisorption of hydrogen induces changes in the Au L(3) and L(2) X-ray absorption near-edge structures. The gold atoms on corner and edge positions dissociate the hydrogen, which does not spill over to the face sites. Therefore, the average number of adsorbed hydrogen atoms per surface gold atom increases with decreasing particle size. With temperature, the hydrogen uptake by supported gold increases or remains constant, whereas it decreases for platinum. Furthermore, in H/D exchange experiments, the activity of Au/Al(2)O(3) increases strongly with temperature. Thus, the dissociation and adsorption of hydrogen on gold is activated.
Bus
Eveline
E
Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH, CH-8093 Zurich, Switzerland.
Miller
Jeffrey T
JT
van Bokhoven
Jeroen A
JA
D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D002384:Catalysis; D041961:Deuterium Exchange Measurement; D006046:Gold / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D017348:Microscopy, Electron, Scanning Transmission; D010316:Particle Size; D013057:Spectrum Analysis
D006046:Gold; D006859:Hydrogen; D000537:Aluminum Oxide