Adsorption of sulfur on bimetallic surfaces: Formation of copper sulfides on Pt(111) and Ru(001)
It has been found that by making specific bimetallic systems (in this case a noble metal deposited on a transition metal surface) one can change the catalytic activity and selectivity of the metals for reactions that lead to the conversion of hydrocarbons. A major problem associated with these catalysts is sulfur poisoning. The interaction of sulfur and copper on Pt(111) and Ru(001) has been examined using X-ray photoelectron spectroscopy (XPS) and thermal desorption mass spectroscopy (TDS). Cu/Pt (111) and Cu/Ru(001) surfaces were exposed to S{sub 2} gas at 300 K. It was found that for both substrates stable copper-sulfide films were formed, of which the Cu-S/Ru(001) system was the more stable. The decomposition of the Cu{sub 2}S films on Pt(111) occurred at 600--850 K and on Ru(001) at 900--1,000 K. Breakdown of the films led to evolution into the gas phase of sulfur (mainly as S{sub 2}) without desorption of copper or the sulfur chemisorbed on the substrate. This chemisorbed sulfur desorbed in a broad feature from 1,000--1,500 K. For the Ru(001) substrate the Cu atoms remained on the surface until they desorbed at 1080 K, while on Pt(111) the Cu atoms migrated into the Pt(111) surface to form a subsurface Cu-Pt alloy and no Cu desorption features were seen at temperatures as high as 1,300 K. On Pt(111), copper-sulfide promoted the formation of a bulk-like platinum sulfide. No sulfidation of ruthenium was detected in the presence of copper-sulfide films. For both substrates the sulfur atoms were found to highly perturb the copper sites, decreasing the ability of the noble-metal ad atoms to adsorb CO.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10191271
- Report Number(s):
- BNL--60952; CONF-941001--4; ON: DE95001994
- Country of Publication:
- United States
- Language:
- English
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