Stages in the modification of a silver surface for catalysis of the partial oxidation of ethylene

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1994.1344· OSTI ID:47972

Bukhtiyarov, V I; Boronin, A I; Savchenko, V I ^[1]

---

1. Boreskov Institute of Catalysis, Novosibirsk (Russian Federation)

The interaction of silver foil with oxygen over a wide range of temperatures and O{sub 2} pressures has been studied by XPS, TPD, and TPR. It has been shown that depending on the treatment conditions two adsorbed oxygen states with a different ionicity of the Ag-O bond can be formed, as well as oxygen dissolved in the silver bulk. {open_quotes}Ionic{close_quotes} oxygen [E{sub b}(O 1s) = 524.4 eV] is formed in the initial step of O{sub 2} adsorption, its incorporation into uppermost silver layer proceeding at T > 420 K. This state is responsible for ethylene adsorption, followed by its destruction and complete oxidation to CO{sub 2} and H{sub 2}O. Dissolution of oxygen atoms in the silver bulk starts at T > 470 K. No effect of the dissolved oxygen on the electronic and catalytic properties of the {open_quotes}ionic{close_quotes} oxygen has been revealed. Accumulation of {open_quotes}covalent{close_quotes} oxygen [E{sub b} (O 1s = 530.5 eV)] occurs at higher temperature and pressure. A possible mechanism for its formation which includes the creation of specific defective sites on silver surface is discussed. Despite a large variation of pressures and temperatures used for the modification of clean silver foil by O{sub 2}, all attempts to produce a surface active in ethylene epoxidation have failed. 36 refs., 6 figs.

• OSTI ID: 47972
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 150; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
40 CHEMISTRY
CATALYTIC EFFECTS
CRYSTAL DEFECTS
ETHYLENE
OXIDATION
PHOTOELECTRON SPECTROSCOPY
SILVER OXIDES
SORPTIVE PROPERTIES
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
X-RAY SPECTROSCOPY