Mechanism of ethylene epoxidation

Journal Article · Tue Apr 01 04:00:00 EST 1986 · J. Catal.; (United States)

OSTI ID:5217185

van Santen, R A; De Groot, C P.M.

The mechanism of the epoxidation of ethylene with oxygen over silver catalysts has been examined. This study was prompted by the notion that if one wishes to increase the selectivity of epoxide formation one should know the phase of adsorbed oxygen that reacts to give epoxide. Experiments were undertaken (a) to determine whether adsorbed atomic oxygen is incorporated into ethylene to give epoxide, and (b) to establish the relative rates of reaction of molecular oxygen impinging from the gas phase and of preadsorbed atomic oxygen. Experiments were performed in a high-vacuum recirculation system designed to allow volumetric absorption studies as well as kinetic studies using a mass spectrometer to be made. The catalyst consisted of silver powder precovered with chemisorbed /sup 16/O such that it gave epoxide upon reaction with ethylene. It was contacted with ethylene/sup 18/O/sub 2/ gas mixtures of different ratios. It is shown that under conditions where oxygen isotope equilibration in the gas phase is slow, ethylene initially reacts more rapidly with preadsorbed oxygen atoms than with molecular oxygen adsorbed in the precursor state (p/sub o/sub 2// < 20 Torr; 1 Torr = 133.3 Nm/sup 2/) if O/sub ads/Ag/sub s/ approx. 1. If in the beginning only subsurface oxygen atoms are present, this subsurface oxygen and gas-phase oxygen are incorporated into ethylene at about equal rates, It is concluded that ethylene reacts with atomic oxygen to give epoxide either directly, or indirectly, after recombination of the oxygen atoms

• Research Organization: Koninklijke/Shell Laboratorium Amsterdam (Netherlands)
• OSTI ID: 5217185
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 98:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020500 -- Petroleum-- Products &amp; By-Products
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
ADSORPTION
ALKENES
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
EPOXIDES
ETHYLENE
EVEN-EVEN NUCLEI
HYDROCARBONS
ISOTOPES
KINETICS
LIGHT NUCLEI
METALS
NONMETALS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN
OXYGEN 18
OXYGEN ISOTOPES
REACTION KINETICS
REFORMER PROCESSES
SILVER
SORPTION
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENTS