THE SILVER CATALYZED OXIDATION OF ETHYLENE: IV. REACTION MECHANISM

1954 ◽  
Vol 32 (4) ◽  
pp. 443-451 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Reaction Mechanism ◽  
Ethylene Oxide ◽  
Temperature Dependent ◽  
Heterogeneous Oxidation ◽  
Initial Oxidation ◽  
Partial Pressures ◽  
Parallel Reactions ◽  
Single Oxygen ◽  
Catalyzed Oxidation ◽  
Adsorbed Ethylene

A reaction mechanism for the silver catalyzed oxidation of C2H4 by oxygen has been formulated which is consistent with kinetic data for this system. It is suggested that both ethylene oxide and CO2 formation involve interaction of single gaseous C2H4 molecules with single oxygen adatoms. This may be a system of two parallel reactions of different activation energy requirements or a common initiation step to form adsorbed ethylene oxide which may then desorb immediately or isomerize to acetaldehyde followed by rapid oxidation to CO2 and H2O. Account is taken of the known adsorption characteristics of O2 on silver to deduce expressions for initial rates of ethylene oxide and CO2 formation as a function of reactant partial pressures. The generalized form of the equation is r = k(1 + a/pE + b/pO)−1, where k, a, and b are temperature dependent constants and pE and pO are partial pressures of ethylene and of oxygen respectively.A mechanism is also suggested for the heterogeneous oxidation of ethylene oxide which involves interaction between a gas phase ethylene oxide molecule and a single oxygen adatom to form an intermediate (probably formaldehyde) which is rapidly oxidized to CO2 and H2O. A similar expression to that above for the initial oxidation rate is deduced. These expressions have been fitted successfully to experimental data.

Temperature-Dependent Hydration/Dehydration Behavior of Poly(ethylene oxide)s in Aqueous Solution

2013 ◽  
Vol 46 (5) ◽  
pp. 1956-1961 ◽  
Author(s):  
Toshiyuki Shikata ◽  
Misumi Okuzono ◽  
Natsuki Sugimoto
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Temperature Dependent ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Dehydration Behavior

n-Butylamine Adsorption onto Amorphous Silica

1972 ◽  
Vol 50 (6) ◽  
pp. 907-911 ◽  
Author(s):  
Colin Clark-Monks ◽  
Bryan Ellis
Keyword(s):  
Elevated Temperature ◽  
Reaction Mechanism ◽  
Ethylene Oxide ◽  
Hydroxyl Groups ◽  
Surface Groups ◽  
Vicinal Surface ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Strong Adsorption ◽  
Oxide Vapor

Gravimetric and infrared spectroscopic observations of n-butylamine adsorption onto silica have shown that strong adsorption is associated primarily with isolated surface hydroxyl groups and also with some vicinal surface groups. Adsorbed material can be totally removed from the surface by outgassing at elevated temperature (to 200 °C) without irreversible changes to the underlying surface. The interaction between adsorbed amine and ethylene oxide vapor has been investigated and a possible reaction mechanism is presented.

Initial Stage of Oxidation on Si(111)-7×7 Surface Investigated by Scanning Tunneling Microscope

1995 ◽  
Vol 404 ◽  
Author(s):  
Jeong Sook Ha ◽  
Kang-Ho Park ◽  
Seong-Ju Park ◽  
El-Hang Lee
Keyword(s):  
Scanning Tunneling Microscope ◽  
Room Temperature ◽  
Scanning Tunneling ◽  
Low Oxygen ◽  
Initial Oxidation ◽  
Initial Stage ◽  
Partial Pressures ◽  
Site Selectivity ◽  
The Difference ◽  
Stm Images

AbstractThe initial oxidation of Si(111)-7×7 surface has been investigated by taking the STM images of samples dosed with oxygen at room temperature and high temperatures between 500°C and 750 °C. In particular, different site selectivities between two oxygen-induced features, bright and dark sites, were observed and explained in terms of the difference in potential energy curves. In addition to such a strong site selectivity under low oxygen partial pressure (l×10-9 torr), heavy surface etching by oxygen was observed at higher O2 partial pressures and temperatures resulting in the high density of monolayer-deep etch marks on terraces.

Orientation of adsorbed ethylene oxide on Ni(110) by X-ray photoelectron diffraction

1993 ◽  
Vol 281 (3) ◽  
pp. 341-346 ◽  
Author(s):  
U. Grosche ◽  
H. Hamadeh ◽  
O. Knauff ◽  
R. David ◽  
H.P. Bonzel
Keyword(s):  
Ethylene Oxide ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Adsorbed Ethylene

Silver-Catalyzed Oxidation of Ethylene to Ethylene Oxide in a Microreaction System

2002 ◽  
Vol 41 (4) ◽  
pp. 710-719 ◽  
Author(s):  
Harry Kestenbaum ◽  
Armin Lange de Oliveira ◽  
Wolfgang Schmidt ◽  
Ferdi Schüth ◽  
Wolfgang Ehrfeld ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Catalyzed Oxidation

THE SILVER CATALYZED OXIDATION OF ETHYLENE: III. KINETICS OF ETHYLENE OXIDE OXIDATION

1954 ◽  
Vol 32 (4) ◽  
pp. 432-442 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Ethylene Oxide ◽  
Initial Rate ◽  
Oxidation Mechanism ◽  
Kinetic Studies ◽  
Main Step ◽  
Direct Oxidation ◽  
Flow Rates ◽  
Rate Determining Step ◽  
Kinetics Of ◽  
Catalyzed Oxidation

A flow type apparatus was used for kinetic studies of the silver catalyzed oxidation of ethylene oxide (EtO) by oxygen at 274 °C. Using N2 as diluent the concentrations of O2 and ethylene oxide were varied independently from 9.9 to 79% and 2.35 to 9.4% respectively while a total pressure of 1 atmosphere was maintained. Flow rates were varied to give a range of contact times varying from 0.06 to 0.25 sec. It was shown that EtO is oxidized without previous dissociation into C2H4 and O2. The dependence of the initial rate of oxidation of EtO on reactant concentrations excludes isomerization of EtO (to acetalde hyde) as a main step in its oxidation, and a direct oxidation mechanism is suggested. The results of a few experiments to determine the extent of isomerization of EtO to acetaldehyde in the absence of oxygen are presented. No steady state could be achieved but the results may be used semiquantitatively to support the belief that isomerization is not the rate determining step in the oxidation of ethylene oxide.

Sign in / Sign up

Export Citation Format

Share Document