Oxygen heterogeneous

Because of uncertainties in the interpretation of measured redox potentials in oxygenated heterogeneous systems, such measurements were not made in the systems studied in this work. However, the general behavior of the components, and the results of the changes in solid... 

Butane-Based Fixed-Bed Process Technology. Maleic anhydride is produced by reaction of butane with oxygen using the vanadium phosphoms oxide heterogeneous catalyst discussed earlier. The butane oxidation reaction to produce maleic anhydride is very exothermic. The main reaction by-products are carbon monoxide and carbon dioxide. Stoichiometries and heats of reaction for the three principal reactions are as follows ... 

In 1982 a study of the usefulness of DBBF in the production of a blood substitute was reported (99). A single modification achieved the dual goals of reduced oxygen affinity and restricted tetramer—dimer dissociation. This work was confirmed in 1987 (98). The product, called aa-hemoglobin, was formulated in Ringer s lactate. P q under physiologic conditions is 3.7 kPa (28.0 torr). Hill s parameter is 2.2, and the Bohr effect was reduced (100). Plasma retention was increased, and the product appeared to be less heterogeneous than some of the other derivatives under study. Its production was scaled up by Baxter Healthcare Corp., under contract to the U.S. Army. 

Dehydrogenation, Ammoxidation, and Other Heterogeneous Catalysts. Cerium has minor uses in other commercial catalysts (41) where the element s role is probably related to Ce(III)/Ce(IV) chemistry. Styrene is made from ethylbenzene by an alkah-promoted iron oxide-based catalyst. The addition of a few percent of cerium oxide improves this catalyst s activity for styrene formation presumably because of a beneficial interaction between the Fe(II)/Fe(III) and Ce(III)/Ce(IV) redox couples. The ammoxidation of propjiene to produce acrylonitrile is carried out over catalyticaHy active complex molybdates. Cerium, a component of several patented compositions (42), functions as an oxygen and electron transfer through its redox couple. 

The critical properties of water are 374°C (705°F) and 218 atm (3,205 psi). Above this condition a heterogeneous mixture of water, organic-compounds, and oxygen may become homogeneous. Then the rate of oxidation may be considerably accelerated because of (1) elimination of diffusional resistances, (2) increase of oxygen concentration by rea-... 

Volume 15 Heterogeneous Catalytic Reactions Involving Molecular Oxygen by G.l. Golodets... 

Bulk polymerisation is heterogeneous since the polymer is insoluble in the monomer. The reaction is autocatalysed by the presence of solid polymer whilst the concentration of initiator has little effect on the molecular weight. This is believed to be due to the overriding effect of monomer transfer reactions on the chain length. As in all vinyl chloride polymerisation oxygen has a profound inhibiting effect. 

The mechanism of inhibition by the salts of the long chain fatty acids has been examined . It was concluded that, in the case of the lead salts, metallic lead was first deposited at certain points and that at these points oxygen reduction proceeded more easily, consequently the current density was kept sufficiently high to maintain ferric film formation in addition, any hydrogen peroxide present may assist in keeping the iron ions in the oxide film in the ferric condition, consequently the air-formed film is thickened until it becomes impervious to iron ions. The zinc, calcium and sodium salts are not as efficient inhibitors as the lead salts and recent work has indicated that inhibition is due to the formation of ferric azelate, which repairs weak spots in the air-formed film. This conclusion has been confirmed by the use of C labelled azelaic acid, which was found to be distributed over the surface of the mild steel in a very heterogeneous manner. ... 

Solid particle-gaseous oxidizer systems have been studied because of applications to propints and expls (Refs 5 14), and hazards due to dust explns (Refs 1,3, 4, 6, 7, 10 15). Strauss (Ref 9) reported on a heterogeneous detonation in a solid particle and gaseous oxidizer mixt the study concerned A1 powder and pure oxygen in a tube. Detonations initiated, by a weak source were obtained in mixts contg 45-60% fuel by mass. Measured characteristics of the detonations agreed with theoretical calcns within about 10%, and detonation pressures of up to 31 atms were observed. With regard to solid particle-air mixts, detonations have not been reported only conditions for expln have been studied (Ref 2)... 

Anderson and Brown then suggested that the effects observed by McAlevy (M3, M4) of oxygen on the ignition characteristics of solid fuels might be the result of exothermic heterogeneous reactions, since the experimental observations of McAlevy as well as those of Shannon and Anderson (S3), can be correlated by Eq. (15). Shannon has also extended the original treatment of Anderson and Brown to include the effects of adsorption and desorption on the predicted results. 

The chemical properties of oxide surfaces have been studied by several methods, including oxygen exchange. This method has been used to investigate the mechanisms of heterogeneous reactions for which oxides are active catalysts [36]. The dimerization step does not necessarily precede desorption and Malinin and Tolmachev [634], in one of the few reviews of decomposition kinetics of solid metal oxides, use this criterion to distinguish two alternative reaction mechanisms, examples being... 

Ethylene oxide is produced by a heterogeneous catalyzed gas phase oxidation of ethylene with pure oxygen at temperatures of 240-290°C and 5-25 bar [63] ... 

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