Some features of the gas phase oxidation of n -butenes

1963 ◽  
Vol 272 (1349) ◽  
pp. 164-191 ◽  
Keyword(s):  
Gas Phase ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Maximum Reaction Rate ◽  
Oxygen System ◽  
Maximum Reaction ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Analytical System ◽  
The Individual

Conventional kinetic techniques (static and flow systems) have been used in conjunction with an integral gas chromatographic analytical system in a study of the oxidation behaviour of butene-1, cis butene-2 and trans butene-2. The cis and trans isomers of butene-2 behaved indistinguishably. All three olefins gave qualitatively the same products, but butene-1 differed in the proportions of the individual products formed, and also in oxidation rate. A mechanism, based on that previously proposed for the ethylene + oxygen system, has been found to account for these differences. The ethylene mechanism is only possible, however, because of the slow rate of oxidation of the allylic type radicals easily formed in the reactions. The relative stability of these radicals provides a natural explanation of the phenomenon of self-inhibition observed in olefin + oxygen reactions. The discontinuous production of intermediate substances noted during the oxidation of butene-2 at high reaction rates, provides further evidence for a thermal theory of cool-fiame formation. Acetaldehyde has been found to be the degenerate branching agent and the maximum reaction rate of these systems was found to be identically related to the concentration of this substance.

Gas-phase oxidation of hexene-1

1958 ◽  
Vol 244 (1238) ◽  
pp. 345-354 ◽  
Keyword(s):  
Oxygen Consumption ◽  
Gas Phase ◽  
Maximum Rate ◽  
Reaction Rate ◽  
Pressure Change ◽  
Early Stages ◽  
Unusual Form ◽  
Phase Oxidation ◽  
Rate Of Oxygen Consumption ◽  
Gas Phase Oxidation

An investigation has been made of the oxidation of hexene-1 at 263°C. The unusual form of dependency of reaction rate on hydrocarbon pressure obtained when the maximum rate of pressure change is used as a measure of reaction rate is explained by the fact that much of the oxygen is consumed before the maximum rate of pressure change is attained. This, and the observation that the maximum rate of oxygen consumption exhibits a different dependence on hexene concentration compared with the maximum rate of pressure change confirm that maximum rate of pressure change is an invalid measure of reaction rate. Analyses have been made for certain intermediates and products throughout the course of the reaction, and it has been possible to explain many of the experimental features in terms of ideas previously propounded. A decrease in pressure which in many experiments precedes the rapid increase in pressure is attributed to polymerization reactions which predominated over oxidative degradations in the early stages of the reaction, particularly when the olefin is present in excess.

Immobilized Glucose Oxidase Used to Measure Glucose in Serum

1974 ◽  
Vol 20 (8) ◽  
pp. 1018-1022 ◽  
Author(s):  
Hans J Kunz ◽  
Milos Stastny
Keyword(s):  
Glucose Oxidase ◽  
Reaction Rate ◽  
Oxygen Depletion ◽  
Maximum Reaction Rate ◽  
Controlled Pore Glass ◽  
Maximum Reaction ◽  
Pore Glass ◽  
Immobilized Glucose Oxidase ◽  
One Year ◽  
Analytical System

Abstract We report an analytical system in which glucose oxidase immobilized on controlled-pore glass is used. The immobilized glucose oxidase was packed in a column that was part of a continuous-flow system. Oxygen depletion of the buffer was measured with a Clark-type electrode, and the resulting data were stored on tape and then evaluated with a PDP-12 computer. The relative advantages of several measurement approaches are given: (a) an endpoint method for prediluted sample, (b) an endpoint method for discrete, undiluted 9-µl samples, and (c) a maximum reaction rate measurement with discrete, undiluted samples. Catalase and mutarotase interferences were considered and found insignificant under the conditions chosen. The effects of protein, fluoride, and oxalate were determined. The column can be re-used for at least 1000 samples. Useful storage life of the immobilized glucose oxidase preparation, measured at intervals during a year, exceeded one year at room temperature.

Catalysis, binding and enzyme-substrate complementarity

1974 ◽  
Vol 187 (1089) ◽  
pp. 397-407 ◽  
Keyword(s):  
Transition State ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Special Role ◽  
Simple Derivation ◽  
Maximum Reaction Rate ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Maximum Reaction

A simple derivation is given that the catalytic term k cat / K S is at a maximum when the structure of the enzyme is complementary to the structure of the substrate in the transition state. In addition, at a constant substrate concentration, [S], the maximum reaction rate is obtained when k cat and K S are individually high so that K S is greater than [S]; the overall reaction rate decreases with decreasing k cat and K S for K S less than [S]. Two corollaries of this are that intermediates accumulating after the initial Michaelis complex are undesirable and also enzymes whose function is to optimize reaction rates should have evolved to exhibit K M values above those of accessible substrate concentrations. This could be achieved by an often ‘distortionless’ strain which consists either of unfavourable interactions in the enzyme substrate complex which are relieved in the transition state or increasingly favourable interactions in the transition state. A possible special role of the backbone NH groups in this context is discussed. The enzyme need not be complementary to the transition state of the substrate for catalysis to occur.

Gas phase oxidation of furfural to maleic anhydride on V 2 O 5 /γ-Al 2 O 3 catalysts: Reaction conditions to slow down the deactivation

2017 ◽  
Vol 348 ◽  
pp. 265-275 ◽  
Author(s):  
N. Alonso-Fagúndez ◽  
M. Ojeda ◽  
R. Mariscal ◽  
J.L.G. Fierro ◽  
M. López Granados
Keyword(s):  
Maleic Anhydride ◽  
Gas Phase ◽  
Reaction Conditions ◽  
Phase Oxidation ◽  
Gas Phase Oxidation
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