Kinetics of deactivation of a solid catalyst in a nonsimple reaction. Isobutene oxidation in gaseous phase by a parallel reaction network

1982 ◽  
Vol 21 (4) ◽  
pp. 551-558 ◽  
Author(s):  
J. Corella ◽  
J. M. Asua
Keyword(s):  
Gaseous Phase ◽  
Reaction Network ◽  
Solid Catalyst ◽  
Parallel Reaction ◽  
Kinetics Of ◽  
Isobutene Oxidation

The effect of composition of cobalt-molybdenum catalysts on their surface acidity and isomerisation activity

1980 ◽  
Vol 45 (3) ◽  
pp. 697-702 ◽  
Author(s):  
Vlastimil Vyskočil ◽  
Miroslav Zdražil
Keyword(s):  
Chromatographic Method ◽  
Surface Acidity ◽  
Parallel Reaction ◽  
Molybdenum Catalysts ◽  
The Difference ◽  
Kinetics Of ◽  
Alumina Catalysts

Kinetics of isomerisation of cyclohexene to methylcyclopentene proceeding as parallel reaction to hydrogenation of cyclohexene to cyclohexane on cobalt-molybdenum catalysts of different composition has been measured. The surface acidity of these catalysts was estimated from the difference in the adsorption of toluene and heptane which was measured by chromatographic method. In a series of catalysts containing molybdenum the acidity parallels isomerisation activity. Cobalt on alumina catalysts and alumina itself have greater acidity but exhibit lower isomerisation activity compared to the catalysts containing molybdenum.

Investigation of non-isothermal pyrolysis kinetics of waste industrial hemp stem by three-parallel-reaction model

2021 ◽  
pp. 126402
Author(s):  
Fangjun Chen ◽  
Fengxia Zhang ◽  
Shiliang Yang ◽  
Huili Liu ◽  
Hua Wang ◽  
...  
Keyword(s):  
Reaction Model ◽  
Parallel Reaction ◽  
Pyrolysis Kinetics ◽  
Industrial Hemp ◽  
Kinetics Of

Reactions of free radicals with aromatic compounds in the gaseous phase. II. Kinetics of the reaction of methyl radicals with phenol

1965 ◽  
Vol 18 (1) ◽  
pp. 20 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams
Keyword(s):  
Free Radicals ◽  
Gaseous Phase ◽  
Hydrogen Abstraction ◽  
High Reactivity ◽  
Phenoxy Radical ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Kinetics Of Formation ◽  
Phenolic Substances ◽  
Kinetics Of

Knowledge of the reactivity of phenols towards simple free radicals is needed to throw light on the behaviour of the phenolic substances involved in the pyrolysis of coal and other organic materials. In the present investigation the reaction between methyl radicals and phenol vapour has been studied a t total pressures from 0.5 to 3 cmHg and temperatures from 445 to 547°K, the concentrations of methyl radicals and phenol being varied from 2 × 10-12 to 4 × 10-11 and 1 × 10-8 to 8 × 10-7 mole cm-3 respectively. The main products identified by gas chromatography were methane and o- and p-cresol, together with a little anisole and 2,4- and 2,6-dimethylphenol. The cresols are produced via hydrogen abstraction Diagram followed by combination of a methyl radical at a ring position of the phenoxy radical either ortho or para to the oxygen atom, e.g. in the case of the para position: Diagram The kinetics can be explained by postulating (a) that the keto forms of the cresols (methylcyclohexadienones) formed initially by reaction (6) have a finite lifetime in the gaseous phase and (b) that these molecules, which contain a tertiary hydrogen atom α to a system of a carbonyl bond and two carbon-carbon double bonds, partly undergo hydrogen abstraction by methyl radicals before they are able to enolize: CH3· + (HCH3 = C6H4 = O → CH4 + CH3C6H4O· The mechanism is consistent with the kinetics of formation of methane, the distribu- tion of the free electron in the phenoxy radical, the formation of o- and p-cresols as major products, the kinetics of formation of the cresols, and the high reactivity of the intermediate product towards methyl radicals.

Effect of irradiation and of replacement of hydrogen by deuterium on the kinetics of hydrogenation of maleic acid on a nickel catalyst

1980 ◽  
Vol 45 (6) ◽  
pp. 1632-1638 ◽  
Author(s):  
Rostislav Kudláček ◽  
Růžena Jelínková
Keyword(s):  
Reaction Rate ◽  
Catalyst Surface ◽  
Catalyst Activity ◽  
Hydrogenation Reaction ◽  
Gamma Dose ◽  
Model Reaction ◽  
Solid Catalyst ◽  
Liquid Phase Hydrogenation ◽  
Kinetics Of ◽  
Preliminary Irradiation

Liquid phase hydrogenation reaction was studied on modifying the solid catalyst by preliminary irradiation and replacing the reacting hydrogen by deuterium; the changes in the reaction rate were measured and the phenomena on the catalyst surface, particularly the change in the catalyst activity, were investigated. For the model reaction, the dependences of the reaction rate on the temperature of reduction and of the successive activation of the catalyst on the absorbed gamma dose were followed, and the dependences of the reaction rate on the reaction temperature were compared for the hydrogenation and deuteration. Isotope effect was found in the influence of the reacting medium on the catalyst property. The activity of the nickel carrier catalyst is governed by its interaction with hydrogen after the reduction, particularly by the temperature of this process.

Programmable Dynamic Steady States in ATP-Driven Non-Equilibrium DNA Systems

2019 ◽  
Author(s):  
Laura Heinen ◽  
Andreas Walther
Keyword(s):  
Self Assembly ◽  
Soft Matter ◽  
Enzymatic Reaction ◽  
Reaction Network ◽  
Steady States ◽  
Supramolecular Systems ◽  
Kinetics Of ◽  
Average Bond ◽  
Full Synchronization ◽  
Non Equilibrium

<div><div><div><p>Inspired by the dynamics of the dissipative self-assembly of microtubules, chemically fueled synthetic systems with transient lifetimes are emerging for non-equilibrium materials design. However, realizing programmable or even adaptive structural dynamics has proven challenging because it requires synchronization of energy uptake and dissipation events within true steady states, which remains difficult to orthogonally control in supramolecular systems. Here, we demonstrate full synchronization of both events by ATP-fueled activation and dynamization of covalent DNA bonds via an enzymatic reaction network of concurrent ligation and cleavage. Critically, the average bond ratio and the frequency of bond exchange are imprinted into the energy dissipation kinetics of the network and tunable through its constituents. We introduce temporally and structurally programmable dynamics by polymerization of transient, dynamic covalent DNA polymers with adaptive steady-state properties in dependence of ATP fuel and enzyme concentrations. This approach enables generic access to non-equilibrium soft matter systems with adaptive and programmable dynamics.</p></div></div></div>

Kinetics of individual steps in reaction network ethanol-diethyl ether-ethylene-water on alumina

1986 ◽  
Vol 51 (4) ◽  
pp. 763-773 ◽  
Author(s):  
Vladimír Morávek ◽  
Miloš Kraus
Keyword(s):  
Diethyl Ether ◽  
Reaction Network ◽  
Reaction Rates ◽  
Rate Equations ◽  
Initial Reaction ◽  
Ethanol Dehydration ◽  
Partial Pressures ◽  
Type Rate ◽  
Kinetics Of ◽  
Hydrolysis Of

The rates of single reactions have been measured at 250 °C in the complex reaction of ethanol dehydration to ethylene and to diethyl ether involving also hydrolysis of the ether, its disproportionation to ethanol and ethylene and its dehydration to ethylene. The found dependences of the initial reaction rates on partial pressures of the reactants were correlated by semiempirical Langmuir-Hinshelwood type rate equations.

Effects of Pressure on the Kinetics of Manganese Evaporation from the Ot4 Alloy / Wpływ Cisnienia Na Kinetyke Procesu Odparowania Manganu Ze Stopu Ot4

2013 ◽  
Vol 58 (1) ◽  
pp. 197-201 ◽  
Author(s):  
L. Blacha ◽  
R. Burdzik ◽  
A. Smalcerz ◽  
T. Matuła
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Gaseous Phase ◽  
Pressure Range ◽  
Evaporation Rate ◽  
Evaporation Process ◽  
Pressure Reduction ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Evaporation Kinetics

In the paper, results of the study on manganese evaporation from the OT4 alloy are presented. In the experiments, the effects of pressure on the manganese evaporation kinetics and the stages that limit the evaporation rate were investigated. It was demonstrated that the rate of manganese evaporation from the alloy increased with pressure reduction in the system. When the pressure decreases from 1000 Pa to 10 Pa, the value of overall mass transfer kMn increases from 3.9*10-6 ms-1 to 208.4*10-6 ms-1. At the same time, the manganese fraction in the alloy decreased from 1.49% mass to 0.045% mass. Within the whole pressure range, the analysed evaporation process is diffusion-controlled. For pressures above 50 Pa, the determining stage is transfer in the gaseous phase, while for pressures below 50 Pa, it is transfer in the liquid phase.

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