Vanadium-phosphorus-oxygen industrial catalysts for n-butane oxidation: characterization and kinetic measurements

1986 ◽  
Vol 25 (4) ◽  
pp. 612-620 ◽  
Author(s):  
Robert W. Wenig ◽  
Glenn L. Schrader
Keyword(s):  
Butane Oxidation ◽  
Kinetic Measurements

Analogues of the active and inactive sodium carbonate

1982 ◽  
Vol 47 (12) ◽  
pp. 3348-3361 ◽  
Author(s):  
Erich Lippert ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Time Dependence ◽  
Water Vapour ◽  
Sulphur Dioxide ◽  
Atmospheric Pressure ◽  
Flow Reactor ◽  
Kinetic Measurements ◽  
Sodium Potassium ◽  
Alkaline Metals ◽  
Hydrogen Carbonates

The reactivity of the anhydrous carbonates of alkaline metals with sulphur dioxide has been studied experimentally in dependence both on the nature of the cation and on the way of preparation of the anhydrous carbonate. The carbonates were prepared either by thermal decomposition of hydrogen carbonates or by thermal dehydration of carbonate hydrates. The carbonates of lithium, sodium, potassium, rubidium and caesium have been investigated. Kinetic measurements were carried out in a flow reactor in the integral regime at 423 K under atmospheric pressure, with a gas containing 0.2 vol.% of sulphur dioxide and 2.0 vol.% of water vapour in the nitrogen as a carrier gas. The reactivities have been compared on the basis of time dependence of the conversion of carbonate to sulphite.

Formation of sodium disulfite in a solid-gas system

1991 ◽  
Vol 56 (8) ◽  
pp. 1575-1579 ◽  
Author(s):  
Jiří Vobiš ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Sodium Sulfite ◽  
Heterogeneous Reaction ◽  
Optimum Conditions ◽  
Kinetic Measurements ◽  
Dissociation Pressure ◽  
Partial Pressures ◽  
Gas System ◽  
Gaseous Sulfur ◽  
Equilibrium Dissociation

The formation of sodium disulfite by the heterogeneous reaction of solid active sodium sulfite with gaseous sulfur dioxide in the presence of water vapour was investigated over the temperature range of 293 to 393 K at SO2. H2O and O2 partial pressures of 1.2-7.4, 1.2-6.4 and 0-11.3 kPa, respectively. The effect of the reaction time was also examined. Kinetic measurements were supplemented with the determination of the equilibrium dissociation pressure of SO2 in contact with sodium sulfite at 373.15 K. The major aim of the work was to establish the optimum conditions for attaining the maximum degree of conversion of the solid reactant to sodium disulfite. The conditions for the formation of virtually pure sodium disulfite were found.

Feedback Reactor and Nonlinear Regression Methods

1992 ◽  
Vol 57 (10) ◽  
pp. 2053-2058
Author(s):  
Václav Dušek ◽  
František Skopal
Keyword(s):  
Nonlinear Regression ◽  
Kinetic Measurements ◽  
Regression Methods ◽  
Linear And Nonlinear

Linear and nonlinear regression methods are compared with respect to their application to the evaluation of chemico-kinetic measurements of a feedback reactor. Their assets and pitfalls are demonstrated.

scholarly journals Helmet Phthalocyaninato Iron Complex as a Primary Drier for Alkyd Paints

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1220
Author(s):  
Jan Honzíček ◽  
Eliška Matušková ◽  
Štěpán Voneš ◽  
Jaromír Vinklárek
Keyword(s):  
Catalytic Performance ◽  
Mechanical Tests ◽  
Iron Complex ◽  
Kinetic Measurements ◽  
Time Resolved ◽  
Strong Activity ◽  
Vis Spectroscopy ◽  
Order Of Magnitude ◽  
Transparent Coatings ◽  
Time Resolved Infrared Spectroscopy

This study describes the catalytic performance of an iron(III) complex bearing a phthalocyaninato-like ligand in two solvent-borne and two high-solid alkyd binders. Standardized mechanical tests revealed strong activity, which appeared in particular cases at concentrations about one order of magnitude lower than in the case of cobalt(II) 2-ethylhexanoate, widespread used in paint-producing industry. The effect of the iron(III) compound on autoxidation process, responsible for alkyd curing, was quantified by kinetic measurements by time-resolved infrared spectroscopy and compared with several primary driers. Effect of the drier concentration on coloration of transparent coatings was determined by UV–Vis spectroscopy.

scholarly journals Direct Kinetic Measurements and Master Equation Modelling of the Unimolecular Decomposition of Resonantly-Stabilized CH2CHCHC(O)OCH3 Radical and an Upper Limit Determination for CH2CHCHC(O)OCH3 + O2 Reaction

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1251-1268 ◽  
Author(s):  
Satya Prakash Joshi ◽  
Prasenjit Seal ◽  
Timo Theodor Pekkanen ◽  
Raimo Sakari Timonen ◽  
Arrke J. Eskola
Keyword(s):  
Master Equation ◽  
Density Functional ◽  
Rate Coefficient ◽  
Decomposition Kinetics ◽  
Basis Sets ◽  
Stationary Points ◽  
Unimolecular Decomposition ◽  
Kinetic Measurements ◽  
Point Energy ◽  
Upper Limit

AbstractMethyl-Crotonate (MC, (E)-methylbut-2-enoate, CH3CHCHC(O)OCH3) is a potential component of surrogate fuels that aim to emulate the combustion of fatty acid methyl ester (FAME) biodiesels with significant unsaturated FAME content. MC has three allylic hydrogens that can be readily abstracted under autoignition and combustion conditions to form a resonantly-stabilized CH2CHCHC(O)OCH3 radical. In this study we have utilized photoionization mass spectrometry to investigate the O2 addition kinetics and thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical. First we determined an upper limit for the bimolecular rate coefficient of CH2CHCHC(O)OCH3 + O2 reaction at 600 K (k ≤ 7.5 × 10−17 cm3 molecule−1 s−1). Such a small rate coefficient suggest this reaction is unlikely to be important under combustion conditions and subsequent efforts were directed towards measuring thermal unimolecular decomposition kinetics of CH2CHCHC(O)OCH3 radical. These measurements were performed between 750 and 869 K temperatures at low pressures (<9 Torr) using both helium and nitrogen bath gases. The potential energy surface of the unimolecular decomposition reaction was probed at density functional (MN15/cc-pVTZ) level of theory and the electronic energies of the stationary points obtained were then refined using the DLPNO-CCSD(T) method with the cc-pVTZ and cc-pVQZ basis sets. Master equation simulations were subsequently carried out using MESMER code along the kinetically important reaction pathway. The master equation model was first optimized by fitting the zero-point energy corrected reaction barriers and the collisional energy transfer parameters $\Delta{E_{{\text{down}},\;{\text{ref}}}}$ and n to the measured rate coefficients data and then utilize the constrained model to extrapolate the decomposition kinetics to higher pressures and temperatures. Both the experimental results and the MESMER simulations show that the current experiments for the thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical are in the fall-off region. The experiments did not provide definite evidence about the primary decomposition products.

scholarly journals The two redox states of the human NEET proteins’ [2Fe–2S] clusters

2021 ◽  
Vol 26 (7) ◽  
pp. 763-774
Author(s):  
Ke Zuo ◽  
Henri-Baptiste Marjault ◽  
Kara L. Bren ◽  
Giulia Rossetti ◽  
Rachel Nechushtai ◽  
...  
Keyword(s):  
Protein S ◽  
Spectroscopic Studies ◽  
Reduced Form ◽  
Rieske Protein ◽  
Kinetic Measurements ◽  
Redox States ◽  
Extra Electron ◽  
Dynamics Simulations ◽  
Reduced State

AbstractThe NEET proteins constitute a unique class of [2Fe–2S] proteins. The metal ions bind to three cysteines and one histidine. The proteins’ clusters exist in two redox states; the oxidized protein (containing two FeIII ions) can transfer the cluster to apo-acceptor protein(s), while the reduced form (containing one ferrous ion) remains bound to the protein frame. Here, we perform in silico and in vitro studies on human NEET proteins in both reduced and oxidized forms. Quantum chemical calculations on all available human NEET proteins structures suggest that reducing the cluster weakens the Fe–NHis and Fe–SCys bonds, similar to what is seen in other Fe–S proteins (e.g., ferredoxin and Rieske protein). We further show that the extra electron in the [2Fe–2S]+ clusters of one of the NEET proteins (mNT) is localized on the His-bound iron ion, consistently with our previous spectroscopic studies. Kinetic measurements demonstrate that the mNT [2Fe–2S]+ is released only by an increase in temperature. Thus, the reduced state of human NEET proteins [2Fe–2S] cluster is kinetically inert. This previously unrecognized kinetic inertness of the reduced state, along with the reactivity of the oxidized state, is unique across all [2Fe–2S] proteins. Finally, using a coevolutionary analysis, along with molecular dynamics simulations, we provide insight on the observed allostery between the loop L2 and the cluster region. Specifically, we show that W75, R76, K78, K79, F82 and G85 in the latter region share similar allosteric characteristics in both redox states. Graphic abstract

scholarly journals Flow cytometric kinetic measurements of neutrophil phospholipase A activation.

1992 ◽  
Vol 267 (30) ◽  
pp. 21465-21470
Author(s):  
T Meshulam ◽  
H Herscovitz ◽  
D Casavant ◽  
J Bernardo ◽  
R Roman ◽  
...  
Keyword(s):  
Phospholipase A ◽  
Kinetic Measurements ◽  
Flow Cytometric

scholarly journals Determining the mass-related reaction effectiveness factor of large, nonspherical fuel particles for bridging between intrinsic and apparent combustion kinetics

2019 ◽  
Vol 141 (2) ◽  
pp. 797-806 ◽  
Author(s):  
Tibor Szűcs ◽  
Pal Szentannai
Keyword(s):  
Combustion Process ◽  
Effectiveness Factor ◽  
Cfd Modeling ◽  
Combustion Kinetics ◽  
Kinetic Measurements ◽  
Environmental Requirements ◽  
Fuel Particles ◽  
Related Reaction ◽  
Kinetics Of ◽  
Internal Pore

AbstractThe utilization of challenging solid fuels in the energy industry is urged by environmental requirements. The combustion kinetics of these fuel particles differs markedly from that of pulverized coal, mainly because of their larger sizes, irregular (nonspherical) shapes, and versatile internal pore structures. Although the intrinsic reaction kinetic measurements on very small amounts of finely ground samples of these particles are mostly available, a bridge toward their apparent reaction modeling is not evident. In this study, a method is introduced to build this bridge, the goodness of which was proved on the example of an industrially relevant biofuel. To do this, the results of a macroscopic combustion measurement with real samples in a well-modelable environment have to be used, and for considering some not negligible effects, 3D CFD modeling of the experimental environment is also to be applied. The outcome is the mass-related reaction effectiveness factor as a function of the rate of conversion. This variable can be considered as the active fraction of the entire particle mass on its periphery, and it can be used as the crucial element in modeling the combustion process of the same particle under other circumstances by including the actual boundary conditions. Another advantage of this method is its covering inherently the entire combustion process (water and volatile release, and char combustion) and also its applicability for reactors utilizing bigger particles like fluidized bed combustors.

scholarly journals Kinetic measurements of the biliary excretion of metabolized compounds

1980 ◽  
Vol 188 (2) ◽  
pp. 561-564
Author(s):  
G M Powell ◽  
J G Jones ◽  
C G Curtis
Keyword(s):  
Kinetic Parameters ◽  
Cholic Acid ◽  
Biliary Excretion ◽  
Kinetic Measurements

1. Rats received constant infusions of bromosulphophthalein or [carboxy-14C]cholic acid at a range of concentrations. 2. Kinetic parameters describing the biliary excretion of the compounds were determined. 3. The biliary excretion of both compounds could be described by the same kinetic parameters already calculated for phenolphthalein disulphate, which is excreted in the bile unchanged.

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