Kinetics of cyclohexene hydrogenation and of thiophene hydrogenolysis over cobalt-molybdenum catalysts of different composition

1979 ◽  
Vol 44 (12) ◽  
pp. 3676-3687 ◽  
Author(s):  
Vlastimil Vyskočil ◽  
Miloš Kraus
Keyword(s):  
Low Temperature ◽  
Rate Constants ◽  
Atmospheric Pressure ◽  
Kinetic Data ◽  
Oxygen Adsorption ◽  
Experimental Rate ◽  
Cyclohexene Hydrogenation ◽  
Molybdenum Catalysts ◽  
Kinetics Of

The kinetics of the title reactions has been measured at 350°C and atmospheric pressure on six Co-Mo-AL2O3 catalysts prepared by successive impregnation of the support with solutions of molybdenum and cobalt salts and containing these components in different ratios as well as on a commercial Cherox 36-00 catalyst. The activity of these catalysts depend strongly on their composition and showed similar trends for both reactions. Kinetic data were correlated by equations of Langmuir-Hishelwood type. Their adsorption coefficients have a similar value for different catalysts and all differences in the activity reflected in rate constants. Surface concentrations of molybdenum were determined by low temperature oxygen adsorption and were correlated with experimental rate constants.

Kinetics of catalytic conversion of methanol at higher pressures

1980 ◽  
Vol 45 (12) ◽  
pp. 3402-3407 ◽  
Author(s):  
Jaroslav Bartoň ◽  
Vladimír Pour
Keyword(s):  
Low Temperature ◽  
Reaction Kinetics ◽  
Water Vapour ◽  
Kinetic Data ◽  
Catalytic Conversion ◽  
The Given ◽  
Kinetics Of

The course of the conversion of methanol with water vapour was followed on a low-temperature Cu-Zn-Cr-Al catalyst at pressures of 0.2 and 0.6 MPa. The kinetic data were evaluated together with those obtained at 0.1 MPa and the following equation for the reaction kinetics at the given conditions was derived: r = [p(CH3OH)p(H2O)]0.5[p(H2)]-1.3.

scholarly journals Kinetics of the Toluene Reaction with OH Radical

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Rui Ming Zhang ◽  
Donald G. Truhlar ◽  
Xuefei Xu
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Atmospheric Chemistry ◽  
Temperature Regime ◽  
Rate Constants ◽  
Chemical Activation ◽  
Reaction Rates ◽  
State Theory ◽  
Partition Functions ◽  
Kinetics Of

We calculated the kinetics of chemical activation reactions of toluene with hydroxyl radical in the temperature range from 213 K to 2500 K and the pressure range from 10 Torr to the high-pressure limit by using multistructural variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT) and using the system-specific quantum Rice-Ramsperger-Kassel method. The reactions of OH with toluene are important elementary steps in both combustion and atmospheric chemistry, and thus it is valuable to understand the rate constants both in the high-pressure, high-temperature regime and in the low-pressure, low-temperature regime. Under the experimental pressure conditions, the theoretically calculated total reaction rate constants agree well with the limited experimental data, including the negative temperature dependence at low temperature. We find that the effect of multistructural anharmonicity on the partition functions usually increases with temperature, and it can change the calculated reaction rates by factors as small as 0.2 and as large as 4.2. We also find a large effect of anharmonicity on the zero-point energies of the transition states for the abstraction reactions. We report that abstraction of H from methyl should not be neglected in atmospheric chemistry, even though the low-temperature results are dominated by addition. We calculated the product distribution, which is usually not accessible to experiments, as a function of temperature and pressure.

Kinetics and mechanism of gold(III) incorporation into tetrakis(1-methylpyridium-4-yl)porphyrin in aqueous solution

2004 ◽  
Vol 08 (11) ◽  
pp. 1269-1275 ◽  
Author(s):  
Ahsan Habib ◽  
Masaaki Tabata ◽  
Ying Guang Wu
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Kinetic Data ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Hydroxyl Group ◽  
Net Charge ◽  
First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the reaction of the tetrakis(1-methylpyridium-4-yl)porphyrin tetracation, [ H 2( TMPyP )]4+, with gold(III) ions were studied along with equilibria of gold(III) species in aqueous medium at 25°C, I = 0.10 M ( NaNO 3). The equilibrium constants for the formation of [ AuCl 4-n( OH ) n ]- ( n = 0,…,4), defined as β n = [ AuCl 4- n ( OH ) n ]- [ Cl -] n / [ AuCl 4-][ OH -] n were found to be that log β1 = 7.94 ± 0.03, log β2 = 15.14 ± 0.03, log β3 = 21.30 ± 0.05 and log β4 = 26.88 ± 0.05. The overall reaction was first order with respect to each of the total [ Au (III)] and [ H 2 TMPyP 4+]. On the basis of pH dependence on rate constants and the hydrolysis of gold(III), the rate expression can be written as d [ Au ( TMPyP )5+]/ dt = ( k 1[ AuCl 4-] + k2[ AuCl 3( OH )-] + k3[ AuCl 2( OH )2-] + k4[ AuCl ( OH )3-])[ H 2 TMPyP 4+], where k1, k2, k3 and k4 were found to be (2.16 ± 0.31) × 10-1, (6.56 ± 0.19) × 10-1, (1.07 ± 0.24) × 10-1, and (0.29 ± 0.21) × 10-1 M -1. s -1, respectively. The kinetic data revealed that the trichloromonohydroxogold(III) species, [ AuCl 3( OH )]-, is the most reactive. The higher reactivity of [ AuCl 3( OH )]- is explained by hydrogen bonding formation between the hydroxyl group of [ AuCl 3( OH )]- and the pyrrole hydrogen atom of [ H 2( TMPyP )]4+. Furthermore, applying the Fuoss equation to the observed rate constants at different ionic strengths, the apparent net charge of [ H 2( TMPyP )]4+ was calculated to be +3.5.

Ultra-low temperature kinetics of neutral–neutral reactions: rate constants for the reactions of OH radicals with butenes between 295 and 23 K

1994 ◽  
Vol 90 (11) ◽  
pp. 1473-1478 ◽  
Author(s):  
Ian R. Sims ◽  
Ian W. M. Smith ◽  
Pascal Bocherel ◽  
André Defrance ◽  
Daniel Travers ◽  
...  
Keyword(s):  
Low Temperature ◽  
Rate Constants ◽  
Oh Radicals ◽  
Low Temperature Kinetics ◽  
Kinetics Of

Some observations on the kinetics of the Jaffé reaction for creatinine.

1977 ◽  
Vol 23 (9) ◽  
pp. 1527-1530 ◽  
Author(s):  
R M Shoucri ◽  
M Pouliot
Keyword(s):  
Rate Constants ◽  
Kinetic Data ◽  
Serum Samples ◽  
First Order ◽  
Order Rate ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Kinetics Of

Abstract The Jaffé reaction for creatinine assay appears to follow pseudo-first-order kinetics; first-order rate constants are different for different samples. Rate constants for 10 different serum samples varied from a low value of 0.0040 +/- 0.0003 s-1 to 0.0084 +/- 0.0008 s-1. We describe an approach for determining first-order rate constants from kinetic data and discuss the effects of the above observations on the mathematical formulations required for reliable kinetic determinations of creatinine.

scholarly journals Kinetics of the catalytic cracking of naphtha over ZSM-5 zeolite: effect of reduced crystal size on the reaction of naphthenes

2014 ◽  
Vol 4 (12) ◽  
pp. 4265-4273 ◽  
Author(s):  
Hiroki Konno ◽  
Ryota Ohnaka ◽  
Jun-ichi Nishimura ◽  
Teruoki Tago ◽  
Yuta Nakasaka ◽  
...  
Keyword(s):  
Rate Constants ◽  
Atmospheric Pressure ◽  
Catalytic Cracking ◽  
Reaction Rate ◽  
Crystal Size ◽  
Activation Energies ◽  
Reaction Rate Constants ◽  
Kinetics Of

The catalytic cracking of model naphthenes over ZSM-5 zeolites of different crystal sizes was examined at reaction temperatures ranging from 748 to 923 K under atmospheric pressure, focusing on the associated reaction rate constants and activation energies.

scholarly journals Predictive modeling of virus inactivation by UV

2020 ◽  
Author(s):  
Nicole C. Rockey ◽  
James B. Henderson ◽  
Kaitlyn Chin ◽  
Lutgarde Raskin ◽  
Krista R. Wigginton
Keyword(s):  
Rate Constants ◽  
Inactivation Rate ◽  
Inactivation Kinetics ◽  
Virus Inactivation ◽  
Prediction Errors ◽  
High Quality ◽  
Experimental Rate ◽  
Wide Range ◽  
Pathogenic Viruses ◽  
Kinetics Of

AbstractDisinfection strategies are commonly applied to inactivate pathogenic viruses in water, food, air, and on surfaces to prevent the spread of infectious diseases. Determining how quickly viruses are inactivated to mitigate health risks is not always feasible due to biosafety restrictions or difficulties with virus culturability. Therefore, methods that would rapidly predict kinetics of virus inactivation by UV254 would be valuable, particularly for emerging and difficult-to-culture viruses. We conducted a rapid systematic literature review to collect high-quality inactivation rate constants for a wide range of viruses. Using these data and basic virus information (e.g., genome sequence attributes), we developed and evaluated four different model classes, including linear and non-linear approaches, to find the top performing prediction model. For both the (+) ssRNA and dsDNA virus types, multiple linear regressions were the top performing model classes. In both cases, the cross-validated root mean squared relative prediction errors were similar to those associated with experimental rate constants. We tested the models by predicting and measuring inactivation rate constants for two viruses that were not identified in our systematic review, including a (+) ssRNA mouse coronavirus and a dsDNA marine bacteriophage; the predicted rate constants were within 7% and 71% of the experimental rate constants, respectively. Finally, we applied our models to predict the UV254 rate constants of several viruses for which high-quality UV254 inactivation data are not available. Our models will be valuable for predicting inactivation kinetics of emerging or difficult-to-culture viruses.

Fast disproportionation of hexacyanomanganate(III) in acidic solution. Formation of hexacyanomanganate(IV) and kinetics of its decomposition

1986 ◽  
Vol 64 (12) ◽  
pp. 2301-2304 ◽  
Author(s):  
Guillermo López-Cueto ◽  
Carlos Ubide
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Solution ◽  
Activation Parameters ◽  
Rate Law ◽  
First Order ◽  
Experimental Rate ◽  
Parallel Pathways ◽  
Solution Formation ◽  
Kinetics Of

When potassium hexacyanomanganate(III) dissolves in acidic solution it rapidly disproportionates into hexacyanomanganate(IV) and Mn(II). Hexacyanomanganate(IV) then slowly decomposes to yield Mn(II) and (CN)2. Kinetics of the latter reaction has been studied. The reaction is found to be first order with respect to [Formula: see text], H+, and Mn(II) concentrations and the experimental rate law has the form v = kobs[Mn(IV)] = (ka + kb[H+] + kc[Mn(II)])[Mn(IV)]. At 40 °C and ionic strength 2.0, ka, kb, and kc values are (1.78 ± 0.01) × 10−4 s−1, (5.97 ± 0.05) × 10−5 s−1 M−1, and (3.40 ± 0.18) × 10−3 s−1 M−1, respectively. A mechanism with three parallel pathways is proposed, the deduced rate law being similar to the experimental one. Activation parameters, ΔH≠and ΔS≠ for the rate constants ka, kb, and kc are also reported.

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