scholarly journals Three-Factor Kinetic Equation of Catalyst Deactivation

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 818
Author(s):  
Zoë Gromotka ◽  
Gregory Yablonsky ◽  
Nickolay Ostrovskii ◽  
Denis Constales
Keyword(s):  
Kinetic Equation ◽  
Kinetic Parameters ◽  
Catalyst Deactivation ◽  
Supported Metal Catalysts ◽  
Tio2 Anatase ◽  
Catalytic Intermediates ◽  
Reversible Deactivation ◽  
Apparent Kinetic Parameters ◽  
State Assumption ◽  
Three Factor

The three-factor kinetic equation of catalyst deactivation was obtained in terms of apparent kinetic parameters. The three factors correspond to the main cycle with a linear, detailed mechanism regarding the catalytic intermediates, a cycle of reversible deactivation, and a stage of irreversible deactivation (aging), respectively. The rate of the main cycle is obtained for the fresh catalyst under a quasi-steady-state assumption. The phenomena of reversible and irreversible deactivation are presented as special separate factors (hierarchical separation). In this case, the reversible deactivation factor is a function of the kinetic apparent parameters of the reversible deactivation and of those of the main cycle. The irreversible deactivation factor is a function of the apparent kinetic parameters of the main cycle, of the reversible deactivation, and of the irreversible deactivation. The conditions of such separability are found. The obtained equation is applied successfully to describe the literature data on the reversible catalyst deactivation processes in the dehydration of acetaldehyde over TiO2 anatase and in crotonaldehyde hydrogenation on supported metal catalysts.

scholarly journals The kinetics of the hydrogen chloride oxidation

2013 ◽  
Vol 78 (12) ◽  
pp. 2115-2130 ◽  
Author(s):  
Martinez Gonzalez ◽  
Tanja Vidakovic-Koch ◽  
Rafael Kuwertz ◽  
Ulrich Kunz ◽  
Thomas Turek ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Gas Phase ◽  
Hydrogen Chloride ◽  
Reaction Order ◽  
Membrane Electrode ◽  
Polarization Data ◽  
Rate Determining Step ◽  
Electrode Assemblies ◽  
Apparent Kinetic Parameters ◽  
Kinetics Of

Hydrogen chloride (HCl) oxidation has been investigated on technical membrane electrode assemblies in a cyclone flow cell. Influence of Nafion loading, temperature and hydrogen chloride mole fraction in the gas phase has been studied. The apparent kinetic parameters like reaction order with respect to HCl, Tafel slope and activation energy have been determined from polarization data. The apparent kinetic parameters suggest that the recombination of adsorbed Cl intermediate is the rate determining step.

The Development of Kinetic Parameters of Hepatic Drug-Metabolizing Enzymes in Perinatal Rats

1975 ◽  
Vol 53 (4) ◽  
pp. 433-437 ◽  
Author(s):  
J. U. Bell ◽  
D. J. Ecobichon
Keyword(s):  
Kinetic Parameters ◽  
Wistar Rats ◽  
Drug Metabolizing Enzymes ◽  
Hepatic Enzymes ◽  
Metabolizing Enzymes ◽  
Hepatic Drug ◽  
Apparent Kinetic Parameters ◽  
Quantitative Changes ◽  
Functionally Diverse ◽  
Conjugating Enzyme

The development of the apparent kinetic parameters Km and Vmax was studied in perinatal Wistar rats for three functionally diverse, hepatic enzymes (p-nitroanisole O-demethylase, carboxylesterase and bromosulphophthalein–glutathione conjugating enzyme), the period studied being from 3 days prepartum to 35 days postpartum. The kinetic parameters underwent marked quantitative changes during development, which appeared to be independent of sex for the first 5 weeks postpartum.

Study on Combustion Characteristics of Impurity Coal Based on TG-DTG-DTA

2012 ◽  
Vol 568 ◽  
pp. 360-363
Author(s):  
Zhan Wen He ◽  
Chuan Cheng Zhang
Keyword(s):  
Kinetic Equation ◽  
Kinetic Parameters ◽  
Heating Rate ◽  
Ignition Temperature ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Diffusion Kinetic

Abstract.Based on TG-DTG-DTA, combustion characteristics and kinetic parameters of impure coal in the 10 °C / min heating rate were studied. The results showed that with the increase in the proportion of impurities, ignition temperature, burned temperature significantly improved; combustion characteristics of index clearly decreased; combustion process can be described by a diffusion kinetic equation

scholarly journals Kinetic study of propane aromatization over Zn/HZSM-5 zeolite under conditions of catalyst deactivation using genetic algorithm

2018 ◽  
Vol 83 (4) ◽  
pp. 473-488 ◽  
Author(s):  
Abbas Roshanaei ◽  
Mehdi Alavi
Keyword(s):  
Genetic Algorithm ◽  
Kinetic Model ◽  
Kinetic Parameters ◽  
Catalyst Deactivation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Kinetic Studies ◽  
Space Velocity ◽  
Propane Aromatization ◽  
Aromatization Reaction

The kinetic studies of propane aromatization reaction over Zn/ /HZSM-5 catalyst at temperature of 500?560?C and space velocity of 500?2500 cm3 gcat -1 h-1, in a plug flow reactor, under catalyst deactivating conditions were performed. A lumped kinetic model consisting of six lumped components and six reaction steps was proposed to describe the aromatization of propane. The kinetic model involves 18 kinetic parameters and one catalyst deactivation constant. The reaction steps orders were obtained by the power law model. Frequency factors and the apparent activation energies of the reaction steps were calculated based on the Arrhenius equation. An exponential function depending on the time-on-stream was applied for the catalyst deactivation model and the kinetic parameters were calculated via a genetic algorithm. The kinetic results indicated that the lumped kinetic model can well estimate the product yields of propane aromatization.

Critical conversion in the processes of polymer formation

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Tamara F. Irzhak ◽  
Vadim I. Irzhak
Keyword(s):  
Kinetic Equation ◽  
Kinetic Parameters ◽  
Substitution Effect ◽  
Gel Point ◽  
Functional Monomer ◽  
Initial Concentration ◽  
Polymer Formation ◽  
Average Functionality ◽  
Functional Blocks ◽  
Critical Conversion

AbstractRelations between the critical conversion of gelation αc and the conditions of polymer formation by living and terminated polymerization were studied. It was shown that the weight average functionality of the initial system given by the formula,Φ22(0)=∑ i(i-1)mi where mi is the initial concentration of an i-functional monomer, is the parameter determining the value of αc. Formulas relating the critical conversion to the kinetic parameters of polymerization processes are presented. For polycondensation processes the kinetic equation based on the concept of bond blocks is proposed. It allows for estimating the gel point even for systems in which the substitution effect takes place for one of the components. The equation α ∑ i(i-1)ni=1 is , where α is the current conversion and ni are the values specifying the concentrations of i-functional blocks. The latter values are functions of α and may be calculated kinetically.

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