Application of additive-reaction-times law to the mixed-control kinetics of oxygen leaching of chalcopyrite

2014 ◽  
Vol 146 ◽  
pp. 164-168 ◽  
Author(s):  
York R. Smith ◽  
Hong Yong Sohn
Keyword(s):  
Reaction Times ◽  
Mixed Control ◽  
Kinetics Of ◽  
Additive Reaction

A Stirred-Flow Reactor for Investigating the Kinetics of Gaseous Reactions: Application to the Decomposition of Di-t-butyl Peroxide

1961 ◽  
Vol 14 (4) ◽  
pp. 534 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams
Keyword(s):  
Excellent Agreement ◽  
Rate Constant ◽  
Flow Reactor ◽  
Reaction Times ◽  
Static Method ◽  
Flow Conditions ◽  
Gaseous Reaction ◽  
Flow Method ◽  
Butyl Peroxide ◽  
Kinetics Of

The uncertainty regarding temperature and flow conditions which attaches to the conventional flow method of determining the rate of a gaseous reaction can be substantially reduced by using a stirred-flow reactor. The reagents, products, and carrier-gas (if any) are mixed sufficiently vigorously for the composition of the gas in the reactor to be virtually uniform. A reactor designed to achieve the required degree of mixing at pressures of about 1 cmHg and reaction times of the order of 1 sec to 1 min is described. The rate constant of the decomposition of di-t-butyl peroxide was determined over the temperature range 430-550 �K. The values derived on the assumption of complete mixing in the reactor were independent of the degree of conversion and in excellent agreement with those obtained by previous authors using the static method.

Kinetics of Coal Liquefaction at Very Short Reaction Times

1996 ◽  
Vol 10 (3) ◽  
pp. 641-648 ◽  
Author(s):  
He Huang ◽  
Keyu Wang ◽  
Shaojie Wang ◽  
Michael T. Klein ◽  
William H. Calkins
Keyword(s):  
Reaction Times ◽  
Coal Liquefaction ◽  
Kinetics Of

Leaching and Kinetic Modeling of Malaysian Low Grade Manganese Ore in Sulfuric Acids

2016 ◽  
Vol 1133 ◽  
pp. 629-633 ◽  
Author(s):  
Suhaina Ismail ◽  
Hashim Hussin ◽  
Syed Fuad Saiyid Hashim ◽  
Norazharuddin Shah Abdullah
Keyword(s):  
Dissolution Kinetics ◽  
Product Layer ◽  
Low Grade ◽  
Manganese Ore ◽  
Leaching Process ◽  
Mixed Control ◽  
New Variant ◽  
Experimental Parameters ◽  
Kinetics Of ◽  
And Diffusion

The leaching process of Malaysian low grade manganese ore (LGMO) using bamboo sawdust (BSD) as reducing agent in acidic medium (H2SO4) and the dissolution kinetics of this ore was investigated. Acid concentration, reaction temperature, and BSD loading were chosen as experimental parameters through application of response surface methodology (RSM). For analysis of the kinetic data in this study, the SCM with surface chemical reaction and diffusion through product layer, the mixed control modelled and also new variant SCM were evaluated. The reaction kinetics of this leaching process was determined, and it is observed that it fits the model of 1-23X-(1-X)23=kt with activation energy of 69.3kJ/mol. The reaction rate for LGMO leaching using BSD was found to be diffusion through product layer.

Kinetics of ASAM and Kraft Pulping of Eucalypt Wood (Eucalyptus globulus)

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Isabel Miranda ◽  
Helena Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Initial Period ◽  
Reaction Times ◽  
Kraft Pulping ◽  
Kraft Pulps ◽  
Final Phase ◽  
Lower Mass ◽  
Lignin Removal ◽  
Mass Losses ◽  
Kinetics Of

Summary The kinetics of ASAM and kraft pulping of eucalypt wood (Eucalyptus globulus) were studied in relation to delignification and polysaccharide removal. In comparison to kraft, ASAM pulping had lower mass losses and delignification for the same temperature and reaction times (59.2% at Kappa 25 vs 50.0% at Kappa 17, at 180°C). The ASAM pulps have a higher brightness. ASAM pulping had a short initial period with no mass loss and lignin removal, followed by two reaction phases: a main phase where 61% of lignin was removed (at 180°C) and a subsequent final phase. In comparison to kraft, the main delignification rates of ASAM pulping were approximately 2.5 slower (at 180°C, −1.8 × 10−2 min−1 for ASAM and −4.2 × 10−2 for kraft pulping), and the calculated Arrhenius activation energies were higher (132.4 kJ mol−1 and 83.5 kJ mol−1, respectively). The loss of cellulose was relatively small (12.5 %) and lower than in kraft pulps.

scholarly journals Universal kinetics of imperfect reactions in confinement

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Thomas Guérin ◽  
Maxim Dolgushev ◽  
Olivier Bénichou ◽  
Raphaël Voituriez
Keyword(s):  
Reaction Time ◽  
Transport Process ◽  
Reaction Times ◽  
Complex Environments ◽  
Analytical Treatment ◽  
Volume Limit ◽  
Normal Diffusion ◽  
The Mean ◽  
Kinetics Of ◽  
Mean Reaction Time

AbstractChemical reactions generically require that particles come into contact. In practice, reaction is often imperfect and can necessitate multiple random encounters between reactants. In confined geometries, despite notable recent advances, there is to date no general analytical treatment of such imperfect transport-limited reaction kinetics. Here, we determine the kinetics of imperfect reactions in confining domains for any diffusive or anomalously diffusive Markovian transport process, and for different models of imperfect reactivity. We show that the full distribution of reaction times is obtained in the large confining volume limit from the knowledge of the mean reaction time only, which we determine explicitly. This distribution for imperfect reactions is found to be identical to that of perfect reactions upon an appropriate rescaling of parameters, which highlights the robustness of our results. Strikingly, this holds true even in the regime of low reactivity where the mean reaction time is independent of the transport process, and can lead to large fluctuations of the reaction time - even in simple reaction schemes. We illustrate our results for normal diffusion in domains of generic shape, and for anomalous diffusion in complex environments, where our predictions are confirmed by numerical simulations.

Kinetics of the direct chlorination of carbon

1970 ◽  
Vol 23 (4) ◽  
pp. 725 ◽  
Author(s):  
JD Blackwood ◽  
BD Cullis
Keyword(s):  
High Temperature ◽  
Carbon Tetrachloride ◽  
Partial Pressure ◽  
Reaction Times ◽  
Not Given ◽  
Kcal Mole ◽  
Predominant Species ◽  
Flow Apparatus ◽  
Wood Char ◽  
Kinetics Of

Carbon, in the form of a wood char activated by treatment with air and chlorine, has been chlorinated directly at temperatures between 600� and 800� and at chlorine pressures between 3.5 and 20 atm in a flow apparatus to produce carbon tetrachloride as sole reaction product. The rate of formation R of carbon tetrachloride can be expressed by the equation R = ilpa where il is the rate constant for the chemisorption of chlorine on carbon and pa is the partial pressure of chlorine. The rate is also dependent on the nature of the carbon, high temperature carbons being less reactive. The energy of activation for the process is 25 kcal mole-1. When carbon tetrachloride is decomposed in a carbon bed, tetrachloroethylene, hexachloroethane, chlorine, and carbon are formed as products, the predominant species depending on the conditions. This indicated that the overall reaction is not given by the simple equation C + 2Cl2 + CCl4 (I) and, on prolonged reaction times, yields of carbon tetrachloride well below the amount expected at equilibrium for this reaction confirm the finding. pa denotes the partial pressure of Cl2, pb that of CCl4, pc that of C2C14, and pa that of CzCl6.The subscript numerals to i and j refer to the equation numbers in the text.

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