Kinetics of mechanochemical transformations

2020 ◽  
Vol 22 (26) ◽  
pp. 14489-14502 ◽  
Author(s):  
Maria Carta ◽  
Evelina Colacino ◽  
Francesco Delogu ◽  
Andrea Porcheddu
Keyword(s):  
Kinetic Model ◽  
Mechanical Processing ◽  
Statistical Nature ◽  
Kinetics Of

To help understanding the mechanisms underlying mechanochemical transformations, we propose a kinetic model that relates macroscopic and microscopic scales while accounting for the statistical nature of the mechanical processing of powder.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

scholarly journals Torrefaction Thermogravimetric Analysis and Kinetics of Sorghum Distilled Residue for Sustainable Fuel Production

2021 ◽  
Vol 13 (8) ◽  
pp. 4246
Author(s):  
Shih-Wei Yen ◽  
Wei-Hsin Chen ◽  
Jo-Shu Chang ◽  
Chun-Fong Eng ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Pso Algorithm ◽  
Nitrogen Atmosphere ◽  
Computational Method ◽  
Weight Changes ◽  
Design And Optimization ◽  
Thermogravimetric Analyzer ◽  
Model Free ◽  
Different Temperatures ◽  
Kinetics Of

This study investigated the kinetics of isothermal torrefaction of sorghum distilled residue (SDR), the main byproduct of the sorghum liquor-making process. The samples chosen were torrefied isothermally at five different temperatures under a nitrogen atmosphere in a thermogravimetric analyzer. Afterward, two different kinetic methods, the traditional model-free approach, and a two-step parallel reaction (TPR) kinetic model, were used to obtain the torrefaction kinetics of SDR. With the acquired 92–97% fit quality, which is the degree of similarity between calculated and real torrefaction curves, the traditional method approached using the Arrhenius equation showed a poor ability on kinetics prediction, whereas the TPR kinetic model optimized by the particle swarm optimization (PSO) algorithm showed that all the fit qualities are as high as 99%. The results suggest that PSO can simulate the actual torrefaction kinetics more accurately than the traditional kinetics approach. Moreover, the PSO method can be further employed for simulating the weight changes of reaction intermediates throughout the process. This computational method could be used as a powerful tool for industrial design and optimization in the biochar manufacturing process.

scholarly journals A Logistic Approach for Kinetics of Isothermal Pyrolysis of Cellulose

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 551
Author(s):  
Jorge López-Beceiro ◽  
Ana María Díaz-Díaz ◽  
Ana Álvarez-García ◽  
Javier Tarrío-Saavedra ◽  
Salvador Naya ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Time Derivative ◽  
Inert Atmosphere ◽  
Second Step ◽  
Rate Parameter ◽  
Thermogravimetric Data ◽  
Different Temperatures ◽  
Parameter Values ◽  
Kinetics Of ◽  
Logistic Functions

A kinetic model is proposed to fit isothermal thermogravimetric data obtained from cellulose in an inert atmosphere at different temperatures. The method used here to evaluate the model involves two steps: (1) fitting of single time-derivative thermogravimetric curves (DTG) obtained at different temperatures versus time, and (2) fitting of the rate parameter values obtained at different temperatures versus temperature. The first step makes use of derivative of logistic functions. For the second step, the dependence of the rate factor on temperature is evaluated. That separation of the curve fitting from the analysis of the rate factor resulted to be very flexible since it proved to work for previous crystallization studies and now for thermal degradation of cellulose.

scholarly journals A kinetic model of ferrous iron oxidation by Acidithiobacillus ferrooxidans in a batch culture

2005 ◽  
Vol 11 (2) ◽  
pp. 59-62 ◽  
Author(s):  
Dragisa Savic ◽  
Miodrag Lazic ◽  
Vlada Veljkovic ◽  
Miroslav Vrvic
Keyword(s):  
Kinetic Model ◽  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Bubble Column ◽  
Iron Oxidation ◽  
Yield Coefficient ◽  
Transfer Rates ◽  
Ferrous Iron Oxidation ◽  
Menten Kinetic ◽  
Kinetics Of

The batch oxidation kinetics of ferrous iron by Acidithiobacillus ferrooxidans were examined at different oxygen transfer rates and pH in an aerated stirred tank and a bubble column. The microbial growth, oxygen consumption rate and ferrous and ferric iron were monitored during the biooxidation. A kinetic model was established on the basis of the Michaelis-Menten kinetic equation for bacterial growth and the constants estimated from experimental data (maximum specific growth rate 0.069 h-1, saturation constant 2.9 g/dm3, and biomass yield coefficient based on ferrous iron 0.003 gd.w./gFe). Values calculated from the model agreed well with the experimental ones regardless of the bioreactor type and pH conditions.

Kinetics of extra-heavy oil upgrading in supercritical water with and without zinc nitrate using the phase separation kinetic model

2020 ◽  
Vol 165 ◽  
pp. 104961
Author(s):  
Seungjae Sim ◽  
Won Bae Kong ◽  
Jonghyeon Kim ◽  
Jimoon Kang ◽  
Hwi-Sung Lee ◽  
...  
Keyword(s):  
Phase Separation ◽  
Kinetic Model ◽  
Supercritical Water ◽  
Heavy Oil ◽  
Zinc Nitrate ◽  
Heavy Oil Upgrading ◽  
Kinetics Of

scholarly journals Detailed kinetics of substituted phenolic species in pyrolysis bio-oils

2019 ◽  
Vol 4 (3) ◽  
pp. 490-506 ◽  
Author(s):  
Matteo Pelucchi ◽  
Carlo Cavallotti ◽  
Alberto Cuoci ◽  
Tiziano Faravelli ◽  
Alessio Frassoldati ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Fast Pyrolysis ◽  
Detailed Kinetics ◽  
Kinetics Of

A comprehensive kinetic model for the pyrolysis and combustion of substituted phenolic species, key components of fast pyrolysis bio-oils.

In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions

2018 ◽  
Vol 20 (16) ◽  
pp. 10753-10761 ◽  
Author(s):  
Radhika L. Moore ◽  
Jason P. Mann ◽  
Alejandro Montoya ◽  
Brian S. Haynes
Keyword(s):  
Phase Transitions ◽  
Kinetic Model ◽  
Xrd Analysis ◽  
Kinetics Of ◽  
Synchrotron Xrd

A kinetic model for the decomposition of α-spodumene and γ-spodumene is derived using in situ XRD to monitor the transitions.

Macro Kinetics of N-Phosphonomethyliminodiacetic Acid Catalytic Oxidation

2012 ◽  
Vol 455-456 ◽  
pp. 872-879 ◽  
Author(s):  
Yan Bao ◽  
Jia Wu ◽  
Xiao Ping Hu
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Measured Data ◽  
Second Step ◽  
Oxidizing Agent ◽  
Dissolved Oxygen Concentration ◽  
Exponential Factor ◽  
In Series ◽  
Kinetics Of ◽  
Made In

The oxidation of N-phosphonomethyliminodiacetic acid (PMIDA) to prepare glyphosate (PMG) over active carbon was investigated. Experiments were carried out with O2 as the oxidizing agent in a 150-mL autoclave made in stainless steel, with reaction temperature ranging from 323.15 to 353.25K and the pressure from 0.12 to 0.40 MPa. The macro kinetic model of the reactions in series was developed, and the pre-exponential factor and activation energy were estimated from the measured data in experiments. The influence of dissolved oxygen concentration was also considered in this macro kinetic model. The results indicated that the two step reactions are all one-order to reactant (PMIDA or PMG) and 0.3 or 0.07 to O2 respectively. The active energy was 12.98kJ/mol for the first step reaction and 10.87kJ/mol for the second step reaction.

Development of Torrefaction Kinetics for British Columbia Softwoods

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Jianghong Peng ◽  
Xiaotao T. Bi ◽  
Jim Lim ◽  
Shabab Sokhansanj
Keyword(s):  
British Columbia ◽  
Weight Loss ◽  
Kinetic Model ◽  
Residence Time ◽  
Order Reaction ◽  
First Order Reaction ◽  
Chemical Components ◽  
First Order ◽  
One Step ◽  
Kinetics Of

Torrefaction is a thermal treatment without air or oxygen in the temperature range of 473-573 K. The pyrolysis kinetics of three chemical components (cellulose, hemicelluloses, and lignin) and wood at low temperatures of relevance to torrefaction conditions have been reviewed. A series of thermogravimetric (TG) experiments have been carried out to study the intrinsic torrefaction kinetics of major chemical components and British Columbia (BC) softwoods. The weight loss during BC softwood torrefaction was found to be mainly associated with the decomposition of hemicelluloses, although there was also certain degree of decomposition of cellulose and lignin. The weight loss of the BC softwoods during torrefaction could be approximately estimated from the chemical composition of wood species and the weight loss data for torrefaction of pure cellulose, hemicelluloses, and lignin, respectively. Based on the fitting of the TG curves of BC softwoods and three chemical components, two different torrefaciton models were proposed. The simple one-step (single-stage) kinetic model with the first order reaction can predict the reaction data reasonably well over the long residence time, with the final sample weight being strongly related to the torrefaction temperature. A two-component and one-step first order reaction kinetic model, on the other hand, gave improved agreement with data over short residence time, and can be used to guide the design and optimization of torrefaction reactors over the weight loss range of 0 to 40% at the temperature range of 533-573 K, which covers the typical range of industrially relevant operations.

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