Influence of the Catalyst Preparation on Properties of Chromium-Magnesium Catalysts for Freon 125 Synthesis

2015 ◽  
Vol 670 ◽  
pp. 152-155
Author(s):  
Aleksandr Zirka ◽  
Ludmila Simonova ◽  
Natalia Kosova ◽  
Irina Kurzina ◽  
Sergey Reshetnikov
Keyword(s):  
Experimental Data ◽  
Gas Phase ◽  
Pore Diameter ◽  
Active Catalyst ◽  
Total Pore Volume ◽  
Catalyst Preparation ◽  
Catalytic Reactions ◽  
Bet Surface Area ◽  
Kinetics Of ◽  
Preparation Techniques

The effect of the chromium-magnesium precursor preparation techniques on physicochemical properties (BET surface area, total pore volume, mean pore diameter) and catalysts activity in the gas-phase hydrofluorination of perchloroethylene to pentafluoroethane (Freon 125) was studied. Kinetics of the catalytic reactions was studied for the most active catalyst. Based on the experimental data, the pathway of perchloroethylene fluorination with HF was suggested.

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.

Realization of Detailed Kinetic Models for the Growth of II-VI Compounds: Adopting DFT Calculations and Experimental Evidences

1999 ◽  
Vol 584 ◽  
Author(s):  
Carlo Cavallotti ◽  
Valeria Bertani ◽  
Maurizio Masi ◽  
Sergio Carrà
Keyword(s):  
Experimental Data ◽  
Kinetic Theory ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Kinetic Scheme ◽  
Kinetic Constants ◽  
Surface Processes ◽  
Gas Phase Reactions ◽  
Elementary Reactions ◽  
Kinetics Of

AbstractThe kinetics of deposition of CdTe, ZnS and ZnSe films was studied. An overall microkinetically reversible kinetic scheme consisting of elementary reactions, comprehensive of gas phase and surface processes was developed. Kinetic constants of gas phase reactions were either found in the literature or determined through quantum chemistry methods. Kinetic constants of surface reactions were first guessed combining kinetic theory with quantum chemical calculations and then their values were refined to reproduce experimental data. The kinetics schemes so developed were tested through the simulation of deposition reactors. Measured growth rates and gas phase compositions were thus compared with those calculated. The major finding of this studies is that the growth of CdTe, ZnS and ZnSe can be represented adopting a surface kinetic scheme constituted essentially by the same fundamental steps.

scholarly journals Modeling and experimental study of polyurethane foaming and gelling reactions

2018 ◽  
Author(s):  
◽  
Luay Jaf
Keyword(s):  
Experimental Data ◽  
Foam Height ◽  
Research Process ◽  
Catalytic Reactions ◽  
Polymerization Process ◽  
Gel Point ◽  
Reaction Proceeds ◽  
Polyurethane Foaming ◽  
Kinetics Of ◽  
Insight Into

Numerous reactions take place within a polyurethane polymerization process. Homogeneous and catalytic reactions occur at the same time and intermediate compounds are formed. As the reaction proceeds, long chains of polymer are formed which drastically affect the kinetics of the reaction. Temperature and viscosity profiles of the reacting mixture are two strong indicators of the extent of reaction and the way the reactions are carried out. Therefore, simulating polyurethane gel and foam systems helps interpret temperature and viscosity profiles and gain insight into the kinetics of the system. Using MATLAB program, a model was introduced which simultaneously solves over 80 ordinary differential equations and provide temperature and viscosity profiles as well as concentration profiles, degrees of polymerization, gel point and foam height for individual formulations. Experimental data were used to validate the code showing the model is fundamentally correct. Simulation results showed good fits to the experimental data providing reaction kinetics of the system. The model was modified to simulate reaction systems with minimal change in kinetic parameters. Finally, the simulation studies of this research provide fundamental insights into mechanism of homogenous and catalytic reactions. This research process places high demands on identifying and testing highly-impacting fundamental mechanism during polymerization that have not previously been identified.

Experimental Research on the Preparation of Porous Activated Carbon from Orange Wastes

2009 ◽  
Vol 79-82 ◽  
pp. 1907-1910
Author(s):  
Zhi Gang Xie
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Total Pore Volume ◽  
Carbonization Temperature ◽  
Bet Surface Area ◽  
Average Pore ◽  
Impregnation Ratio ◽  
Heat Preservation

Porous activated carbon was prepared from orange wastes using zinc chloride as an activating agent by one-step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on pore characteristics of activated carbon were studied. The porous structures of the orange wastes activated carbon were investigated by BET, D-R equations, BJH equations and Kelvin theory. The morphology was observed using transmission electron microscopy (TEM). The mesoporous activated carbon is gained when the impregnation ratio is 3:1; the carbonization temperature is 550°Cand heat preservation time is 1.0 h. The activated carbon has total pore volume 2.098 cm3/g, mesoporous pore volume 1.438 cm3/g, with a high BET surface area 1476m2/g. The pore distribution of the mesoporous activated carbon is very concentrative, with average pore diameter of 3.88nm. While, the high specific surface area activated carbon is gained when the impregnation ratio is 2:1; the carbonization temperature is 550°Cand heat preservation time is 1.0 h. The activated carbon has high BET surface area 1909 m2/g, while the total pore volume is only 1.448cm3/g and microporous pore volume is 0.889cm3/g, with average pore diameter of 2.29 nm.

Structure and catalytic performance of Zn-doped TiO2 film

2019 ◽  
Vol 48 (6) ◽  
pp. 508-514 ◽  
Author(s):  
Mei Yang ◽  
Tingyu Huang ◽  
Ning Tang ◽  
Ben Ou ◽  
Wenhao Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Total Pore Volume ◽  
Methyl Orange Solution ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
Reaction Conditions ◽  
Content Type ◽  
Degradation Ratio ◽  
Micro Arc Oxidation ◽  
Kinetics Of

Purpose This paper aims to investigate the photocatalytic activity of zinc doped MAO-TiO2 films under the optimum MAO treatment condition. Design/methodology/approach The coating was prepared by micro arc oxidation, and the influence of doping on the properties of the coating was also investigated. Findings The results show that the BET surface area is 78.25±0.03m2/g, total pore area is 76.32 ± 0.04m2/g, and the total pore volume is 0.2135 ± 0.0004cm3/g. The degradation ratio of the film electrode with Zn-doped in methyl orange solution is up to 94%. When the react circles is 10 times, the degradation ratio is up to more than 85% and remains steady. With the different reaction conditions, these kinetics of the reactions show some different formulas. Originality/value A kinetic equation for photocatalytic activity is established.

Characterization and Analysis on the Thermal Transformation of Boehmite Synthesized by Yoldas Method

2012 ◽  
Vol 532-533 ◽  
pp. 3-7
Author(s):  
Qiu Cheng Su ◽  
Shao Hong Zhang ◽  
Pei Li Chen ◽  
Xin Jun Li ◽  
Juan Fu ◽  
...  
Keyword(s):  
Pore Diameter ◽  
Thermal Transformation ◽  
Total Pore Volume ◽  
Physicochemical Process ◽  
Bet Surface Area ◽  
Aluminium Isopropoxide ◽  
N2 Adsorption ◽  
Α Al2o3 ◽  
Adsorption Desorption ◽  
Xrd And Tem

The boehmite (AlOOH) sol derived from aluminium isopropoxide was synthesized by Yoldas method. The physicochemical process and phase transition of AlOOH were investigated by TG-DSC, N2 adsorption-desorption, XRD and TEM. The results showed that upon heating, AlOOH lost the physicsorbed water first, and then lost the chemisorbed water at 242 °C, and the dehydroxylation occurred at 361 °C. The BET surface area, total pore volume and pore diameter increased, since the waters were lost. The orthorhombic AlOOH transformed to the cubic γ-Al2O3 at 361 °C, the cubic η-Al2O3 appeared after 484 °C, the monoclinic θ-Al2O3 and rhombohedral α-Al2O3 appeared after 1026 °C, and it totally turned into α-Al2O3 at 1237 °C.

A fuzzy neural network approach for modeling the growth kinetics of FeB and Fe2B layers during the boronizing process

2018 ◽  
Vol 106 (6) ◽  
pp. 603 ◽  
Author(s):  
Bendaoud Mebarek ◽  
Mourad Keddam
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Fuzzy Neural Network ◽  
Treatment Time ◽  
Calculation Model ◽  
Average Error ◽  
Network Approach ◽  
Neural Network Approach ◽  
Fuzzy Neural ◽  
Kinetics Of

In this paper, we develop a boronizing process simulation model based on fuzzy neural network (FNN) approach for estimating the thickness of the FeB and Fe2B layers. The model represents a synthesis of two artificial intelligence techniques; the fuzzy logic and the neural network. Characteristics of the fuzzy neural network approach for the modelling of boronizing process are presented in this study. In order to validate the results of our calculation model, we have used the learning base of experimental data of the powder-pack boronizing of Fe-15Cr alloy in the temperature range from 800 to 1050 °C and for a treatment time ranging from 0.5 to 12 h. The obtained results show that it is possible to estimate the influence of different process parameters. Comparing the results obtained by the artificial neural network to experimental data, the average error generated from the fuzzy neural network was 3% for the FeB layer and 3.5% for the Fe2B layer. The results obtained from the fuzzy neural network approach are in agreement with the experimental data. Finally, the utilization of fuzzy neural network approach is well adapted for the boronizing kinetics of Fe-15Cr alloy.

Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them

2020 ◽  
Vol 86 (12) ◽  
pp. 46-53
Author(s):  
M. M. Gadenin
Keyword(s):  
Experimental Data ◽  
Elastoplastic Deformation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading Cycle ◽  
Additional Variable ◽  
Dynamic Creep ◽  
Variable Stresses ◽  
Kinetics Of ◽  
Deformation Diagrams

The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.

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