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reaction-kinetics
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Total 160 records
Kinetics of Incomplete Reduction of Hematite Low Grade Iron Ore to Magnetite Using Mixture of CO and CO2
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
In this research the process of incomplete reduction of hematite low iron ore to magnetite in a fluidized bed reactor was investigated. Temperature, composition of reduction air, particle size, and stay time were investigated as effective parameters. In this way, temperatures of 560, 580, 600, 620 and 640 degrees of centigrade, input air with flows of 1.2, 1.3 and 1.4 l/s, particles size of 425-850 µm, 850 µm-1.4 mm, and 1.4-2 mm, stay times of 4, 8, 12, 16, and 20 min were used in this research. The reduced specimens were analyzed by XRD and chemical analysis. The results illustrated that increase of temperature, decrease of input air flow, decrease of particles size, and increase of stay...
CFD Simulation of Rotating Disk Apparatus for Determining Reaction Equation Parameters of VES and Carbonate Minerals
, M.Sc. Thesis Sharif University of Technology ; Bazargan, Mohammad (Supervisor) ; Jamshidi, Saeed (Supervisor)
Abstract
Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation....
Kinetic Study of Partial Oxidation of Methane in Non-Catalytic Porous Media
, M.Sc. Thesis Sharif University of Technology ; Fotovat, Farzam (Supervisor) ; Soltanieh, Mohammad (Supervisor)
Abstract
Partial oxidation of methane (POX) is one of the most common processes to produce synthesis gas. In this study the kinetics of this process is examined and some reduced mechanisms are introduced to model it in this study. The experimental data from Research Institute of Petroleum Industry are used as reference experimental data. Inlets of this reactor are oxygen and methane with equivalence ratio between 2.53 and 2.9. Moreover, the experimental results of previous studies with the air as the oxidant in equivalence ration between 2.4 and 2.6 are used as basis for comparison of simulation results. During the first step, partial oxidation of methane in non-catalytic porous media is simulated by...
Biodiesel Production from Used Sunflower Oil Via Transesterification Using Green Solid Nanocatalysts Derived from Animal Bone Support
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Sadjadi, Samahe Sadat (Supervisor)
Abstract
This project evaluates the feasibility of using waste salmon fish bones as the reusable and low cost solid catalyst support for synthesis of biodiesel from waste sunflower oil via transestrification method. Calcinated waste fish bone derived hydroxyapatite (HAP) was employed as the supporter for KOH & K2CO3 to prepare an efficient solid base catalyst for biodiesel production. The catalyst were characterized by SEM-EDS, XRD, FTIR, BET, TGA, ICP. The effects of catalyst preparation conditions (such as fish bone and KOH or K2CO3 calcination temperature, loading of KOH or K2CO3 on the support), reaction conditions (such as reaction time, methanol/oil molar ratio, reaction temperature and...
Study on the Kinetics of Enzymatic Biodiesel Production Using Castor Oil
, M.Sc. Thesis Sharif University of Technology ; Khorashe, Farhad (Supervisor) ; Kariminia, Hamid Reza (Supervisor)
Abstract
Increasing emissions of greenhouse gases from one hand and decline in the fossile resources of energy on the other hand has raised the motivation of searching for renewable sources. Biodiesel, because of having perfect feature for replacing with petroleum diesel, has been considered as candidate for this purpose. Using enzymatic reaction is one of the methods for biodiesel production. Understanding the kinetics of this reaction is important to achieve higher production rates.
In present work, the kinetic of transesterification of castor oil with use of Novozyme 435 (as enzyme) was investigated. Enzymatic biodiesel production is a bi-substrate (oil and alcohol) reaction. Genetic algorithm...
In present work, the kinetic of transesterification of castor oil with use of Novozyme 435 (as enzyme) was investigated. Enzymatic biodiesel production is a bi-substrate (oil and alcohol) reaction. Genetic algorithm...
Modeling of Side Reactions in Propane Dehydrogenation Over Pt-Sn/γ-Al2O3 Catalyst
, M.Sc. Thesis Sharif University of Technology ; Khorasheh, Farhad (Supervisor)
Abstract
The kinetics of side reactions in dehydrogenation of propane over a supported platinum catalyst modified by tin was investigated. Catalytic dehydrogenation over a commercial Pt-Sn/γ-Al2O3 was carried out in a laboratory-scale plug-flow reactor at 580 to 620oC under atmospheric pressure. Several kinetic models derived from different reaction mechanisms were tested using experimental data obtained over a range of reaction conditions. It was found that the kinetics of the main dehydrogenation reaction was best described in terms of a Langmuir-Hinshelwood mechanism where adsorption of propane was the rate controlling step. Simple power low rate expressions were used to express the kinetics of...
Synthesis of Modified Porous Nanostructures and Investigation of Oxidation Reaction Kinetics
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
In this work ،we used the hydrothermal method for prepared the Bivo4 nano particles. For the best photocatality property these nano particles stabilized on the different basis. This catalysis characterized by UV-vis, XRD, BET, FTIR and SEM. The size of zeolites catalyst were 22 nm and size of Bivo4 were 54 nm and the SEM showed that the BivO4 were sphere. By addition of BiVO4 nano particles to the surface of zeolite, the surface area was increase, but addition of BiVO4 nano particles to surface, the average of holes size decreased and distribution of holes will be monotonous and the surface area increased. In the continue for investigation of photo catalyst activity of nano particle, we used...
Pereparation, Characterization and Photocatalytic Application of Some Polyoxometalates in Degradation of Oraganic Pollutants
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
In this project photocatalysts TiO2, H3PW12O40, H3PMo6W6O40, H3PW12O40 / TiO2, H3PMo6W6O40 / TiO2, K2.5H0.5PW12O40, Cs2.5H0.5PW12O40, (NH4) 2.5H0.5PW12O40 and H3PW12O40 / M-TiO2 that M = La , Ce, Cr, Fe, Co were characterized by techniques DRS, FT-IR, BET, 31P NMR, SEM and XRD. The results of SEM and XRD particle size and page crystalline nanoscale catalysts, with size less than 40nm, respectively. FT-IR analysis confirmed the structure of heteropolyacid was produced. DRS analysis of the degradation reactions during wavelenght longer upheld. Degradation of methylene blue and pollutants such as Tinopal CBS-x to the polyoxometalates keggin is homogeneous and composite titanium dioxide two...
Efficient Friedel-crafts alkylation of indoles and pyrrole with enones and nitroalkene in water
, Article Organic and Biomolecular Chemistry ; 2006, Volume 4, Issue 23, Pages 4275-4277 ; Arynasab, F ; Saidi, M. R ; Sharif University of Technology
Abstract
An operationally simple and entirely green protocol for heteropoly acid catalyst conjugate addition of indoles and pyrrole to unsaturated carbonyl compounds and nitro-alkene in water was investigated. It is important that the products arising from 1,2-addition were not observed under the reaction conditions. Pyrroles also readily underwent Michael addition at Α-positions under the same reaction conditions. Indole and many of its derivatives are present in many substances commonly found in nature. Micheal addition reactions are performed in organic solvents with the reactions in water are relatively scarce. The Michael addition between indole and methyl vinyl ketone in the presence of...
An investigation of the oxidative dehydrogenation of propane kinetics over a vanadium-graphene catalyst aiming at minimizing of the COx species
, Article Chemical Engineering Journal ; Vol. 250 , 2014 , Pages 14-24 ; ISSN: 13858947 ; Kazemeini, M ; Khorasheh, F ; Rashidi, A ; Sharif University of Technology
Abstract
Application of the DOE with the ANN in kinetic study of the ODHP was investigated.•The catalyst of vanadium/graphene synthesized through the hydrothermal technique.•The ANN and RSM's simulations were utilized to generate the extra data points.•Power law models and corresponding parameters determined to describe the reactions.•The optimization conducted in order to minimize the COx production. In the current investigation, an application of the design of experiments (DOE) along with the artificial neural networks (ANN) in a kinetic study of oxidative dehydrogenation of propane (ODHP) reaction over a synthesized vanadium-graphene catalyst at 400-500. °C presented aiming at minimizing the CO. x...
Numerical modeling of surface reaction kinetics in electrokinetically actuated microfluidic devices
, Article Analytica Chimica Acta ; Vol. 838, issue , August , 2014 , pp. 64-75 ; ISSN: 00032670 ; Amini, Y ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
Abstract
We outline a comprehensive numerical procedure for modeling of species transport and surface reaction kinetics in electrokinetically actuated microfluidic devices of rectangular cross section. Our results confirm the findings of previous simplified approaches that a concentration wave is created for sufficiently long microreactors. An analytical solution, developed for the wave propagation speed, shows that, when normalizing with the fluid mean velocity, it becomes a function of three parameters comprising the channel aspect ratio, the relative adsorption capacity, and the kinetic equilibrium constant. Our studies also reveal that the reactor geometry idealized as a slit, instead of a...
Extended quantum yield: A dimensionless factor including characteristics of light source, photocatalyst surface, and reaction kinetics in photocatalytic systems
, Article Industrial and Engineering Chemistry Research ; Vol. 53, issue. 30 , July , 2014 , pp. 11973-11978 ; ISSN: 08885885 ; Vossoughi, M ; Simchi, A. R ; Micklic, M ; Sharif University of Technology
Abstract
Quantum yield relations were extended by adding effective conditional parameters in photodegradation of organic pollutants such as intensity of light, wavelength of light, average distance from light source, concentrations of dye/pollutant and photocatalyst, and volume of reactor. The geometry of light source and thin film and particulate photocatalytic systems were considered in analysis. Extended quantum yield that is a dimensionless factor is applicable in various types of dye and photocatalyst. This extended quantum yield allowed us to classify photodegradation as reported by scientific groups, performed in various operational conditions in order to identify the degree of similarity...
Kinetic modeling of oxidative dehydrogenation of propane (ODHP) over a vanadium-graphene catalyst: Application of the DOE and ANN methodologies
, Article Journal of Industrial and Engineering Chemistry ; Vol. 20, issue. 4 , July , 2014 , p. 2236-2247 ; ISSN: 1226086X ; Kazemeini, M ; Khorasheh, F ; Rashidi, A ; Sharif University of Technology
Abstract
In this research the application of design of experiment (DOE) coupled with the artificial neural networks (ANN) in kinetic study of oxidative dehydrogenation of propane (ODHP) over a vanadium-graphene catalyst at 400-500 °C and a method of data collection/fitting for the experiments were presented. The proposed reaction network composed of consecutive and simultaneous reactions with kinetics expressed by simple power law equations involving a total of 20 unknown parameters (10 reaction orders and 5 rate constants each expressed in terms of a pre-exponential factors and activation energies) determined through non-linear regression analysis. Because of the complex nature of the system, neural...
The modeling of kinetics and catalyst deactivation in propane dehydrogenation over Pt-Sn/γ-Al2O3 in presence of water as an oxygenated additive
, Article Petroleum Science and Technology ; Vol. 32, issue. 10 , Mar , 2014 , pp. 1139-1149 ; ISSN: 10916466 ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
Abstract
A reduction in catalyst's activity with time-on-stream and the formation of side products are two of the problems associated with catalytic propane dehydrogenation (PDH). Previous studies have indicated that the presence of small amounts of oxygenated additives such as water can reduce coke formation and enhance catalyst activity. The aim of the present work was to develop an appropriate kinetic model for PDH over a commercial Pt-Sn/γ-Al 2O3 catalyst in the presence of small amounts of water. Experimental data were obtained from a previous study where catalytic PDH was carried out in a bench scale reactor system at atmospheric pressure in the temperature range of 575-620°C in the presence of...
Removal of zirconium from aqueous solution by Aspergillus niger
, Article Scientia Iranica ; Vol. 21, Issue. 3 , 2014 , pp. 772-780 ; ISSN: 10263098 ; Yaghmaei, S ; Roostaazad, R ; Mohammad-Beigi, H ; Sharif University of Technology
Abstract
Removal of zirconium from its dilute aqueous solution using Aspergillus niger as a dried and living biomass was investigated. Through that, the effect of some operational parameters on biosorption, including pH, temperature, contact time, initial concentration of zirconium and dose of biomass, were studied. Based on the results, it was concluded that the uptake of zirconium by both dried and living biomasses is pH dependent, and maximum uptake was observed in pH = 3.1 for both biomasses. The maximum uptake capacity of the living biomass was obtained at 30°C. However, the biosorption of zirconium by dried biomass was not affected by temperature. The maximum uptake capacity for living and...
Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors
, Article Applied Physics A: Materials Science and Processing ; Vol. 117, issue. 4 , 2014 , pp. 2087-2094 ; ISSN: 09478396 ; Faraji, M ; Sharif University of Technology
Abstract
Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc–cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic...
Direct dyes removal using modified magnetic ferrite nanoparticle
, Article Journal of Environmental Health Science and Engineering ; Vol. 12, Issue. 1 , 28 May , 2014 ; ISSN: 2052336X ; Abdi, J ; Bastani, D ; Sharif University of Technology
Abstract
The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6(DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L...
In-situ nitrate remediation using nano iron/nickel particles
, Article Environment Protection Engineering ; Vol. 40, issue. 3 , 2014 , p. 75-86 ; Vossoughi, M ; Shamsai, A ; Sharif University of Technology
Abstract
Originally, the application of nano zero valent iron/nickel (nZVI/Ni) particles for nitrate removal in porous media was studied. nZVI/Ni was prepared and employed in batch and continuous modes. Based on batch experiments, the reaction kinetics was consistent with the adsorption model by the order of 1-1.5. The variation of the kinetics order depends on pH and nickel content. So that highest reactivity was observed for nZVI with 10% of Ni at pH ≤ 3. Nitrate remediation in a continuous system was mostly influenced by seepage velocity, quantity and freshness of nZVI/Ni and particle size of porous media. In a batch mode, the maximum nitrate removal was 99% while in a continuous mode it did not...
Optimization of biomass and biokinetic constant in Mazut biodegradation by indigenous bacteria BBRC10061
, Article Journal of Environmental Health Science and Engineering ; Vol. 12, issue. 1 , June , 2014 ; Mashreghi, M ; Yaghmaei, S ; Sharif University of Technology
Abstract
Optimization based on appropriate parameters can be applied to improve a process. Mazut degradation as a critical issue in environment requires optimization to be efficiently done. To provide biodegradation conditions, experiments were designed on the least interactions among levels of parameters consisting of pH, Tween 80, glucose, phosphorous source, nitrogen source, and time. Kinetic constants and biomass were calculated based on 16 assays, designed using Taguchi method, which constructed various mazut biodegradation conditions. Kinetics of mazut degradation by newly isolated bacteria Enterobacter cloacae closely followed second order kinetic model. Results of the 16 experiments showed...
Intracellular viral infection kinetics using a stochastic approach
, Article Progress in Reaction Kinetics and Mechanism ; Volume 38, Issue 4 , 2013 , Pages 359-376 ; 14686783 (ISSN) ; Taherkhani, F ; Rezania, H ; Akbarzadeh, H ; Sharif University of Technology
2013
Abstract
Stochastic simulation is carried out to investigate intracellular viral reaction kinetics and the time evolution of the average particle number ( N̄) and coefficient variation (CV) for genome, template, and structural protein. The coefficient variation of these components is found to be ordered as: CV template > CV structural protein > CVgenome. The average particle number is also calculated via a deterministic approach. The magnitude value of the difference between the stochastic and deterministic approaches is found to be N̄ template ̃ N̄ structural protein > N̄ genome. The Poisson algorithm has been used to investigate the number of particles in the dynamics of intracellular viral...