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    Biodiesel Production from Used Sunflower Oil Via Transesterification Using Green Solid Nanocatalysts Derived from Animal Bone Support

    , M.Sc. Thesis Sharif University of Technology Mohebolkhames, Erfan (Author) ; 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... 

    Synthesis of Modified Porous Nanostructures and Investigation of Oxidation Reaction Kinetics

    , M.Sc. Thesis Sharif University of Technology Gholizadeh, Sepideh (Author) ; 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... 

    CFD Simulation of Rotating Disk Apparatus for Determining Reaction Equation Parameters of VES and Carbonate Minerals

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Esmaeil (Author) ; 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.... 

    Modeling of Side Reactions in Propane Dehydrogenation Over Pt-Sn/γ-Al2O3 Catalyst

    , M.Sc. Thesis Sharif University of Technology Farjoo, Afrooz (Author) ; 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... 

    Study on the Kinetics of Enzymatic Biodiesel Production Using Castor Oil

    , M.Sc. Thesis Sharif University of Technology Zare Jousheghani, Fatemeh (Author) ; 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... 

    Kinetic Study of Partial Oxidation of Methane in Non-Catalytic Porous Media

    , M.Sc. Thesis Sharif University of Technology Rahimpour Kalkhoran, Mehrnaz (Author) ; 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... 

    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 Heidari, Aidin (Author) ; 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... 

    Pereparation, Characterization and Photocatalytic Application of Some Polyoxometalates in Degradation of Oraganic Pollutants

    , M.Sc. Thesis Sharif University of Technology Ahmadpour, Zahra (Author) ; 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... 

    Chemoselective and convenient preparation of 1,1-diacetates from aldehydes, mediated by solid lithium perchlorate under solvent-free conditions

    , Article Journal of Molecular Catalysis A: Chemical ; Volume 238, Issue 1-2 , 2005 , Pages 138-141 ; 13811169 (ISSN) Ziyaei, A ; Azizi, N ; Saidi, M. R ; Sharif University of Technology
    2005
    Abstract
    A simple, efficient, and general method has been developed for the conversion of aldehydes to 1,1-diacetates with the use of acetic anhydride and solid LiClO4 under first solvent-free and mild conditions in good yields. This method applies to not only simple but also to conjugated aldehydes. © 2005 Elsevier B.V. All rights reserved  

    Carbon quantum dots modified anatase/rutile TiO2 photoanode with dramatically enhanced photoelectrochemical performance

    , Article Applied Catalysis B: Environmental ; Volume 269 , 2020 Zhou, T ; Chen, S ; Li, L ; Wang, J ; Zhang, Y ; Li, J ; Bai, J ; Xia, L ; Xu, Q ; Rahim, M ; Zhou, B ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and... 

    Numerical study of the pseudo-boiling phenomenon in the transcritical liquid oxygen/gaseous hydrogen flame

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; 2020 Zeinivand, H ; Farshchi, M ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    The interactions and effects of turbulent mixing, pseudo-boiling phenomena, and chemical reaction heat release on the combustion of cryogenic liquid oxygen and gaseous hydrogen under supercritical pressure conditions are investigated using RANS simulations. Comparisons of the present numerical simulation results with available experimental data reveal a reasonably good prediction of a supercritical axial shear hydrogen-oxygen flame using the standard k-ε turbulence model and the eddy dissipation concept combustion model with a 23 reaction steps kinetics for H2-O2 reaction. The present simulation qualitatively reproduced oxygen injection and its reaction with the co-flowing hydrogen, which is... 

    Mathematical modeling and analytical solution of two-phase flow transport in an immobilized-cell photo bioreactor using the homotopy perturbation method (HPM)

    , Article International Journal of Hydrogen Energy ; Volume 41, Issue 41 , 2016 , Pages 18405-18417 ; 03603199 (ISSN) Zeibi Shirejinia, S ; Fattahi, M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    In the present study, a theoretical model of a reaction–diffusion within an entrapped-cell photobioreactor packed with gel-granules containing immobilized photosynthetic bacterial cells is presented. The model is based on a system of two coupled nonlinear reaction–diffusion equations under steady-state condition for biochemical reactions occurring in the photobioreactor that describes the substrate and product concentration within the gel-granule. Simple analytical expressions for the concentration of substrate and product have been derived for all values of reaction–diffusion parameters, demonstrating competition between the diffusion and reaction in the gel-granule, using the homotopy... 

    Transesterification of sunflower oil to biodiesel fuel utilizing a novel K2CO3/Talc catalyst: Process optimizations and kinetics investigations

    , Article Industrial Crops and Products ; Volume 156 , 2020 Zehtab Salmasi, M ; Kazemeini, M ; Sadjadi, S ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    A novel efficient and cost-effective heterogeneous catalyst for the production of biodiesel from transesterification of sunflower oil was prepared through the impregnation of K2CO3 upon the Talc material. The physicochemical features of the catalyst were studied through several characterization analyses. The effect of the K2CO3 loading was investigated by comparing the catalytic activity of various prepared catalysts. Moreover, the effect of the calcination temperature upon the catalytic activity was examined. To maximize the yield of the produced biodiesel fuel, reaction variables such as the reaction time and temperature, catalyst concentration, and methanol: oil molar ratio were... 

    Kinetic modelling of enzymatic biodiesel production from castor oil: Temperature dependence of the Ping Pong parameters

    , Article Canadian Journal of Chemical Engineering ; Volume 94, Issue 3 , 2016 , Pages 512-517 ; 00084034 (ISSN) Zarejousheghani, F ; Kariminia, H. R ; Khorasheh, F ; Sharif University of Technology
    Wiley-Liss Inc  2016
    Abstract
    Biodiesel is considered an alternative replacement for petroleum diesel, and enzymatic reaction is one method for biodiesel production. Understanding the kinetics of this reaction is important to achieve higher production rates. The kinetics of transesterification of castor oil using Novozym 435 was investigated in this study. The genetic algorithm was employed for estimation of kinetic parameters including Vmax, KmTG, and KmA in the Ping Pong kinetic model at different temperatures. In most enzymatic reactions that follow the Ping Pong mechanism, inhibition by alcohol has been taken into consideration. Here, we examined a competitive inhibition mechanism and found no inhibition effect at... 

    Factors affecting platinum extraction from used reforming catalysts in iodine solutions at temperatures up to 95 °C

    , Article Hydrometallurgy ; Volume 97, Issue 1-2 , 2009 , Pages 119-125 ; 0304386X (ISSN) Zanjani, A ; Baghalha, M ; Sharif University of Technology
    2009
    Abstract
    Platinum extraction from the spent reforming catalysts in iodine-iodide solutions at temperatures from 25 to 95 °C was investigated. The reforming catalyst mostly consists of a porous gamma alumina support with metallic platinum finely dispersed on the walls of the nano-pores of the catalyst support. The effect of a variety of factors, including catalyst particle size, impeller agitation speed, reactant concentrations, liquid to solid mass ratio, temperature and the solution pH on the Pt extraction rate and recovery were investigated. It was found that the catalyst particle sizes less than 106 μm and impeller agitation speed higher than 700 rpm eliminated the effects of catalyst size and... 

    Modeling of multiple noncatalytic gas-solid reactions in a moving bed of porous pellets based on finite volume method

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 43, Issue 9 , 2007 , Pages 881-894 ; 09477411 (ISSN) Valipour, M. S ; Saboohi, Y ; Sharif University of Technology
    2007
    Abstract
    A mathematical model is presented to simulate the multiple heterogeneous reactions with complex set of physicochemical and thermal phenomena in a moving bed of porous pellets. This model is based on both heat and mass transfer phenomena of gaseous species in a porous medium including chemical reactions at interfaces whose areas vary during the conversion. This model accounts for both the exothermic and endothermic reactions which can be equimolar or nonequimolar. Furthermore it considers simultaneously the reactions in the nonisothermal transient condition. A powerful technique based upon finite volume fully implicit approach has been implemented to solve the complicated governing equations... 

    Mathematical modeling of the reaction in an iron ore pellet using a mixture of hydrogen, water vapor, carbon monoxide and carbon dioxide: An isothermal study

    , Article Advanced Powder Technology ; Volume 17, Issue 3 , 2006 , Pages 277-295 ; 09218831 (ISSN) Valipour, M. S ; Motamed Hashemi, M. Y ; Saboohi, Y ; Sharif University of Technology
    VSP BV  2006
    Abstract
    A mathematical time-dependent and isothermal model based on the grain model has been developed to simulate the kinetic and thermal behaviors of a porous iron oxide pellet undergoing chemical reactions with a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. Its novelty consists in fact that it can deal with a multi-species reducing gas and oxide pellet. In spite of previous models in which the pure reductant was applied as reducing gas, this model can indicate an actual view of pellet reduction including the effects of reducing gas utility and reducing gas ratio. A finite volume fully implicit technique was applied for solving the governing equations. The model has been... 

    Reactor modeling of direct conversion of methane to methanol in a catalytic fluidized bed reactor

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Vafajoo, L ; Ghods, M ; Kazemeini, M ; Sharif University of Technology
    2006
    Abstract
    Direct conversion of methane to methanol is a more recently developed technique by which the intermediate and expensive process of formation of synthesis gas is eliminated. On the other hand, fluidized-bed technology for heterogeneous reversible reactions posses a couple of key advantages in comparison to the commonly used fixed bed reactors. These include, pore diffusion resistances being largely eliminated due to small catalyst pellet sizes utilized. In other words, industrial fixed bed pellets are in the order of 6-12 mm diameter, whereas fluidized catalyst used may be smaller than 100 μm. In addition, equilibrium limitations induced by the reversibility of the reaction(s) are broken in... 

    Mechanisms and kinetics of Thiotepa and tepa hydrolysis: DFT study

    , Article Journal of Molecular Modeling ; Volume 18, Issue 8 , 2012 , Pages 3563-3576 ; 16102940 (ISSN) Torabifard, H ; Fattahi, A ; Sharif University of Technology
    Springer  2012
    Abstract
    N,N′,N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine. The second one is a direct nucleophilic ring opening of... 

    A kinetic study on the electrodeposition of nickel nanostructure and its electrocatalytic activity for hydrogen evolution reaction

    , Article Journal of Applied Electrochemistry ; Volume 40, Issue 11 , November , 2010 , Pages 1941-1947 ; 0021891X (ISSN) Torabi, M ; Dolati, A ; Sharif University of Technology
    2010
    Abstract
    The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker's equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni 2+ concentration. Atomic force microscopy was used to...