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Design and Synthesis of Heterogeneous Nano Catalyst Based on Immobilized Palladium Metal on Double Network Hydrogel and Its Application in Organic Reactions
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
In the past few decades, many attempts have been made to combine the benefits of homogeneous and heterogeneous catalysts. The immobilization of homogeneous catalysts onto the surface of heterogeneous supports is the result of such efforts. In this research, immobilized heterogeneous catalysts were designed and synthesized based on double network hydrogels, which produce from interpenetrating of two biocompatible and biodegradable polymer networks. In order to provide magnetic responsibility and easy separation of catalyst from the reaction mixture, the magnetic nanoparticles were dispersed onto the surface of double network hydrogel. Finally, various metal nanoparticles such as palladium and...
Design and Synthesis of Heterogeneous Nanocatalysts Based on Immobilized Metals on Polymeric Substrates and their Applications in Organic Reactions
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Today, catalysts have shown the growing applications in chemical industries especially for drug synthesis. Using immobilized heterogeneous catalysts is a sensible way to benefit from advantages of both heterogeneous and homogeneous catalysts. In this regards, homogeneous catalysts are immobilized on to a solid support through various methods. However, low loading amount of homogenous part and subsequently insufficient catalytic activity are main limitations of immobilized heterogeneous catalysts. For this reason, polymeric supports have been introduced to immobilize metal ions or nanoparticles. These polymeric supports not only possess advantages such as anti-corrosive properties, simple...
Synthesis and Characterization of Cis-dioxomolybdenum(VI) Complex with an ONO Type Tridentate Schiff base Ligand and its Application as Catalyst for Epoxidation of Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
A new dioxomolybdenum(VI) complex, (Cis-[MoO2(L)])n, has been synthesized by reacting 4-bromo-2-((2-hydroxy-5-methylphenylimino)methyl)phenol as a ligand and [MoO2(acac)2] in methanolic solution. For characterization and structure determination of the synthesized complex, different techniques were performed such as elemental analyses, 1H NMR, IR, UV-Vis and X-ray crystallography. The complex was tested as a catalyst for the homogeneous epoxidation of olefins, using tert-butyl hydperoxide (TBHP) as an oxidant. The catalytic system showed high yield, selectivity and turnover number in olefin epoxidation reactions under atmospheric conditions. For example, when the molar ratio of catalyst,...
Naphtha Continuos Catalytic Reforming Optimization
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor)
Abstract
Catalytic Reforming is a chemical process to convert naphtha feed stock into aromatic hydrocarbons and high-octane products. This process firstly was used in 1940s and since then has been considering as one the main units in oil refineries. It involves several complicated reactions which occur at high temperature and pressure in three or four series of reactors. There are various technologies for regeneration of the catalysts. The latest technology for this process is continuous catalytic regeneration.
The aim of this study was to optimize the catalytic reforming process by minimizing the deposited coke on catalyst surface and maximizing the octane number. To reach this aim, the...
The aim of this study was to optimize the catalytic reforming process by minimizing the deposited coke on catalyst surface and maximizing the octane number. To reach this aim, the...
Synthesis and Characterization of Tetrakis (4-sulfunatophenyl) Porphyrin-Mn(III) Chloride Complex and Study of the Catalytic Activity of the Complex in Homogeneous and Heterogeneous Catalytic Systems for Epoxidation of Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor) ; Mohammadi Boghaei, Davar (Supervisor)
Abstract
Epoxidation of alkenes by Mn(III)meso-tetra(4-sulfonatophenyl)porphyrin chloride (MnTPPS4Cl) in the various homogeneous and heterogeneous catalytic systems was investigated. In the case of homogeneous catalysis, epoxidation of cyclooctene in CH2Cl2/MeOH mixture using urea hydrogen peroxide (UHP) as an oxidant and imidazole as a co-catalyst results in the formation of cycloocetene oxide in 87% yield. Using this catalytic system various alkenes successfully oxidized to their corresponding epoxide in high conversions and selectivity. Cyclic alkenes oxidized more easily than linear alkenes. In addition, epoxidation of alkenes was investigated in the heterogeneous catalytic systems. For this...
Design and Synthesis of Metal Nanocatalysts Immobilized on Magnetic Nanoparticles and their Application in Organic Reactions such as Coupling and Synthesis of Triazoles
, Ph.D. Dissertation Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
In this thesis, heterogenous catalysts based on magnetic nanoparticles coated with organosilanes and poly(ionic liquids) were synthesized. These catalysts were synthesized by hydrolysis of tetraethyl organosilanes and other organosilicons such as 3-aminopropyl triethoxy silane and polymerization of some monomers in the presence of ionic cross-link agents. The synthesized matrixes were used to stabilize precious metals such as Pd and Au. The magnetic properties of the catalysts aid to easy separation from the reaction medium by an external magnetic field. High thermal stability low toxicity and high-level loading of metals are some beneficiaries of the magnetic catalysts. At the end,...
Preparation of Conductive and Semi-Conductive Nanocomposites based on Biocompatible Polymers and Investigation of their Conductive, Mechanical and Electrochemical Properties
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
In this study, conductive and semi-conductive nanocomposites based on biocompatible and biodegradable polymers were prepared and their applications in different areas were studied. Considering huge environmental contaminants derived from various industries, biodegradable polymers (synthetic or natural) have attracted more attention in industrial and biological applications. Aside from their eco-friendly properties, there are other advantages such as availability, different chemical structures, uniqe physical properties and capability to improve their characteristics.One way to improve the properties of the biocompatible polymers is fabrication of their composites with different materials to...
Reducing Sulfur Dioxide Using NANO-Structured Materials
, M.Sc. Thesis Sharif University of Technology ; Safekordi, Ali Akbar (Supervisor)
Abstract
In this research, absorption and oxidation catalytic scenarios were examined using previous studies in the field of SO2 removal. Nanostructures zeolite 13X, 5A zeolite, gamma alumina and activated carbon were purchased, then structure, function and adsorption isotherm of each adsorbent were evaluated in 5 concentrations of 250, 500, 750, 1000 and 1250 ppm of contaminants. Final results showed that zeolite 13X compared to other Nano-adsorbents has higher ability to SO2 absorption, and thus the final tests such as temperature and pressure evaluation were performed on the selected sorbent. To further evaluation, the absorbent curves based on two models of BDST (Bed depth service time) and...
Fabrication and Characterization of Patterned Carbon Nanotubes Network on the Silicon Wafer, by Plasma Enhanced Chemical Vapor Deposition
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
Carbon nanotubes, due to their extraordinary electronic and physical properties, have attracted much attention in the last decade. Some of their potential applications are in CNT-field effect transistor, field emission devices, physical and chemical sensors, micro and Nanoelectromechanical systems and Nano antenna. In this thesis, we have first reviewed some features of carbon nanotubes and the advantages of PECVD method compared with thermal CVD. In the second part the role of some of the materials (such as H2/NH3/C2H4) in CNT growth are studied. We created a square pattern on the silicon wafer by photolithography. Afterwards, titanium and nickel deposition is done on the mentioned pattern....
Synthesis and Application of Magnetic Nanocatalysts Cated by Ploy (Ionic Lquid) s
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
In this thesis, heterogenous catalysts based on poly(ionic liquids) were synthesized. These catalysts were prepared by polymerization of functionalized ionic liquid monomers in the presence of an ionic cross-linker. Several types of poly(ionic liquids) such as acidic ionic liquid, basic ionic liquid and their complexs with copper and palladium were prepared. Some of these polymers were coated onto the magnetic nanoparticles to produce a catalyst with magnetic prppertise with easy magnetic separation from the reaction medium. Such catalysts have high loading level and high thermal stability. Most of prepared catalysts have high loading level due to the macromolecular nature of polymer. At the...
Fabrication and Investigation of Silicon Based Nanostructures Surface Properties
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
Nowadays, silicon based devices especially carbon nanotubes received lots of attentions and advancement from researchers and industries. Because of amazing electrical and mechanical properties and wide range of applications, CNTs are received a lot of attention from nanoelectronics experts. There are lots of CNT growth methods such as: Arc Discharge, Laser Ablation, Surface Decomposition, CVD and PECVD.
In this thesis, we are going to use PECVD method to synthesis CNT. A typical PECVD system includes two parallel electrodes that have been packed in vacuum chamber and gases like argon, hydrogen and NH3 are introduced to chamber as a reactant gas.
In this thesis, firs we had fixed...
In this thesis, we are going to use PECVD method to synthesis CNT. A typical PECVD system includes two parallel electrodes that have been packed in vacuum chamber and gases like argon, hydrogen and NH3 are introduced to chamber as a reactant gas.
In this thesis, firs we had fixed...
Experimental Investigation of a Monopropellant Thruster Using Hydrogen Peroxide
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
Monopropellant thrusters are one of the most common types of propulsion systems that are used extensively in space applications. Especially thrusters with a capacity of less than 50N, they are used on space satellites and are developing rapidly. Problems such as contamination, toxicity of the propellant, difficulty in storing and custody, as well as price, led to the removal of the hydrazine from the focus of attention and focus on green propulsion. One of these, is the green propellant of hydrogen peroxide, which is decomposed in the proper catalytic vicinity, and the only chemical decomposition products are oxygen and water vapour. The present study aims to design and construct mono...
Construction of The Catalyst Layer of a PEM Fuel Cell Using Electrospray Method
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
Due to Reduction of fossil fuels resources and the pollution caused by using them, it seems inevitable to shift to using reproducible energies. Among different resource of reproducible energy, fuel cell is one of suitable technologies for investigation and development. Fuel cell is an electrochemical system to convert chemical energy of fuel directly to electrical energy. Each fuel cell has seven part (two Bipolar Plate, two electrode, two catalyst layer and polymeric Membrane). Oxidation occur in anode of fuel cell and created electron enters external circuit and then riches the cathode. The positive ion created in the anode reaches the cathode through the membrane (electrolyte) and...
Synthesis and Characterization of Ni-Pd-0.1CNT/PU Nanocatalyst, Applicable for Methane Reforming
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
Influence of attachment of Multi Walled Carbon Nanotubes (MWCNT) on various nickel nanocatalysts produced by the electroless plating method was investigated via Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), Atomic Absorption Spectroscopy (AAS), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) measurements, Temperature Programmed Reduction (TPR) and Temperature Programmed Oxidation (TPO) tests. Application of TPR/TPO data to Kissinger (Redhead) Equation yielded the activation energies of both nickel reduction and nickel oxidation reactions. Addition of MWCNT improved the catalytic effects by easing of...
PEM Power Density Optimization Based on Non-Uniform Catalyst Distribution
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
In many previous Polymer Electrolyte Membrane Fuel Cell (PEMFC) models,the catalyst distribution in Catalyst Layer (CL) was assumed to be uniform and there are just a few models which consider variation of catalyst loading across the CL. In this research, a half-cell PEMFC cathode model is applied to investigate the effect of catalyst loading in CL plane under the land and channels of bipolar plates. In addition, the agglomerate model which has been shown to be more complete representation of the fuel cell CL is used. It is necessary to mention, in many previous PEMFC models, the catalyst layer was treated as a pseudohomogenous layer. In both models, the micro structure of CL and its effect...
Modeling Reaction and Distribution of Water in Nanopores of the Cathode Catalyst Layer of PEM Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; baghalha, morteza (Supervisor)
Abstract
In the proton exchange membrane fuel cells (PEM, the produced water would be divided into two phases of vapor and liquid. distribution of both liquid and vapor phases in different cell layers affects the performance, the efficiency and the life of a fuel cell significantly. Moreover, Nano pores of the cathode catalyst layer are involved with some phenomena such as electrochemical reaction kinetics, heat and mass transfer and interface phase change. One of the most important problems in the performance of fuel cells is distribution of liquid water in the porous areas. Water flooding in fuel cells causes to delay in oxygen transport to active sites in the catalyst layer because the pores of...
Modeling of Deactivation of Midrex Reforming Process and Structural Changes of Nano Pores
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
In this study, deactivation of Midrex reforming catalysts is evaluated kinetically by 3.5-year data of Mobarakeh Steel Company direct reduction site. The variation of Midrex catalyst’s structure is characterized by XRD and BET test. Two deactivation mechanism are characterized, methane cracking carbone deposition and sintering. The project results demonstrate that victorious mechanism is carbon deposition. The methane cracking carbone cause layer by layer deactivation of catalyst during 5.5 months. Although, XRD and BET showed pore volume and radius reduction and Ni crystal increasing, approximated constant activity of catalyst were approved by kinetic evaluation
Effects of Nano Metallic Catalysts on The Life-Time and Efficiency of Proton Exchange Membrane Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Vesaghi, Mohammad Ali (Supervisor)
Abstract
The Fuel cell is an energy converter which converts the chemical energy of a chemical reaction to electricity and heat directly and without any pollution. One of the most important types of fuel cells is the proton exchange membrane (PEM) fuel cell. The importance of PEM fuel cells is a result of their high energy density, quick start up ability, lower operating temperature, high efficiency and low or zero emissions. Catalysts play an important role in both costs and durability of PEM fuel cells. Alloying the Pt with other metals can increase the activity of the catalysts of the fuel cells and also reduces the amount of costly Pt. In this study, the nanoparticles of Ni were added to the...
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...
Separation of Catalyst from Wax Using Internal Filtration in Fischer-Tropsch Process
, M.Sc. Thesis Sharif University of Technology ; Bastani, Daruoosh (Supervisor) ; Rohani, Ali Asghar (Supervisor)
Abstract
Fischer-Tropsch synthesis is a major part of gas-to-liquid (GTL) technology, which converts natural gas into liquid fuels with very low sulfur and aromatic content. Nowadays, this exothermic reaction is performed in slurry reactors; therefore it is essential to separate solid catalyst particles, suspended in the liquid products. In this study, without performing real experiment and chemical reaction, separation of Alumina supported Cobalt Catalyst from wax is carried out by internal filtration. For the first time in this research, the effect of different parameters like pressure difference, wax viscosity and filter pore size on the quantity and quality of filter performance is investigated....