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molybdenum
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Synthesis and Characterization of Mo(VI)–Schiff Base Complexes and Study its Catalytic Application in Homogenous and Hetrogenous Systems for Epoxidation of Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this project a novel molybdenum(VI) complex with tridentate Schiff base ligand which is soluble in water was synthesized and characterized. In the first step of complex synthesis, chloromethylation of salicylaldehyde was carried out and then, corresponding pyridine salt prepared in the second step. Ligand N-[(3-pyridinium chloride) salicylidene]-2-aminophenol was formed by reaction with aminophenol. In the presence of MoO2(acac)₂ the final product, cis-dioxo(N- (3-pyridinumchloride)salicylidene]-2-aminophenolato)ethanol olybdenum(VI) complex synthesized. The complex was characterized by CHN elemental analysis and spectroscopic methods UV, NMR and FT-IR.We used a high-yield (80-98%) and...
Heterogenization of Ionic Complexes of Mo(VI) with Sulfonated Schiff Base Ligands on the Polysiloxane as Support for Catalytic Epoxidation of Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this project a new molybdenum (VI) complex with tetradentate Schiff base ligand which was soluble in water was synthesized and characterized. In the first step of ligand synthesis, the reaction was performed between salicylaldehyde and aniline, and then used concentrated sulfuric acid for sulfonation. In the next step 5- sulfosalicylaldehyde sodium salt was formed by removing of aniline with heating and using sodium carbonate. In the presence of ethylendiamine and bis (acetylacetonato) dioxomolybdenum(VI) the final product, cis-dioxo sodium (N,N-bis (5-sulfonatosalicyldene)1,2-diaminoethane) molybdenum (VI) complex was synthesized. The complex was characterized by (CHN) elemental...
Optimization of the Solvent Extraction of Rhenium from Acidic Solution Produced by Pressure Leaching of Molybdenite Concentrate
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
The extraction of molybdenum and rhenium from acidic solution produced by pressure leaching of molybdenite concentrate, using organophosphorus solvents has been investigated. First, extraction of molybdenum by Di-2-EthyHexyl Phosphoric Acid (D2EHPA) extractant dissolved in kerosene diluents was done. Extraction experiments were designed using Taguchi L16b orthogonal array. The effects of four factors: Shaking time, Organic solvent concentration, Organic to aqueous phase ratio, pH were studied in four levels. Optimum conditions occur at: shaking time: 35 min, organic solvent concentration: 30 volumetric percent, organic to aqueous phase ratio: 3, pH: 7 and molybdenum is completely extracted....
Investigation of MoSi2/MoSi2 Joining
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
The present work investigates joining of two MoSi2 parts through Cusil/Zr/Cusil interlayer with Cusil being a commercial eutectic of Ag-Cu alloy. The joining operation was implemented in an inert gas tube furnace by brazing. The brazing temperature ranged at 800-930°C while the operation lasted for 1hr. Interfacial microstructure was studied by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) techniques. Applying the temperature of 830°C was led to uniform dense joint consisting of various reaction phases with excellent bonding within interfaces. Diffusion of Si to the liquid phase will transform MoSi2 to Mo5Si3 which bears Ag to some...
Immobilized Manganese-porphyrin and Molybdenum-Schiff Base Complexes on Functionalized Magnetic Nanoparticles as Efficient Recyclable Nanocatalysts in Hydrocarbon and Sulfide Oxidation Reactions
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this thesis, functionalized Fe3O4 nanoparticles have been utilized as a support for immobilization of homogeneous catalysts. The catalytic activity of the supported heterogeneous nanocatalysts was investigated in hydrocarbon and sulfide oxidation reactions. In the first part of this research, imidazole functionalized Fe3O4 nanoparticles (Fe3O4@SiO2-Im) were used as a support to anchor manganese porphyrin complex, [MnT(4-OMeP)P]OAc; via axial ligation. Catalytic application of the immobilized manganese porphyrin was studied in oxidation of alkenes and sulfides. To find suitable reaction conditions, the effect of different parameters such as solvent and temperature on immobilization process...
Growth of Two-Dimensional Molybdenum Disulfide Structures for Gas Sensing Application
, Ph.D. Dissertation Sharif University of Technology ; Irajizad, Azam (Supervisor) ; Asgari, Reza (Supervisor)
Abstract
Molybdenum disulfide (MoS2) nanoflakes, a two-dimensional crystal with tunable bandgap depends on number of layers, is a promising candidate for future nanoelectronic devices. In the present research, flower shaped MoS2 nanoflakes have been synthesized via hydrothermal method. As part of the research, the growth of triangular MoS2 monolayer up to 10 micrometers has optimized by carring out several chemical vapor deposition experiments with varying deposition parameters. The prepared samples were characterized using optical, scanning electron, and atomic force microscopes, x-ray diffraction analysis, and Raman spectroscopy. Based on the experimental results, the growth mechanism has been...
Reduction of Sulfur Content of Model Feed by Oxidative Process in them Presence of Carbon Structures Based W-Mo Nanocatalysts
, Ph.D. Dissertation Sharif University of Technology ; Kazemini, Mohammad (Supervisor) ; Rashidi, Alimorad (Supervisor) ; Hajjar, Zeinab (Co-Supervisor)
Abstract
In this research, molybdenum and tungsten catalysts modified with cobalt and nickel on a carbon support have been synthesized and investigated in the oxidation desulfurization process. A model fuel was used to evaluate the synthesized catalysts. This model fuel was n-decane. dibenzothiophene was also used as a sulfur model. The synthesized catalysts were subjected to various analyzes such as XRD, FTIR, Raman, BET-BJH, NH3-TPD, TEM and ICP-OES for structural evaluation. On the other hand, synthetic parameters such as metal loading rate, molar or weight ratio of secondary metal (cobalt and nickel) to primary metal (molybdenum and tungsten) and molar ratio of citric acid to primary metal as...
Evaluation the Effect of Oxidized Nano MoS2 on Epoxy Novolac Corrosion Resistance and Rheological Properties
, M.Sc. Thesis Sharif University of Technology ; Ramezani Saadat Abadi, Ahmad (Supervisor) ; Mousavi, Abbas (Supervisor)
Abstract
This study investigated the effect of oxidized molybdenum disulfide (MoS2) nanosheets on the anti-corrosion and rheological properties of epoxy resin. Raw MoS2 sheets were obtained as layered nanosheets with a thickness of 50 to 100 nm using acid washing, oxidation, and heat shock methods. The use of nanoparticle characterization tests such as XRD, FT-IR, FE-SEM, EDS, and TGA supports this claim. Then, in the next step, epoxy coatings containing different percentages (0, 0.3, 0.5, 0.8, and 1.5 wt%) of MoS2 nanosheets were prepared with polyamide hardener to investigate the effect of adding nanosheets and the optimal percentage. The best effect on the corrosion properties of the coating in a...
Synthesis and Characterization of Polymer Nanofibers Modified by Using of Radiated Grafting for Adsorption of Molybdenum Ions from Aqueous Solution
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad (Supervisor) ; Asadollahzadeh, Mehdi (Supervisor) ; Torkaman, Rezvan (Co-Supervisor) ; Torab Mostaedi, Meysam (Co-Supervisor)
Abstract
Molybdenum is one of the important elements of the intermediary metal with atomic number 42, which is used in various industries, but among the important uses of this metal in the nuclear industry, we can mention the presence of this element in the production of yellow cake as an impurity and also as a precursor for the production of radiopharmaceuticals. It is one of the impurities that remain in all stages of yellow cake production along with uranium, and the high presence of this element causes the centrifuges to become unbalanced during the injection of "U" "F" _"6" gas, and on the other hand, technetium, the main ingredient in the production of radiopharmaceuticals, It comes from the...
Separation of Re and Mo from roasting-dust leach-liquor using solvent extraction technique by TBP
, Article Separation and Purification Technology ; Volume 86 , February , 2012 , Pages 143-148 ; 13835866 (ISSN) ; Darvishi, D ; Haghshenas, D. F ; Yousefi, N ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Re/Mo separation is studied by a new solvent extraction technique which is based on extraction mechanisms of the constituent metals. Based on McCabe-Thiele plots, a flow diagram has been proposed for separation and purification of Re over Mo. Re-recovery section of the diagram shows that Re is extracted when major amount of Mo is removed. For removal of the remained Mo, a two-stage extraction is required at pH = 2 and V a/V o = 1. In order to obtain Re, the resulted aqueous phase is stripped by adding sulfuric acid. According to the results, while more Re is extracted at less pH, optimum extraction of Mo happens at pH = 1.2. Re selectivity over Mo maximizes by approaching of the pH to zero
On the pseudocapacitive behavior of nanostructured molybdenum oxide
, Article Journal of Solid State Electrochemistry ; Volume 14, Issue 4 , 2010 , Pages 643-650 ; 14328488 (ISSN) ; Gobal, F ; Raissi, H ; Moghiminia, S ; Sharif University of Technology
Abstract
Nanostructured molybdenum oxide was potentiodynamically deposited onto a stainless steel surface from an aqueous bath by cycling the potential between 0 and -0.75 V vs. Ag/AgCl. The deposit consisted of particulates in the range of 30 to 80 nm. Electrochemical studies under galvanostatic charge/discharge and also impedance spectroscopy revealed capacitive behavior in the potential range of -0.3 to -0.55 V vs. Ag/AgCl with the value of 477 F g-1 at 0.1 mA/cm2. An equivalent circuit comprising of three parallel branches consisting of double-layer capacitance, Warburg impedance, and a constant phase element signifying pseudo-capacitance each coupled with their corresponding resistances was...
Intermolecular C-H⋯O and n → π∗ and short intramolecular σ → π∗ interactions in the molybdenum(0) tetracarbonyl complex of a very twisted 14-membered tetraazaannulene macrocyclic ligand: Structural and computational studies
, Article CrystEngComm ; Volume 21, Issue 35 , 2019 , Pages 5222-5226 ; 14668033 (ISSN) ; Hosseini, M ; Abdolrahimi, A ; Mahmoudi, M ; Sharif University of Technology
Royal Society of Chemistry
2019
Abstract
The structural and computational studies of a new molybdenum tetracarbonyl complex of 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine, a 14-membered tetraazaannulene macrocyclic ligand, Me2Ph2H2TAA, were carried out by X-ray crystallography and density functional and natural bond orbital (NBO) theories. The complex showed an interesting intermolecular C-H⋯O hydrogen bond which was supported by n → π∗ interaction, forming a one-dimensional extended chain along the b-axis. Interesting intramolecular C-H⋯π and very short σ → π∗ (C-H⋯CO) interactions stabilized the twisted geometry of the coordinated ligand. © 2019 The Royal Society of Chemistry 2019
Intermolecular C-H⋯O and n → π∗ and short intramolecular σ → π∗ interactions in the molybdenum(0) tetracarbonyl complex of a very twisted 14-membered tetraazaannulene macrocyclic ligand: Structural and computational studies
, Article CrystEngComm ; Volume 21, Issue 35 , 2019 , Pages 5222-5226 ; 14668033 (ISSN) ; Hosseini, M ; Abdolrahimi, A ; Mahmoudi, M ; Sharif University of Technology
Royal Society of Chemistry
2019
Abstract
The structural and computational studies of a new molybdenum tetracarbonyl complex of 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine, a 14-membered tetraazaannulene macrocyclic ligand, Me2Ph2H2TAA, were carried out by X-ray crystallography and density functional and natural bond orbital (NBO) theories. The complex showed an interesting intermolecular C-H⋯O hydrogen bond which was supported by n → π∗ interaction, forming a one-dimensional extended chain along the b-axis. Interesting intramolecular C-H⋯π and very short σ → π∗ (C-H⋯CO) interactions stabilized the twisted geometry of the coordinated ligand. © 2019 The Royal Society of Chemistry 2019
Synthesis of Titanium Carbide Mxene-Carbonaceous Material Composite as Capacitive Deionization Electrode for Water Desalination
, M.Sc. Thesis Sharif University of Technology ; Khachatourian, Adrineh Malek (Supervisor)
Abstract
Capacitive deionization (CDI) is a suitable method for water desalination with low energy consumption and high efficiency, which does not have secondary pollution and is environmentally friendly. The hybrid capacitive deionization uses a faradaic electrode next to the carbonaceous electrode, taking advantage of both electrodes, and high capacities have also been reported. Titanium carbide Mxene is an important candidate in CDI due to its high electrical conductivity and tunable interlayer distance, but Mxene suffers from low oxidation resistance. Therefore, in this research, molybdenum disulfide (MoS2) that is an essential member of the 2D transition metal dichalcogenides family, was used as...
Immobilization of dioxomolybdenum(VI) complex bearing salicylidene 2-picoloyl hydrazone on chloropropyl functionalized SBA-15: A highly active, selective and reusable catalyst in olefin epoxidation
, Article Applied Catalysis A: General ; Vol. 475 , April , 2014 , pp. 55-62 ; ISSN: 0926860X ; Zare, M ; Salemnoush, T ; Ozkar, S ; Akbayrak, S ; Sharif University of Technology
Abstract
A novel organic-inorganic hybrid heterogeneous catalyst system was obtained from the reaction of the molybdenum(VI) complex of salicylidene 2-picoloyl hydrazone with mesoporous silica containing 3-chloropropyl groups prepared by a direct synthetic approach involving hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) and 3-chloropropyltrimethoxysilane in the presence of the triblock copolymer P123 as template under acidic conditions. Characterization of the functionalized materials by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), N2 adsorption/desorption, FT-IR and UV-Vis spectroscopy, and thermogravimetric...
Characterization of pulse reverse Ni-Mo coatings on Cu substrate
, Article Surface and Coatings Technology ; Vol. 238 , 2014 , pp. 158-164 ; ISSN: 02578972 ; Ghorbani, M ; Sharif University of Technology
Abstract
The effect of pulse reverse current (PRC) method on Ni-Mo coatings electroplated from chloride solution was investigated by various plating parameters such as plating duration, the anodic duty cycle, the anodic current density and the cathodic current density. By increasing the anodic duty cycle and anodic current density, the Mo content of coatings reached 68wt.% and 78wt.%, respectively at cathodic current densities of 500 and 300mAcm-2. The Mo content of coatings increases by the preferential dissolution of Ni on the anodic pulse and also by the replenishment of Mo complexes in the diffusion layer near the substrate surface during the anodic pulse. In comparison with the direct current...
Joining of MoSi 2 to itself using partial transient liquid phase (PTLP) method
, Article IBSC 2012 - Proceedings of the 5th International Brazing and Soldering Conference ; 2012 , Pages 259-265 ; 9781615039753 (ISBN) ; Kokabi, A. H ; Faghihi Sani, M. A ; Sharif University of Technology
2012
Abstract
Molybdenum disilicide (ModSi 2) is an attractive structural material due to its unique combination of properties, namely excellent oxidation resistance, high melting point (2030°C) and relatively low density (6.3g.cm -3). The present work investigates joining of two MoSi 2 parts through Cusil/Zr/Cusil interlayer with Cusil being a commercial eutectic of Cu-Ag alloy. The joining operation was implemented in an inert gas tube furnace by brazing. The brazing temperature ranged at 830-930°C while the operation lasted for 1hr. Interfacial microstructure was studied by Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) techniques. Applying the...
Naphtha hydrodesulfurization over micro and nanostructure MoO3 catalysts
, Article Scientia Iranica ; Volume 18, Issue 3 C , June , 2011 , Pages 479-485 ; 10263098 (ISSN) ; Kazemeini, M ; Rashidi, A. M ; Jozani, Kh. J ; Sharif University of Technology
2011
Abstract
Highly active unsupported MoO3 and Co -MoO3 catalysts were prepared by a simple solution reaction method in the presence of different organic additives. Catalysts were characterized by the XRD, BET surface area measurement, SEM and TEM techniques. Results suggested that utilizing different additives produced different morphologies OfMoO3 microstructures. Optimizing reaction conditions was found to produce more active molybdenum oxide nanoparticles when urea and PEG200 additives were utilized. XRD and TEM results indicated crystal growth restriction after cobalt incorporation. Catalytic activities of prepared materials were evaluated in the hydrodesulfurization reaction of Naphtha. Products...
Mo(vi) complex supported on Fe3 O4 nanoparticles: magnetically separable nanocatalysts for selective oxidation of sulfides to sulfoxides
,
Article
RSC Advances
;
Volume 5, Issue 66
,
Jun
,
2015
,
Pages 53349-53356
;
20462069 (ISSN)
; Balali, M
; Haghdoost, M. M
; Bagherzadeh, M
;
Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
A molybdenum complex, [MoO2 Cl2 (DMSO)2 ], was immobilized on amino propyl and Schiff base modified magnetic Fe3 O4 @SiO2 nanoparticles by covalent linkage. The resulting nanoparticles were used as efficient and recyclable catalysts for the selective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as the oxidant. The complete characterization of catalysts was carried out by means of thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), elemental analysis, FT-IR and Raman microprobe...
Modeling of a vertical tunneling transistor based on graphene-mos2 heterostructure
, Article IEEE Transactions on Electron Devices ; Volume 64, Issue 8 , 2017 , Pages 3459-3465 ; 00189383 (ISSN) ; Faez, R ; Pourfath, M ; Darvish, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
In this paper, for the first time, we present a computational study on the electrical behavior of the field-effect tunneling transistor based on vertical graphene-MoS2 heterostructure and vertical graphene nanoribbon-MoS2 heterostructure. Our simulation is based on nonequilibrium Green's function formalism along with an atomistic tight-binding (TB) model. The TB parameters are obtained by fitting the bandstructure to first-principle results. By using this model, electrical characteristics of device, such as I ON/I OFF ratio, subthreshold swing, and intrinsic gate-delay time, are investigated. We show that the combination of tunneling and thermionic transport allows modulation of current by...