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Kinetic Modeling of Coke Formation and Deactivation in Catalytic Dehydrogenation of Propane
, M.Sc. Thesis Sharif University of Technology ; Khorasheh, Farhad (Supervisor) ; Nazeran, Iraj (Co-Advisor)
Abstract
The study on the propane dehydrogenation process has been receiving significant attention due to the growing demand for propylene. Many efforts have been made to enhance the propylene yield by developing new catalysts with high-activity, high-stability and high-selectivity. Among these, platinum supported catalysts have been reported widely. Firstly, the current study mentions related work in the modeling of coke formation and deactivation of catalyst, experimental setup and catalysts which are conventionally used for propane dehydrogenation reaction. Then, a monolayer–multilayer mechanism is proposed for modelling the coke formation. In addition, the reaction rate of coke formation and its...
Kinetically Investigation of Catalyst Deactivation in Catalytic Reforming Process
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor) ; Taghikhani, Vahid (Supervisor)
Abstract
Catalytic reforming of naphtha is an important process to convert of low-octane number naphtha into high-octane number gasoline. Deactivation of catalysts, is the major problem for this process. In this study, catalytic reforming unit of Tabriz oil refinery investigated, and Smith’s kinetic model used for modeling. Also, several models presented for activity of catalysts. To find the parameters of presented models, the difference between the calculated and experimental values of outlet temperatures of each bed and aromatics, paraffin and naphthene yields simultaneously must be minimized. Using Genetic Algorithm Toolbox in Matlab software, optimization was performed and results indicated that...
Synthesis of Pt- Nanoparticle in Ionic Liquid Coated on Alumina and the Investigation of the Nature and Thickness of Ionic Liquid on Catalyst Pt / Al2O3
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
In this project ionic liquid and there mixtures were coated on Pt/ Al2O3 , the prepared catalyst were characterization by SEM, BET and XRD techniques.In the first stage the effect of the coated ionic liquid on the Pt/Al2O3 were investigated, on the rate of C=C hydrogenation. in the second stage effect of the thickness of ionic liquids on the rate of the cyclohexene hydrogenation were studied. Result revelad that by increasing the ionic liquid polarity, the reaction rate increased. Also the reaction rate decreased by increasing the thickness of ionic liquid
Kinetics Modeling of Platinum Leaching from Reforming Spent Catalysts by iodine/iodide Solution
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
Platinum is one of the most used catalysts in refining and petrochemical industries. Also, Platinum uses in other industries like automobile catalytic convertor. As respect to importance of Platinum in these industries, growth of its consumption in recent decades and its very high price, recovery of Platinum is essential. Hence, many of various methods including hydro-metallurgy are applied. In despite of these wide spreading experimental investigations, due to low information about the reactions and the nature of reaction products, a few investigations were done on kinetics of Platinum recovery. A new method that used iodine solution to extract Platinum from spent reforming catalysts was...
Study of Biological Extraction Kinetics of Heavy Metals from Spent Catalyst by Thermophilic Bacteria
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheyla (Supervisor) ; Mousavi, Mohammad (Supervisor)
Abstract
Every year, an enormous amount of catalysts are consumed in oil refineries during refining processes. After some regeneration cycles in order to recover their activity, they are not anymore effective and must be disposed. These spent catalysts are regarded as dangerous solid wastes as they significantly include some contaminations like vanadium, nickel, arsenic, sodium. From another point of view, the metals present in spent catalysts are highly valuable and are used extensively in steel industry and manufacture of special alloys. So, it sounds profitable to extract and recover these metals from such a cheap source instead of minerals and ores. Basically, there are two main processes, hydro-...
Nickel Recovery from Spent Catalyst of Reformers
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
In this research, Nickel recovery has been investigated from spent catalyst (NiO/Al2O3) in reformers of direct reduction iron plant (Midrex). Genetic Algorithm method was applied for screening and optimization of the parameters affecting on the Ni dissolution in sulphuric acid by means of Design Expert Software. In accordance with the results, temperature, time, acid concentration and particle size were introduced as the effective parameters on the catalyst leaching. In the next step, the optimization experiments, the optimal parameters were achieved as following: Temperature = 95 C, Acid concentration = 5 Molar, Time = 255 minute, Stirring speed = 600 rpm, Particle size = 50-60 micron and...
Design and Structural Study of Functionalized Nanoporous Catalysts Confined with Ionic Liquids and Their Applications in Some Organic Transformations
, M.Sc. Thesis Sharif University of Technology ; Mahmoodi Hashemi, Mohammad (Supervisor)
Abstract
The current thesis deals with designing of functionalized nanoporous catalysts modified with organic groups and ionic liquids and their applications for some challenging organic reactions such as synthesis of adipic acid and fatty acid esterifications. In this condition the catalysts show enhanced activity since the hydrophobicity of the surface can tune by applying organic groups. In this regard, oxidation of cyclohexene was performed using hydrogen peroxide as oxidant in the present of tungstate based task–specific ionic liquids and silica–functionalized ammonium tungstate as green catalysts. The results indicate that adipic acid achieves in high yield with excellent selectivity....
Synthesis of Transition Metal Nanocatalysts Immobilized on to the Poly (Ionic Loquid) Coated Graphene and Utilization in Organic Transformations
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Nowadays, because of the importance of saving energy resources and also environmental issues, utilization of catalysts are increased in industry and products. In the last decades, a lot of efforts have been devoted to develop novel methods for heterogenizing of the homogeneous catalyst in order to combine the advantages of the both the homogeneous and the heterogeneous catalysts. Among the different solid supports, graphene with high surface area and distinctive mechanical and electronical properties have been introduces as an emerging support for heterogenizing of the homogeneous catalysts. On the other hand, the use of ionic liquid has been developed due to a broad range of polarity, low...
Stabilization of 2-(4-phenyl-1H-1,2,3-triazol-1-yl) on the Magnetic Nano Particle Fe3O4 as Suitable Ligand for Stabilization of Cu (II) and Use It in the Huisgen's Reaction & The Readuction of Nitro Compounds in the Presence of Gold Nanoparticles Immobilized on Magnetic Nanoparticle Fe3O4 Functionalized with Ionic Liquid
, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
A novel magnetic heterogeneous copper catalyst was synthesized by immobilization ofcopper ion onto the triazole functionalized Fe3O4. The catalyst was fully characterized by FTIR, TGA, CHN, SEM, TEM, EDX and atomic adsorption spectroscopy. The resulting catalystwas used in the synthesis of 1,2,3-triazoles via one-pot three component reaction of alkynes,alkyl halides, sodium azides under green condition. The catalyst was reused for ten times andno significant loss of activity was observed. Supported gold (III) on poly(ionic liquid) coated on magnetic nanoparticles produced a highly active, stablerecoverable and high loading for the synthesis of propargylamines (A3 coupling reaction) under...
Mathematical Modeling of Catalyst Deactivation of the Methanol to Gasoline (MTG) Process in a Fixed-bed Reactor
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor)
Abstract
Nowadays, with respect to environmental pollution and energy supply, producing gasoline from methanol or syngas is one of the most interesting research subjects. Gasoline production from methanol is a catalytic process that produces high-quality gasoline with minimum unwanted compounds. So this gasoline is a clean fuel and it can be replaced to petroleum gasoline. Because of that, it can be a valuable process in the petrochemical industry. One of the most important aspects of this process is catalyst deactivation with respect to time on stream. Catalyst deactivation is usually caused by poisoning, sintering, blocking pores, and coking. In this research, material and energy balance equations...
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Khorasheh, Farhad (Supervisor)
Abstract
Diesel oxidizing catalysts (DOCs) based on precious metals of Platinum and Palladium are among the most important and most widely used catalysts in the exhaust aftertreatment system of diesel cars. DOCs are used to oxidize CO and hydrocarbons to reduce their emissions to the environment. In spite of the excellent performance of DOCs, sulfur exposure can lead to their deactivation. Sulfur is mainly in the form of SO2 at the combustion chamber exit, which can be further oxidezed to SO3 on the DOC. The deactivation impact of SO2 and SO3 on DOCs are different, with SO3 leadig to higher degrees of deactivation. In this study, a kinetic model for SO2 oxidation on a bimetallic Pt-Pd-based catalyst...
The Effects of Catalyst Preparation Parameters on Carbon Nanotube Growth
, Ph.D. Dissertation Sharif University of Technology ; Vessaghi, Mohammad Ali (Supervisor) ; Taghavinia, Nima (Co-Advisor) ; Shafiekhani, Azizollah (Co-Advisor)
Abstract
In this study three different methods; hot filament chemical vapor deposition (HFCVD), pulsed laser ablation (PLA) and electrochemical deposition were utilized to prepare catalyst thin films or nanoparticles and thermal chemical vapor deposition (TCVD) was used to grow multiwall carbon nanotubes (MWCNTs). We found that even though the three mentioned techniques have been rarely applied by researchers, they are appropriate and efficient methods to produce catalytic basis for CNT growth. In the TCVD step, liquid petroleum gas (LPG) was applied as carbon source. Although, this gas is a mixture of different hydrocarbons and further contains some sulfur, our results verify that utilizing of LPG...
Design and Fabrication of Gold Nanocatalyst for Aerobic Oxidation
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Manoochehr (Supervisor) ; Simchi, Abdolreza (Supervisor)
Abstract
Aerobic oxidation plays important role in industrial processes and pollutant remediation. The catalysts accelerating oxidation reaction rate are included thermal (typical) catalysts such as Pt or Au on oxide supports and photocatalysts such as TiO2 or ZnO. Although well-studied Au/TiO2 system have been under deep
investigations but Au/ZnO system have less investigated because Au/ZnO has low activity relative to Au/ZnO. Gold nanoparticles supported on ZnO nanostructures were prepared through a simple chemical-thermal method and characterized by SEM, TEM, XRD, BET and photo luminescence (PL) spectroscopy. Effect of
annealing temperature on catalytic activity of these Au/ZnO...
investigations but Au/ZnO system have less investigated because Au/ZnO has low activity relative to Au/ZnO. Gold nanoparticles supported on ZnO nanostructures were prepared through a simple chemical-thermal method and characterized by SEM, TEM, XRD, BET and photo luminescence (PL) spectroscopy. Effect of
annealing temperature on catalytic activity of these Au/ZnO...
Synthesis of Magnetically Recyclable Core-shell Nanocatalysts for Epoxidation of Alkenes and Reduction of Sulfoxide to Sulfides and Oxygen Atom transfer by Mo(VI) Complexes
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In the first part of this thesis, the application of core-shell magnetic nanoparticles supported V(V), Mo(VI) and Mn(III) complexes in the catalytic oxidation and reduction reactions was discussed. A magnetically recyclable vanadium(V) catalyst was synthesized by covalent anchoring of VO(salen)Cl on silica coated Fe3O4 nanoparticles. These nanoparticles were efficient catalysts for selective oxidation of sulfides to corresponding sulfoxides with urea hydrogen peroxide in excellent yields. Leaching and recycling experiments revealed that the nanocatalyst can be applied for nearly complete oxidation of sulfides for at least five successive cycles. A manganese(III) complex was immobilized on...
Characterization of V2O5 Spent Catalyst & Feasibility Study of its Regeneration
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor) ; Farzami, Faezeh ($item.subfieldsMap.e)
Abstract
In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the...
Fabrication and Evaluation of Catalytic Microreactors to Verify the Conversion of Ethyl Mercaptan
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor)
Abstract
Sulfur compounds are largely an impurity in fossil fuels such as natural gas, crude oil and coal. In natural gas, the main sulfur compounds are hydrogen sulfide (H2S), carbonyl sulfide (COS),and C1-C3 mercaptans.Commercial methods for removing these compounds require the introduction of additional reactive substances (O2, H2, Olefins, NaOH, etc.), which often results in the production of other pollutants. Microfluid is a branch of science and technology that involves studying the behavior of fluid, the use of fluid and the manufacture of equipment or systems that are carried out in micro-channels.The dimensions of these canals are about ten to several hundred micrometers, and high of...
Preparation and Evaluation of Mesoporous Nanostructured Nickel Catalysts for Syngas Production by Combined Reforming of Methane
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor) ; Rezaei, Mehran (Supervisor)
Abstract
In this study, the effect of nano-structure mesoporous supports on the performance of the nickel catalysts in the combined reforming process was investigated. In the first part, magnesium aluminate spinel was prepared using a sol-gel method and employed as a catalyst support for the preparation of nickel catalysts with various nickel contents. The samples were characterized using BET, XRD, TPR, TPO, CO chemisorption and SEM techniques. The results showed that increasing the nickel content up to 7.5 wt.% improved the catalytic activity, but further increase in nickel content decreased the activity due to the decrease in the nickel dispersion. The catalysts except of the sample with 2.5 wt.%...
Experimental Investigation and Modeling of Ferrous Biooxidation in a Monolithic Bioreactor
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Manoochehr (Supervisor) ; Alemzadeh, Iran (Supervisor)
Abstract
The bio-oxidation of ferrous iron is a potential industrial process in the regeneration of ferric iron and the removal of H2S in combustible gases. Bio-oxidation of ferrous iron may be an alternative method of producing ferric sulfate, which is a reagent used for removal of H2S from biogas, tail gas and pulp and paper industry. For practical use of this process, this study evaluated the optimal pH and initial ferric concentration. pH control looks like a key factor as it acts both on growth rate and on solubility of materials in the system. Some process variables such as pH and amount of initial ferrous ions on oxidation by A. ferrooxidans and the effects of such process variables dilution...
Synthesis of Several Multiphasic Ionic Liquid-Coated Pt/Al2O3 Catalysts: Selective Synchronous Hydrogenation of C=C and C=O Bond and Modeling of the Ionic Liquid and Solvent Effects
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
In this study various ionic liquids (ILs) and their mixtures were coated on Pt/Al2O3 catalyst and the resulted IL-coated catalyst were used in synchronous hydrogenation of cyclohexene and acetone. The rate constants (k) and seletivities (S) toward C=O hydrogenation were determined for several catalysts in various solvents. The solvatochromic parameters (ETN, normalized polarity parameter; π*, dipolarity/polarizability; β, hydrogen- bond acceptor basicity; α, hydrogen-bond donor acidity) were determined for used ILs and solvents and all obtained selectivities were modeled based on solvatochromic parameters of IL layer and bulk solvent using Multiparameter Linear Regression (MLR) method for...
Experimental Investigation for Enhancing the Lifetime of Co,Ru/La(γ-Al2O3) Catalyst in Fischer Tropsch Synthesis
, Ph.D. Dissertation Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Khorasheh, Farhad (Supervisor) ; Zarkesh, Jamshid (Co-Advisor)
Abstract
Fischer-Tropsch synthesis (FTS) is the main part of a Gas to Liquid (GTL) process. In this reaction which shall be done based upon iron or cobalt catalysts, H2 and CO molecules (namely Syngas) transform to long hydrocarbon chains. Regarding all of the advantages of cobalt catalysts in comparison with iron counterparts, Research Institute of Petroleum Industry (RIPI) began investigations since two decade ago. The present catalyst comprised of cobalt as active metal, ruthenium as activity promiter and lanthanum as support (gamma alumina) modifier. By the way, still some areas such as its lifetime duration and deactivation needs to be improved by complimentary researches. The present...