Sharif Digital Repository

Due to imminent shortage of fossil fuels, environmental issues that occur from their intensive use, population growth and industrialization of societies moving towards renewable energy sources is inevitable. Sun is the most clean and abundant source of energy but it is needed to be accompanied with an energy storage system as it is intermittent and cannot supply our required energies on demand. Water splitting electrochemical cells are promising solutions to cope with this problem by producing hydrogen as a clean fuel. The overpotential imposed by anode is the bottleneck of the water splitting reaction. The anodes with sufficient efficiency that are used today are made from precious and... 

In this research polypropylene/carbon nanotube nano composites were prepared via in situ polymerization using Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes(MWCNT) functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 and TiBA were used as catalyst and co catalyst respectively. After defining the polymerization optimum conditions and considering its parameters constant, nano composites with different carbon nanotube contents were produced by changing the polymerization time. Scanning Electron Microscopy (SEM) images certified very good dispersion of MWCNTs throughout polypropylene matrix. The thermal properties behavior of... 

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 the first section, due to the important role of nanocatalysts in different fields of chemistry, magnetic metal ferrite nanoparticles were synthesized. Nickel ferrite and cobalt ferrite magnetic nanoparticles were synthesized using co-precipitation method and were characterized. Then, these nanoparticles which have been crystalized in spinel structure were employed to catalyzed different C-C and C-heteroatom bond formation reactions through C-X bond activaion. In all cases, the proposed catalytic systems could catalyze the reactions efficiently and the optimized reaction conditions were milder and more effective than the previous reported methods. In the next section, C-halogen bond... 

In the first section, due to the important role of nanocatalysts in different fields of chemistry, magnetic metal ferrite nanoparticles were synthesized. Ferrite nanoparticles were synthesized using co-precipitation method and were characterized. Then, these nanoparticles were applied as catalyst system for one-pot β-ketophosphonates and thiophosphate synthesis.This is a green and efficient route for S-P and C-P bond construction using copper ferrite nanoparticles as catalyst. The application of a highly active recyclable heterogeneous nanocopper ferrite catalyst for the oxyphosphorylation reaction of various alkenes was conducted under ligand-free conditions, in acetonitrile as solvent at... 

The sulfur compounds in crude oil cause air pollution, metallic equipments’ corrosion and refinery catalysts poisoning like reforming catalysts. Therefore it is necessary to use hydrodesulfurization catalysts for sulfur content reduction. Hydrodesulfurization is the most common desulfurization method in the industry. In this method, sulfur compounds react with the hydrogen in presence of ComMo/γ Al2O3 catalyst and under hard operational conditions like high temperature ( 300-340 ͦC) and high pressure (20-100 atm of hydrogen). Then,these compounds are turned into hydrogen sulfide and hydrocarbons. In the next step, produced hydrogen sulfide will be eliminated from oil cutting.In this... 

The hydrogenation of carbon dioxide to methanol represents a promising route for the efficient use of an anthropogenic greenhouse gas, in which catalysts play a key role in carbon dioxide conversion and methanol selectivity. In this study, firstly, CuO-ZnO-Al2O3, CuO-ZnO-ZrO2, CuO-ZnO-ZrO2-Al2O3, CuO-ZnO-Al2O3-CeO2 and CuO-ZnO-ZrO2-CeO2 catalysts were made using co-precipitation method, then these catalysts were characterized by inductively coupled plasma optical emission spectrometry, specific surface area and pore size distribution, X-ray diffraction, Field Emission Scanning Electron Microscopy, temperature programmed reduction. Finally, in order to compare the performance of the catalysts... 

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.%... 

Liquide phase catalytic exchange (LPCE) between liquid water and hydrogen is an important reaction for separation of the hydrogen isotope from liquid water. One of the application of this reaction is heavy water production. This method is mainly used hydrophobic catalysts with Pt active metal. The use of hydrophobic catalyst is necessary, because liquid water in the LPCE reaction, resulted in block the catalyst pores and loss of catalyst activity. Design of experiment has been done by using of Design Expert 7.0.0 for determination of number of tests and optimization of Pt weight percent. Alumina and carbon (included graphene, single-walled and multi-walled carbon nanotube) supported 5% wt Pt... 

Water Gas Shift (WGS) reaction is an old reaction in which syngas is used for producing Hydrogen. At the present time, the major application of this reaction is in fuel cells, since the necessary Hydrogen for these cells is provided by this reaction.
The present study investigate the influence of different preparation methods on properties of Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction, which is now known as the Commercial catalyst for low temperature WGS, and its influence on performance of Cu-ZnO/Al2O3 catalyst to derive an optimal Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction. Cu-ZnO/Al2O3 catalysts was synthesized by CP, DP, DP-Ultra, IWI , CP-Urea, and... 

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... 

According to the reports of the Tehran Air Quality Control Company, mobile sources are responsible for the emission of 70-85% of air pollutant in this metropolis. Over the past decades, compressed natural gas (CNG) is known as a cleaner fuel and a suitable alternative to gasoline and diesel fuels in the transportation section in some countries. However, methane emissions from natural gas vehicles is a significant challenge because it is a potent greenhouse gas and plays important role in global warming. In addition, because of another pollutant emissions from these vehicles, exhaust gas treatment is a crucial issue. Using Three-Way catalysts (TWC) is the conventional method in order to... 

In this research a novel palladium nanocatalyst was synthesized over single-wall carbon nanotube (SWNT) support and then applied in the selective hydrogenation of acetylene in an ethylene rich-flow stream. This nanocatalyst displayed a very promising selectivity toward ethylene production upon rising of the temperature, as well as suppressing oligomer formation during acetylene hydrogenation. It was rationalized that the overwhelming governing mechanism for the acetylene hydrogenation over the 0.48 wt% Pd/SWNT was the hydrogen transfer. Furthermore, new operating conditions for selective hydrogenation of acetylene in ethylene rich-flow were introduced through which the selective... 

Selective oxidation of H2S to elemental sulfur in a fixed bed reactor over seven nanocatalysts has been investigated and compared to commercial claus catalyst. Among them, Al2O3-supported sodium oxide nanocatalyst prepared with wet chemical technique and Al2O3 nanocatalyst prepared with spray pyrolysis method were the most active catalysts for selective oxidation of H2S to elemental sulfur. The remaining nanocatalysts were deactivated, mainly due to the interaction with H2S and conversion into sulfides. For synthesis of Al2O3 with spray pyrolysis method we use statistical design of experiments (box-behnken design) in order to screen the effects of significant synthesizing parameters  

The number of operating vehicles has increased in recent years and as a result global pollutants have widely spread. Therefore, the regulations on the vehicle exhaust emissions have become much stricter. For an automobile to pass the emission tests successfully an accurate calibration of the ECU tables is needed, especially the tables which have direct impact on the amount of pollutant emissions. To achieve the optimum performance of the catalyst existing in the exhaust system of the engine, the fuel/air ratio must have nearly stoichiometric value. The present research studies the ECU strategies for implementing this objective by appropriate management and control of catalyst and oxygen... 

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.... 

The aqueous phase reforming (APR) of glycerol is an attractive yet challenging pathway to convert abundant biomass into value added hydrogen. Pt catalysts have received attention due to their ability to produce hydrogen-rich gas under APR conditions. In this work, the conversion of glycerol into hydrogen is demonstrated using Pt0.05CexZr0.95-xO2 (x=0, 0.29, 0.475, 0.66 and 0.95) solid solution catalysts and a series of M-doped Pt-MgO (M = Pd, Ir, Re, Ru, Rh and Cr) sheet-shaped nano-catalysts. Both characteristic (XRD, BET, H2-TPR, CO-chemisorption, TEM and XPS) and reactivity measurements were used to investigate the activity of the catalysts. Results indicated that reactivity depended on... 

Silicon carbide due to its noticeable mechanical and thermal properties, uses in various industries either main substrate or reinforcement. SiC has low specific surface area according to its resistivity against sintering. Recently, a lot of scientists have been worked on SiC in order to fabricating small ones ; subsequently, better sintering will be achieved. Chemical vapor deposition method (CVD) is a method to produce fine SiC with deposition of products by reacting of initial materials from gas environment. In this study normal CVD as proper method and hydrogen, silicon tetrachloride and activated carbon as initial materials are chosen. Using of iron and nickel catalysts in temperature... 

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... 

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...