Sharif Digital Repository

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... 

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... 

Developing a simple, cost effective and accurate detection method for L-lysine (Lys), L-leucine (Leu) and glycine (Gly) as the important analytes in clinical diagnostics, biological processes and food industries is of great interest. Therefore, in the first part of this research, cellulose nanofibrils (CNFs) were coated on a quartz crystal microbalance (QCM) surface by spin coating to achieve a QCM biodetector for Gly. Thus, the two-layer CNFs coating was selected as sensing film and was applied for following experiments. In the next step, the coated QCMs were carefully characterized before and after interaction with Gly using water contact angle (WCA), Fourier transform infrared... 

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... 

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... 

Green chemistry seeks to reduce or eliminate the use of hazardous substances in the chemical industry through the development of new products and processes .The replacement of harmful, widely used solvents and reagents is a key part of this approach. Supercritical fluid such as CO2 or water are good solvent for replaceement Exchange reactions involving the displacement of hydrogen bonded to carbon by deuterium are of interest in a broad variety of disciplines, such as the preparative chemistry of isotopically labeled materials, fundamental studies of carbonehydrogen bond activation processes, and studies of the nature of catalysts. The low cost of water and its environmental friendliness... 

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... 

The present study was aimed at investigating the use of platinum and platinum nanoparticles stabilized on zeolite as catalyst for the reduction reaction of p-nitrotoluene as one of the dangerous pollutants. The adsorption properties of platinum based on zeolite have been studied for some heavy metals. Monodispersed platinum nanoparticles were synthesized through reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone (PVP) as a stabilizer, and then were immobilized on four types of zeolites. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. In order to investigate the catalytic properties, operating... 

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... 

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... 

Iran’s big cities air pollution is one of the major challenges to authorities in view of public health. Tehran City has been facing more and more air quality problems over the last decade. The criteria pollutants in Tehran are PM2.5, PM10. Particulates and especially ultrafine particles have been identified as the most toxic component of the polluting mixture. Considering diesel engine operation concepts, these types of engines are one of the main source emission of ultrafine particles, with more than 58%, in Tehran. So controlling particulates emitted from these sources, is one of the first steps to improve air quality. Diesel Particulate Filters (DPFs) are well-known and effective way to... 

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... 

Decomposition of seawater with the help of sunlight is one of the most promising ways to produce hydrogen as a clean and acceptable fuel in the future. Tungsten photoelectrode is a suitable option for seawater decomposition due to its medium bandwidth, excellent load transfer properties, good chemical stability in acidic and neutral environments, abundance and cost-effectiveness. On the other hand, intermediate metal catalysts (Fe, Ni, Co) are very important due to their abundance in the earth's crust and their stability in alkaline and neutral environments instead of oxides of precious metals (RuO2, IrO2). In this study, tungsten plate (WO3) nanostructures were grown on the surface of a... 

Dry reforming methane is a process during which two greenhouse gases, CH4 and CO2, using Ni-based catalysts, are altered into valuable H2 and CO gases, which are very useful from an economic and environmental point of view. The main problem with Ni-based catalysts is the formation of carbon in the dry methane reforming, which leads to rapid deactivation of the catalyst. In this research, a 10Ni-5Co/Al2O3 bimetallic catalyst was prepared by one-pot microwave-assisted combustion synthesis with a stoichiometric amount of fuel (urea) and without the use of additives. The catalyst was then calcined for 12 h at 550oC. The structure, chemical composition, particle distribution, and morphology of... 

Nowday, one of the important goals of researchers is to develop and improve the properties of intermediate tempreture solid oxide fuel cells with range of 600-800˚C. Therefore, choosing the right material as a cathode with good performance in this temperature range is very important. For this purpose, various materials with ionic and electron conductivity mixtures (MIECs) are used, especially oxides with a Radelsden-Paper structure. These oxides are shown by the formula An+1BnC3n+1, which are actually composed of a combination of perovskite layers (ABO3) that are alternately superimposed between two layers of rock salt (AO). In the present study, Sr3Fe2O7 powder with different amounts... 

Methane steam reforming (MSR) is an assuring reaction using steam to produce H2 as clean energy over a nickel-based catalyst. We synthesized monometallic NiMgAl2O4 and bimetallic NiCoMgAl2O4 catalysts in a two-step combustion method using urea, glycine, and sucrose, as fuel. BET-BJH, XRD, TGA, TPR, FESEM, and EDX-mapping characterized surface area, porosity, morphology, crystalline structure, and metal-support interaction behavior. The products exhibited well-structured, simple MgAl2O4 spinel and NiO without NiAl2O4, in both specimens. The MSR evaluation tests at 750℃ under atmospheric pressure, CH4: H2O feed ratio of 1:1.6 showed the bimetallic catalyst has the highest conversion (99.30%)... 

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... 

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... 

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... 

In the present work, aluminothermic reduction of vanadium pentoxide have been used to produce aluminium vanadium alloys. The effect of addition of lime and excess aluminium on the produced alloy was studied. The experiments were carried out in air and in argon. The alloys microstructure were analyzed bu light and scanning electron microscopy. Other methods such as XRD, XRF, ICP, AAS and titration were employed to analyzed the alloy and the slag. It was found that the addition of lime and excess aluminium increase the yield of the alloy. Vanadium recovery was not affected by the atmosphere used.