Sharif Digital Repository

The aim of this project is to investigate and synthesize CaO-based nanocatalysts derived from chicken eggshell calcination with alkali metals and sodium-potassium compounds promoters used in the transesterification reaction of canola oil and methanol. Sections of this thesis include the synthesis of nanocatalysts, catalyst characterization tests, and investigation of reaction under optimal conditions. Two groups of catalysts containing different weight percentages of alkali metals based on CaO and 1 %wt sodium-potassium based on CaO with different weight percentages of these two elements were synthesized by wet impregnation method and used in the reaction under optimum condition. Catalyst... 

During the last few decades, efforts have been made to replace fossil fuels with clean and non-absorbent energy sources. One of the promising strategies is energy production by hydrogen storage using water splitting. For this purpose, different methods of using light, heat and electricity are provided. Electrolysis of water with a simple environment such as very high purity of hydrogen produced, controllable, device, no need for high temperature and pressure in the reactor and huge potential for industrial applications has been very much considered. Water electrolysis consists of two reactions: reduction of water to hydrogen (HER) and oxidation of water to oxygen (OER). The second reaction... 

In recent decades, desulfurization processes have become necessary to reduce environmental pollution due to fuel sulfur emissions. In this research, in order to photocatalytic oxidation desulfurization of liquid fuel, a model fuel (normal octane) under visible light irradiation of 250 W sodium lamp, using H2O2 oxidant and methanol solvent in the presence of BMO/Fe@MIL(x%) composite. BMO and Fe@MIL were investigated. From the tests, X-ray diffraction, scanning and transmission electron microscope imaging, absorption and desorption of nitrogen gas, infrared spectrometer-Fourier transform, visible-ultraviolet reflection spectroscopy, optical radiation spectroscopy and vibration magnetometer in... 

Due to the increasing consumption of fuel, the use of new methods with high efficiency to remove sulfur from fossil fuels is felt more than ever. Hydrogenation and oxidation of sulfur organic matter, such as thiophenes, is an old method of desulfurization of liquid fuels. Using a photocatalyst, everything can be done in an environment that is very low cost. In this study, the photocatalytic elimination of dibenzothiophene was investigated. For this purpose, carbon-doped thiamine dioxide was used as the photocatalytic base, which is synthesized by hydrothermal method. This method is the same source of titanium and carbon. To increase the performance of the catalyst, platinum metal was loaded... 

The conversion of CO2 gas into value-add chemicals known as solar fuel technology attracted much consideration from the beginning of the 21st century owing to the potential of this technology in solving the climate change and energy shortage issues. In the present study, a well-known photocatalyst, TiO2, was doped with Bismuth element and was subjected to Pt nanoparticles loading as a cocatalyst to boost the photocatalytic CO2 conversion. Pristine TiO2 and Bi-doped samples were prepared by sol gel method. Then, a facile photo-deposition method was employed to introduce Pt onto the surface of TiO2. Various characterization techniques including XRD, DRS, BET, PL, FTIR, FESEM and TEM, were used... 

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... 

The aim of this project is to fabricate and study heterogeneous CaO-based nanocatalysts with lithium and zinc enhancers for the esterification reaction of rapeseed oil and methanol to produce biodiesel as a renewable and alternative fuel for fossil fuels. Is. First, Zn-Li / CaO catalysts with weight ratio Li: Zn: CaO, 2: 2: 7 and by combining different percentages of Li100% promoter, Li75% -Zn25%, Li50% -Zn50%, Li25% -Zn75%, 100% Zn were made on the basis of CaO by wet inoculation. Characterization tests to evaluate the structure and characterization such as X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (EDX) spectroscopy, Bruner-Emmett-Teller... 

In recent decades, desulfurization processes have become essential to decrease environmental pollution due to the emission of sulfur from fuels. In this study, in order to desulfurize liquid fuel, a model fuel (normal heptane) was investigated under visible light ) 350-watt sodium lamp(, using H2O2 as oxidant and methanol as a solvent in the presence of Cu-C-TiO2 nanostructure. C-TiO2 was synthesized by the hydrothermal method. In order to modify and improve the properties, we doped the copper metal by impregnation method with different loading of Cu. Experimental results exhibited the highest activity among samples attributed to 0.5% Cu-C-TiO2 Which caused 98.27% degradation of DBT after 2... 

The increase in demand for liquid hydrocarbon fuels in recent years in the transportation sector as well as in industry has led to an increase in the concentration of pollutants in the atmosphere. Sulfur oxides are known as one of the most challenging pollutants in the world today. In recent years, with the increase in the amount of pollutants in the air and the problems caused by them, which endanger the health of the society, sensitivities have arisen regarding the entry of pollutants into the air. Therefore, the Environmental Protection Organization has set specific standards regarding the allowed amount of sulfur in liquid fuels. One of the new ways to reduce the amount of sulfur in... 

Carbon dioxide photocatalytic reduction is one of the promising methods used to produce a wide range of renewable hydrocarbon fuels using sunlight in the presence of photocatalysts. In this study, a series of Nickel and Bismuth doped titanium dioxide samples were synthesized by Sol-gel method. After performing photocatalytic carbon dioxide recovery experiments and finding the optimum percentage of Nickel and Bismuth doped titanium dioxide,Ni and Bi co-doped TiO2 sample showed the highest photocatalytic activity. Amount of methane production was 21.13 μmol/gcat in the presence of co-doped sample that was about 6.5 times higher than the amount of methane produced in the presence of pure TiO2... 

In recent years, there have been many concerns about the environment. One of them is the increase in greenhouse gases that cause warming and air pollution. On the other hand, fossil fuels are running out, so we need to look for clean alternative fuels. One of these options is hydrogen gas, which can be produced with the help of electrocatalysts and the water splitting reaction. In the electrolysis of water, the oxygen evolution reaction (OER) limits the reaction kinetics, so the synthesis of efficient electrocatalysts is important. As a result, the goal of this work is the synthesis of a cheap electrocatalyst using transition metals. The basic compound used for this work was a cobalt-based... 

In recent years, providing clean water and addressing pollution caused by toxic organic compounds—especially phenolic compounds—have become major global challenges. Among these hazardous pollutants, 4-nitrophenol (4-NP) is of particular concern due to its high toxicity and carcinogenic potential, making it a priority for removal from water sources. In this study, two types of nanocomposites photocatalysts, including titanium dioxide nanotubes (TNT) and titanium dioxide nanodandelions (TND) doped with 5 wt% bismuth vanadate (BiVO4), were synthesized and applied for the photocatalytic degradation of 4-NP under visible light irradiation. To identify the structural and surface characteristics of... 

The quest for sustainable energy solutions has positioned hydrogen as a pivotal alternative fuel due to its clean emission profile, producing only water vapor and heat. However, efficient hydrogen storage remains a formidable challenge due to its low energy density at standard conditions. Metal-Organic Frameworks (MOFs) offer a promising solution due to their high surface area, tunable pore structures, and reversible adsorption properties. This study leverages computational screening and machine learning (ML) methodologies to identify high-capacity MOFs for hydrogen storage. We utilized a large dataset of known and hypothetical MOFs from comprehensive databases and employed advanced neural... 

Ti-UIO-66(Zr) nanocomposites have been prepared via a modified one-step solvothermal methodology and evaluated in photocatalytic oxidative desulfurization. Extensive characterization by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption-desorption, and thermogravimetric analysis (TGA), have revealed the role of Ti loading, on Ti speciation and the structure of the composite materials. Their performance have been... 

The global energy outlook has been altered as a result of mounting concerns regarding fossil fuels. Electrocatalysts have become a favorable alternative for renewable energy production processes, particularly in the fields of hydrogen evolution reactions (HER) and oxygen evolution (OER). This study focuses on the production and enhancement of nanocatalysts, specifically materials based on ZIF-67, for the purpose of water splitting. The initial phase included the synthesis of the ZIF-67 structure through the simple room-temperature coprecipitation process, utilizing cerium as a dual-metal component. The molarity of the cerium was optimized in the ZIF-67 framework to achieve the most desirable... 

Increasing demand for finding eco-friendly and everlasting energy sources is now totally depending on fuel cell technology. Though it is an eco-friendly way of producing energy for the urgent requirements, it needs to be improved to make it cheaper and more eco-friendly. Although there are several types of fuel cells, the hydrogen (H2) and oxygen (O2) fuel cell is the one with zero carbon emission and water as the only byproduct. Achievement to affordable and efficient energy sources is possible by design and construction of suitable nanocatalysts. In this regard, a metal-organic framework containing cobalt, nickel, copper, and 5,3,1-benzenetricarboxylic acid was synthesized through... 

Today, due to the decreasing of fossil fuel reserves and the need to use clean fuels, hydrogen is a suitable alternative, and hydrogen production has received considerable attention. One of the best methods of hydrogen production is water splitting. Overall water splitting can be divided into two half reactions including the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which selecting the appropriate electrocatalyst for these half reactions plays an important role. The four-electron transfer process in OER leads to slow kinetics of the reaction and a large overpotential. The noble metal-based oxides, including IrO2 and RuO2, are known as outstanding OER... 

In this advanced research, titanium dioxide nanotubes were initially synthesized using the hydrothermal method. Subsequently, they were coated with polyaniline, polyindole, or a combination of both polymers using oxidative polymerization. The application of these composites for the removal of the organic pollutant 4-nitrophenol in wastewater was investigated under visible light irradiation from a 250-watt sodium lamp and in the presence of hydrogen peroxide as an oxidizing agent. To characterize the synthesized photocatalysts, various tests were conducted, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS),... 

High-capacity electrode materials are crucial for enhancing the performance of supercapacitors. Transition metal sulfides are considered promising materials for supercapacitor applications due to their high theoretical capacity and good electrical conductivity. Additionally, cerium oxide improves the performance of supercapacitors due to stable reversible oxidation states and greatly supported the faradaic redox reaction. In this study, ceria nanosheets incorporated with MCoS (M=Mn, Zn, Cu) were synthesized successfully through a facile hydrothermal method by sulfidation of MCo LDH/CeO2. The structural and morphological characteristics were analyzed using X-ray diffraction, scanning electron...