Sharif Digital Repository

Biodiesel can be a good alternative for fossil diesel since it isrenewable, biodegradable and non-toxic. Also, in comparison with fossil fuels, it emits less air pollutants and greenhouse gases.Findacost effective and environmentally friendly wayforcontinuousproductionofbiodieselcanaddressmany of our environmental concerns. In this study, we applied heterogeneous alkali-catalyzed transesterification as method and used waste frying oil as a low cost feedstock for biodiesel production. The project was performed in two phases. First, experiments were conducted in astirred reactor to finda suitable catalyst which was strontium carbonate calcinated for 3:24 hours in 975̊C.
RPB(rotating... 

The purpose of this project is the prediction of the activation barriers and enthalpy for elementary steps in the process of Fischer-Tropsch over the surfaces of Fe, Cu and Fe/Cu alloys catalyst by using of UBI-QEP method aiming at finding prediction of the activity and selectivity on the basis of energy criteria.
UBI-QEP methods is based on conservation of bond index of adsorbed molecules and follow the quadratic exponential potential for energy, calculate the enthalpy and activation barriers of reaction pathways in a heterogeneous catalytic process and select the most desirable path to take.
The elementary steps such as dissociation of CO, hydrogenation of carbidic carbon, C-C... 

The aim of this project is to investigate the mechanisms of absorption and reactions of H2, O2, HCO2H on the single crystal surfaces of transition metals alloys such as Ni-Cu and Ni-Fe and …as well as the ability to control the properties of the mentioned alloys with change in constitutions percentage. In order to achieve the objectives, Unity Bond Index-Quadratic Exponential Potential, UBI-QEP method have been employed. Using this method, the thermodynamic parameters (heat of adsorption and reaction enthalpy changes) and kinetic parameters (activation energy of the reaction) can be calculated, and using these results, intermediate, and as a result, the mechanism of heterogeneous catalytic... 

In this thesis, heterogenous catalysts based on magnetic nanoparticles were synthesized. In these catalysts, magnetic nanoparticles were coated with defferent fuctional groups to produce a catalyst with magnetic properties which is easily separated from the reaction medium. The structure of synthesized catalyst was characterized using techniques such as transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and CHNS elemental analysis. Easy preparation, low cost, biodegradability and high thermal stability are advantages of these catalysts. At the end, the catalytic properties of resulted catalysts were investigated in many... 

In this study, polyoxometalate (POM) intercalated in the layered double hydroxide (LDH) was synthesized by a selective ion-exchange method. For this purpose, the nanocluster [VW12O40]3- was immobilized on the Mg2+/A13+/Cl–LDH support. The heterogeneous catalyst was characterized by FT-IR, XRD, SEM and analysis of ICP. The LDH-POM was applied as a catalyst in efficient oxidation of sulfides to sulfoxides using UHP as oxidant and CH3OH/ CH¬2¬Cl¬2 ¬as a solvent at room temperature, as well as epoxidation of olefins using TBHP as an oxidants and C¬2H4Cl2 as a solvent in 84°C. This catalyst showed excellent catalytic activities for a substrate/catalyst ratio (200:1). For example, this catalytic... 

Recently, biopolymers such as alginate, cellulose, chitosan, gelatine, starch and wool have been used as supports for catalytic applications. Several interesting features of the biopolymers for example, bio-degradable, environmentally safe, high sorption capacity, physical and chemical versatility make them attractive to use as supports. This study, the four functionalized biopolymer-based composites were designed and synthesized as well as heterogeneous catalysts used in the synthesis of 1,2,3-triazoles, oxidation of alcohol, reduction of nitroarenes and carbon-carbon coupling reactions.A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported... 

TiO2/SiO2/HPAsnanocompositeswas prepared by the sol-gel technique at room tempareture and used as the heterogeneous catalysts for the acylation of alcohols employing acetic anhydrid under solvent-free conditions at room tempareture. It was found that the catalytic activity of TiO2/SiO2/HPAs, in all cases of HPAs, was much higher than that of TiO2/SiO2. The most catalytic activity was obtained by TiO2/SiO2/H14NaP5W30O110 which completed the acylation reaction of benzyl alcohol at 1h. Examining the various concentrations of H14NaP5W30O110 in the composite, 9% w/w concentration of TiO2/SiO2/HPAs showed maximum catalytic activity, and by increasing the HPA concentration, activity remains... 

Reduced supplies of fossil fuels worldwide attention to the economic and energy-efficient processes for the production of fuel from renewable sources is diverted.Biomass has the potential shown because it has features such as frequency and is renewable. Because of the high solubility of hydrocarbons derived from biomass in large amounts of water and oxygen, the process is then performed on the aqueous phase is considered. Recent research for the production of alkanes by the deformation of the aqueous phase (Aqueous Phase Reforming) by Catalyst on hydrocarbons derived from biomass, such as glycerol, ethylene glycol, sorbitol, glucose, and etc. has been done. Here is our attempt to use the APR... 

In the contest of conversion of water to hydrogen and oxygen there is a need for catalysts which will effectively support the oxidation of water. In nature, photosystem II relies on manganese for the oxidation of water. The water oxidizing complex (WOC) contains a cluster of four manganese atoms. In the past few years, there has been a tremendous surge in research on the synthesis of various manganese compounds aimed at simulating WOC of PS II. In this project, several manganese oxides as heterogeneous catalysts in water oxidation have been synthesized and characterized by FT-IR, X-ray diffraction, TGA, XPS, SEM and BET. Some of these oxides are able to oxidize water in the presence of... 

Two new copper(II) complexes, [CuL2] and [Cu(phox)2], were synthesized by reaction of 1-((4-bromophenylimino)methyl)naphthalen-2-ol, HL, and 2-(2′-hydroxyphenyl)-2-oxazoline, Hphox, as ligands and copper(II) acetate mono-hydrate with the ratio 2:1 (ligand:metal), respectively. For characterization and structure determination of synthesized complexes, different techniques were performed such as FT-IR, elemental analyses (CHN), and X-ray crystallography. The geometry around Cu atom is almost square planar in both complexes. The catalytic activity of the complexes was evaluated in azide–alkyne cycloaddition reaction in water without need of any additional agent. The reaction conditions for the... 

Water-gas shift reaction (CO(g) + H2O(g) ↔ CO2(g) + H2(g)) is performed as the key step in the hydrogen and ammonia industrial plant. In this work, Fe/Cr/Cu high temperature water gas shift catalysts were synthesized by coprecipitation method, using sulfate precursors, in order to improve the catalytic performance and particular emphasis is placed on the catalytic activity affected by aging time, precipitating agent and ways of increasing the mechanical strength. Finally the prepared and industrial catalysts were compared when they were situated in the operating conditions (at 360oC and 2 bar) and were characterized by BET, XRD, TPR, TEM and crushing strength analysis. Catalysts being made... 

Epoxidation of alkenes by Mn(III)meso-tetra(4-sulfonatophenyl)porphyrin chloride (MnTPPS4Cl) in the various homogeneous and heterogeneous catalytic systems was investigated. In the case of homogeneous catalysis, epoxidation of cyclooctene in CH2Cl2/MeOH mixture using urea hydrogen peroxide (UHP) as an oxidant and imidazole as a co-catalyst results in the formation of cycloocetene oxide in 87% yield. Using this catalytic system various alkenes successfully oxidized to their corresponding epoxide in high conversions and selectivity. Cyclic alkenes oxidized more easily than linear alkenes. In addition, epoxidation of alkenes was investigated in the heterogeneous catalytic systems. For this... 

In this research, synthesis of new heterogeneous catalysts has been studied. These catalysts were prepared in three different areas of the synthesis of coordination polymers and metal-organic frameworks, supported palladium nanoparticles on these polymers, and production of metal oxide nanoparticles. At first, metal organic frameworks of cobalt and manganese transition metals were synthesized through hydrothermal method. In order to prepare these frameworks, 1,4-benzenedicarboxylic acid (terephthalic acid) and 2-amino-1,4-benzenedicarboxylic acid ligands were utilized as spacer ligands. X-ray analysis indicated that the structure of polymers is composed of secondary building units (SBUs) of... 

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... 

We have reported a new and efficient synthesis of tetrahydrothiopyrano [2,3-b]indole skeletons via unique tandem reaction of indoline-2-thiones to Baylis-Hillman adduct acetates. This protocol is a very mild and simple method for construction heterocycles in a one-step process. This is a convenient and diastereoselective synthesis of methyl 4-aryl-2,3,4,9-tetrahydrothiopyrano[2,3-b]indole-3-carboxylate systems in the presence of K2CO3 in acetonitrile. The major benefits of the current study are the one-pot procedure, high yields and diastereoselectivity, short reaction times and the similarity of the products to the biologically active moieties.
In addition 1, 4-diazabicyclo [2.2.2]... 

This study aims at synthesizing and investigating of heterogeneous catalysts for biodiesel production as an alternative to fossil fuel with a transesterification reaction of sunflower oil and methanol. Three main sections of this thesis concern the synthesis of clay base catalyst, characterization analysis, and investigation of the transesterification reaction under different conditions. Talc clay base catalyst impregnated with a 40 wt.% of K2CO3 as active and stable catalysts to study the transesterification reaction of sunflower oil and methanol for biodiesel production. Synthesized catalysts have been characterized by power X-ray diffraction (XRD), scanning electron microscopy (SEM),... 

In this study polyoxotungstate-based inorganic-organic hybrid [C272H162N80Cu16.5W36O129Na9] .80.5H2O was synthesized in situ. This inorganic-organic hybrid resulted from the reaction between copper salt and sodium tungstate with the benzimidazole ligand. Combining inorganic-organic hybrid with polyoxotungstate improved the ability of this catalytic system in oxidation and cycloaddition reactions. The resulting product was identified by IR, X-ray diffraction (XRD), elemental analysis (CHNS), inductively coupled plasma (ICP-OES), field emission scanning electron microscope (FE-SEM) and EDX were technique. The catalyst was used in optimal conditions in sulfide oxidation and azide-alkyne... 

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... 

Nowadays, the use of microreactors is receiving a great deal of attention due to the unique characteristics of such systems, such as high surface-to-volume ratio, low material loss, greater safety, and minimizing mass and heat transfer limitations. In this study, the optimization of the continuous-flow synthesis of Plavix by Cu-MOF heterogeneous catalyst utilizing a glass microreactor was investigated. Structural characteristics of the catalyst were investigated using X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and BET surface area studies to describe the structure and morphology of the catalyst. In order to build... 

Bread scraps with transition metals oxides spinels have been utilized to synthesize¬ magnetic nanocatalyst. The heterogeneous catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The reaction was performed for tandem Knoevenagel-Micheal reaction in the presence of synthesized nanocatalyst as a heterogeneous, environmentally benign, cost-effective catalyst with high catalytic activity using EtOH as a green solvent. The magnetic nanocatalyst was applied to synthesize tetraketones and pyranopyrazoles...