Sharif Digital Repository

Nowadays, due to depletion of fossil fuels and the emission of green house gases, biodiesel has attracted lots of attention as a renewable, non-toxic, and biodegradable fuel. Biodiesel can be produced from different resources such as vegetable oil, animal fat and algae oil. In this study, waste frying oil was used as a raw material that can reduce the probable hazardous effects of its disposal and produce a clean fuel at the same. Biofuel was produced through an enzymatic method using the whole cell of Rizopu oryzae (a filamentous fungus) in both immobilized and free forms. In order to find the optimum conditions for biodiesel production, four variables including temperature, methanol to oil... 

Superparamagnetic core/shell nonporous (S1) and core/shell/shell mesoporous (S2 and S3) nanocomposite magnetite/silica particles with a magnetite cluster core of 130±30 nm, a nonporous silica shell of 90±10 nm thickness, and a mesoporous silica shell of 70±15 nm thickness were prepared thorough a simple method. Mesoporous particles were prepared with two BJH pore sizes (2.44 for S2 and 3.76 nm for S3 particles, respectively). The fabricated S1, S2 and S3 particles present high saturation magnetization values of 20, 13 and 17 emu/g, respectively. As a biological application, the lipase from Pseudomonas cepacia was successfully immobilized onto the amino-functionalized nanocomposite particles... 

Biodiesel as an alternative fuel for fossil diesel has many benefits such as reducing regulated air pollutants emissions, reducing greenhouse gases emissions, being renewable, biodegradable and non-toxic. In this study, used frying oil was used as a low cost feedstock for biodiesel production by sodium silicate as an alkaline catalyst in transesterification reaction in order to optimize the conditions of biodiesel production. The factors studied were: reaction temperature, molar ratio of methanol to oil, catalyst amount and catalyst recovering. The optimum conditions of reaction obtained as follows: methanol to oil molar ratio of 7:1(mol⁄mol), catalyst amount of 3% w/w and reaction... 

In this work the transesterification reaction of waste cooking oil in the present of solid catalyst as a type of solid-liquid catalytic reaction, has been studied. For this purpose, two types of alkali solid catalysts were synthesized. CaO-ZrO2 and KOH/γ-Al2O3 catalysts were prepared by co-precipitation and impregnation method, respectively. These catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), BET surface area, and temperature programmed desorption of CO2 (TPD-CO2). The obtained results for the CaO-ZrO2 catalysts indicate that with increasing Ca/Zr atomic ratio, the activity of catalysts increases, but the stability... 

Biodiesel as an alternative fuel for fossil diesel has many benefits such as reducing regulated air pollutants emissions, reducing greenhouse gases emissions, being renewable, biodegradable and non-toxic. In this study, used frying oil was used as a low cost feedstock for biodiesel production by alkali-catalyzed transesterification. The used frying oil was originally a mixture of various oils obtained from vegetables that are native to Iran. The design of experiments was performed using a 5-level-5-factor central composite design coupled with response surface methodology in order to study the effect of factors on the yield of biodiesel and optimizing the reaction conditions. The factors... 

The enzymatic transesterification of castor oil with methanol in a solvent free media is carried out using lipase catalyst. The influence of several operation conditions on the production of biodiesel was analyzed i.e. the amount of enzyme, molar ratio of methanol to castor oil, reaction temperature and reaction time. It is observed that with increase in molar ratio, reaction time and enzyme amount, the amount of product (biodiesel) increased. When reaction temperature increased, the amount of biodiesel increased firstly and then decreased. The optimum conditions for the reaction were as follows: enzyme amount 300 mg, molar ratio of methanol to oil 9:1 and temperature 55°C. The maximum... 

Thermodynamic quantities such as proton affinity (PA) and molecular basicity (GB) for (CaO)n nanoclusters with n=2–16 have been calculated using three computational models of the DFT (B3LYP, M06, PW91, CAM–B3LYP and ωB97XD functionals), MP2, and HF with the cc-PVNZ (n = D and T) basis set in the gas phase. Absolute deviation error (AAD%) indicates that obtained PA and GB values using DFT model and the B3LYP method with mean percentage errors of 0.77 and 0.90 %, respectively, have the higher accuracy than the other methods and models. Owing to the unique physical and chemical properties of ILs, can be used as catalysts, promoters and modifiers of catalyst in many organic reactions. Therefore,... 

The current study deals with application of a surfactant-like Brønsted acidic ionic liquid (IL) 1-dodecyl-3-methylimidazolium hydrogensulfate (catalys 1) for Mannich reaction at room temperature. The reaction has been efficiently proceeds in water as solvent without using any harmful and expensive organic additives. Our observation has been shown that the reaction is selective for cyclohexanone and no product was observed by using cyclopentanone at room temperature. Density functional theory (DFT) calculations were performed to provide evidence about the nature of reactivity of the cyclohexanone/cyclopentanone. The activity of the catalyst 2 (1-dodecyl-2,3-dimethylimidazolium... 

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....