Sharif Digital Repository

Volatile Organic Compounds (VOCs) have become an important source of air pollution due to their extended use as solvents in many industrial processes. Aliphatic and aromatic VOC removal from contaminated air can be achieved by a variety of methods including catalytic oxidation, adsorption, and biological treatment. Catalytic oxidation is often the preferred process due to its low cost and high efficiency. Supported transition metal catalysts are effective and inexpensive catalysts for VOC removal from contaminated air. The objective of this project was to prepare low cost transition metal catalysts (Fe, Ni, Co, and Cu) supported on alumina for catalytic oxidation of cyclohexane (as a... 

Because of the importance of purification units at the refineries, in this research the process of sulfur removing compounds from light naphtha product with 1 ppm concentration by adsorption method in a fixed bed tower was simulated by COMSOL Multiphysics software. In this work, simulation was done using two macro and micro perspectives. In the Macro-scale mass transfer takes place between the spherical particles of catalyst and in the micro-scale mass transfer takes place within the spherical particles and these two scales were coupled together by reaction rate variable. In Macro-scale one-dimensional and two-dimensional geometry were considered for model. Naturally, the result of the... 

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  

Octahedral crystals of Fe-Metal-organic frameworks like Fe-MIL-101, which is the most stable and active metal-organic frameworks; in combination with graphitic carbon nitride nanosheets could significantly enhance the photocatalytic activity of g-C3N4 for inorganic dye degradation under the irradiation of visible light application. This appropriate cocatalyst modifies the performance of semiconductor via suppressing the recombination of photo-induced carriers and since the synthesized composite prepared by in-situ procedure possesses close contact between each other, the migration of electrons in the photocatalytic reaction will be continued, so the degradation process via the active species... 

One of the most important world issues is environmental constraints regarding the pollutants released by transportation fuels and refinery products, sulfur reduction being one of the most significant objectives. Deep hydrodesulfurization processes result in great sulfur reduction in refinery streams. However, such harsh process conditions increase undesired side reactions and facilitate coke formation as well as affecting the surfaces. More effective alternatives for hard process conditions are highly active and selective hydrodesulfurization catalysts, which enable the process to be performed at milder pressure and reaction conditions. Catalyst bases play a very important role in hydrogen... 

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... 

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...