Sharif Digital Repository

Today, the global environmental restrictions as well as; energy problems have directed researchers toward developing ideas of producing a clean liquid fuel from coal or natural gas as a major research topic. In this regard, a special attention is paid to the dimethyl ether (DME) as a clean material containing 34.8% oxygen possessing enough positive potential to replace the diesel and LPG fuels. One of the most economic routes for producing the DME is known to be the direct conversion of the synthesis gases and carbon dioxide first to the methanol and then its dehydration to the DME. Moreover, the DME is not limited to a particular country or resource area since small reservoirs of natural... 

Dwindling fossil fuel reserves with attendant rising crude oil price and the relatively rapid growth in global population have made the search for sustainable energy supply more imperative. Among the various renewable resources, biomass has attract much more attention. Glycerol as the major by-product of the biodiesel production process, can be converted to hydrogen. One of the methods for converting glycerol to hydrogen is aqueous phase reforming (APR). In the current research, glycerol aqueous phase reforming is modeled and then simulated with MATLAB software. The reactor diameter is 5 mm and its length is 20 cm and reactor operated at 250℃ and 50 bar. Glycerol conversion obtained is... 

Artemisinin as a natural peroxide possess a high anti parasite, and antivirus (Covid-19) properties which could be synthesized through the photooxygenation of dihydroartemisinic acid. This production possesses a lot of difficulties, for example, homogeneous catalyst is used for the photooxygenation reaction which makes photocatalyst and solvent non-reusable. In addition, separation of products from solvent and photocatalysts is difficult. Photooxygenation needs high pressure and low temperature which is very costly. Besides, because of several by-products which are producing during photooxygenation and protonation reactions, Artemisinin yield decreases. The aim of this study is to optimize... 

In order to fabricate batch and continuous systems to synthesize Pirfenidone (PFD), Solidwork and COMSOL software were used. Effects of parameters on reaction yield including; microreactors, micromixer, solvents, temperature, reaction time, and catalysts were understudied. Moreover, FTIR, NMR and HPLC analyses used to evaluate the prepared PFD. Its yield in microfluidic (30.5 %) was higher than that of batch (17.1 %) reactor. Besides, reaction yield in the presence of DMSO was higher than DMF in both reactors. It was shown that, adding a micromixer enhanced reaction time. leading to a higher PFD yield. Nonetheless, the yield was reduced by enhancing the temperature when DMF was utilized.... 

Samples of the V2O5 catalysts supported on nanostructures of TiO2 and γ-Al2O3 were synthesized via hydrothermal method for the oxidative dehydrogenation of propane (ODHP) to propylene. The TiO2 support was utilized in both commercial microstructures and prepared nanostructures from their corresponding salts. Furthermore,the γ-Al2O3 was also prepared from two novel methods. Moreover, the vanadium catalysts supported on hybrid TiO2 and γ-Al2O3 were prepared. The performances of the prepared catalysts were subsequently examined in a fixed-bed reactor. The main products were propylene, ethylene and COx.The vanadium catalyst over TiO2 and γ-Al2O3 had the best performance under the reactor test... 

Nowadays, with respect to environmental pollution and energy supply, producing gasoline from methanol or syngas is one of the most interesting research subjects. Gasoline production from methanol is a catalytic process that produces high-quality gasoline with minimum unwanted compounds. So this gasoline is a clean fuel and it can be replaced to petroleum gasoline. Because of that, it can be a valuable process in the petrochemical industry. One of the most important aspects of this process is catalyst deactivation with respect to time on stream. Catalyst deactivation is usually caused by poisoning, sintering, blocking pores, and coking. In this research, material and energy balance equations... 

High demand and price and restricted availability of Platinum Group Metals (PGMs) have made platinum recovery a major field of study for researchers and industries. Various methods have been introduced for this purpose. Ion exchange, leaching and liquid-liquid extraction (LLE) are just a few examples. Nowadays Solvent Extraction (SX) is one of the most challenging areas of study for platinum recovery from spent catalysts due to its simplicity and optimum cost. In this study, the commercial spent catalyst’s platinum was dissolved in aqua-regia after XRF analysis. Then it was extracted by the organic material Trioctylphosphineoxide diluted in toluene in the presence of Alkaline metal salts.... 

Liquide phase catalytic exchange (LPCE) between liquid water and hydrogen is an important reaction for separation of the hydrogen isotope from liquid water. One of the application of this reaction is heavy water production. This method is mainly used hydrophobic catalysts with Pt active metal. The use of hydrophobic catalyst is necessary, because liquid water in the LPCE reaction, resulted in block the catalyst pores and loss of catalyst activity. Design of experiment has been done by using of Design Expert 7.0.0 for determination of number of tests and optimization of Pt weight percent. Alumina and carbon (included graphene, single-walled and multi-walled carbon nanotube) supported 5% wt Pt... 

Biodiesel has drawn the attention of many researches to itself as a replacing source for crude oil, recently. Transesterification is one of the most popular methods used for biodiesel production. Enzyme transesterification is a more simple method in comparison with acidic or basic transesterification. However, the high price and low yield of enzyme transesterification has caused many obstacles in its application. Enzyme engineering has gained much attention as a way to improve enzyme performance. In this thesis, biodiesel production by a native enzyme named Bacillus thermocatenulatus, and two engineered-enzymes is studied. First, effective parameters and variables in biodiesel production by... 

Sulfur compounds are largely an impurity in fossil fuels such as natural gas, crude oil and coal. In natural gas, the main sulfur compounds are hydrogen sulfide (H2S), carbonyl sulfide (COS),and C1-C3 mercaptans.Commercial methods for removing these compounds require the introduction of additional reactive substances (O2, H2, Olefins, NaOH, etc.), which often results in the production of other pollutants. Microfluid is a branch of science and technology that involves studying the behavior of fluid, the use of fluid and the manufacture of equipment or systems that are carried out in micro-channels.The dimensions of these canals are about ten to several hundred micrometers, and high of... 

In this study, the viability of handling flue gas streams as a source of CO2 for the thermocatalytic conversion was investigated as a CO2 emissions reduction strategy and an intermittent energy storage solution. A transient mathematical model for dynamic catalyst deactivation was validated with experimental results and then used to study HEX membrane reactor. A simulation-based study of novel Sabatier reactor configurations was performed to study the effect of distributed H2 supply on Ni-based catalyst deactivation and to optimize the production of CH4. First, a heat-exchanger type, actively cooled Sabatier reactor is analyzed using a transient mathematical model to assess its feasibility.... 

Nanoporous metal-organic frameworks are among the new and advanced compounds that have attracted attention of researchers due to their unique properties such as high surface area, high porosity and regular structure. These compounds can catalyze and degrade pollutants. Due to the high consumption of organic compounds, especially textile dyes, the pollution caused by wastewater is increasing in various industries. Disposal of wastewater containing organic pollutants into aquatic environments can alter the natural color, change the taste of water and disturb the life of living organisms. If the dyes are left untreated in aquatic ecosystems, they can remain in the environment for a very long... 

Microfluidic devices carry fluids in channels with the diameter in the scale of micrometers. Low consumption of raw materials, higher selectivity, enhancement of heat and mass transfer, and improved safety considerations are benefits of the application of microfluidic devices. In this venue, catalytic microreactors get high potential in the filed of the catalytic reaction. In recent years due to strict international environmental regulations, the sulfur content in fossil fuels should be at the minimum content. MEROX process is to most common route to remove mercaptan from the LPG dreams in the material gas refineries. However, in this process, the production of DiSulfid Oil (DSO) is a... 

Catalytic cracking of iso and normal butane over HZSM-5 at several temperatures and a variety of contact time and different partial pressures of hydrocarbon feed was conducted. Experiments indicate that the operating conditions have considerable effects on final product distribution and feed conversion. Results show that high temperatures, low contact time and partial pressure of paraffin feed favor the light olefin production, particularly propylene production. Results obtained for iso-butane show a similar conversion values in comparison to n-butane but a higher olefin and propylene selectivity. Finally kinetic modeling of both iso and normal butane cracking was performed based on a lump... 

In the present work, wet air oxidation of phenol over 7/3 MnO2/CeO2 composite oxide catalyst in trickle-bed and packed-bubble column reactors was modeled. Complexity of wet air oxidation reactions and catalyst poisoning with carbonaceous groups, on the surface and in the pores of catalyst, make the modeling process complicated. Plurality of mass balance equations which are confirmed in the catalyst pellet and in dynamic and static bed phase, also the equation of catalyst deactivation, lead us solve them simultaneously. In addition, the equations are two dimension and unsteady state and carbon of oxidation intermediates are present which make the modeling process more complicated. We are... 

Highly active unsupported MoO3 and (Co) MoO3 catalysts were synthesized utilizing the solution combustion method where the Ammonium molybdate powder and an organic additive were used as precursors. Different organic materials including Ethylene Diamin Tetra-acetic acid (EDTA), Polyethylene Glycol 200 (PEG 200), Sorbitol and Urea were used as additive in order to investigate the effect of additive structure on morphology and particle size of products. Also various reaction parameters such as the additive/Mo molar ratio, concentration of metal ion in solution, pH of the reaction and temperature of the synthesis media were changed to study effects on product morphology and size. Outcomes were... 

In this project, a model which had been suggested for a lithium battery is used with the assumption of using C.N.T instead of activated carbon for the cathode. This battery include lithium foil, C.N.T and solution as anode, cathode and electrolyte. The electrolyte solution consist of lithium salt and a separator. The mathematical solving of the model consisted of using two CPM and DFM methods. In DFM method, a concentration gradient was considered as the driving force for diffusion and in the CPM method chemical potential as the driving force. Furthermore CPM method considered energy interaction between ions. Changing physical parameters of cathode and modification of model parameters... 

In this study the feasibility of xenon separation from xenon-krypton mixture was investigated by utilizing of the chromatographic column filled with nano and micron sized NaY zeolite. For this purpose the nano NaY with the yield of 100% related to Al2O3 and the average size of 98.6 nm was synthesized through the clear solution method with the mid-adding of NaOH. Furthermore, a novel method for granulation of nano zeolite was developed by utilizing sodium alginate as an external template. In this method the production of uniform spherical granules with the different sizes in the range of several milimiteres to 100 µm was easily performed. Moreover, the results showed that the adding of... 

In this study, both axial dispersion and perfect mix mathematical model to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether (DME) from syngas and CO2 is developed. This large-scale reactor is modeled by using mass and energy balances, catalyst sedimentation and single-bubble as well as; two-bubbles’ class flow hydrodynamics. A comparison between the two hydrodynamic models with pilot plant experimental data from the literature showed that heterogeneous two-bubbles flow model is in better agreement with the experimental data than homogeneous single-bubbles gas flow model. Also, by investigating the heterogeneous gas flow and axial dispersion model for... 

Existing processes to improve the quality of heavy oil cuts catalytic converter hydroconversion can be mentioned in the slurry phase. This process is usually done in the temperature 440˚C to 470˚C be a heavy craking led to the production of light weight thermal feed can be more. With more products light, adverse reaction can also lead to the formation of coke be. Coke formation of secondary radical reactions can be feed from cracking of heavy compounds. Coke production is to eliminate or limit the ability of homogeneous catalysts (eg sulfide Molybdium) about 600-1000 ppm disposable food adds to be used. The main role of catalyst in the stable radicals fail thermal compound feed is heavy. The...