Sharif Digital Repository

The purpose of this study is to evaluate an anaerobic system (ABR) cultured by chemoautotrophic bacteria for biodesulfurization of natural gas. In this study anaerobic baffled reactor with five compartments and active volume of 10 l was used. For increasing solid retention time, reactor was packed by pumice with 0.5-2 cm diameter which active volume decreased to 9 l. Inoculation was performed by activated sludge from municipal sewage treatment, which was kept in anaerobic condition for 1 year. The synthetic wastewater which contains S2O32- ion was used in start-up and S -2 for running of ABR. Performance of the reactor was evaluated at three equivalent hydraulic retention times (HRT) of 50,... 

In this study, organic contaminant degradation was intensified by increasing the oxidative capacity of the reaction system through simultaneous photocatalysis and heterogeneous persulfate activation. Fe nanoparticles were served as a multifunctional modifier to enhance the photoactivity of graphitic carbon nitride (CN), by tuning optical properties as well as persulfate (PS) activation rate, by introducing a new activation pathway. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-visible... 

In order to decrease CO 2 emission into the atmosphere and develop renewable energy sources for carbon capture, an integrated system is considered for co-production of electricity and methanol. In this research, methanol synthesis unit through captured CO 2 from fossil fuel power plant and produced H 2 from water electrolysis unit by wind renewable energy is developed. An oxy-fuel combustion carbon capture method is considered in large scale Matiant power plant based on utilization of oxygen from water electrolysis unit. Technical and economical analysis of the proposed system shows that when the price of natural gas is 7.8US$/GJ, the total CO 2 avoided cost is 93US$/(tonne of CO 2) and... 

Since the beginning of industrial age the atmospheric concentration of greenhouse gases has been increased significantly due to excessive use of fossil fuels. An effective way for decreasing emission of greenhouse gases is injection of CO2 in geological formations. Moreover, from the reservoir engineering point of view, CO2 injection has been considered as a method of enhancing oil and gas recovery. While using CO2 for enhanced oil recovery (EOR) has been the subject of several studies in the past decades, enhanced gas recovery (EGR) has not been fully studied in the gas reservoirs, mainly because of high recovery factor of gas reservoirs and mixing of the reservoir gas and CO2. In this... 

MFI zeolite membranes were prepared on porous α-alumina substrates, using secondary growth of nano-seeded layers. The resulting membranes were characterized by means of Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), and pervaporation performance tests for separation of Benzene, Toluene and Xylene (BTX) mixture from contaminated water. The morphology, thickness, homogeneity, crystal preferential orientation and permeation properties of these membranes have been studied in relation to the seed layers. Successful separation of BTX mixture from water was performed by using the manufactured MFI zeolite membrane. The influence of temperature, feed concentration on the membrane... 

A mathematical model has been developed that is based the dual sorption in the dense layer and pore flow in the porous layer. In the porous layer a resistance model is applied where four mechanisms, i.e., Knudsen, Viscous, Slip, and Surface flows, are superimposed. Steady-state, constant pressure along the membrane and constant physical properties are assumed. Its application to the separation of H 2S/CH 4 gas mixtures as a sour gas in natural gas sweetening by using a PPO hollow fiber module is put forward. The Quasi Newton method is used to determine the parameters of membrane transport model for the case of H 2S/CH 4 separation. The H 2S and CH 4 permeances increased by increasing the... 

Natural gas contains several impurities, e.g., CO 2 and H 2S, which have undesirable effects on the performance of the glassy polymeric membranes. The plasticization effect of H 2S at high concentrations on the gas separation performance of polyphenylene oxide hollow fiber membrane has been studied at different compositions of H 2S and feed pressures. The existence of high concentrations of H 2S in CH 4 feed mixture, which is present in many natural gas sources in Iran, enhances plasticization. For a H 2S/CH 4 mixture containing 5008 ppm H 2S at ≈ 75 psig, the H 2S permeance reduces by > 45% from its initial value. H 2S acts as a plasticizer in H 2S/CH 4 membrane separation at elevated... 

One of the most effective measures for building energy conservation is the implementation of energy codes. The building energy codes introduction in Iran started two decades after the first oil crisis in the early 1970s by establishing the building energy conservation regulation called Issue 19. Nowadays, due to some financial and executive barriers, the implementation of Issue 19 is faced with some difficulties. The most critical obstacle is the low price of energy carriers, which lead to high subsidies of energy and the reluctance of the building owners to implement the regulation. The main goal of this paper is the introduction of an innovative financial and executive mechanism for... 

A series of bifunctional catalysts, including Cu-ZnO-ZrO 2 and H-Y zeolite catalysts, were prepared and tested for conversion of maleic anhydride (MA) to tetrahydrofuran (THF). Cu-ZnO-ZrO 2 catalyst was used as the hydrogenating component and H-Y zeolite as the dehydrating component. The appropriate ratio of Cu/ZnO in the hydrogenation catalyst was 50:45, for which the conversion of MA and selectivity of THF reached 100 and 46%, respectively, at 50 bar and 493 K. The bifunctional catalyst of Cu-ZnOZrO 2/H-Y can produce THF from MA with high activity, selectivity, and stability. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering... 

The liquid-phase dehydration of 1,4-butanediol to tetrahydrofuran was investigated over various materials including synthetic zeolites, namely, ZSM-5, Y, Mordenite, Ferrierite, and Beta as well as silica and alumina. The key characters investigated were the Si/Al ratio and cation exchange. The results showed that the ZSM-5 zeolite exchanged with NH4+ exhibited the highest activity in dehydration of 1,4-butanediol. In all tests, nearly 100% selectivity to tetrahydrofuran was observed. After finding the most active catalyst, the kinetics of dehydration of 1,4-butanediol to tetrahydrofuran was studied over this material. The influence of operating parameters such as temperature, pressure, and... 

In the present work, Tetrahydrofuran was produced from 1,4-butanediol by catalytically dehydration of 1,4-butanediol in contact with a catalyst. Material used as catalyst were Synthesized and natural zeolites as well as alumina and silica. Synthesized zeolites were investigated in different aspect such as pore size, cation and Si/Al ratio. Results indicated that with increasing the Si/Al ratio, the activity of the zeolite used for 1, 4-butanediol dehydration step was reduced. Furthermore, it was observed that, upon the replacement of sodium with hydrogen and ammonium cations, the conversion of the 1, 4-butanediol into tetrahydrofuran was increased. It was shown zeolites possessing smaller... 

The prospects of the Clean Development Mechanism (CDM) and for carbon income, up to and beyond 2012, in the industrial sectors of Iran and five other Asian countries are investigated. The attractiveness and suitability of each host country, the status of their industrial sectors (based on four post-2012 scenarios), and the post-2012 potential of the CDM (or similar carbon projects) in these sectors are all examined. A multi-criteria analysis of Iran, Saudi Arabia, the UAE, Qatar, China, and India, based on seven sets of criteria (institutional, regulatory, economic, political, social, CDM experience, and energy production/consumption), is conducted, and the post-2012 potential carbon incomes... 

Exhaust gas emissions from mobile sources and its importance in urban pollution have currently attracted lots of interests towards studying on alternative fuel systems for road vehicles usage. One of the best replacements is the natural gas/diesel dual fuel, which offers an alternative to standard compression-ignition diesel engines. In the dual fuel system the primary fuel is natural gas, which may replace as much as 90% of the diesel fuel with a small amount of diesel fuel required ensuring effective ignition. Methane, the main constituent of natural gas, has high combustion efficiency. Dual fuel engines produce lower NOx emissions and fewer particulates. However, at moderate engine loads,... 

An integrated hydrogen and power co-generation system with CO2 capture has been proposed and evaluated techno-economically. The proposed system is an alternative low cost clean power generation while supplying hydrogen for process plants. The baseline configuration has been designed based on the literature. Different cases are simulated in Aspen Plus and are evaluated economically. Thermodynamic models have been validated against the results of previous publications. The co-generation system with different product shares of hydrogen and power has been compared with CO2 captured and CO2-vented hydrogen plants by means of defined techno-economic-environmental indicators. Sensitivity analysis... 

Most sulfide oxidizing bioreactors are based on pure cultures or artificial mixes of microorganisms with strict requirements for growth, which make the system unstable and do not guarantee their long term performance. The ultimate goal of this study is to develop a natural mix of chemotrophic bacteria that may be applied anaerobically for the treatment of sour gas. Activated sludge from local municipal wastewater treatment plant that was maintained in endogenous anaerobic conditions for one year was used in this study. Total suspended solids (TSS) and volatile suspended solids (VSS) of the sludge was 22 gl-1 and 14.3 gl-1, respectively. A glass culture vessel had a volume of 0.65 L was used... 

In this work, an experimental and theoretical study has been conducted to investigate the permeability reduction due to CaSO4 scale deposition in packed column porous media. Permeability reduction by calcium sulphate deposition follows a systematic trend considering various important parameters that are affected in this complex process. Hence, a novel dimensionless model has been proposed for the prediction of permeability reduction rate with high accuracy. The developed model is based on the data obtained from glass bead and carbonate grain packed column at low pressure. The proposed model was validated with Berea sandstone cores data at high pressure (100-20,678 kPa), various flow rates... 

Excess enthalpy data measured at 298.15 K were collected from the literature. The data contains 48 binary systems (812 data points). The experimental data were correlated by the Redlich-Kister equation. In this research work the following thermodynamics models were also tested, Wilson, NRTL models and their parameters were calculated. A modified NRTL with composition-dependent (α12) parameter were also proposed. The correlation of excess enthalpy data in the systems using this model provides good results  

Dilatometric measurements of excess molar volumes, VE and excess partial molar volumes, V̄iE have been made for binary mixtures of acetonitrile with 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, and 1,2-hexanediol at 20°C over the entire composition range. VE for acetonitrile + 1,2-ethanediol and 1,2-propanediol mixtures are negative over the entire range of mole fractions and positive values are obtained for all remaining mixtures. The results are explained in terms of dissociation of the self-associated 1,2-alkanediol molecules and the formation of aggregates between unlike molecules through O-H. . . N≡C hydrogen bonding. From the experimental results, VE were... 

A comprehensive model for pervaporation in thin membrane channels was developed to study the effect of changing temperature and concentration on mass flux. This model consists of momentum, energy and species mass balances along and across the membrane in the flow channel. A computational fluid dynamics (CFD) code was written in C++ programming language to solve the coupled non-linear transport equations in the channel by finite volume method. The Semi-Implicit Pressure Link Equation (SIMPLE) CFD algorithm is used to modify the dependent variables in each of the iterations. The effect of variation of temperature and concentration on transport and thermodynamic properties were considered by... 

In this work, permeation of mixed gases H2S/CH4 through commercial polyphenylene oxide (PPO) hollow fiber and poly (ester urethane) urea (PEUU) flat membranes was studied at pressures of 345–689 kPa, at ambient temperature and at 313.15 K. Various H2S concentrations of about 100–5000 ppm in CH4 binary synthetic gas mixtures as well as a real natural gas sample obtained from a gas refinery containing 0.3360 mol.% H2S (equivalent to 3360 ppm) were tested. It was observed that the permeance of components was affected by the balance between competitive sorption and plasticization effects. Separation factors of H2S/CH4 were in the range of 1.3–2.9, 1.8–3.1 and 2.2–4.3 at pressures of 345, 517 and...