Silica Membranes: Preparation, Modelling, Application, and Commercialization
Abstract
Silica Membranes: Preparation, Modelling, Application, and Commercialization
Current Trends and Future Developments on (Bio-) Membranes Microporous Membranes and Membrane Reactors
Abstract
Current Trends and Future Developments on (Bio-) Membranes Microporous Membranes and Membrane Reactors
Adsorption of diclofenac on mesoporous activatedcarbons: Physical and chemical activation,modeling with genetic programming andmolecular dynamic simulation
Abstract
Adsorption of diclofenac on mesoporous activatedcarbons: Physical and chemical activation,modeling with genetic programming andmolecular dynamic simulation
This work aims at the preparation of AC from chemical activation (H3PO4, KOH, and HCl)and physical activation (thermal treatment under N2atmosphere at 500 and 700◦C) of Astra-galus Mongholicus (AM) (a low-cost bio-adsorbent and agro-industrial waste), used as carbonprecursor. The obtained materials were further applied in the adsorption of diclofenac(DCF) from water/wastewater. The physicochemical properties of the as-prepared ACs andcommercial activated carbons (CAC) were evaluated by SEM, XRD, FT-IR, and BET analyses,revealing the high surface area and mesoporous proportion of AC when compared to CAC. Adsorption results showed that the efficiency of AC-700◦C (774 m2g−1) for DCF removal(92.29%) was greater than that of AC-500◦C (648 m2g−1, 83.5%), AC-H3PO4(596 m2g−1, 80.8%),AC-KOH (450 m2g−1, 59.3%), AC-HCl (156 m2g−1, 29.8%) and CAC (455 m2g−1, 67.8%). The opti-mization of effective parameters in adsorption was examined at a laboratory-scale using theselected AC-700◦C. The Langmuir isotherm and the pseudo-second-order model fitted wellthe experimental data. The regeneration efficiency was maintained at 96% (DI-water) and97% (heating) after three cycles. Besides, genetic programming (GP) and molecular dynam-ics (MD) simulations were applied to predict the adsorption behavior of DCF from aqueousphase as well as in the ACs structure. It was found that the adsorption mechanisms involvedwere electrostatic interaction, cation– interaction, and – electron interaction.
Removal of Heat‐Stable Salts from Lean Amine of a Gas Refinery via Electrodialysis
Abstract
Removal of Heat‐Stable Salts from Lean Amine of a Gas Refinery via Electrodialysis
Heat‐stable salts (HSS) can be generated by degradation of amines during absorptive CO2 capture. The removal of HSS from lean amine using electrodialysis was carried out with the aims of enhancing HSS removal efficiency and reducing energy consumption as high as possible using homogeneous and heterogeneous ion exchange membranes. The results demonstrate the significant effects of concentrated solution on removal efficiency, energy consumption, amine loss, and amount of effluent. In the case of using a lean amine of the gas refinery and water as a concentrated solution, the HSS removal can be enhanced by 30 % and the amount of effluent can be reduced by 40 % using a homogeneous membrane instead of a heterogeneous membrane. Furthermore, the energy consumption decreased by 51 %.
Application of NF Polymeric Membranes for Removal of Multicomponent Heat-Stable Salts (HSS) Ions from Methyl Diethanolamine (MDEA) Solutions
Abstract
Application of NF Polymeric Membranes for Removal of Multicomponent Heat-Stable Salts (HSS) Ions from Methyl Diethanolamine (MDEA) Solutions
This study presents an efficient and scalable process for removing the heat-stable salts (HSS) ions from amine solution while recovering methyl diethanolamine (MDEA) solution for its reuse in gas sweetening plants. The presence of HSS in the amine solution causes the loss of solvent capacity, foaming, fouling, and corrosion in gas sweetening units so their removal is crucial for a more well-performing process. Furthermore, the recovery of the amine solution can make the sweetening step a more sustainable process. In this study, for the first time, the removal of a multicomponent mixture of HSS from MDEA solution was investigated via a nanofiltration process using flat-sheet NF-3 membranes. The impact of operating parameters on salts and amine rejection, and flux, including the operating pressure, HSS ions concentration, and MDEA concentration in the feed solution was investigated. Results based on the nanofiltration of an amine stream with the same composition (45 wt.% MDEA solution) as that circulating in a local gas refinery (Ilam Gas refinery), demonstrated a removal efficiency of HSS ions in the range from 75 to 80% and a MDEA rejection of 0% indicating the possibility of reusing this stream in the new step of gas sweetening
Experimental and Theoretical Investigation of Gelation Time of Nanostructured Polymer Gels by Central Composite Approach
Abstract
Experimental and Theoretical Investigation of Gelation Time of Nanostructured Polymer Gels by Central Composite Approach
Currently available polymers as a component of in-situ gels are unsuitable for treating hightemperature/high-salinity reservoirs due to their chemical and thermal degradation. In this study, a new copolymer-based gel system including high molecular weight nanostructured polymers (NSPs) was developed to address the excessive water production problem in reservoirs under harsh conditions. The stability of conventional polymer systems and NSPs was investigated under conditions of 40 days aging at 87000 ppm salinity and 90 °C. Then, gelation time optimization of gel systems composed of NSPs and chromium (III) acetate was performed with regards to the effect of copolymer concentration and copolymer/cross-linker ratio and their interactions during the gelation time. The central composite approach was used to design experiments and build a mathematical model. The analysis of variance (ANOVA) was used to estimate the deviation of the model predictions from the data. The results of stability analysis demonstrated the advantages of NSPs over conventional polymers by a viscosity reduction of 69, 36, and 18% for Flopaam3310, AN105, and NSPs respectively. The model developed for the prediction of gelation time of NSPs gel was significant at a confidence level of 98.6% against the test data. Moreover, it was found that gelation time became longer with a decrease in copolymer concentrations and/or increase in copolymer/crosslinker ratio.
Preparation of Pt-ZSM-5 zeolite membrane catalysts for isomerization of linear alkane
Abstract
Preparation of Pt-ZSM-5 zeolite membrane catalysts for isomerization of linear alkane
A ZSM-5 supported membrane was synthesized by secondary growth method. The Pt-ZSM5 membrane was prepared by impregnation method. The membrane was characterized by single gas permeation step at room temperature. The isomerization of n-pentane was chosen as a probe reaction for evaluating the catalytic performance of the membrane. In particular, the effect of the space velocity and the time on stream were considered. After the catalytic tests, the membrane was characterized by SEM, EDX and XRD. N2 permeance for the membrane, after calcination, was equal to 2.9 × 10-7 mol/m2.s.Pa indicating a coverage of the larger support pores by the zeolite crystals. This results was also confirmed by the SEM investigation. In addition, XRD analysis showed as the ZSM-5 was the desired zeolite-type. During the catalytic tests, it was observed a decrease of the nC5 conversion and an increase of the iC5 selectivity with WHSV. The nC5 conversion was decreased from 2.5 to less than 0.5, with an enhancement in weight hourly space velocity (WHSV), while the selectivity increases from 30 to over 70. On the other hand, it's conversion on catalyst enhanced from 10% to approximately 38%, with an increase in the reaction temperature from 250 to 450°C.
Chemical study of asphaltene inhibitors effects on asphaltene precipitation of an Iranian oil field
Abstract
Chemical study of asphaltene inhibitors effects on asphaltene precipitation of an Iranian oil field
The amount of precipitated asphaltene can be considerably reduced with pretreatment of asphaltene inhibitor, in the crude oil. Efficiency of asphaltene inhibitors mainly depends on some parameters such as pH of the oil and the chemical structure of asphaltene inhibitors. In this paper, the amounts of asphaltene precipitation have been experimentally measured using two n-paraffin precipitants; n-heptane and n-hexane. The performance of the studies on the asphaltene accumulation was studied using Fourier-Transform Infrared (FTIR) Spectroscopy analysis. The onset point has been determined by three different commercial asphaltene inhibitors. The results show that when an asphaltene inhibitor is not injected into the mixture of synthetic oil/ n-heptane, AOP (Asphaltene Onset Point) occurs at 35 vol.% of n-heptane, while with addition of 3000 ppm of asphaltene B inhibitor, AOP occurs at 60 vol.% of n-heptane.
Synthesis optimization and characterization of high molecular weight polymeric nanoparticles as EOR agent for harsh condition reservoirs
Abstract
Synthesis optimization and characterization of high molecular weight polymeric nanoparticles as EOR agent for harsh condition reservoirs
In this study, inverse emulsion polymerization (IEP) of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was conducted with a constant monomer AAm/AMPS feed ratio of 80%:20%. The effects of important reaction parameters on monomer conversion, intrinsic viscosity and molecular weight of nanostructured polymers (NSPs) were comprehensively assessed and the optimal synthesis conditions (in terms of the high molecular weight characteristics) was obtained using Box–Behnken design (BBD) combined with response surface methodology (RSM). The glass transition temperature (Tg) of the synthesized NSP was obtained at 165 °C by differential scanning calorimetry (DSC). The rheology measurements demonstrated the long–term stability of the synthetized NSPs after 50 days of aging at 90 °C within the 87,000 ppm brine. Regarding the high molecular weight and acceptable long–term stability at elevated temperatures and salinity levels, the synthesized NSP could be considered as potential candidates for enhanced oil recovery (EOR) applications under harsh condition reservoirs
Optimization and genetic programming modeling of humic acid adsorption onto prepared activated carbon and modified by multi-wall carbon nanotubes
Abstract
Optimization and genetic programming modeling of humic acid adsorption onto prepared activated carbon and modified by multi-wall carbon nanotubes
Milk vetch species (MV) as activated carbon (AC) precursors were prepared and modified by multi-wall carbon nanotubes (CNTs) in order to remove humic acid (HA) removal. Scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (FTIR) and Brunauer Emmett Teller (BET) techniques were applied to characterized MVAC/CNTs. The HA adsorption presented the highest value (22.57 mg/g) at pH 3, while the equilibrium state was reached after 30 min. By increasing the adsorbent’s dosage (0.4–0.5 g/L), the removal efficiency was also improved from 90.3 to 97.6%. The kinetics of adsorption were fitted to the pseudo-second-order model (R2 = 0.9991). The Langmuir isotherm model was well fitted to the equilibrium data revealing monolayer adsorption model of HA onto the MVAC/CNTs with the maximum capacity of 73.29 mg/g (R2 = 0.9967). The obtained values of thermodynamic parameters indicated that the HA adsorption was spontaneous, endothermic and physical in nature. Also, genetic programming was used to obtain an appropriate equation revealing the relationship between the variables. The results showed that the introduced equation can successfully predict the HA removal. All experimental results suggested that MVAC/CNTs are promising adsorbents for the contaminated (with HA) water.
Ions transport modeling in the amine solution through nanofiltration membrane
Abstract
Ions transport modeling in the amine solution through nanofiltration membrane
.The Performance of flat sheet polyamide nanofiltration membrane in rejection of binary mixture of heat stable salts (acetate and sulfate) from methyl-diethanolamine (MDEA) solution was investigated. The effects of pressure and concentration of MDEA solution on rejection of acetate and sulfate ions were studied. At MDEA concentration of 20% wt. and pressure of 70 bar, 80% and 98% rejection can be obtained for acetate and sulfate ions, respectively. Membrane performance and transport coefficients investigated using Spiegler-Kedem-Katchalsky (SKK) model, film theory and extended Nernst-Planck (FT-ENP) model. The results of FT-ENP model show accurate agreement with experimental results. This result can be obtained due to the considering the charge repulsion of sulfate ions. For sulfate ions, both models show errors less than 1% with >R2=0.98. In case of acetate, errors less than 3% (>R2=0.75) and 2% (>R2=0.89) were obtained for SKK and FT-ENP models, respectively.
Study on the separation of H2 from CO2 using a ZIF-8 membrane by molecular simulation and maxwell-stefan model
Abstract
Study on the separation of H2 from CO2 using a ZIF-8 membrane by molecular simulation and maxwell-stefan model
The purification of H2-rich streams using membranes represents an important separation process, particularly important in the viewpoint of pre-combustion CO2 capture. In this study, the separation of H2 from a mixture containing H2 and CO2 using a zeolitic imidazolate framework (ZIF)-8 membrane is proposed from a theoretical point of view. For this purpose, the adsorption and diffusion coefficients of H2 and CO2 were considered by molecular simulation. The adsorption of these gases followed the Langmuir model, and the diffusion coefficient of H2 was much higher than that of CO2. Then, using the Maxwell–Stefan model, the H2 and CO2 permeances and H2/CO2 permselectivities in the H2–CO2 mixtures were evaluated. Despite the fact that adsorption of CO2 was higher than H2, owing to the simultaneous interference of adsorption and diffusion processes in the membrane, H2 permeation was more pronounced than CO2. The modeling results showed that, for a ZIF-8 membrane, the H2/CO2 permselectivity for the H2–CO2 binary mixture 80/20 ranges between 28 and 32 at ambient temperature.
The Selection of amine solvent in process of gas treating considering physical and process criteria using multiple criteria decision-making techniques (Case Study: Ilam Gas Treating Company)
Abstract
The Selection of amine solvent in process of gas treating considering physical and process criteria using multiple criteria decision-making techniques (Case Study: Ilam Gas Treating Company)
In the current work, a framework is presented for amine solvent selection in process of gas treating. The appropriate decision making in this field affects the capital and operational costs. Multi Attribute Decision Making(MADM) techniques have been used to rank alternatives.Determination of criteria and alternatives is the most important aspect in the MADM. Criteria have been divided in two categories: physical and process.Twelve physicalindexes andnine process indexes are detected. MEA, DEA, DIPA, DGA and MDEAare intended as alternatives.Importance of criteria are expressed by weights.Weights are determined by AHPmethod. The traditional TOPSIS method has been applied for physical criteria with crisp data. The modified interval TOPSIS technique has been appliedto study the process criteria with interval data. Data of criteria and alternatives have been collected from Ilam Gas Treating Company. Solution for sour gas sweeteningis ranked by proposed approach.Based on our computations, MDEAisdefined as the best amine solvent with the average ranking 1.5.
Study of adsorption and diffusion of methyl mercaptan and methane on FAU zeolite using molecular simulation
Abstract
Study of adsorption and diffusion of methyl mercaptan and methane on FAU zeolite using molecular simulation
In the present research study the principal purpose is to understand the adsorption of methyl mercaptan and methane as a single-component and mixture and diffusion of methyl mercaptan in zeolite NaX at different temperature and pressure using molecular simulation. The results showed that adsorption of methyl mercaptan on NaX zeolite with Compass force field is in acceptable agreement with experimental data and follows the Langmuir model. The methane and mercaptan absorption behavior in a binary mixture condition was different from single-component adsorption. It is due to competition and priority in the adsorption of components in the mixture condition. Therefore, adsorption ratio of mercaptan to methane was much higher in single-component condition than in the mixed state. Also, the diffusivity of mercaptan in zeolite was studied in different loading of mercaptan. The results showed that mercaptan permeability increased with increasing loading, indicating a strong interaction of zeolite with mercaptan molecules.
Photo-catalytic dye degradation of methyl orange using Zirconia-zeolite nanoparticles
Abstract
Photo-catalytic dye degradation of methyl orange using Zirconia-zeolite nanoparticles
In this research, the dye photo-catalytic removal was investigated using zirconia (ZrO2) nanocatalysts, zeolite (Ze), ZrO2-Ze with different percentages, and optimized ZrO2-Ze doped via urea, copper oxide, and cerium oxide. In order to determine the optimal condition, the effect of different catalysts and parameters such as dye concentration, UV lamp power, amount of the loaded catalyst and pH were investigated. The response surface methodology (RSM) was used to obtain optimal experimental condition. Physical and chemical properties of materials were investigated by XRD, FTIR, SEM and BET. Completely Methyl Orange (MO)-dye removal (100%) was achieved at optimal condition under UV light during 80 minutes. The optimal operational condition for MO photo-catalytic decomposition using an optimal N-doped 10 wt. % ZrO2-Zeolite nanocatalyst was obtained at UV lamp power, the pH, catalyst loading and dye concentration of 15 W, 3, 0.4 g/L, and 5 mg/L, respectively. Photo-catalytic degradation kinetics of MO well described using pseudo-first order which is in accordance with Langmuir-Hinshelwood model (kapp = 0.031 min-1).
Molecular simulation of the ion exchange behavior of Cu2+, Cd2+ and Pb2+ ions on different zeolites exchanged with sodium
Abstract
Molecular simulation of the ion exchange behavior of Cu2+, Cd2+ and Pb2+ ions on different zeolites exchanged with sodium
In this research, the molecular dynamics simulation of separating metal ions from water at 298 K using LAMMPS software for LTA, FAU, LTN, THO, NAT and EDI zeolites and electrolyte solutions containing Cu2+, Cd2+ and Pb2+ individually and in pairs of ions have been studied. Among the single ions, the lowest ion exchange rate was Pb2+ and the highest was Cd2+, as well as the adsorption rate and ion exchange, which was directly related to the size of zeolite cavities. The FAU zeolite with the largest cavity diameter had the fastest adsorption rate. The LTA structure with the adsorption of 69% of cadmium and FAU with 46% adsorption had the highest and lowest ion exchange rate. Furthermore, the highest ion displacement in different types of zeolites was related to copper ion due to its low weight. In two cations electrolytes solutions, all the structures tended to adsorb cadmium ion EDI structures with 100% cadmium adsorption and 85% copper, FAU with 78% cadmium adsorption and 40% copper have been shown the highest and lowest selectivity and uptake of cadmium relative to copper, respectively. In addition, for electrolyte containing cadmium and lead, EDI structure with 100% cadmium adsorption against 60% lead and THO structure with 70% cadmium adsorption versus 38% lead had the highest and lowest selectivity for cadmium. In copper-leaded electrolytes, copper was superior to selected. EDI adsorbed 100% copper versus 60% lead, and FAU had a 40% copper uptake, compared to 65% lead.
Molecular dynamics simulations of asphaltene aggregation under different conditions
Abstract
Molecular dynamics simulations of asphaltene aggregation under different conditions
The formation of organic sediments, especially asphaltene in reservoirs, wells and equipment, has a harmful effect on the oil production economy, which reduces oil production and can block oil production facilities. In order to investigate the asphaltene aggregation and solubility, a series of molecular dynamics simulations in different conditions were performed on two famous asphaltene based model, of M1 and VI. VI asphaltene has two high aliphatic side chains, whereas M1 asphaltene has only two methyl groups on its sides. The simulation results show that the solubility parameter increases with increasing number of aromatic rings and decreasing the number of carbon atoms in the side chain. The aggregation of asphaltene molecules in toluene, heptane and isopropyl benzene solvents and also in the mixture of solvents has been investigated. The results show that the aggregation of M1 asphaltene in toluene and isopropyl benzene is lower than that of VI asphaltene. The mixture isopropyl benzene-heptane is appropriate solvent for both asphaltenes M1 and VI which represents less interaction between asphaltene molecules. The effect of six types of inhibitors on the aggregation of asphaltene was investigated. Based on the simulation results, the aggregation of asphaltene with the presence of DETPMP inhibitor significantly decreases due to the delay in the growth of crystals and by increasing the concentration of all used inhibitors, their inhibitory properties were decreased.
Catalytic performance of nanostructured Pt/ZSM-5 catalysts synthesized by extended Charnell’s method in hydroisomerization of n-pentane
Abstract
Catalytic performance of nanostructured Pt/ZSM-5 catalysts synthesized by extended Charnell’s method in hydroisomerization of n-pentane
Na-ZSM-5 zeolite, synthesized by extended Charnell’s method was used to prepare Pt/ZSM-5 catalyst for n-pentane hydroisomerization. The influence of ion exchange, alkaline treatment and method of platinum incorporation on the Na-ZSM-5 zeolite was investigated. It was found that the presence of Trien affected the physicochemical properties of the synthesized catalyst. The synthesized catalysts showed high performance so that the sample prepared in rotating mode at 24 h and Pt loaded via impregnation showed conversion and selectivity about 75 and 97%, respectively. Also, a maximum yield for this catalyst was achieved at 250 C
Molecular dynamics simulation of the effect of ions in water on the asphaltene aggregation
Abstract
Molecular dynamics simulation of the effect of ions in water on the asphaltene aggregation
In this study, the effect of aqueous ions and sediment inhibitors on asphaltene aggregation was investigated. The effect of NaCl, MgCl2 and CaCl2 salts on three asphaltene models of M1, A1 and modified Yen and also the combined effect of two different inhibitors and these salts have been investigated by using molecular dynamics (MD). The results showed that due to presence of Na+, Mg2+ and Ca2+ cations, asphaltene aggregation has an ascending, descending, ascending trend, respectively and the amount of asphaltene aggregation in the A1 model due to having more electronegative atoms is higher than the other two. In the presence of diethylene triamine-penta methylene phosphonic acid (DETPMP) and poly-phosphino carboxylic acid (PPCA) inhibitors, the amount of sediment was reduced in all three models of asphaltene, but the asphaltene aggregation with the presence of DETPMP inhibitor significantly decreases due to the delay in the growth of crystals
Synthesis and application of Cu-x zeolite for removal of antibiotic from aqueous solution: process optimization using response surface methodology
Abstract
Synthesis and application of Cu-x zeolite for removal of antibiotic from aqueous solution: process optimization using response surface methodology
13X zeolite was synthesized for removal of tetracycline from aqueous solution. To improve the removal efficiency, FAU zeolite was exposed to ion exchange process with Cu+2. The experiments were designed by the Expert Design 7.0.0 software. The effect of experimental parameters including, initial tetracycline (TC) concentration (50, 156.5, 525, 893.5, 1000 ppm) Cu+2 dosages (0, 0.3, 1.3, 2.2, 3 gr/gr) solution pH (2, 3, 6.5, 10, 11) and contact time(20, 34.6, 85, 135.4 min) was evaluated on TC removal efficiency. For minimizing the number of experiments for a complete evaluation, response surface methodology (RSM) and central composite design (CCD) were applied by means of Expert Design 7.0.0 software. Results revealed that FAU zeolite adsorbent was effective in removal of tetracycline, where the removal efficiency was 85 %. In fact, by increasing initial TC concentration from 156.5 to 890 mg/L, the removal efficiency was increased. While, further increase in initial TC concentration over 890 mg/L, did not cause a significant enhancement in its removal efficiency. Amount of exchanged Cu to 1.75 g/g had a positive effect on the removal efficiency but in over1.75 g/g dosages, the removal efficiency showed a decreasing trend. The Expert Design 7.0.0 software was reported that the optimal operating conditions is initial tetracycline (TC) concentration 810.5 ppm, Cu+2 dosages 0.6 gr/gr, solution pH 5.3, and contact time is 113.6 min. The adsorption isotherms were fitted by Sips and Freundlich and Redlich-Peterson models. Finally, the adsorption kinetics were also studied by pseudo-second order equation.
Removal of HSS from Industrial Amine Solution by Anionic Resin (Case Study: Ilam Gas Refinery)
Abstract
Removal of HSS from Industrial Amine Solution by Anionic Resin (Case Study: Ilam Gas Refinery)
In this research, the removal of heat stable salts was considered as one of the most effective factors in the process of amine degradation. To remove this type of salts, ion exchange method was used. A resin purification system was investigated to separate the heat stable salt ions of acetate, formaldehyde, chloride, oxalate, thiosulphate, sulphate and sulphite from alkanolamine solution flowing in the Ilam gas refinery sweetening units. In order to remove the existing ions in the lean amine solution, a strong anionic resin designated as INDION GS 300 was tested. Ion-exchange systems operated in batch and continuous mode (fixed-bed column) were applied to remove these salts. The effects of different operating variables such as contact time, temperature and amount of resin were examined. The optimum values of amount of resin and temperature found for both systems were 5 g and 25°C, respectively. Furthermore, the optimum times for batch and continuous systems were 30 and 10 min, respectively. Results of experiments revealed that around 95.5 and 97 % of salts were removed using batch and column operations, respectively. Moreover, the amine solution pH increased from 10 to 11, indicating a corrosion rate reduction in the amine system of the Ilam gas refinery.
Isomerization of C5 isomers in the BZSM-5 membrane reactor packed with Pt/SZ nanocatalyst
Abstract
Isomerization of C5 isomers in the BZSM-5 membrane reactor packed with Pt/SZ nanocatalyst
Abstract Isomerization of nC5/iC5 was investigated at atmospheric conditions and temperatures of 180–260 °C in a BZSM-5 membrane reactor packed with Pt-SZ/Al catalyst. Pt-SZ/Al catalyst was synthesized by precipitation method. BZSM-5 membrane was prepared by in situ nucleation and secondary growth on the outer surface of the support. The effects of reaction temperature and sweep gas flow rate were investigated. Also, a comparison between the performance of the MR and conventional reactor was performed. The prepared sulfated zirconia is nanoscale in size and has predominantly tetragonal crystalline phase. A continuous and uniform layer of BZSM-5 was formed on support surface. Feed conversion increased with increasing temperature and selectivity decreased. Increase in the sweep gas flow rate which reduce contact time between reactant and catalyst, decreased n-C5 conversion and increased selectivity toward iC5. The positive effect of membrane was observed on iC5 selectivity in the investigated temperature range, but nC5 conversion was affected by different membrane mechanisms. An increase in RON of the product (∼10%) was also observed.
A Molecular Simulation of Natural Gas Dehydration by 3A Zeolite Nanostructure
Abstract
A Molecular Simulation of Natural Gas Dehydration by 3A Zeolite Nanostructure
The adsorption and separation properties of 3A zeolite are investigated by using Grand Canonical Monte Carlo (GCMC) simulation. To obtain the adsorption isotherms of water, methyl mercaptan, and methane on 3A zeolite, COMPASS Force Filed is used. The adsorption isotherms of the pure components and the ternary mixtures of water, methyl mercaptan, and methane on 3A zeolites are calculated. The Sips Model is taken into account for the description of water adsorption on 3A zeolite. In addition, the effects of pressure and temperature on the adsorption of components are examined. The results demonstrate that the water has high adsorption selectivity on 3A zeolite, and this kind of adsorbent is a good candidate for the dehydration of natural gas.
Enhanced i-C5 production by isomerization of C5 isomers in BZSM-5 membrane reactor packed with Pt/ZSM-5 nanocatalyst
Abstract
Enhanced i-C5 production by isomerization of C5 isomers in BZSM-5 membrane reactor packed with Pt/ZSM-5 nanocatalyst
In this study, isomerization of C5 was carried out in a combined separation and reaction system using tubular BZSM-5 membrane packed with Pt/ZSM-5 nanocatalyst. The feed mixture is passed over the BZSM-5 membrane and linear n-C5 molecules were separated from branched ones before contacting the catalyst bed. The catalytic performance of the membrane reactor was compared with that of a conventional packed bed reactor with similar dimensions and at comparable operation conditions. These results showed that membrane reactor significantly enhanced i-C5 yield in isomerization of n-C5. The influence of operating conditions on the performance of membrane reactor was evaluated. The membrane reactor displayed a maximum increase in i-C5 yield compared to packed bed reactor of 6300% at 220 °C.
Hydroisomerization of n-Pentane over Pt/Mordenite Catalyst: Effect of Feed Composition and Process Conditions
Abstract
Hydroisomerization of n-Pentane over Pt/Mordenite Catalyst: Effect of Feed Composition and Process Conditions
The hydroisomerization of pure n-pentane over H-mordenite supported Pt-catalyst was investigated in a fixed bed reactor by changing reaction parameters such as temperature, pressure, and WHSV, as well as the H2/HC ratio. The maximum yield of isopentane over Pt/mordenite catalyst was achieved at 220 °C and a relatively low reaction pressure. To address the effect of feed composition on the catalytic performance of the samples, the catalysts were assessed for activity and selectivity in the isomerization of a mixture consisting of n-pentane (70 wt.%) and isopentane (30 wt.%) at 220 °C. The effects of pressure, WHSV, and H2/HC ratio on the catalyst performance were also studied using binary mixtures of the pentane isomers as a feedstock. It was observed that an effect of WHSV and H2/HC on the catalytic performance was similar to its behavior in pure n-pentane isomerization, while the conversion of n-pentane in the binary mixture showed a different trend and had a minimum value at 1.5 bar. It could be due to the presence of isopentane in feed and adsorption phenomenon of binary mixture on mordenite-supported catalyst. Keywords
Gelation studies of high molecular weight polymeric nanoparticles for application in fractured oil reservoirs with harsh conditions
Abstract
Gelation studies of high molecular weight polymeric nanoparticles for application in fractured oil reservoirs with harsh conditions
Nanostructured polymers (NSPs) due to the high water absorption, suitable dispersing in water, low initial viscosity, and deep penetration into the reservoir are potential alternative for common polymers in water shut-off processes. In this study, gelation kinetic of high molecular weight NSPs including copolymer of acrylamide (AAm) and 2-acrylamido-2-methylpropanosulfonic acid (AMPS) in combination with chromium (III) acetate was studied by bottle test and rheology measurements. Finally, the potential of the NSPs gel to block harsh condition fractures was investigated by performing core flow experiments. The gelation time of 82 h was observed for a gel system containing 5500 ppm of poly(AAm-co-AMPS) nanoparticle and copolymer/cross-linker ratio (CCR) of 20 under aging at 90°C and 87,000 ppm salinity. The results of core flow experiments showed that the NSPs gel has strong blocking capacity to reduce fracture permeability by two orders of magnitude. Furthermore, gel blocking efficiency was found to be depended on both the fracture opening and salinity difference between gel solvent and produced water.
مطالعه سینتیکی و ترمودینامیکی جذب آسفالتین بر روی نانوذرات زئولیت ZSM-5
چکیده
مطالعه سینتیکی و ترمودینامیکی جذب آسفالتین بر روی نانوذرات زئولیت ZSM-5
آسفالتین یکی از ترکیبات موجود در نفت خام با سنگینترین کسر میباشد که این ویژگی سبب تهنشین شدن و رسوب آن بر روی سنگ مخزن یا لولههای استخراج و انتقال میشود. تاکنون روشهای مختلفی برای جداکردن و یا حذف آن پیشنهاد شده است که جذب آسفالتین با استفاده از نانوذرات یکی از کارآمدترین آنها است. به منظور بهینهسازی فرآیند جذب سطحی آسفالتین، اثر پارامترهایی همچون غلظت آسفالتین، پارامتر دما و میزان جاذب بارگذاری شده (زئولیت ZSM-5) مورد بررسی قرار گرفتند. مشخصات فیزیکی و شیمیایی جاذب نیز توسط SEM، XRD و FTIR بررسی گردید. تصاویر SEM نشان داد که نانوذرات تابوتی شکل زئولیتZSM-5 در جذب آسفالتین بسیار کارا بوده و بعد از جذب به صورت کلوخه در میآیند. آنالیزهای XRD و FT-IR نیز حضور آسفالتین در زئولیت ZSM-5 را بعد از فرآیند جذب سطحی تأیید نمودند. دادههای تعادلی با ایزوترمهای لانگمویر و فرندلیچ برای اطلاع از همدمای جذب، برازش شدند. نتایج بهدست آمده نشان داد که رفتار جذبی آسفالتین بر روی زئولیتZSM-5 را میتوان با استفاده از همدمای لانگمویر بخوبی توصیف نمود. نتایج سینتیکی نشان دادند که آسفالتین به سرعت و در مدت زمان کمتر از ۲ ساعت جذب نانو ذرات زئولیت میشوند. با مقایسه مدل های سینتیکی شبه مرتبهی اول و شبه مرتبه ی دوم می توان دریافت که مدل سینتیکی شبه مرتبهی دوم به خوبی رفتار سینتیکی جذب آسفالتین را بر روی نانو ذرات زئولیت ZSM-5 پیشبینی میکند.
شبیه سازی مونت کارلو اثر نسبت سیلیسیم به آلومینیم موجود در ساختار زئولیت MFI روی جداسازی ایزومرهای پنتان
چکیده
شبیه سازی مونت کارلو اثر نسبت سیلیسیم به آلومینیم موجود در ساختار زئولیت MFI روی جداسازی ایزومرهای پنتان
جداسازي ايزومرهاي آلكانها توسط زئوليتها از اهميت ويژهاي برخوردار است. در اين تحقيق روش مونتكارلو براي شبيهسازي مولكولي جذب ايزومرهاي پنتان بهصورت مورداستفاده قرار گرفته است. اثر مقدار MFI خالص و مخلوط دوجزئي روي زئوليت 31 و ∞ ) روي جذب ، با نسبت سيليسيم به آلومينيم 18 ) MFI آلومينيم در زئوليت ايزومرهاي پنتان موردبررسي قرار گرفت. نتايج بهدستآمده نشان داد كه ساختارهاي با نسبت سيليسيم به آلومينيم متفاوت داراي خواص جذب و انتخابگري جذب متفاوتي هستند و اين به ساختار حفرات مستقيم و زيگزاگي زئوليت مربوط است. همچنين نتايج نشان ميدهد كه با افزايش فشار ميزان انتخابگري ساختار زئوليت نسبت به آلكان خطي در مخلوط ايزومرها افزايش مييابد. به دليل فاكتور MFI رقابت در جذب، انتخابگري در جذب در حالت مخلوط از حالت خالص بالاتر است. با افزايش دما ميزان جذب كاهش مييابد و ميزان انتخابگري وابسته به فشار عملياتي است.
ررسی تاثیر سورفکتانت آنیونی سدیم دودسیل سولفات بر کشش بین سطحی دودکان و آب بصورت آزمایشگاهی و شبیه سازی مولکولی
چکیده
ررسی تاثیر سورفکتانت آنیونی سدیم دودسیل سولفات بر کشش بین سطحی دودکان و آب بصورت آزمایشگاهی و شبیه سازی مولکولی
در اين مطالعه با استفاده از روش تجربی و شبيه سازی ديناميک مولکولی به بررسی عملکرد سورفکتانت آنيونی سديم دودسيل سولفات در کاهش کشش بين سطحی آب و نفت که در ازدياد برداشت مهم است پرداخته شده است. برای ين منظور، کشش بين سطحی محلول آب و قطره دودکان در دو حالت بررسی شد که در حالت اول محلول فقط شامل مولکولهای آب و دودکان است و در حالت دوم سورفکتانت سديم دودسيل سولفات به محلول اضافه گرديد. در حالت دوم سيستمها به دو صورت انجام شد که در يکی سيستمی که 32 مولکول سورفکتانت، 120 مولکول دودکان و 800 مولکول آب داشت با عنوان سيستم (SDS1) معرفی شد، کشش بين سطحی(IFT) اين سيستم از mN/m 54.83 به mN/m 7.32 کاهش يافت و سيستمی که در آن تعداد مولکولهای آب و دودکان نصف شده بودند، يعنی 60 مولکول دودکان و 400 مولکول آب ولی با همان تعداد مولکول سورفکتانت يعنی 32 مولکول که با عنوان سيستم (SDS2) معرفی شد، کشش بين سطحی از mN/m 59.06 به mN/m 8.28 کاهش يافت. نتايج نشان داد که در حالت دوم، اضافه کردن سورفکتانت آنيونی سديم دودسيل سولفات به محلول آب و دودکان موجب کاهش کشش بين سطحی میشود، از طرفی با بررسی و مقايسه تعداد مولکولهای هر دو سيستم SDS1 و SDS2 در حالت دوم دريافت شد که نسبت مولکولها در روند کاهش کشش بين سطحی تأثير دارد. طبق يافته ها، هرچه تعداد مولکولهای سورفکتانت نسبت به آب و آلکان بيشتر باشد، کاهش کشش بين سطحی آن بيشتر است. همچنين برای بررسی اثر غلظت سورفکتانت در تعداد ثابت آب و آلکان (16 مولکول سورفکتانت، 120 مولکول دودکان و 800 مولکول آب) ، شبيه سازی مولکولی انجام شد(SDS3). نتایج نشان داد که کشش بين سطحی به mN/m 12.66 کاهش يافت. که عملکرد کمتری نسبت به حالت SDS1 دارد
molecular dynamic simulation of asphaltene precipitation in three solvents of toluene, isopropyl benzene and heptane
Abstract
molecular dynamic simulation of asphaltene precipitation in three solvents of toluene, isopropyl benzene and heptane
The asphaltenes precipitation has been established for decades by numerous research. To study asphaltene precipitation, molecular dynamic simulation is one way to specified microscopic molecular interactions and structures. In this paper, molecular dynamics simulation was used to study the solubility and aggregation of M1 and VI asphaltenes. For this purpose, solubility parameters of heptane, isopropyl benzene and toluene solvents and as well as M1 and VI asphaltenes were calculated. The molecular dynamic results show that the asphaltene M1 solubility parameter is larger than VI. Isopropyl benzene is a suitable solvent for both asphaltene and toluene is more effective than heptane solvent.
Effect of Inhibitor on Precipitation Asphaltene for Crude Oil of Azar Oils Field
Abstract
Effect of Inhibitor on Precipitation Asphaltene for Crude Oil of Azar Oils Field
Amount of precipitated asphaltene be reduce considerable with pretreatment asphaltene inhibitor, into mixture of crude oil. Efficiency of asphaltene inhibitors is depend on many parameter like pH andchemical structure of asphaltene inhibitors In this paper. The amounts of asphaltene precipitation have been measured using seven n-heptane as precipitants. The onset points has been determined using asphaltene inhibitor with pH=3.8. the result show that adding 465 ppm of acidic asphaltene inhibitor is optimum amount and onset point occurred in 35 vol. % of n-heptane.
MERCAPTAN REMOVAL FROM CONDENSATE USING ZEOLITE ADSORBENTS
Abstract
MERCAPTAN REMOVAL FROM CONDENSATE USING ZEOLITE ADSORBENTS
In this study, the removal of mercaptan from condensate from Ilam Refinery was investigated by using adsorption on the ion-exchanged x-zeolites in a batch system. Batch experiments were performed to evaluate the influence of parameters like adsorbent dosage, contact time, concentration of the adsorbate and temperature. It was observed that adsorption of mercaptan followed pseudo second order kinetics in both the cases. Adsorption data fitted well with the Langmuir and Freundlich models. However, Langmuir isotherm displayed a better fitting. The results revealed that the mercaptan is considerably adsorbed on ion-exchanged zeolites and it could be an economical method for the removal of mercaptan from condensate.
Study on transport parameters in nanofiltration membrane for ion removal
Abstract
Study on transport parameters in nanofiltration membrane for ion removal
Understanding of transport parameters in nanofiltration membrane is critical for effective membrane and system design. In this study, the removal of anions using nanofiltration membrane process and the main parameters of membrane separation were investigated. The removal of Cl- and SO4-2 with the purpose to understandthe transport parameters in the Nanofiltration membrane were studied. Thestudyhasbeencarriedoutwiththe NF (DowFilmtec)membrane.Theeffectofoperatingpressure(1–10 bar) onthemembraneseparation performance hasbeeninvestigated. Then, the membrane performance was evaluated based on three transport parameters the water permeability (L_P), the salt transmittance (ϕ) and the effective salt transfer coefficient (K_eff). Rejection of sulfate was nearly 100% and the salt transmittance was obtained about 2.282%.
Investigation the Effect of Concentration on Limiting Current Density in Electrodialysis process
Abstract
Investigation the Effect of Concentration on Limiting Current Density in Electrodialysis process
The efficiency and performance of electrodialysis process can be affected by the limiting current density (LCD). LCD is a critical parameter that should be determined based on operation condition of electrodialysis. In this study, the effect of concentration on LCD was investigated. LCD was determined using different methods, i.e., V/I, R/I and ????/I curves. The multi-salt solution of Na2SO4, Na2C2O4, and NaCH3COO were used with three concentrations of 1000, 700 and 300 ppm. The results showed that LCD value increased with increasing feed concentration, and increasing the current intensity more than the limiting current value does not have much effect on the removal of the ions and only water molecules are degraded.
حذف رسوب آسفالتین در نفت توسط نانو ذرات زئولیت
چکیده
حذف رسوب آسفالتین در نفت توسط نانو ذرات زئولیت
یکی از ترکیبات در نفت خام آسفالتین میباشد که سنگینترین کسر را در نفت دارد که این ویژگی سبب تهنشین شدن و رسوب آن بر روی سنگ مخزن یا لولههای استخراج و انتقال میشود. استفاده از نانوذرات برای جذب آسفالتین بر روی آن تا این رسوب¬گذاری دیرتر انجام شود و بتوان راندمان استخراج را بالا برد. در این مطالعه اثر دما بر جذب آسفالتين توسط زئولیت ZSM-5 در دماهای°C ۲۵، °C 40 و °C 50، با غلظت اولیه mg / L2۰۰۰ -5۰، دوز جاذب 10 گرم بر لیتر و زمان تماس 2 ساعت مورد مطالعه قرار گرفت. درجه حرارت پایین تر باعث تسهیل جذب آسفالتین در زئولیت ZSM-5 شد.
شبیه سازي مولکولی جذب کربن دي اکسید روي زئولیتFAU–DDR - MFI -LTA
چکیده
شبیه سازي مولکولی جذب کربن دي اکسید روي زئولیتFAU–DDR - MFI -LTA
زئولیتها به عنوان یک جاذب اید هآل براي حذف آلاینده ها در نظر گرفته می شوند، زیرا داراي ظرفیت بارگیري مناسب و ساختار پایدار هستند. در این تحقیق با استفاده از شبیه سازي مولکولی جذب گاز دي اکسید کربن استفاده از شبی هسازي شده شامل 96 LTA مورد بررسی قرار گرفته است. زئولیت FAU-DDR-MFI–LTA زئولیت سیلیکات، 96 آلومینیوم و 384 اتم اکسیژن است که به صورت سه بعدي در نظر گرفته شده است. پتانسیل استفاده شده در این کار شامل کولمبیک، لنارد جونز و باکینگهام است و اثرات آن بر شبی هسازي مورد بررسی قرار گرفته، علاوه بر این اثر فشار و دما بر میزان جذب بررسی شده و نتایج حاصل از شبی هسازي با دادههاي آزمایشگاهی موجود در مراجع مقایسه شده است، نتایج شبیه سازي انجام گرفته روي زئولیت ها نشان م یدهد روند ایزوترم جذب بررسی شده چنین است .FAU>LTA>DDR>MFI
FAU و LTA ,MFI ,DDR شبی هسازي مولکولی جذب آب روي زئولیتهاي
چکیده
FAU و LTA ,MFI ,DDR شبی هسازي مولکولی جذب آب روي زئولیتهاي
زئولیت ها فضایی خوبی براي جذب آب دارند و داراي ساختار پایدار میباشند که به صورت طبیعی و مصنوعی دردسترس هستند و داراي خواص ساختاري منحصر به فرد و نسبت سطح به حجم بالا و تخلخل زیاد هستند. در این 323 و 343 کلوین و فشار 0.001 ، در دماي 298 FAU–DDR – MFI -LTA تحقیق میزان جذب آب روي زئولیت هاي تا 1000 کیلوپاسکال، توسط شبیه ساز مونت کارلو مورد بررسی قرار گرفته است. ایزوترم جذب براي آب روي زئولیت ها با نتایج تجربی مقایسه گردیده است. نتایج نشان می دهد که تاثیر سطح و فضاي داخلی زئولیت ها بر مقدار جذب LTA آب به اندازه تاثیر دما و فشار است. با بررسی تاثیر سه فاکتور اصلی در میزان جذب بیشترین میزان مربوط به زئولیت است.
شبیه سازی جداسازی گاز کربن دی اکسید از غشا پلیمری پلی وینیل استات
چکیده
شبیه سازی جداسازی گاز کربن دی اکسید از غشا پلیمری پلی وینیل استات
شبیهسازی جداسازی ایزومرهای پنتان با استفاده از غشای زئولیتی MFI
چکیده
شبیهسازی جداسازی ایزومرهای پنتان با استفاده از غشای زئولیتی MFI
در این تحقیق جداسازی ایزومرهای پنتان با استفاده از غشاهای زئولیتی MFI مدلسازی شده و اثر پارامترهای فرایندی روی کارایی غشا بررسی شد. در مدلسازی نفوذ ایزومرهای پنتان از حفرات زئولیتی از مدل استفان - ماکسول و برای جذب این اجزاء از مدل لانگمیر دو سایتی استفاده شد. مطالعه شار عبوری از غشای زئولیتی MFI با تغییر فشار برای مخلوط دو جزئی 50 50 از ایزومرهای پنتان در دمای K433 ، شار نرمال پنتان کاملاً از ایزوپنتان بالاتر است و این به دلیل جذب و ضریب نفوذ بالاتر نرمال پنتان در مقایسه با ایزوپنتان است. در مطالعه انتخابگری غشا با افزایش سهم حفرات غیر زئولیتی از شار عبوری از غشا مشاهده شد که انتخابگری غشا حتی برای مقادیر ناچیز این سهم، کاهش قابلتوجهی از خود نشان میدهد. نتایج حاصل از مدلسازی جداسازی ایزومرهای پنتان با استفاده از غشاهای زئولیتی MFI بیان میکند که عوامل اصلی جداسازی اختلاف در جذب و ضریب نفوذ ایزومرهای پنتان در ساختار زئولیت است
مدلسازي فرايند ريفرمينگ متان در راكتور غشايي بستر پرشده
چکیده
مدلسازي فرايند ريفرمينگ متان در راكتور غشايي بستر پرشده
مدلسازي يك بعدي، همدما و غير همفشار فرايند ريفرمينگ متان در حضور بخار آب در يك راكتور غشايي از نوع بستر پرشده انجام شده است. غشاء مورد استفاده از نوع پالاديوم ميباشد. غشاء پالاديوم نسبت به هيدروژن 100 درصد نفوذ گزين بوده و از لحاظ كاتاليستي خنثي است. در اين تحقيق پارامترهاي دما، نسبت بخار آب به متان در خوراك ورودي، فشار محيط واكنش، ضخامت غشاء، دبي گاز جارويي و طول راكتور جزء وروديها بوده و مقدارشان مشخص است و ميزان تبديل متان در خروجي راكتور مجهول ميباشد. با استفاده از نرم افزار كامسول اثر اين پارامترها بر كارايي فرايند ريفرمينگ متان در راكتور غشايي كاتاليستي مورد ارزيابي قرار گرفته است. نتايج مدلسازي نشان ميدهد كه افزايش دما و نسبت بخار آب به متان در ورودي باعث افزايش درصد تبديل متان و افزايش فشار سمت واكنش و ضخامت غشاء درصد تبديل متان را كاهش ميدهد. نتايج حاصل از مدلسازي با نتايج آزمايشگاهي موجود در مراجع معتبر در توافق خوبي ميباشد.
مدلسازي فرايند ريفرمينگ متان در راكتور بستر پرشده
چکیده
مدلسازي فرايند ريفرمينگ متان در راكتور بستر پرشده
در اين تحقيق مدلسازي يك بعدي، همدما و همفشار فرايند ريفرمينگ متان در حضور بخار آب در يك راكتور بستر پرشده انجام شده است. اثر پارامترهاي دما، نسبت بخار آب به متان در خوراك ورودي، فشار محيط واكنش و طول راكتور بر كارايي فرايند ريفرمينگ متان در راكتور بستر پرشده با استفاده از نرم افزار كامسول مورد ارزيابي قرار گرفته است. نتايج مدلسازي نشان ميدهد كه افزايش دما و نسبت بخار آب به متان در ورودي باعث افزايش درصد تبديل متان ميگردد و افزايش فشار سمت واكنش تبديل متان را كاهش ميدهد. نتايج حاصل از مدلسازي با نتايج آزمايشگاهي موجود در مراجع معتبر در توافق خوبي ميباشد. كلمات كليدي
مدلسازي فرايند ريفرمينگ متان در راكتور غشايي بستر سيال*
چکیده
مدلسازي فرايند ريفرمينگ متان در راكتور غشايي بستر سيال*
در اين تحقيق مدلسازي يك بعدي، همدما و غير همفشار فرايند ريفرمينگ متان در حضور بخار آب در يك راكتور غشايي با غشاء پالاديوم از نوع بستر سيال انجام شده است. اثر پارامترهاي دما، نسبت بخار آب به متان در خوراك ورودي، فشار محيط واكنش، ضخامت غشاء، دبي گاز جارويي و طول راكتور بر كارايي فرايند ريفرمينگ متان در راكتور غشايي كاتاليستي با استفاده از نرم افزار كامسول مورد ارزيابي قرار گرفته است. نتايج مدلسازي نشان ميدهد كه افزايش دما و نسبت بخار آب به متان در ورودي باعث افزايش درصد تبديل متان و افزايش فشار سمت واكنش و ضخامت غشاء درصد تبديل متان را كاهش ميدهد.
بررسی فتوکاتالیستی نانوذرات اصلاح شده دی اکسید زیرکونیوم ترکیب شده با زئولیت
چکیده
بررسی فتوکاتالیستی نانوذرات اصلاح شده دی اکسید زیرکونیوم ترکیب شده با زئولیت
رنگ ها یکی از مهم ترین گروه مواد شیمیایی آلاینده محیط زیست می باشند. به دلیل قابلیت حل شدن و پایداری بالای رنگ ها در آب، توجه فزآینده ای به تخریب و تصفیه آن ها از پساب های صنعتی معطوف شده است. در این مطالعه کارایی نانوذرات ZrO2 نشانده شده بر زئولیت به عنوان فتوکاتالیست برای تخریب رنگ متیل اورنج از آب تحت نور UV بررسی شد. نتایج این مطالعه نشان داد که نانو فتوکاتالیست ۱۰ درصد وزنی زیرکونیا – زئولیت کارایی بالایی در تخریب رنگزای آنیونی متیل اورنج داشته و می توان از آن به عنوان یک گزینه کارآمد برای تصفیه پسابهای رنگی و تخریب آلاینده های زیست محیطی استفاده کرد. تخریب فتوکاتالیستی متیل اورنج از معادله سینتیکی شبه درجه اول مطابق با مدل لانگمیر - هینشلوود پیروی کرد.
Silica Membranes: Preparation, Modelling, Application, and Commercialization
Abstract
Silica Membranes: Preparation, Modelling, Application, and Commercialization
Current Trends and Future Developments on (Bio-) Membranes Microporous Membranes and Membrane Reactors
Abstract
Current Trends and Future Developments on (Bio-) Membranes Microporous Membranes and Membrane Reactors
Adsorption of diclofenac on mesoporous activatedcarbons: Physical and chemical activation,modeling with genetic programming andmolecular dynamic simulation
Abstract
Adsorption of diclofenac on mesoporous activatedcarbons: Physical and chemical activation,modeling with genetic programming andmolecular dynamic simulation
This work aims at the preparation of AC from chemical activation (H3PO4, KOH, and HCl)and physical activation (thermal treatment under N2atmosphere at 500 and 700◦C) of Astra-galus Mongholicus (AM) (a low-cost bio-adsorbent and agro-industrial waste), used as carbonprecursor. The obtained materials were further applied in the adsorption of diclofenac(DCF) from water/wastewater. The physicochemical properties of the as-prepared ACs andcommercial activated carbons (CAC) were evaluated by SEM, XRD, FT-IR, and BET analyses,revealing the high surface area and mesoporous proportion of AC when compared to CAC. Adsorption results showed that the efficiency of AC-700◦C (774 m2g−1) for DCF removal(92.29%) was greater than that of AC-500◦C (648 m2g−1, 83.5%), AC-H3PO4(596 m2g−1, 80.8%),AC-KOH (450 m2g−1, 59.3%), AC-HCl (156 m2g−1, 29.8%) and CAC (455 m2g−1, 67.8%). The opti-mization of effective parameters in adsorption was examined at a laboratory-scale using theselected AC-700◦C. The Langmuir isotherm and the pseudo-second-order model fitted wellthe experimental data. The regeneration efficiency was maintained at 96% (DI-water) and97% (heating) after three cycles. Besides, genetic programming (GP) and molecular dynam-ics (MD) simulations were applied to predict the adsorption behavior of DCF from aqueousphase as well as in the ACs structure. It was found that the adsorption mechanisms involvedwere electrostatic interaction, cation– interaction, and – electron interaction.
Removal of Heat‐Stable Salts from Lean Amine of a Gas Refinery via Electrodialysis
Abstract
Removal of Heat‐Stable Salts from Lean Amine of a Gas Refinery via Electrodialysis
Heat‐stable salts (HSS) can be generated by degradation of amines during absorptive CO2 capture. The removal of HSS from lean amine using electrodialysis was carried out with the aims of enhancing HSS removal efficiency and reducing energy consumption as high as possible using homogeneous and heterogeneous ion exchange membranes. The results demonstrate the significant effects of concentrated solution on removal efficiency, energy consumption, amine loss, and amount of effluent. In the case of using a lean amine of the gas refinery and water as a concentrated solution, the HSS removal can be enhanced by 30 % and the amount of effluent can be reduced by 40 % using a homogeneous membrane instead of a heterogeneous membrane. Furthermore, the energy consumption decreased by 51 %.
Application of NF Polymeric Membranes for Removal of Multicomponent Heat-Stable Salts (HSS) Ions from Methyl Diethanolamine (MDEA) Solutions
Abstract
Application of NF Polymeric Membranes for Removal of Multicomponent Heat-Stable Salts (HSS) Ions from Methyl Diethanolamine (MDEA) Solutions
This study presents an efficient and scalable process for removing the heat-stable salts (HSS) ions from amine solution while recovering methyl diethanolamine (MDEA) solution for its reuse in gas sweetening plants. The presence of HSS in the amine solution causes the loss of solvent capacity, foaming, fouling, and corrosion in gas sweetening units so their removal is crucial for a more well-performing process. Furthermore, the recovery of the amine solution can make the sweetening step a more sustainable process. In this study, for the first time, the removal of a multicomponent mixture of HSS from MDEA solution was investigated via a nanofiltration process using flat-sheet NF-3 membranes. The impact of operating parameters on salts and amine rejection, and flux, including the operating pressure, HSS ions concentration, and MDEA concentration in the feed solution was investigated. Results based on the nanofiltration of an amine stream with the same composition (45 wt.% MDEA solution) as that circulating in a local gas refinery (Ilam Gas refinery), demonstrated a removal efficiency of HSS ions in the range from 75 to 80% and a MDEA rejection of 0% indicating the possibility of reusing this stream in the new step of gas sweetening
Experimental and Theoretical Investigation of Gelation Time of Nanostructured Polymer Gels by Central Composite Approach
Abstract
Experimental and Theoretical Investigation of Gelation Time of Nanostructured Polymer Gels by Central Composite Approach
Currently available polymers as a component of in-situ gels are unsuitable for treating hightemperature/high-salinity reservoirs due to their chemical and thermal degradation. In this study, a new copolymer-based gel system including high molecular weight nanostructured polymers (NSPs) was developed to address the excessive water production problem in reservoirs under harsh conditions. The stability of conventional polymer systems and NSPs was investigated under conditions of 40 days aging at 87000 ppm salinity and 90 °C. Then, gelation time optimization of gel systems composed of NSPs and chromium (III) acetate was performed with regards to the effect of copolymer concentration and copolymer/cross-linker ratio and their interactions during the gelation time. The central composite approach was used to design experiments and build a mathematical model. The analysis of variance (ANOVA) was used to estimate the deviation of the model predictions from the data. The results of stability analysis demonstrated the advantages of NSPs over conventional polymers by a viscosity reduction of 69, 36, and 18% for Flopaam3310, AN105, and NSPs respectively. The model developed for the prediction of gelation time of NSPs gel was significant at a confidence level of 98.6% against the test data. Moreover, it was found that gelation time became longer with a decrease in copolymer concentrations and/or increase in copolymer/crosslinker ratio.
Preparation of Pt-ZSM-5 zeolite membrane catalysts for isomerization of linear alkane
Abstract
Preparation of Pt-ZSM-5 zeolite membrane catalysts for isomerization of linear alkane
A ZSM-5 supported membrane was synthesized by secondary growth method. The Pt-ZSM5 membrane was prepared by impregnation method. The membrane was characterized by single gas permeation step at room temperature. The isomerization of n-pentane was chosen as a probe reaction for evaluating the catalytic performance of the membrane. In particular, the effect of the space velocity and the time on stream were considered. After the catalytic tests, the membrane was characterized by SEM, EDX and XRD. N2 permeance for the membrane, after calcination, was equal to 2.9 × 10-7 mol/m2.s.Pa indicating a coverage of the larger support pores by the zeolite crystals. This results was also confirmed by the SEM investigation. In addition, XRD analysis showed as the ZSM-5 was the desired zeolite-type. During the catalytic tests, it was observed a decrease of the nC5 conversion and an increase of the iC5 selectivity with WHSV. The nC5 conversion was decreased from 2.5 to less than 0.5, with an enhancement in weight hourly space velocity (WHSV), while the selectivity increases from 30 to over 70. On the other hand, it's conversion on catalyst enhanced from 10% to approximately 38%, with an increase in the reaction temperature from 250 to 450°C.
Chemical study of asphaltene inhibitors effects on asphaltene precipitation of an Iranian oil field
Abstract
Chemical study of asphaltene inhibitors effects on asphaltene precipitation of an Iranian oil field
The amount of precipitated asphaltene can be considerably reduced with pretreatment of asphaltene inhibitor, in the crude oil. Efficiency of asphaltene inhibitors mainly depends on some parameters such as pH of the oil and the chemical structure of asphaltene inhibitors. In this paper, the amounts of asphaltene precipitation have been experimentally measured using two n-paraffin precipitants; n-heptane and n-hexane. The performance of the studies on the asphaltene accumulation was studied using Fourier-Transform Infrared (FTIR) Spectroscopy analysis. The onset point has been determined by three different commercial asphaltene inhibitors. The results show that when an asphaltene inhibitor is not injected into the mixture of synthetic oil/ n-heptane, AOP (Asphaltene Onset Point) occurs at 35 vol.% of n-heptane, while with addition of 3000 ppm of asphaltene B inhibitor, AOP occurs at 60 vol.% of n-heptane.
Synthesis optimization and characterization of high molecular weight polymeric nanoparticles as EOR agent for harsh condition reservoirs
Abstract
Synthesis optimization and characterization of high molecular weight polymeric nanoparticles as EOR agent for harsh condition reservoirs
In this study, inverse emulsion polymerization (IEP) of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was conducted with a constant monomer AAm/AMPS feed ratio of 80%:20%. The effects of important reaction parameters on monomer conversion, intrinsic viscosity and molecular weight of nanostructured polymers (NSPs) were comprehensively assessed and the optimal synthesis conditions (in terms of the high molecular weight characteristics) was obtained using Box–Behnken design (BBD) combined with response surface methodology (RSM). The glass transition temperature (Tg) of the synthesized NSP was obtained at 165 °C by differential scanning calorimetry (DSC). The rheology measurements demonstrated the long–term stability of the synthetized NSPs after 50 days of aging at 90 °C within the 87,000 ppm brine. Regarding the high molecular weight and acceptable long–term stability at elevated temperatures and salinity levels, the synthesized NSP could be considered as potential candidates for enhanced oil recovery (EOR) applications under harsh condition reservoirs
Optimization and genetic programming modeling of humic acid adsorption onto prepared activated carbon and modified by multi-wall carbon nanotubes
Abstract
Optimization and genetic programming modeling of humic acid adsorption onto prepared activated carbon and modified by multi-wall carbon nanotubes
Milk vetch species (MV) as activated carbon (AC) precursors were prepared and modified by multi-wall carbon nanotubes (CNTs) in order to remove humic acid (HA) removal. Scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (FTIR) and Brunauer Emmett Teller (BET) techniques were applied to characterized MVAC/CNTs. The HA adsorption presented the highest value (22.57 mg/g) at pH 3, while the equilibrium state was reached after 30 min. By increasing the adsorbent’s dosage (0.4–0.5 g/L), the removal efficiency was also improved from 90.3 to 97.6%. The kinetics of adsorption were fitted to the pseudo-second-order model (R2 = 0.9991). The Langmuir isotherm model was well fitted to the equilibrium data revealing monolayer adsorption model of HA onto the MVAC/CNTs with the maximum capacity of 73.29 mg/g (R2 = 0.9967). The obtained values of thermodynamic parameters indicated that the HA adsorption was spontaneous, endothermic and physical in nature. Also, genetic programming was used to obtain an appropriate equation revealing the relationship between the variables. The results showed that the introduced equation can successfully predict the HA removal. All experimental results suggested that MVAC/CNTs are promising adsorbents for the contaminated (with HA) water.
Ions transport modeling in the amine solution through nanofiltration membrane
Abstract
Ions transport modeling in the amine solution through nanofiltration membrane
.The Performance of flat sheet polyamide nanofiltration membrane in rejection of binary mixture of heat stable salts (acetate and sulfate) from methyl-diethanolamine (MDEA) solution was investigated. The effects of pressure and concentration of MDEA solution on rejection of acetate and sulfate ions were studied. At MDEA concentration of 20% wt. and pressure of 70 bar, 80% and 98% rejection can be obtained for acetate and sulfate ions, respectively. Membrane performance and transport coefficients investigated using Spiegler-Kedem-Katchalsky (SKK) model, film theory and extended Nernst-Planck (FT-ENP) model. The results of FT-ENP model show accurate agreement with experimental results. This result can be obtained due to the considering the charge repulsion of sulfate ions. For sulfate ions, both models show errors less than 1% with >R2=0.98. In case of acetate, errors less than 3% (>R2=0.75) and 2% (>R2=0.89) were obtained for SKK and FT-ENP models, respectively.
Study on the separation of H2 from CO2 using a ZIF-8 membrane by molecular simulation and maxwell-stefan model
Abstract
Study on the separation of H2 from CO2 using a ZIF-8 membrane by molecular simulation and maxwell-stefan model
The purification of H2-rich streams using membranes represents an important separation process, particularly important in the viewpoint of pre-combustion CO2 capture. In this study, the separation of H2 from a mixture containing H2 and CO2 using a zeolitic imidazolate framework (ZIF)-8 membrane is proposed from a theoretical point of view. For this purpose, the adsorption and diffusion coefficients of H2 and CO2 were considered by molecular simulation. The adsorption of these gases followed the Langmuir model, and the diffusion coefficient of H2 was much higher than that of CO2. Then, using the Maxwell–Stefan model, the H2 and CO2 permeances and H2/CO2 permselectivities in the H2–CO2 mixtures were evaluated. Despite the fact that adsorption of CO2 was higher than H2, owing to the simultaneous interference of adsorption and diffusion processes in the membrane, H2 permeation was more pronounced than CO2. The modeling results showed that, for a ZIF-8 membrane, the H2/CO2 permselectivity for the H2–CO2 binary mixture 80/20 ranges between 28 and 32 at ambient temperature.
The Selection of amine solvent in process of gas treating considering physical and process criteria using multiple criteria decision-making techniques (Case Study: Ilam Gas Treating Company)
Abstract
The Selection of amine solvent in process of gas treating considering physical and process criteria using multiple criteria decision-making techniques (Case Study: Ilam Gas Treating Company)
In the current work, a framework is presented for amine solvent selection in process of gas treating. The appropriate decision making in this field affects the capital and operational costs. Multi Attribute Decision Making(MADM) techniques have been used to rank alternatives.Determination of criteria and alternatives is the most important aspect in the MADM. Criteria have been divided in two categories: physical and process.Twelve physicalindexes andnine process indexes are detected. MEA, DEA, DIPA, DGA and MDEAare intended as alternatives.Importance of criteria are expressed by weights.Weights are determined by AHPmethod. The traditional TOPSIS method has been applied for physical criteria with crisp data. The modified interval TOPSIS technique has been appliedto study the process criteria with interval data. Data of criteria and alternatives have been collected from Ilam Gas Treating Company. Solution for sour gas sweeteningis ranked by proposed approach.Based on our computations, MDEAisdefined as the best amine solvent with the average ranking 1.5.
Study of adsorption and diffusion of methyl mercaptan and methane on FAU zeolite using molecular simulation
Abstract
Study of adsorption and diffusion of methyl mercaptan and methane on FAU zeolite using molecular simulation
In the present research study the principal purpose is to understand the adsorption of methyl mercaptan and methane as a single-component and mixture and diffusion of methyl mercaptan in zeolite NaX at different temperature and pressure using molecular simulation. The results showed that adsorption of methyl mercaptan on NaX zeolite with Compass force field is in acceptable agreement with experimental data and follows the Langmuir model. The methane and mercaptan absorption behavior in a binary mixture condition was different from single-component adsorption. It is due to competition and priority in the adsorption of components in the mixture condition. Therefore, adsorption ratio of mercaptan to methane was much higher in single-component condition than in the mixed state. Also, the diffusivity of mercaptan in zeolite was studied in different loading of mercaptan. The results showed that mercaptan permeability increased with increasing loading, indicating a strong interaction of zeolite with mercaptan molecules.
Photo-catalytic dye degradation of methyl orange using Zirconia-zeolite nanoparticles
Abstract
Photo-catalytic dye degradation of methyl orange using Zirconia-zeolite nanoparticles
In this research, the dye photo-catalytic removal was investigated using zirconia (ZrO2) nanocatalysts, zeolite (Ze), ZrO2-Ze with different percentages, and optimized ZrO2-Ze doped via urea, copper oxide, and cerium oxide. In order to determine the optimal condition, the effect of different catalysts and parameters such as dye concentration, UV lamp power, amount of the loaded catalyst and pH were investigated. The response surface methodology (RSM) was used to obtain optimal experimental condition. Physical and chemical properties of materials were investigated by XRD, FTIR, SEM and BET. Completely Methyl Orange (MO)-dye removal (100%) was achieved at optimal condition under UV light during 80 minutes. The optimal operational condition for MO photo-catalytic decomposition using an optimal N-doped 10 wt. % ZrO2-Zeolite nanocatalyst was obtained at UV lamp power, the pH, catalyst loading and dye concentration of 15 W, 3, 0.4 g/L, and 5 mg/L, respectively. Photo-catalytic degradation kinetics of MO well described using pseudo-first order which is in accordance with Langmuir-Hinshelwood model (kapp = 0.031 min-1).
Molecular simulation of the ion exchange behavior of Cu2+, Cd2+ and Pb2+ ions on different zeolites exchanged with sodium
Abstract
Molecular simulation of the ion exchange behavior of Cu2+, Cd2+ and Pb2+ ions on different zeolites exchanged with sodium
In this research, the molecular dynamics simulation of separating metal ions from water at 298 K using LAMMPS software for LTA, FAU, LTN, THO, NAT and EDI zeolites and electrolyte solutions containing Cu2+, Cd2+ and Pb2+ individually and in pairs of ions have been studied. Among the single ions, the lowest ion exchange rate was Pb2+ and the highest was Cd2+, as well as the adsorption rate and ion exchange, which was directly related to the size of zeolite cavities. The FAU zeolite with the largest cavity diameter had the fastest adsorption rate. The LTA structure with the adsorption of 69% of cadmium and FAU with 46% adsorption had the highest and lowest ion exchange rate. Furthermore, the highest ion displacement in different types of zeolites was related to copper ion due to its low weight. In two cations electrolytes solutions, all the structures tended to adsorb cadmium ion EDI structures with 100% cadmium adsorption and 85% copper, FAU with 78% cadmium adsorption and 40% copper have been shown the highest and lowest selectivity and uptake of cadmium relative to copper, respectively. In addition, for electrolyte containing cadmium and lead, EDI structure with 100% cadmium adsorption against 60% lead and THO structure with 70% cadmium adsorption versus 38% lead had the highest and lowest selectivity for cadmium. In copper-leaded electrolytes, copper was superior to selected. EDI adsorbed 100% copper versus 60% lead, and FAU had a 40% copper uptake, compared to 65% lead.
Molecular dynamics simulations of asphaltene aggregation under different conditions
Abstract
Molecular dynamics simulations of asphaltene aggregation under different conditions
The formation of organic sediments, especially asphaltene in reservoirs, wells and equipment, has a harmful effect on the oil production economy, which reduces oil production and can block oil production facilities. In order to investigate the asphaltene aggregation and solubility, a series of molecular dynamics simulations in different conditions were performed on two famous asphaltene based model, of M1 and VI. VI asphaltene has two high aliphatic side chains, whereas M1 asphaltene has only two methyl groups on its sides. The simulation results show that the solubility parameter increases with increasing number of aromatic rings and decreasing the number of carbon atoms in the side chain. The aggregation of asphaltene molecules in toluene, heptane and isopropyl benzene solvents and also in the mixture of solvents has been investigated. The results show that the aggregation of M1 asphaltene in toluene and isopropyl benzene is lower than that of VI asphaltene. The mixture isopropyl benzene-heptane is appropriate solvent for both asphaltenes M1 and VI which represents less interaction between asphaltene molecules. The effect of six types of inhibitors on the aggregation of asphaltene was investigated. Based on the simulation results, the aggregation of asphaltene with the presence of DETPMP inhibitor significantly decreases due to the delay in the growth of crystals and by increasing the concentration of all used inhibitors, their inhibitory properties were decreased.
Catalytic performance of nanostructured Pt/ZSM-5 catalysts synthesized by extended Charnell’s method in hydroisomerization of n-pentane
Abstract
Catalytic performance of nanostructured Pt/ZSM-5 catalysts synthesized by extended Charnell’s method in hydroisomerization of n-pentane
Na-ZSM-5 zeolite, synthesized by extended Charnell’s method was used to prepare Pt/ZSM-5 catalyst for n-pentane hydroisomerization. The influence of ion exchange, alkaline treatment and method of platinum incorporation on the Na-ZSM-5 zeolite was investigated. It was found that the presence of Trien affected the physicochemical properties of the synthesized catalyst. The synthesized catalysts showed high performance so that the sample prepared in rotating mode at 24 h and Pt loaded via impregnation showed conversion and selectivity about 75 and 97%, respectively. Also, a maximum yield for this catalyst was achieved at 250 C
Molecular dynamics simulation of the effect of ions in water on the asphaltene aggregation
Abstract
Molecular dynamics simulation of the effect of ions in water on the asphaltene aggregation
In this study, the effect of aqueous ions and sediment inhibitors on asphaltene aggregation was investigated. The effect of NaCl, MgCl2 and CaCl2 salts on three asphaltene models of M1, A1 and modified Yen and also the combined effect of two different inhibitors and these salts have been investigated by using molecular dynamics (MD). The results showed that due to presence of Na+, Mg2+ and Ca2+ cations, asphaltene aggregation has an ascending, descending, ascending trend, respectively and the amount of asphaltene aggregation in the A1 model due to having more electronegative atoms is higher than the other two. In the presence of diethylene triamine-penta methylene phosphonic acid (DETPMP) and poly-phosphino carboxylic acid (PPCA) inhibitors, the amount of sediment was reduced in all three models of asphaltene, but the asphaltene aggregation with the presence of DETPMP inhibitor significantly decreases due to the delay in the growth of crystals
Synthesis and application of Cu-x zeolite for removal of antibiotic from aqueous solution: process optimization using response surface methodology
Abstract
Synthesis and application of Cu-x zeolite for removal of antibiotic from aqueous solution: process optimization using response surface methodology
13X zeolite was synthesized for removal of tetracycline from aqueous solution. To improve the removal efficiency, FAU zeolite was exposed to ion exchange process with Cu+2. The experiments were designed by the Expert Design 7.0.0 software. The effect of experimental parameters including, initial tetracycline (TC) concentration (50, 156.5, 525, 893.5, 1000 ppm) Cu+2 dosages (0, 0.3, 1.3, 2.2, 3 gr/gr) solution pH (2, 3, 6.5, 10, 11) and contact time(20, 34.6, 85, 135.4 min) was evaluated on TC removal efficiency. For minimizing the number of experiments for a complete evaluation, response surface methodology (RSM) and central composite design (CCD) were applied by means of Expert Design 7.0.0 software. Results revealed that FAU zeolite adsorbent was effective in removal of tetracycline, where the removal efficiency was 85 %. In fact, by increasing initial TC concentration from 156.5 to 890 mg/L, the removal efficiency was increased. While, further increase in initial TC concentration over 890 mg/L, did not cause a significant enhancement in its removal efficiency. Amount of exchanged Cu to 1.75 g/g had a positive effect on the removal efficiency but in over1.75 g/g dosages, the removal efficiency showed a decreasing trend. The Expert Design 7.0.0 software was reported that the optimal operating conditions is initial tetracycline (TC) concentration 810.5 ppm, Cu+2 dosages 0.6 gr/gr, solution pH 5.3, and contact time is 113.6 min. The adsorption isotherms were fitted by Sips and Freundlich and Redlich-Peterson models. Finally, the adsorption kinetics were also studied by pseudo-second order equation.
Removal of HSS from Industrial Amine Solution by Anionic Resin (Case Study: Ilam Gas Refinery)
Abstract
Removal of HSS from Industrial Amine Solution by Anionic Resin (Case Study: Ilam Gas Refinery)
In this research, the removal of heat stable salts was considered as one of the most effective factors in the process of amine degradation. To remove this type of salts, ion exchange method was used. A resin purification system was investigated to separate the heat stable salt ions of acetate, formaldehyde, chloride, oxalate, thiosulphate, sulphate and sulphite from alkanolamine solution flowing in the Ilam gas refinery sweetening units. In order to remove the existing ions in the lean amine solution, a strong anionic resin designated as INDION GS 300 was tested. Ion-exchange systems operated in batch and continuous mode (fixed-bed column) were applied to remove these salts. The effects of different operating variables such as contact time, temperature and amount of resin were examined. The optimum values of amount of resin and temperature found for both systems were 5 g and 25°C, respectively. Furthermore, the optimum times for batch and continuous systems were 30 and 10 min, respectively. Results of experiments revealed that around 95.5 and 97 % of salts were removed using batch and column operations, respectively. Moreover, the amine solution pH increased from 10 to 11, indicating a corrosion rate reduction in the amine system of the Ilam gas refinery.
Isomerization of C5 isomers in the BZSM-5 membrane reactor packed with Pt/SZ nanocatalyst
Abstract
Isomerization of C5 isomers in the BZSM-5 membrane reactor packed with Pt/SZ nanocatalyst
Abstract Isomerization of nC5/iC5 was investigated at atmospheric conditions and temperatures of 180–260 °C in a BZSM-5 membrane reactor packed with Pt-SZ/Al catalyst. Pt-SZ/Al catalyst was synthesized by precipitation method. BZSM-5 membrane was prepared by in situ nucleation and secondary growth on the outer surface of the support. The effects of reaction temperature and sweep gas flow rate were investigated. Also, a comparison between the performance of the MR and conventional reactor was performed. The prepared sulfated zirconia is nanoscale in size and has predominantly tetragonal crystalline phase. A continuous and uniform layer of BZSM-5 was formed on support surface. Feed conversion increased with increasing temperature and selectivity decreased. Increase in the sweep gas flow rate which reduce contact time between reactant and catalyst, decreased n-C5 conversion and increased selectivity toward iC5. The positive effect of membrane was observed on iC5 selectivity in the investigated temperature range, but nC5 conversion was affected by different membrane mechanisms. An increase in RON of the product (∼10%) was also observed.
A Molecular Simulation of Natural Gas Dehydration by 3A Zeolite Nanostructure
Abstract
A Molecular Simulation of Natural Gas Dehydration by 3A Zeolite Nanostructure
The adsorption and separation properties of 3A zeolite are investigated by using Grand Canonical Monte Carlo (GCMC) simulation. To obtain the adsorption isotherms of water, methyl mercaptan, and methane on 3A zeolite, COMPASS Force Filed is used. The adsorption isotherms of the pure components and the ternary mixtures of water, methyl mercaptan, and methane on 3A zeolites are calculated. The Sips Model is taken into account for the description of water adsorption on 3A zeolite. In addition, the effects of pressure and temperature on the adsorption of components are examined. The results demonstrate that the water has high adsorption selectivity on 3A zeolite, and this kind of adsorbent is a good candidate for the dehydration of natural gas.
Enhanced i-C5 production by isomerization of C5 isomers in BZSM-5 membrane reactor packed with Pt/ZSM-5 nanocatalyst
Abstract
Enhanced i-C5 production by isomerization of C5 isomers in BZSM-5 membrane reactor packed with Pt/ZSM-5 nanocatalyst
In this study, isomerization of C5 was carried out in a combined separation and reaction system using tubular BZSM-5 membrane packed with Pt/ZSM-5 nanocatalyst. The feed mixture is passed over the BZSM-5 membrane and linear n-C5 molecules were separated from branched ones before contacting the catalyst bed. The catalytic performance of the membrane reactor was compared with that of a conventional packed bed reactor with similar dimensions and at comparable operation conditions. These results showed that membrane reactor significantly enhanced i-C5 yield in isomerization of n-C5. The influence of operating conditions on the performance of membrane reactor was evaluated. The membrane reactor displayed a maximum increase in i-C5 yield compared to packed bed reactor of 6300% at 220 °C.
Hydroisomerization of n-Pentane over Pt/Mordenite Catalyst: Effect of Feed Composition and Process Conditions
Abstract
Hydroisomerization of n-Pentane over Pt/Mordenite Catalyst: Effect of Feed Composition and Process Conditions
The hydroisomerization of pure n-pentane over H-mordenite supported Pt-catalyst was investigated in a fixed bed reactor by changing reaction parameters such as temperature, pressure, and WHSV, as well as the H2/HC ratio. The maximum yield of isopentane over Pt/mordenite catalyst was achieved at 220 °C and a relatively low reaction pressure. To address the effect of feed composition on the catalytic performance of the samples, the catalysts were assessed for activity and selectivity in the isomerization of a mixture consisting of n-pentane (70 wt.%) and isopentane (30 wt.%) at 220 °C. The effects of pressure, WHSV, and H2/HC ratio on the catalyst performance were also studied using binary mixtures of the pentane isomers as a feedstock. It was observed that an effect of WHSV and H2/HC on the catalytic performance was similar to its behavior in pure n-pentane isomerization, while the conversion of n-pentane in the binary mixture showed a different trend and had a minimum value at 1.5 bar. It could be due to the presence of isopentane in feed and adsorption phenomenon of binary mixture on mordenite-supported catalyst. Keywords
Gelation studies of high molecular weight polymeric nanoparticles for application in fractured oil reservoirs with harsh conditions
Abstract
Gelation studies of high molecular weight polymeric nanoparticles for application in fractured oil reservoirs with harsh conditions
Nanostructured polymers (NSPs) due to the high water absorption, suitable dispersing in water, low initial viscosity, and deep penetration into the reservoir are potential alternative for common polymers in water shut-off processes. In this study, gelation kinetic of high molecular weight NSPs including copolymer of acrylamide (AAm) and 2-acrylamido-2-methylpropanosulfonic acid (AMPS) in combination with chromium (III) acetate was studied by bottle test and rheology measurements. Finally, the potential of the NSPs gel to block harsh condition fractures was investigated by performing core flow experiments. The gelation time of 82 h was observed for a gel system containing 5500 ppm of poly(AAm-co-AMPS) nanoparticle and copolymer/cross-linker ratio (CCR) of 20 under aging at 90°C and 87,000 ppm salinity. The results of core flow experiments showed that the NSPs gel has strong blocking capacity to reduce fracture permeability by two orders of magnitude. Furthermore, gel blocking efficiency was found to be depended on both the fracture opening and salinity difference between gel solvent and produced water.
مطالعه سینتیکی و ترمودینامیکی جذب آسفالتین بر روی نانوذرات زئولیت ZSM-5
چکیده
مطالعه سینتیکی و ترمودینامیکی جذب آسفالتین بر روی نانوذرات زئولیت ZSM-5
آسفالتین یکی از ترکیبات موجود در نفت خام با سنگینترین کسر میباشد که این ویژگی سبب تهنشین شدن و رسوب آن بر روی سنگ مخزن یا لولههای استخراج و انتقال میشود. تاکنون روشهای مختلفی برای جداکردن و یا حذف آن پیشنهاد شده است که جذب آسفالتین با استفاده از نانوذرات یکی از کارآمدترین آنها است. به منظور بهینهسازی فرآیند جذب سطحی آسفالتین، اثر پارامترهایی همچون غلظت آسفالتین، پارامتر دما و میزان جاذب بارگذاری شده (زئولیت ZSM-5) مورد بررسی قرار گرفتند. مشخصات فیزیکی و شیمیایی جاذب نیز توسط SEM، XRD و FTIR بررسی گردید. تصاویر SEM نشان داد که نانوذرات تابوتی شکل زئولیتZSM-5 در جذب آسفالتین بسیار کارا بوده و بعد از جذب به صورت کلوخه در میآیند. آنالیزهای XRD و FT-IR نیز حضور آسفالتین در زئولیت ZSM-5 را بعد از فرآیند جذب سطحی تأیید نمودند. دادههای تعادلی با ایزوترمهای لانگمویر و فرندلیچ برای اطلاع از همدمای جذب، برازش شدند. نتایج بهدست آمده نشان داد که رفتار جذبی آسفالتین بر روی زئولیتZSM-5 را میتوان با استفاده از همدمای لانگمویر بخوبی توصیف نمود. نتایج سینتیکی نشان دادند که آسفالتین به سرعت و در مدت زمان کمتر از ۲ ساعت جذب نانو ذرات زئولیت میشوند. با مقایسه مدل های سینتیکی شبه مرتبهی اول و شبه مرتبه ی دوم می توان دریافت که مدل سینتیکی شبه مرتبهی دوم به خوبی رفتار سینتیکی جذب آسفالتین را بر روی نانو ذرات زئولیت ZSM-5 پیشبینی میکند.
شبیه سازی مونت کارلو اثر نسبت سیلیسیم به آلومینیم موجود در ساختار زئولیت MFI روی جداسازی ایزومرهای پنتان
چکیده
شبیه سازی مونت کارلو اثر نسبت سیلیسیم به آلومینیم موجود در ساختار زئولیت MFI روی جداسازی ایزومرهای پنتان
جداسازي ايزومرهاي آلكانها توسط زئوليتها از اهميت ويژهاي برخوردار است. در اين تحقيق روش مونتكارلو براي شبيهسازي مولكولي جذب ايزومرهاي پنتان بهصورت مورداستفاده قرار گرفته است. اثر مقدار MFI خالص و مخلوط دوجزئي روي زئوليت 31 و ∞ ) روي جذب ، با نسبت سيليسيم به آلومينيم 18 ) MFI آلومينيم در زئوليت ايزومرهاي پنتان موردبررسي قرار گرفت. نتايج بهدستآمده نشان داد كه ساختارهاي با نسبت سيليسيم به آلومينيم متفاوت داراي خواص جذب و انتخابگري جذب متفاوتي هستند و اين به ساختار حفرات مستقيم و زيگزاگي زئوليت مربوط است. همچنين نتايج نشان ميدهد كه با افزايش فشار ميزان انتخابگري ساختار زئوليت نسبت به آلكان خطي در مخلوط ايزومرها افزايش مييابد. به دليل فاكتور MFI رقابت در جذب، انتخابگري در جذب در حالت مخلوط از حالت خالص بالاتر است. با افزايش دما ميزان جذب كاهش مييابد و ميزان انتخابگري وابسته به فشار عملياتي است.
ررسی تاثیر سورفکتانت آنیونی سدیم دودسیل سولفات بر کشش بین سطحی دودکان و آب بصورت آزمایشگاهی و شبیه سازی مولکولی
چکیده
ررسی تاثیر سورفکتانت آنیونی سدیم دودسیل سولفات بر کشش بین سطحی دودکان و آب بصورت آزمایشگاهی و شبیه سازی مولکولی
در اين مطالعه با استفاده از روش تجربی و شبيه سازی ديناميک مولکولی به بررسی عملکرد سورفکتانت آنيونی سديم دودسيل سولفات در کاهش کشش بين سطحی آب و نفت که در ازدياد برداشت مهم است پرداخته شده است. برای ين منظور، کشش بين سطحی محلول آب و قطره دودکان در دو حالت بررسی شد که در حالت اول محلول فقط شامل مولکولهای آب و دودکان است و در حالت دوم سورفکتانت سديم دودسيل سولفات به محلول اضافه گرديد. در حالت دوم سيستمها به دو صورت انجام شد که در يکی سيستمی که 32 مولکول سورفکتانت، 120 مولکول دودکان و 800 مولکول آب داشت با عنوان سيستم (SDS1) معرفی شد، کشش بين سطحی(IFT) اين سيستم از mN/m 54.83 به mN/m 7.32 کاهش يافت و سيستمی که در آن تعداد مولکولهای آب و دودکان نصف شده بودند، يعنی 60 مولکول دودکان و 400 مولکول آب ولی با همان تعداد مولکول سورفکتانت يعنی 32 مولکول که با عنوان سيستم (SDS2) معرفی شد، کشش بين سطحی از mN/m 59.06 به mN/m 8.28 کاهش يافت. نتايج نشان داد که در حالت دوم، اضافه کردن سورفکتانت آنيونی سديم دودسيل سولفات به محلول آب و دودکان موجب کاهش کشش بين سطحی میشود، از طرفی با بررسی و مقايسه تعداد مولکولهای هر دو سيستم SDS1 و SDS2 در حالت دوم دريافت شد که نسبت مولکولها در روند کاهش کشش بين سطحی تأثير دارد. طبق يافته ها، هرچه تعداد مولکولهای سورفکتانت نسبت به آب و آلکان بيشتر باشد، کاهش کشش بين سطحی آن بيشتر است. همچنين برای بررسی اثر غلظت سورفکتانت در تعداد ثابت آب و آلکان (16 مولکول سورفکتانت، 120 مولکول دودکان و 800 مولکول آب) ، شبيه سازی مولکولی انجام شد(SDS3). نتایج نشان داد که کشش بين سطحی به mN/m 12.66 کاهش يافت. که عملکرد کمتری نسبت به حالت SDS1 دارد
molecular dynamic simulation of asphaltene precipitation in three solvents of toluene, isopropyl benzene and heptane
Abstract
molecular dynamic simulation of asphaltene precipitation in three solvents of toluene, isopropyl benzene and heptane
The asphaltenes precipitation has been established for decades by numerous research. To study asphaltene precipitation, molecular dynamic simulation is one way to specified microscopic molecular interactions and structures. In this paper, molecular dynamics simulation was used to study the solubility and aggregation of M1 and VI asphaltenes. For this purpose, solubility parameters of heptane, isopropyl benzene and toluene solvents and as well as M1 and VI asphaltenes were calculated. The molecular dynamic results show that the asphaltene M1 solubility parameter is larger than VI. Isopropyl benzene is a suitable solvent for both asphaltene and toluene is more effective than heptane solvent.
Effect of Inhibitor on Precipitation Asphaltene for Crude Oil of Azar Oils Field
Abstract
Effect of Inhibitor on Precipitation Asphaltene for Crude Oil of Azar Oils Field
Amount of precipitated asphaltene be reduce considerable with pretreatment asphaltene inhibitor, into mixture of crude oil. Efficiency of asphaltene inhibitors is depend on many parameter like pH andchemical structure of asphaltene inhibitors In this paper. The amounts of asphaltene precipitation have been measured using seven n-heptane as precipitants. The onset points has been determined using asphaltene inhibitor with pH=3.8. the result show that adding 465 ppm of acidic asphaltene inhibitor is optimum amount and onset point occurred in 35 vol. % of n-heptane.
MERCAPTAN REMOVAL FROM CONDENSATE USING ZEOLITE ADSORBENTS
Abstract
MERCAPTAN REMOVAL FROM CONDENSATE USING ZEOLITE ADSORBENTS
In this study, the removal of mercaptan from condensate from Ilam Refinery was investigated by using adsorption on the ion-exchanged x-zeolites in a batch system. Batch experiments were performed to evaluate the influence of parameters like adsorbent dosage, contact time, concentration of the adsorbate and temperature. It was observed that adsorption of mercaptan followed pseudo second order kinetics in both the cases. Adsorption data fitted well with the Langmuir and Freundlich models. However, Langmuir isotherm displayed a better fitting. The results revealed that the mercaptan is considerably adsorbed on ion-exchanged zeolites and it could be an economical method for the removal of mercaptan from condensate.
Study on transport parameters in nanofiltration membrane for ion removal
Abstract
Study on transport parameters in nanofiltration membrane for ion removal
Understanding of transport parameters in nanofiltration membrane is critical for effective membrane and system design. In this study, the removal of anions using nanofiltration membrane process and the main parameters of membrane separation were investigated. The removal of Cl- and SO4-2 with the purpose to understandthe transport parameters in the Nanofiltration membrane were studied. Thestudyhasbeencarriedoutwiththe NF (DowFilmtec)membrane.Theeffectofoperatingpressure(1–10 bar) onthemembraneseparation performance hasbeeninvestigated. Then, the membrane performance was evaluated based on three transport parameters the water permeability (L_P), the salt transmittance (ϕ) and the effective salt transfer coefficient (K_eff). Rejection of sulfate was nearly 100% and the salt transmittance was obtained about 2.282%.
Investigation the Effect of Concentration on Limiting Current Density in Electrodialysis process
Abstract
Investigation the Effect of Concentration on Limiting Current Density in Electrodialysis process
The efficiency and performance of electrodialysis process can be affected by the limiting current density (LCD). LCD is a critical parameter that should be determined based on operation condition of electrodialysis. In this study, the effect of concentration on LCD was investigated. LCD was determined using different methods, i.e., V/I, R/I and ????/I curves. The multi-salt solution of Na2SO4, Na2C2O4, and NaCH3COO were used with three concentrations of 1000, 700 and 300 ppm. The results showed that LCD value increased with increasing feed concentration, and increasing the current intensity more than the limiting current value does not have much effect on the removal of the ions and only water molecules are degraded.
Removal of Asphaltene deposits in petroleum by zeolite nanoparticles
Abstract
Removal of Asphaltene deposits in petroleum by zeolite nanoparticles
Molecular Simulation of Co2 adsorption on FAU-DDR-MFI-LTA zeolite
Abstract
Molecular Simulation of Co2 adsorption on FAU-DDR-MFI-LTA zeolite
molecular simulation of water adsorption on LTA,MFI,DDR and FAU zeolite
Abstract
molecular simulation of water adsorption on LTA,MFI,DDR and FAU zeolite
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Photocatalytic study of modified zirconium dioxide modified nanoparticles with zeolite
Abstract
Photocatalytic study of modified zirconium dioxide modified nanoparticles with zeolite