Nashrieh Shimi va Mohandesi Shimi Iran
Year:2017 | Volume:36 | Issue:1|Papers Count:21

Due to its unique characteristics, helium gas has found widespread applications, particularly in medical, nuclear and space industries. At the present, natural gas is considered as the main industrial source of helium and should contain at least 0.05 mole% helium in order to make the extraction process which is primarily based on cryogenic economically available. Because of multiple advantages of membrane technology, helium extraction using membranes has been the subject of numerous studies for more than half a century. Some inorganic membranes such as silica have shown good performance for helium separation, but the fabrication of such membranes is costly and complicated. On the contrary, polymeric membranes are low-priced and require performance improvement through modifications. Besides blending and employment of inorganic fillers, one of the most effective ways to improve the performance of these membranes is the development of copolymeric membranes. In addition, a hybrid system comprising a combination of cryogenic distillation, membrane technology, and pressure swing adsorption can lead to lower energy consumption and costs.

Mixed matrix membranes consisting of a polymeric matrix and dispersed mineral particles in nanoscale are new kinds of membranes that have been developed to eliminate polymeric membranes limitation. In this research, polyesterurethane mixed matrix membranes based on polycaprolactone (PCL) containing 3 Wt. % of unmodified silica and fluorinated silica nanoparticles were prepared by solvent casting method. Prepared nanocomposite membranes were identified by different methods such as TGA, DSC and FT-IR. Separation properties of the membranes were analyzed via laboratory reverse osmosis system by using Shiraz Petrochemical wastewater contaminated by ammonia as a feed. The obtained results of polyurethane–silica membranes show that the membrane containing fluorinated silica nanoparticles has a proper output for ammonia retention up to 62% at 10 bar in comparison with untreated one. Increasing operating pressure to 20 bar causes increasing permeate flux through the prepared membranes, but it significantly decreases the membrane efficiency for ammonia retention.

A method for the preconcentration of trace mercury ion in environmental samples has been reported. Nowadays efforts are being focused on the development of microextraction techniques. In this study, we describe an efficient approach with good reproducibility, fast, simple, cheap and relatively environmentally friendly for preconcentration of mercury in ppb level in the real samples. This technique is compatible with many analytical instruments. In this work, the Samples preconcentration were measured by ICP-AES. As a result, the major advantage of this method was enrichment factor of 168, LOD less than 10 ppb and RSD% less than 4%. Highly sensitive Hg analysis was therefore required for determining the low levels of Hg in natural waters.

CNT-based cobalt catalysts were made with Ca, Ce, K and Zr promoters. Then the addition of Ca / Ca and K / Zr was carried out by impregnation method and the synergetic effect of an alkaline, alkaline earth promoter with a transition metal or lanthanide promoter was investigated. The structural properties of the catalysts were investigated based on technologies such as X-Ray Diffraction (XRD), total surface area measurement and pore size distribution of catalysts (BET), atomic emission (ICP) and Temperature-Programmed Reduction (TPR). The FTS performance of the catalysts was studied in a fixed-bed micro-reactor under conditions of 220 °C, 18bar, and H2/CO = 2 (v/v). The results of the test showed that simultaneously adding Ca-Ce to the Co / CNT catalyst and its synergetic effect increased the conversion rate of CO by 7%, and also by adding K-Zr promoters to the Co / CNT catalyst and their synergetic effect C5 + selectivity increased From 72% to 82%.

confirmed by FESEM images. The TPD-NH3 results revealed that more desirable acidic properties were obtained by employing clinoptilolite compared to other zeolitic supports, resulting in high stability. Based on the EDX results, a higher dispersion of chromium species could be achieved using synthetic supports especially HZSM-5 due to their much higher specific surface area. This reflects in the higher content of redox Cr species stabilized in comparison with SAPO-34 and clinoptilolite, which alongside homogenous and fine surface nanoparticles and fewer agglomerations account for the superior catalytic performance of Cr/ZSM-5. Based on the characterization results, the low surface area of clinoptilolite and low dispersion of Cr species in Cr/Clinoptilolite and surface coverage and micropore blockage in Cr/SAPO-34 are mainly responsible for low ethylene yield of this catalyst compared with implementing ZSM-5 support. It was found that Cr/ZSM5 effectively dehydrogenated ethane to ethylene in the presence of CO2 at 700 °C, giving 45.4% ethylene yield. Coke deposition as a result of the presence of strong acid sites is mainly responsible for decreasing trend observed for catalytic performance with increasing reaction time.

Notice to importance and application of dihydropyrimidine heterocycles as diverse biological and pharmaceutical compounds in chemistry and biochemistry, in this project, an efficient synthesis of 3, 4-dihydropyrimidin-2 (1H) - ones (DHPM) derivatives is achieved from an one-pot tree component reaction of aromatic aldehydes, ethyl acetoacetate and urea in the presence of iron ore pellet as natural and reusable catalyst in H2O / EtOH solution. This methodology offered several advantages such as good yields, cheap natural and reusable catalyst, simple procedure and simple purification steps. The use of water as the reaction medium makes the process environmentally and eco-friendly benign.

In the present work, 50%Ni and promoted 50%Ni-10%M (M=Ce, Mn, Mo, Pd) catalysts supported on nanocrystalline gamma alumina were prepared by sol-gel method and employed in the thermocatalytic decomposition of methane for production of COx-free hydrogen and carbon nanofibers. The catalysts were prepared by the wet impregnation method and characterized by XRD, BET, SEM, TPO and TPR techniques. The results revealed that the prepared samples exhibited mesoporous structure with high surface area. The g-alumina support possessed a high surface area of 188.2 m2/g. In addition, the promoted catalysts showed the BET surface area in the range of 89.0 to 45.8 m2/g depending on the type of promoter. Moreover, TPR profiles revealed that the addition of palladium improved the catalyst reducibility. The thermocatalytic decomposition of methane was performed at different temperatures in order to investigate the effects of promoters and reaction temperature on the catalytic performance. The obtained results demonstrated that the addition of palladium compared to the other promoters improved the catalytic activity, especially at high temperatures. In the other hands, the results of stability test showed that the addition of palladium to the nickel-based catalysts significantly improved the catalyst lifetime. Also, the SEM analysis confirmed the formation of carbon nanofibers on the spent catalysts.

In this study, hydrogen production with an industrial catalyst in the steam methane reforming process was investigated. Due to the abundant application and its rules as fuel in the future, hydrogen is so valuable. In industry, this process carried out at 750-900°C. In order to decrease energy consumption, development of catalysts to decrease operation temperature was considered. In this project, to find catalyst disadvantages, industrial catalyst performance in the different conditions was investigated. CHN analysis for carbon content of catalyst and XRD analysis as well as Scherrer equation for catalyst sintering were carried out During the experiment, methane conversion at 750 °C and 850°C were 75.8 and 84.4, respectively, and almost unchanged, but at 650°C and 550 °C methane conversion followed a decreasing trend. Methane conversion percent and hydrogen mole percent increased with the increasing temperature but after 750 °C, slop of hydrogen mole percent decreased. According to hydrogen production and methane conversion, The most suitable temperature is 750°C and after this temperature, hydrogen yield did not have significant change, in addition, CO selectivity increased that is not suitable.Methane conversion slowly increased and CO selectivity decreased with the increasing steam to methane ratio. Decreasing particle size of catalyst led to increasing methane conversion. During the experiment, carbon content in the catalyst decreased with the increasing temperature.Catalyst deactivation with sintering had a greater impact than carbon deposit in the industrial catalyst.

The assembly of phosphomolybdic acid of Keggin-type polyoxoanion, [(PO4)Mo12O36]3-, and [La(DMF)8]3+ fragments via layer method under mild condition led to the formation of a new hybrid inorganic-organic compound with formula [La(DMF)8][(PO4)Mo12O36] (1) (DMF = N,N- dimethylformamide). The hybrid is characterized by using elemental analysis, IR spectroscopy, Energy Dispersive X-ray Spectroscopy analysis (EDS), cyclic voltammetry, and single crystal X-ray diffraction. This compound crystallizes in the orthorhombic system, space group Pna21 with four molecules per unit cell. The unit cell parameters are: a = 27.1550 (5) A,b =18.5111 (4) A, c = 13.5055 (3) A, and a = b= γ =90o. The final R value was 0.0424 for 65109 observed reflections. The crystal structure is stabilized by non-covalent interactions of type C-H···O, linking the various components into a three-dimensional framework, which results in the formation of a supramolecular structure. Redox activities for the molybdenum centers of 1 have been observed using cyclic voltammetry.

Click synthesis of 1,4 and 1,5-disubstituted 1,2,3 triazoles from benzyl azide and ethyl propiolate has been studied by means of Density Functional Theory (DFT) from the structural and thermochemical viewpoints in the gas phase and in presence of three different solvent, water, dioxane and tetrahydrofuran (THF) using polarized continuum model. On the basis of calculated thermodynamical results, it has been demonstrated that the production of 1,4-disubstituted regioisomer is more favorable than 1,4-disubstituted regioisomer. Moreover, a significant decrease in the computed values of the reaction enthalpy and free energy changes was obtained in the three solution phases in comparison with the gas phase. Furthermore, the thermodynamical preference in using water as the solvent was obtained in comparison with dioxane and THF to that is in agreement with experimental observations. In next step, electronic and structural origins of regioselectivity were investigated via analysis of variations in the calculated values of some key bond lengths and bond orders. Finally, to present a more concise interpretation on the regioselectivity, we performed the topological analysis of electronic indices via Quantum Theory of Atoms in Molecule (QTAIM) approach.

In this study, the structural and electronic properties of a boron nitride nanocone (BNNC) with 120° disclination were investigated using density functional theory calculations. In the considered model, there are one tetragonal ring and 56 hexagonal rings, with the mouth of nanocone saturated by the hydrogen atoms. In the second step, with making defect in boron nitride nanocone and transverse cutting on its apex, the structure similar to porphyrin was induced in preliminary boron nitride nanocone and the P-BNNC compound was produced. In the third step, the Mg2+ ion was placed in the center of the produced core in P-BNNC and the chlorophyll like structure (Mg- P-BNNC) was formed. In the final step, the interactions between CO2, CO, H2 and O2 gas molecules and the exterior and interior surface of Mg- P-BNNC compound was studied. The CO2 and H2 gas molecules adsorbed only on the Mg metal atom on the exterior site but, the CO molecule was adsorbed from both the exterior and interior site of Mg- P-BNNC. However, the O2 gas molecule has high adsorption only from the interior site of Mg- P-BNNC. With the adsorption of CO2, CO and H2 gases on Mg- P-BNNC, the band gap is approximately constant and so, the conductivity of Mg- P-BNNC molecule has not significantly changed. The noticeable point is that the amount of Mg- P-BNNC band gap, as well as conductivity, has significant change with the adsorption of O2 gas on its interior site. So, the Mg- P-BNNC is the good and selective sensor for the O2 gas in the presence of CO2, CO and H2 gases. The Density of State (DOS) and Natural Bond Orbital (NBO) calculations have confirmed the above results.

Polyvinyl pyrrolidone (PVP)/carboxyl functionalized multiwalled carbon nanotube (MWCNT-COOH) nanocomposite was prepared in aqueous media. The structure, morphology, and thermal characterization of PVP/MWCNT-COOH nanocomposite were done by FT-IR, SEM, TGA and DSC techniques. According to the DSC analysis, the glass transition temperature of 159 °C is observed for PVP/MWCNT-COOH (5% w/w). The addition of MWCNT-COOH (5% W/W) to PVP increases the thermal stability of PVP to 400 oC which was indicated in TGA thermogram.The FT-IR spectra showed the hydrogen bonding has been takes place between MWCNT-COOH and PVP in the PVP/MWCNT-COOH (5% w/w) nanocomposite. The SEM images of the PVP/MWCNT-COOH (5% w/w) nanocomposite clearly exhibited the presence of MWCNT-COOH in PVP polymer matrix.

This paper presents the results of a national research project entitled “Production and quality control of copper-62/zinc-62 radiopharmaceutical generators for positron emission tomography purposes “which has been implemented for the first time in the nuclear science and technology research institute. In this project, after verifying various nuclear codes for cyclotron production, multiple purification chemical reactions and target plating using tetrachloroauric acid,, The industrial scale of  zinc-62 chloride (5 Curie per production) with purity of 99/98% was prepared.Quality control of the prepared radionuclide was done after the production process. Then, the products were loaded on three different types of generators and was ready to send to nuclear medicine centers for clinical use.

Activated carbon is produced from pyrolysis of plant material containing carbon and is undergoing activation. In this study, citrus, olive and tamarisk’s woods is used as raw materials to produce activated carbon, all samples were prepared from Darab city. The density measurement and moisture content and chemical analysis (cellulose, lignin, extractives, and ash) and also thermal analysis of wood samples show that there is no relation between carbon content with chemical analysis, but carbon content directly related to the density which is verified by DSC-TGA. Also, it has been seen that the thermal degradation of olivewood has been carried out at higher temperatures. The activated carbon was produced from wood samples in three methods, without activation, with physical activation (with steam) and chemical activation (with zinc chloride), and their properties (such as free surface by BET, iodine number, thermal analysis and SEM) show that. The activated carbon produced by chemical activation is more stable than other methods.In the case of activated carbon from citrus wood, the Iodine number of chemically activated carbon is observed chemically activation has significant difference compared to other methods of activation. With increasing amounts of chemical activation agent from 50 to 100%, the iodine number and surface area will increase, but increasing of this parameter from 100% to 150% has no significant effect on that properties. The maximum iodine number and BET for activated citrus wood with 150% ZnCl2 have resulted relatively 980.97 and 1050.22. The comparison of activated carbon from olive wood relative to other woods shows that olive carbon active has better characterization in all methods of activation. It also can be seen the thermal resistance of olive activated carbon is more than other woods.

The purpose of this study was to optimize the granulation process of sodium percarbonate in a top spray conical fluidized bed. Granular particles are obtained by coupling fluidized particles with a solution of sodium percarbonate, and the physical properties of the granules, such as particle size and their distribution, can be increased. The variables studied in the design of experiment were the fluidization air temperature (T), the spraying pressure (P), the amount of soluble solvent (M), and the concentration of the binding solution (C). Response surface methodology (RSM) was carried out using Design Expert 7 software. The results showed that by increasing the fluidization air temperature and the spraying pressure, the particle size decreased and the particle size increased with increasing solubility and binding concentration. RSM method is able to determine the range for the best production conditions for an acceptable granule size. In this study, an experimental correlation was presented for the size of the granule, in terms of the variables.

Three new organic days have been synthesized with phenothiazine as the electron donor group and cyanoacrylic acid, thioxothiazolidin and tetrazole as the electron acceptor anchoring group. The proposed dyes were sensitized from phenothiazine as the starting material by standard reactions and characterized by different techniques such as melting point, FT-IR, 1HNMR, elemental analysis and UV-Visible spectroscopy after purification. Spectrophotometric measurements of the synthesized dyes in solution and on a TiO2 substrate were carried out in order to assess changes in the status of the dyes. The wavelengths of maximum absorption for synthesized dyes in solution are 415 nm, 432 nm and 448 nm and on TiO2 films are 440 nm, 456 nm and 471 nm, respectively. Finally, the proposed dyes used as a sensitizer in a dye solar cell structure and their photovoltaic properties investigated. The Conversion efficiencies for organic dyes are 3.15%, 5.29% and 5.79%, respectively.

The ability to control sand production wells in oil reservoirs in the world is a big industrial challenge. Therefore, so many efforts have been made by using different methods to reduce the amount of produced sand and subsequently to increase the amount of oil production. In this study, in order to control sand production, the hydrogel injected as a chemical method have been used for the formation strength as a new method. Hydrogels were prepared from Acrylamido Propyl Sulfonated Acid as polymers and chromium (III) acetate as a crosslinker, ensuring their injectivity ability were used for the consolidation of sand in the reservoir. In order to select and design the suitable hydrogel structure of the polymer andthe crosslinker focusing on gelation time, lifetime, injectivity into the sand bed capacity and gel strength, some experiments such as bottle, rheology and compressive strength tests were performed. Finally, the efficiency of the selected hydrogel was evaluated by applying the sand packed core-flooding tests to reduce sand production. The results showed that the compressive strength increased about 20 times after injection of 1 pv hydrogel. In addition, the hydrogel injection decreased the sand production by 90%. However, water permeability decreased in sand packed 77 times after polymer gel injection and 4 times for oil permeability. Due to the severe reduction in water permeability of the sand packed, hydrogel with double efficiency can be used to reduce the water production and control the sand production in oil and gas reservoirs. Keywords Hydrogel; Gelation time; Sand production; Rheology; Gel strength; Coreflooding The ability to control sand production wells in oil reservoirs in the world is a big industrial challenge. Therefore, so many efforts have been made by using different methods to reduce the amount of produced sand and subsequently to increase the amount of oil production. In this study, in order to control sand production, the hydrogel injected as a chemical method have been used for the formation strength as a new method. Hydrogels were prepared from Acrylamido Propyl Sulfonated Acid as polymers and chromium (III) acetate as a crosslinker, ensuring their injectivity ability were used for the consolidation of sand in the reservoir. In order to select and design the suitable hydrogel structure of the polymer andthe crosslinker focusing on gelation time, lifetime, injectivity into the sand bed capacity and gel strength, some experiments such as bottle, rheology and compressive strength tests were performed. Finally, the efficiency of the selected hydrogel was evaluated by applying the sand packed core-flooding tests to reduce sand production. The results showed that the compressive strength increased about 20 times after injection of 1 pv hydrogel. In addition, the hydrogel injection decreased the sand production by 90%. However, water permeability decreased in sand packed 77 times after polymer gel injection and 4 times for oil permeability. Due to the severe reduction in water permeability of the sand packed, hydrogel with double efficiency can be used to reduce the water production and control the sand production in oil and gas reservoirs. Keywords Hydrogel; Gelation time; Sand production; Rheology; Gel strength; Coreflooding The ability to control sand production wells in oil reservoirs in the world is a big industrial challenge. Therefore, so many efforts have been made by using different methods to reduce the amount of produced sand and subsequently to increase the amount of oil production. In this study, in order to control sand production, the hydrogel injected as a chemical method have been used for the formation strength as a new method. Hydrogels were prepared from Acrylamido Propyl Sulfonated Acid as polymers and chromium (III) acetate as a crosslinker, ensuring their injectivity ability were used for the consolidation of sand in the reservoir. In order to select and design the suitable hydrogel structure of the polymer and the crosslinker focusing on gelation time, lifetime, injectivity into the sand bed capacity and gel strength, some experiments such as bottle, rheology and compressive strength tests were performed. Finally, the efficiency of the selected hydrogel was evaluated by applying the sand packed core-flooding tests to reduce sand production. The results showed that the compressive strength increased about 20 times after injection of 1 pv hydrogel. In addition, the hydrogel injection decreased the sand production by 90%. However, water permeability decreased in sand packed 77 times after polymer gel injection and 4 times for oil permeability. Due to the severe reduction in water permeability of the sand packed, hydrogel with double efficiency can be used to reduce the water production and control the sand production in oil and gas reservoirs.