Scientia Iranica
Volume:24 Issue: 3, 2017

Hydrogen uptake of MWCNT was enhanced via a two-step activation/deposition process. At the first step, MWCNT was chemically activated by KOH. The hydrogen uptake of the activated MWCNT was considerably higher than the pristine one. The BET analysis of the activated MWCNT demonstrated a great improvement in its textural properties compared to the pristine MWCNT. This was attributed to defects generated on its external surface during activation as evidenced by Raman and SEM analyses. At the second step, electroless deposition technique without any surface pretreatment was employed for preparation of Ni-MWCNT composite. The successful deposition of nickel onto the activated MWCNT was approved by the EDS analysis and its amount was determined by ICP spectroscopy which was 2.8 wt.% with respect to the Ni available in the electroless deposition bath. The maximum H2 storage capacity achieved by Ni doped MWCNT sample was ∼1 wt. % at 288 K and 45 bar.

Abstract Several complexes of alumaphosphinine ring with cations (Li, Na, K, Be2, Mg2 and Ca2) were optimized at the B3LYP/6-311(d,p) and the single point calculations were performed at the MP2/6-311(d,p) level of theory. Different aspects of the cation-π interaction including interaction energy calculations, charge transfer values, and the variations in the aromaticity of the ring upon complexation were also considered. Natural bond orbital (NBO) analysis was performed to calculate thecharge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules (QTAIM) was also applied to analyze the properties of the bond critical points in the complexes. Finally, Nucleus Independent Chemical Shift (NICS) method was applied for evaluating the variation of aromaticity of the alumaphosphinine ring induced upon complexation.

Catalytic activity of fly ash converted zeolite X (FAZ-X) material was investigated by means of copper oxide incorporation. All the catalysts were characterized by XRF, FTIR, SEM-EDX and BET methods. Activity of the prepared catalysts for wet oxidative degradation of methylene blue (MB) with hydrogen peroxide was investigated. Influence of pH, H2O2, concentration of dye, catalyst dosage and CuO loading on activity was investigated. Under the optimal condition (catalyst dose 250 mg/L, 100 ppm dye, pH = 6.8, 1 ml H2O2, room temperature) the degradation of MB was about 100% in 120 min by CuO/FAZ-X. Based on the degradation products identified by HPLC-(-ESI)-TOF-MS, the degradation pathways of MB were proposed. Concludingly, FAZ-X has certain role in MB degradation but CuO incorporation remarkably improved the catalytic activity of FAZ-X. Efficiency of the catalyst did not decrease very much even after six reaction cycles.

Thermolysis of the mixture of [CuMoO4(N2C12H8)].H2O and [Cu3ICl(4,4´-bipy)4][CuII(1,10-phen)2Mo8O26] (4,4´-bipy = 4,4´-bipyridine and 1,10-phen = 1,10-phenanthroline) coordination polymershas led to the formation of MoO3/CuMoO4 nanoparticles (NPs).The nanomaterial was characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, dynamic light scattering (DLS) and inductive coupled plasma optical emission spectroscopy (ICP-OES). The MoO3/CuMoO4 NPs were employed as heterogeneous catalyst in the epoxidation of olefins and allylic alcohols with tert-butyl hydroperoxide (TBHP) or cumene hydroperoxide (CHP) as oxidants in different solvents such as CHCl3, CH2Cl2 and CH3CN. The resulting catalyst displayed high activity and selectivity towards the epoxidation of olefins and allylic alcohols.

Fe3O4@SiO2-SO3H nanocatalysthas been used as an efficient catalyst for the preparation of pyrazolopyridines by a multicomponent reaction of ethyl acetoacetate, an aldehyde, hydrazine hydrate and ammonium acetateunder microwave irradiation. Atom economy, wide range of products, excellent yields in short times,using of microwave as green method, reusability of the catalyst and little catalyst loading are some of the important features of this protocol.

In this study, the performance of advanced oxidation process using titanium and iron oxides based on the natural zeolite (clinoptilolite) as nano photocatalyst was studied and the effects of various factors on the furfural degradation such as pH, dosage of catalyst, initial concentration of furfural and contact time were examined. The co-precipitation method was applied for the synthesis of nano photocatalyst. The SEM and XRD analyses showed a uniform distribution of titanium dioxide and iron nanoparticles on the zeolite.The furfural degradation could successfully happen at neutral to alkaline solutions. Moreover, increasing the amount of catalyst does not have significant effects on the degradation efficiency. By enhancement of the initial concentration of furfural, the rate of degradation decreases. The maximum efficiency of 98% could be achieved within 120 minutes.

Drilling Fluid is one of the most important and expensive aspects of any drilling process. Colloidal Gas Aphron (CGA) has been found e ective in controlling the ltration rate by bridging the pores of the reservoir rock; hence, reducing the formation damage. This work aims to synthesize the CGA in water based drilling Fluids to study the stability, rheology, ltration loss characteristics and formation damage properties of the resulting Fluid. Besides, an investigation on type of polymer, surfactant, and their concentration eff ects on the characteristics of the Fluid, as well as optimum ratios of polymers in drilling Fluid was performed. Experimental results showed that Xanthan Gum (XG) provides more acceptable rheological properties (especially viscosity) in comparison to Guar Gum (GG) for preparing the base Fluid. Moreover, the Sodium Dodecyl Sulfate (SDS) produces more stable micro-bubbles than Hexadecyl Trimethyl Ammonium Bromide (HTAB) as a surfactant. Bubble size measurement to observe the e ffect of polymer, surfactant type and concentration was performed. Through the experiments, the pH of the drilling Fluid was monitored which proved the CGA introduced the best performance around a pH of 9. Furthermore, a XG/GG ratio of 3:1 is suggested to reduce the cost while maintaining the Fluid properties.

Platinum containing sulfated zirconia (Pt-SZ/Al) catalyst was prepared by precipitation method. The characterization of prepared catalyst was performed using XRD and SEM and catalytic activity was studied for isomerization of nC5 at atmospheric conditions and temperatures of 180-240 C in a flow reactor. The effects of reaction temperature, H2/nC5 ratio and WHSV were investigated. As revealed by SEM and XRD, the prepared sulfated zirconia is nanoscale in size and has predominantly tetragonal crystalline phase. n-Pentane conversion increased with increasing temperature and selectivity decreased.The optimal reaction temperature was 220 C where n-pentane conversion and isopentane selectivity were 70 % and 94 %, respectively. The positive effect of H2/nC5 ratio was observed on nC5 conversion and iC5 selectivity in the investigated H2/nC5 ratio range. This trend of variation was related to the role of acid and metallic sites on the reaction pathway. As expected, increase in the WHSV which reduce contact time between reactant and catalyst, decreased nC5 conversion and increased selectivity toward iC5. The RON of the product increased with increasing temperature then showed slight decrease at higher temperature. The decrease in the activation energy was observed which can be attributed to thedifferent reaction mechanisms or different rate-determining steps.

The present work aims to employ the differential evolution (DE) algorithm to optimize ethylene oxychlorination process to produce 1,2-dichloroethane in a fluidized bed reactor as a feedstock of PVC production. A steady-state reactor model, based on the two-phase theory of fluidization, is developed to investigate the effect of various parameters on C2H4 and HCl conversions. The model results compared favorably with the industrial data obtained from a pilot plant working in Italy. The feed temperature, pressure, HCl and O2 molar flow rates, and cooling medium temperature are selected as decision variables to minimize an objective function subject to the environmental constraints. The highest performance was found at HCl/C2H4 and O2/C2H4 molar ratios of 2 and 0.55, respectively, pressure of 367.6 kPa, feed and cooling medium temperatures of 440 and 360 K, respectively. The results show a decrease of 20 oC in the feed temperature, which leads to saving energy and reducing the size of the pre-heater.

Conjugated linoleic acid (CLA) was produced from castor oil using washed cells of Lactobacillus plantarum PTCC 1058 and Lactobacillus plantarum subsp. plantarum PTCC1745as the catalyst. Under the optimal reaction conditions washed cells of Lactobacillus plantarum PTCC1058 produced 1661.26mg CLA/L reaction mixture (36% yield of production) from 4.6mg/ml castor oil after 121h using 15% (w/v) cell. The resulting CLA was a mixture of two CLA isomers, cis-9, trans-11 (or trans-9, cis-11)-octadecadienoic acid (CLA1, 44% of total CLA) and trans-10, cis-12-octadecadienoic acid (CLA2, 46% of total CLA).The total production of CLA is extracellular in all of the reactions performed with Lactobacillus plantarum PTCC1058AlsoLactobacillus plantarum PTCC1745produced 1590.31mg CLA/L reaction mixture (16.5% production yield) from 9.6mg/ml castor oil after 121h using 15% (w/v) cell. Therefore Lactobacillus plantarum PTCC1058 was suggested for CLA production due to more production ability and CLA extracellular production.

In this study, the ensemble Kalman filter is used to characterize three-phase flow in porous media through simultaneous estimation of three-phase relative permeabilities and capillary pressures from production data. Power-law models of relative permeability and capillary pressure curves are used and the associated unknown parameters are estimated by assimilating measured historical data. The estimation procedure is demonstrated on a twin numerical setup with two different scenarios, in which a synthetic 2D reservoir under three-phase flow is considered. In the first scenario, all the endpoints are assumed to be known and only the shape factors are estimated during the assimilation process. In the second, all the endpoints and shape factors are estimated by assimilating observed data. Accurate estimation of the unknown model parameters is obtained by assimilating oil, water, and gas production rates of the producers, and bottom hole pressure of the injector. Moreover, sensitivity analysis of the observations with respect to the parameters defining the relative permeabilities and capillary pressures shows that for the most sensitive parameters, better estimation and lower uncertainty are obtained at the end of the assimilation process.