Scientia Iranica
Volume:23 Issue: 3, 2016

LiCl-doped mesoporous silica MCM-48 with cubic mesostructure, using a di erent doping concentration of LiCl, has been prepared. The LiCl-MCM-48 type materials were characterized employing XRD, FT-IR, SEM, and nitrogen adsorptiondesorption isotherm. We had the humidity sensors on a ceramic substrate with two Ag-Pd interdigital electrodes with ve ngers. The sample with 15 wt% LiCl-doped MCM-48 shows an excellent linearity in the whole humidity range of 11%-97%. It has very good response and recovery time, about 22 and 30 sec, respectively.

The experimental X-ray charge density analysis of a hydrazone derivative was obtained by multipolar Hansen-Coppens formalism refinement through high resolution low-temperature X-ray diffraction data at 100(1) K and the results compared to its theoretical calculation data by Gaussian wavefunctions in connection to the AIM2000 program package. The molecular properties of the title compound resulted from the combined experimental and the quantum theory of atoms in molecules (QTAIM) studies. The topological properties of the covalent bonds, intramolecular and intermolecular interactions such as hydrogen bonding, ππ, C–HO and (NO2)NO(NO2) have been investigated.

The heterobinuclear platinum(0)-gold(I) complex [(t-Bu3P)2PtAu(PPh3)] BF4, 5, was synthesized by the reaction of trinuclear cluster complex f[(PPh3)Au]3(- O)gBF4, 4, with one equiv of [(t-Bu3P)2Pt] at room temperature. The heterobinuclear complex 5 was characterized using multinuclear NMR spectroscopy and elemental microanalysis and was further identi ed by single crystal X-ray structure determination. Crystal structure of 5 shows a T-shaped geometry with an unsupported short distance Pt-Au dative bond.

A new, efficient, and environmentally benign protocol for the one-pot, four-component synthesis of dihydropyrano[2,3-c]pyrazoles by condensation of ethylacetoacetate, hydrazine hydrate, aromatic aldehyde, and malononitrile catalyzed by3-methyl-1-sulfonic acid imidazolium chloride([Msim]Cl) as an ecofriendly catalyst with high catalytic activity and reusability at 30 0C under solvent-free conditions is reported. The reactions proceed to completion within 5–15 min in 87–97% yield.

Condensation of 2,5-dimethoxytetrahydrofuran and aniline derivatives has been carried out in aqueous media in the presence of mesoporoushydrogen sulfated MCM-41 (MCM-41-SO3H). The reaction is smoothly catalyzed by very low loading of heterogeneous MCM-41-SO3H to afford a wide variety of N-substituted pyrroles. This procedure is clean, environmentally friendly and has many advantages including short reaction time, high yields, low cost and simple work-up. The catalyst could be recycled at least 3 times without substantial decrease of its catalytic activity.

BF3/nano-sawdust as a green, inexpensive, natural, biodegradable and readily available biopolymer solid acid catalyst was synthesized and characterized. This catalystwas used successfully for the synthesis of various tri-substituted imidazoles in high yields under solvent free conditions.

A cost effective IPMC was fabricated by using recycled Flemion membrane from chlor-alkali industry. An even distribution of platinum particles on the surface and the bulk was shown by line SEM-EDX. Pt particles and the stiffness of the recycled IPMC were gradually increasing during impregnation-reduction process to form a conventional fractured metallic surface layer displaying discrete islands according to SEM photographs. A highly reproducible current-time diagram was obtained at even low voltages despite no observable motion and no offset current due to water electrolysis by chronoamperometry. However, the sensible motion was observed after 1.5 V with a significant increase in current and appearance of offset current developing with voltage. Due to capacitive characteristics of the recycled IPMC, peak current decreases with frequency linearly while the plateau current was observed only at low frequencies or time periods, Tp, longer than five times constant. The normalized maximum tip force generated at different voltages along with tip displacement and Young’s modulus were measured by load cell and compared with those of a Nafion-based IPMC (N-IPMC). Very close values were obtained confirming the recycling does not have a sensible effect on the mechanics of the recycled IPMC.

The preparation history of Al2O3 strongly determines its properties for the application as a catalyst support. The interaction of calcination heating rate and temperature and its influence on the structural, textural, and acidic properties of alumina were studied. Commercial-alumina was calcined at 800C, 900C, 1000C, 1050C, 1100C, and 1150C by 2.5C/min, 5C/min, and 10C/min. By increasing temperature up to 1050C, transition aluminas (, , and ) were reported, but the heating rate accelerated phase transformation and changed the amount of each phase in the samples. At 1100C and 1150C, -alumina appeared. Mesopore alumina with di erent surface areas (265-126 m2/g) was synthesized at calcination temperature from 800C to 1050C; when temperature reached 1100C, the surface area decreased drastically and was around 14 m2/g. Interaction of heating rate on the temperature had minimal e ect on the surface area of samples, but considerable e ect on the acidic properties. The intensity of acidic properties was a ected by heating rate with nonlinear pro les. By increasing the heating rate, the ratio of Al cations occupied tetrahedral per octahedral sites and defect of crystal structures increased, so the surface acidity of aluminas was increased.

The goals of this work are to synthesize and evaluate the potential of hydroxy sodalite membrane in the separation of helium from natural gas. Sodalite membrane was synthesized via direct hydrothermal method (conventional heating) on tubular alumina support. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and single gas permeation using helium and N2. After drying of the membrane, permeances of single gases were found to be of the order Helium > CH4 > N2 > CO2 at low temperatures and the membrane was impermeable to N2, CO2 and CH4 at high temperatures (>85 °C). In the investigated range of temperature 35-180 °C, membrane performance tended to high selectivity. The maximum separation factors (helium/N2 ~ 8.8, helium/CO2 ~ 16.5 and helium/CH4 ~ 5) with acceptable permeance were observed at 85 °C.

This study reports a reclamation method of ground tire rubber (GTR) and electronic wastes into a tunable stiffness composite namely magnetorheological elastomers (MREs). The composite matrix was the GTR that has been separated from its metals and yarns. Meanwhile, the fillers were fabricated from magnetic cores of the cathode ray tubes (CRTs) monitor waste through high energy ball milling in wet condition. Some physicochemical characterizations of the powders were initially conducted to collect the physical and chemical properties. Based on the examination, the ground powders were identified as pure magnetite (Fe3O4) having low remnant and high magnetization. The MREs samples were prepared by high-temperature high-pressure sintering. The mixed of crumb rubber and magnetite powder was vulcanized under simultaneous pressure, and temperature in the absence of magnetic fields resulted in an isotropic MREs type. The specimens were examined their abilities in responding to the external magnetic field through static and dynamic compression test. The experimental investigation showed that the static and dynamic stresses of the stiffness increased by the increment of magnetic fields until a particular point of flux density. The tunability of the stiffness indicated that the elastomers can provide wide ranges of the storage and loss modulus.

In this paper oxidation of the H2S into elemental sulfur over synthesized alumina-based nanocatalysts was physiochemically investigated and the results compared with a commercial Claus catalyst. The wet chemical, co-precipitation and spray pyrolysis techniques employed to synthesize several alumina nanostructures. Then, the SEM, XRD and ASAP analysis methods utilized to characterize in order to choose the best nanocatalyst. The sulfur andH2S contents determined through the standard UOP techniques. Amongst these as-synthesized materials, Al2O3-supported sodium oxide prepared through the wet chemical and Al2O3 nanocatalyst via spray pyrolysis methods were the most active catalysts for the purpose at hand. In addition, the titanium dioxide nanostructure and a hybrid of nano alumina support (made via the wet chemical method) decorated on the carbon nanotube prepared for this goal. Moreover, the statistical design of experiments screening of the significant synthesizing parameters performed through the Box-Behnken (e.g.;Response Surface Methodology (RSM)) technique. Ultimately, the best chemically characterized nanocatalyst was subjected to evaluations in a fixed bed reactor while effects of temperature, metal loading and GHSV understudied. It was observed that, the alumina nanoparticles prepared through the wet chemical and spray pyrolysis methods led H2S into elemental sulfur in a reproducible manner with 97 and 98% conversions, respectively. Both of these were more desirable than that obtained utilizing the commercial catalysts (i.e.: CR-3S and CRS-31) providing nearly 96% conversion.

The concentration and temperature behaviors of the self-diff usion coecient were analyzed in glycerol-water and methanol-water solutions using Di usion-Ordered Spectroscopy (DOSY) experiment. Our results indicate that the self-di usion coecient dips with increasing concentration and decreasing temperature. The concentration behavior shows that there is hydrogen bond interaction between water and alcohol, which declines the self-diff usion coecients of both in the aqueous binary mixtures. The self-diff usion activation energies were estimated 13.6, 29.4, and 32.8 (kJ/mol) for methanol and 24.8, 25.5, and 27.6 (kJ/mol) for water in the methanol-water solutions with 0.03, 0.10, and 0.20 mole fractions of methanol, respectively. The methanol self-di usion activation energy, in the very dilute methanol-water solution (0.03 mole fraction of methanol), is consistent with the formation of iceberg-like structure which helps methanol to di use quickly. The water self-diff usion activation energies indicate that water network is not signi cantly perturbed by methanol and the water molecules di use in the same manner in methanolwater solutions.

A simplified pore network model divided pore structure into cube lattices was developed base on the digital core extracted from micro computerized tomography (μ-CT) in this study. It rolled the complex topology and connectivity of pore structure into adjacent cubes. The static property of each cube was determined by the statistic CT data. The connectivity of adjacent cubes and flow regime were determined by the capillary pressure difference which is a function of tunnel size, interfacial tension, wet contact angle, and external pressure gradient. In this simplified pore network model, the flow capacity properties are determined by number and size distribution, mobile tunnels, and fluid viscosity. The flow velocity and sweep efficiency are non liner as mobile tunnels increase nonlinearly with increasing driving force before all tunnels start flowing. The critical pressure gradient that changes the non liner flow to liner flow was performed as the threshold pressure gradient. The dynamic mobile performance of oil in place (OIP) is determined by the number of mobile tunnels and their diameter distribution for different pressure gradient. The relationship of microscopic sweep efficiency, water cut and pressure gradient to oil recovery can be quantified by flow simulation in this pore network model.