Journal of Applied Research in Chemistry
Year:2013 | Volume:7 | Issue:3|Papers Count:9

Environmental restrictions will force refineries to increase the severity in the operating conditions in order to match more stringent specifications. In the European Union, automotive fuels have to meet the so-called ultra-low sulfur (ULSD) specifications (10 ppm wt total sulfur in diesel), which are probably to be applied worldwide. In this research, production of ULSD from vacuum gas oil in a pilot scale plant is investigated. To perform experiments, the catalytic bed is charged with three layers consisting of hydrotreating, hydrocracking, and hydrotreating catalysts from top to the bottom, respectively. In comparison to the usual catalytic beds, third layer i.e., an excess hydrotreating section is added to the reactor. Results show that at the constant feed flow rate, hydrogen to hydrocarbon ratio, and pressure the yield of the hydrocracking increases versus temperature, and at the start of run temperature (about 4000C) the yield of naphtha, kerosene, and diesel is about 47%. Moreover, at this temperature, the sulfur content of diesel is about 10 ppm wt. It is concluded that the hydrogen consumption of the process is about 1.2 mass percent of vacuum gas oil feed that is in the range of the hydrogen consumption of commercial scale reactors.

In this study, the effect of chain orientation and nanosilicate layers orientation on solvent transport behavior of natural rubber (NR) was studied. Using the double network concept, orientation of natural rubber chain in the presence of nanosilicate layers and absence of nanosilicate layers were studied. In this regard, desired orientation in compounds was created by the tensile strain in the vulcanization step and effects of orientation on solvent sorption of natural rubber nanocomposites were studied. Orientation of the natural rubber chains by using anisotropic swelling test and morphological studies (X-ray diffraction and transmission electron microscopy) were evaluated. Transport properties of solvent, such as diffusion, sorption and permeability coefficients of toluene in natural rubber nanocomposites were measured. The effect of temperature on the solvent transport in the prepared nanocomposites in temperature range of 25-45oC was evaluated and temperature dependence of diffusion and permeability coefficients and diffusion mechanisms were identified. Also, thermodynamic parameters, such as activation energy, enthalpy and entropy changes for solvent transport process in prepared nanocomposites were investigated. Change of enthalpy for solvent sorption process in pure natural rubber presents dominant mechanism base on Henry type, while the addition of nanoclay into NR changes mechanism to the Langmuir mechanism. Base on solvent transport behavior of natural rubber, mode or state of chain and microstructure of prepared nanocomposites were evaluated indirectly. The results show that the chain orientation is more in the presence of nanoclay and this has a significant effect on the permeability behavior of natural rubber.

In presence of water and triethylamine, various aldehydes and ketones undergo a rapid and efficient Knoevenagel condensation with malononitrile derivatives to produce the respective a.b-unsaturated systems within short time periods in high yields. Products can be either stepwise or in situ employed in a Gewald reaction to give their respective 2-aminothiophenes after a few hours at room temperature.

In this report sulfuxamide derivatives of calixarene has been choosed from as capable molecular hosts. First of all chlorosulfunation reaction has been done an para teri butyle calix [4]arene and the obtained product has been reacted with para phenyle azo benzen and tetra aza sulfuxamide derivative of calixarene was prepared.The obtained product has been characterized by FTIR, 13CNMR, 1HNMR and TOF-MS techniques. The results showed the obtained product has stable cone conformation. The calixarene with large cavities and stable conformations can be used as capable molecular receptor in host-geant chemistry.

Due to the nature of photovoltaic in solar cells, the light-absorbing materials will only absorb certain energy level from photon. Therefore, tunable band-gap semiconductors are interesting for the fabrication of sensitized solar cells.  In this article the structural and electronic properties of rutile TiO2 quantum dots (QDs) as a function of the size for improving the efficiency of solar cells, are investigated via the first-principle method. Structural properties as total energies, and electronic properties such as density of states and HOMO-LUMO densities have been analyzed.

For increasing of the selectivity of mixed matrix membranes (MMM), we have used a new types of additives based on 5, 7, 11, 23-tetra-tert-butylcalix [4]arene which has been coated on the surface of TiO2 nanoparticles. The nanoparticles were characterized with FT-IR and photoluminesance experiments. The effect of TiO2 nanoparticles addition on mixed matrix membranes (MMMs) based on Pebax 1657 prepared by using solution-casting method has been investigated. Our results show that the modified membranes have increased the permeability and gas separation performance of CO2. The morphology of MMM was evaluated by Scanning Electron Microscopy (SEM), FT-IR and DSC.

Over the last 10 years, subcritical water is used as a solvent to extract a variety of organic compounds. Subcritical water extraction has a direct advantage over techniques that employ organic solvents to dissolve hydrophobic organic compounds. The aim of this paper is to review the literature that describes subcritical water as a solvent to solubilize organic compounds. Subcritical water extraction, measurement of the solubility of organic compounds in subcritical water, and the use of the solubility data in solubility modeling have been reported in the literature. Also, factors affecting extraction efficiency including temperature, chemical structure of the extract, kinetics of extraction, flow rate, degradation, pressure, and pH were investigated and various methods for solubility modeling of organic compounds in subcritical water such as empirical models, semi-empirical models based on pure component properties, the regular solution theory (RST) which is based on the solubility parameter concept, dielectric constant model, cubic-plus-association (CPA) equation of state, and universal functional activity coefficient (UNIFAC) based models were discussed as well.

In this article, the ability of Fe2O3-CuO magnetic nanocomposite was studied for adsorptive removal of Pb (II) ions from aqueous solution. Batch adsorption experiments were carried out to examine the effect of various parameters, such as pH, adsorbent dosage, time and initial concentration. Under optimum condition, the removal efficiency was 99%. The kinetic studies demonstrated that the equilibrium was reached after about 10 min of contact time and the best fit was achieved by the second order equation. The regeneration studies revealed that Fe2O3-CuO nanocomposite could be successfully reused. The effect of some foreign ions was also studied and the results showed no serious interferences. Adsorption parameters were determined using both Langmuir and Frundlich isotherms, but the experimental data fitted well with Langmuir model with maximum adsorption capacity of 333 mg/g.