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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Inorganic Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Phosphine,Ullmann cross-coupling,Palladium catalyst,Hammett correlation,Mechanistic study
- چکیده:
- چکیده انگلیسی: Catalytic activity of a Pd/biphenyl based- phosphine system in the Ullmann cross-coupling reaction of various para-substituted aryl bromides were investigated. The results showed that the bulky electron-rich phosphine efficiently modify the electronic and steric properties of palladium center and promote the cross-coupling reaction. Mechanistic study using the Hammett correlation revels that electron-withdrawing substituents decrease the electron density at the palladium center and decrease the rate of oxidative-addition step such that this step will become the rate determining step (rds). On the other hand, electron-donating groups increase the rate of oxidative-addition step such that the reductive-elimination step will become the rds.
- انتشار مقاله: 19-04-1399
- نویسندگان: Sara Eavani,Ehsan Azadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Physical Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Sol-gel method,Syngas,Fischer-Tropsch synthesis,Co/Fe nano catalyst
- چکیده:
- چکیده انگلیسی: The SiO2 supported cobalt-iron nano catalysts were prepared by the sol-gel method. This research investigated the effects of (Co/Fe) wt.%, different Co/Fe ratio at different temperature and loading of KCl wt.% for Fisher-Tropsch synthesis (FTS). The results were showed that the catalyst containing 50 wt.% (Co/Fe)/SiO2 (Co/Fe ratio is 70/30) which promoted with 0.6 wt.% KCl is an optimal nano catalyst for conversion CO+H2 to a range of hydrocarbons especially light olefins. Also the results showed that optimal operating conditions for optimal nano catalyst are 250 °C, H2/CO molar ratio 2/1 under 1 bar of pressure. Characterization of catalyst precursors and calcined catalysts were done by different methods such as: powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 physisorption and thermal analysis methods such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).
- انتشار مقاله: 18-09-1396
- نویسندگان: Mostafa Feyzi,Mohammad Joshaghani,Shirin Nadri
- مشاهده
- جایگاه : پژوهشی
- مجله: Physical Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Bitumen,Ash removal,Pyrite sulphur removal,Column Flotation process
- چکیده:
- چکیده انگلیسی: An efficient method was employed for the ash and pyrite sulphur removal from bitumen using column flotation process. The bitumen samples containing 9.6% sulphur (6.81% in the pyrite sulphur form) and 26.4% ash were successfully showed up to 75.20% of pyrite sulphur (e.g.; 51.66% of total sulphur) and 70.81% of ash removal. The Box-Behnken Design (BBD) was employed to design the experiments, to optimize and evaluate the individual and interactive effects of six effective independent factors: the amounts of collector and frother agents, solid weight percentage in the pulp, particle size, wash water rate and feed rate. In order to investigate system a laboratory scale rig was built. In all experiments, pine oil and kerosene were considered as frother and collector agents, respectively. The best result for column flotation process were amount of collector (1.5 kg/tbitumen), amount of frother (0.3 ppm), pulp content (10% of solid), particle size (100 mesh), wash water rate (0.4 L/min), feed rate (1.5 L/min) and flotation time (10 min). The coefficient of determination, R2, showed that the RSM model can specify the variations with the accuracy of 0.924 and 0.938 for the percentage of ash and pyrite sulphur removal from bitumen, respectively.
- انتشار مقاله: 22-05-1395
- نویسندگان: Yasser Vasseghian,Mojtaba Ahmadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Particle Science & Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Bitumen,Ash removal,Pyrite sulphur removal,Column Flotation process
- چکیده:
- چکیده انگلیسی: This study investigates removing ash and pyrite sulphur from bitumen by column flotation process. Central composite design (CCD) of response surface methodology (RSM) was applied for modeling and optimization of the percentage of ash and pyrite sulphur removal from bitumen. The effects of five parameters namely the amounts of collector and frother agents, particle size, wash water rate and feed rate on percentage of ash and pyrite sulphur removal from bitumen were investigated. The used bitumen sample has 26.4% ash and sulphur content of 9.6% (6.81% in the pyrite sulphur form). All the tests were carried out under aeration rate of 4L/min and pulp containing 5% of solid using pine oil and kerosene as frother and collector agents, respectively. The coefficient of determination, R2, showed that the RSM model can specify the variations with the accuracy of 0.971 and 0.975 for ash and pyrite sulphur removal from bitumen, respectively, thus ensuring a satisfactory adjustment of the model with the experimental data. The RSM was used to optimize the process conditions, which showed that initial amount of collector of 2.00kg/tbitumen, amount of frother of 0.2ppm, particle size of 101.29mesh, wash water rate of 0.5L/min and feed rate 1.26L/min were the best conditions. Under the optimized conditions, the maximum percentage of ash and pyrite sulphur removal from bitumen was 88.74% and 90.89%, respectively.
- انتشار مقاله: 21-02-1395
- نویسندگان: Yasser Vasseghian,Mojtaba Ahmadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Potentiometry,Complex formation,Stability constant,2-Amino pyridine,Wilson’s disease
- چکیده:
- چکیده انگلیسی: The complexation reactions of some transition metal ions and 2-aminopyridine (2-ampy) were studied potentiometrically in aqueous solution at µ=0.1 M and 25 °C. The overall stability constants log β’s of all species are obtained by computer refinement of pH-volume data with using the BEST computer program. Several models were tested and the best one accepted according to the least sum of squared deviations. The main species are MHL, ML, ML2, ML3, and ML2(OH)2. For ML complexes the order of stability confirms the Irwing-Williams series.
- انتشار مقاله: 10-07-1380
- نویسندگان: Mohammad Joshaghani,Masoud Sotodehnejad
- مشاهده
- جایگاه : پژوهشی
- مجله: Inorganic Chemistry Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Phosphine,Ullmann cross-coupling,Palladium catalyst,Hammett correlation,Mechanistic study
- چکیده:
- چکیده انگلیسی: Catalytic activity of a Pd/biphenyl based- phosphine system in the Ullmann cross-coupling reaction of various para-substituted aryl bromides were investigated. The results showed that the bulky electron-rich phosphine efficiently modify the electronic and steric properties of palladium center and promote the cross-coupling reaction. Mechanistic study using the Hammett correlation revels that electron-withdrawing substituents decrease the electron density at the palladium center and decrease the rate of oxidative-addition step such that this step will become the rate determining step (rds). On the other hand, electron-donating groups increase the rate of oxidative-addition step such that the reductive-elimination step will become the rds.
- انتشار مقاله: 19-04-1399
- نویسندگان: Sara Eavani,Ehsan Azadi,Mohammad Joshaghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Nanochemistry
- نوع مقاله: Journal Article
- کلمات کلیدی: Electrical explosion of wire,Aluminum nanoparticles,Alumina nanoparticles,Design of experiments
- چکیده:
- چکیده انگلیسی: Aluminum nanoparticles (AlNPs) and aluminum oxide (AlONPs) nanoparticles were selectively produced in large quantities by the electrical explosion of wire (EEW) process in different conditions. Transmission electron microscopy (TEM), laser particle size analyzing, X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy were carried out to characterize the purity, morphology, particle and crystallite size of the nanoparticles. The effects of wire diameter, feed rate, electrode distance, pulse time, voltage, carrier gas pressure, and fan pressure in the exploding wire chamber on the particle size were analyzed by a preliminary Taguchi design of experiment. The results show that the wire diameter, feed rate, pulse time, voltage, and electrode distance are the main five factors. An ultimate response surface methodology (RSM) design showed the particle size increases with decreasing voltage and increasing other factors.
- انتشار مقاله: 24-03-1398
- نویسندگان: Maryam Darvishpour,Davoud Yazdani,Mostafa Faizi,Mohammad Joshaghani
- مشاهده