Akbar Irandoukht - Academia.edu (original) (raw)

Papers by Akbar Irandoukht

Energy Conversion and Management, 2008

This study describes the activated carbon (AC) preparation for methane storage. Due to the need f... more This study describes the activated carbon (AC) preparation for methane storage. Due to the need for the introduction of a model, correlating the effective preparation parameters with the characteristic parameters of the activated carbon, a model was developed by neural networks. In a previous study [Namvar-Asl M, Soltanieh M, Rashidi A, Irandoukht A. Modeling and preparation of activated carbon for methane storage: (I) modeling of activated carbon characteristics with neural networks and response surface method. Proceedings of CESEP07, Krakow, Poland; 2007.], the model was designed with the MATLAB toolboxes providing the best response for the correlation of the characteristics parameters and the methane uptake of the activated carbon. Regarding this model, the characteristics of the activated carbon were determined for a target methane uptake. After the determination of the characteristics, the demonstrated model of this work guided us to the selection of the effective AC preparation parameters. According to the modeling results, some samples were prepared and their methane storage capacity was measured. The results were compared with those of a target methane uptake (special amount of methane storage). Among the designed models, one of them illustrated the methane storage capacity of 180 v/v. It was finally found that the neural network modeling for the assay of the efficient AC preparation parameters was financially feasible, with respect to the determined methane storage capacity. This study could be useful for the development of the Adsorbed Natural Gas (ANG) technology.

Reaction Kinetics and Catalysis Letters, 2006

Page 1. Jointly published by React.Kinet.Catal.Lett. Akadémiai Kiadó, Budapest Vol. 88, No. 1, 12... more Page 1. Jointly published by React.Kinet.Catal.Lett. Akadémiai Kiadó, Budapest Vol. 88, No. 1, 127−133 (2006) and Springer, Dordrecht DOI:10.1556/RKCL.88.2006.1.17 0133-1736/2006/ US$ 20.00. © Akadémiai Kiadó, Budapest. All rights reserved. RKCL 4800 ...

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 2010

Hydrocracking is a very important refining process used to upgrade low cost vacuum gas oil (VGO) ... more Hydrocracking is a very important refining process used to upgrade low cost vacuum gas oil (VGO) into precious products like gasoline and diesel. In this present work, the hydrocracking of VGO using a dual functional amorphous catalyst is studied. Hydrocracking is carried out at pilot plant scale under the following reaction conditions: pressure of 156 bar, hydrogen-to-oil ratio of 1780 Nm3/Sm3, LHSV from 0.5 to 2 h-1 and temperatures from 380 to 440°C. The effluent of the reactor based on the most value added products is characterized to dry gas, light naphtha, heavy naphtha, kerosene, diesel and unconverted VGO. Then, a 6-lump discrete lumping approach with a hydrocracking reaction scheme with 15 reactions is developed for the prediction of the yield of hydrocracking products. The pilot tests demonstrated that performing experiments beyond the recommended temperature and LHSV by catalyst vendor not only shows unstable conditions but also changes the hydrocracking behavior of the catalyst. Then, to simulate the behavior of the reactor, two kinds of models, kinetic base model and neuro-fuzzy logic model, were developed to estimate the yields of hydrocracking products and simulate the behavior of the hydrocracking reactor. It is concluded that the fuzzy-logic approach is better than the kinetic base approach in the estimation accuracy, but the kinetic base approach can give information on the reaction path and functionality of the catalyst.

International Journal of Chemical Reactor Engineering, 2010

Hydrocracking is an important upgrading process in the petroleum refinery, and it is generally us... more Hydrocracking is an important upgrading process in the petroleum refinery, and it is generally used to process feedstocks ranging from vacuum gas oil (VGO) to vacuum residue. In this work, hydrocracking of VGO using a dual functional amorphous catalyst was carried out at a pilot scale unit under the following reaction conditions: liquid hourly space velocity (LHSV) from 1 to 1.5 hr-1 and reaction temperatures of 360-440°C at the constant pressure and hydrogen to oil, 156 bar and 1780 Nm3/m3, respectively. The effluent of the reactor was characterized to dry gas, naphtha, kerosene, diesel and unconverted VGO or residue. The pilot tests demonstrated that performing experiments beyond the temperature, recommended by catalyst vendor, lead the process to unstable hydrocracking. To describe the yield of hydrocracking products a five-lump discrete lumping approach with ten reactions was proposed. At first, the kinetic model contained twenty kinetic constants which were estimated by using t...

Reaction Kinetics and Catalysis Letters, 2003

The effect of calcination temperature on the activity and some properties of low temperature wate... more The effect of calcination temperature on the activity and some properties of low temperature water gas shift reaction catalysts has been investigated. The activities of catalysts have been determined using a fixed bed catalytic reactor. The following results may be deduced from the present study. 1. The catalysts' total surface area decreased with increasing calcination temperature, presumably due to the partial sintering of the catalysts particles. 2. The presence of an amorphous CuO phase within the structure of some catalysts may be related to the desirable conditions prevailing during synthesis of the latter. 3. Observation of a similar trend between the increase in copper crystallite particle size and enhancement of catalyst activities with increasing calcination temperature demonstrates the important contribution made by the copper crystallite phase to the overall activities of water gas shift reaction catalysts.

Afinidad, 2002

e effect of calcination temperature on the activity and some properties of low temperature water ... more e effect of calcination temperature on the activity and some properties of low temperature water gas shift reaction catalysts has been studied. It has been found that the catalysts' surface area decreased with increase incalcination temperature. The presence of an amorphous CuO phase within the structure of some catalysts has been related to the desirable conditions prevailed during the synthesis of the latter. The copper crystallite particle size has been observed to increase with temperature. The activities of catalysts have been determined using a fixed bed catalytic reactor. It has been observed that the catalyst's activities were normally enhanced with increase in temperature and pressure of the reaction systems.

International Journal of NanoScience and Nanotechnology, 2020

In this research, Ni-Mo/Cs1.5H1.5PW12O40/S (S=SiO2 or Al2O3 or ASA (amorphous silica alumina)) na... more In this research, Ni-Mo/Cs1.5H1.5PW12O40/S (S=SiO2 or Al2O3 or ASA (amorphous silica alumina)) nanocatalysts with different supports were prepared via 2 steps with impregnation method and the effect of support on the characteristic and catalytic properties of the prepared samples was studied. The synthesized samples were characterized by X-ray diffraction (XRD), temperature programmed desorption (TPD), temperature programmed reduction (TPR), and energy dispersive X-ray spectroscopy (EDX). Morphology of the samples was studied by field emission scanning electron microscope (FE-SEM) and the surface area, pore volume and pore size of the catalysts were determined by BET (Brunauer-Emmett-Teller) method. In the XRD patterns of the prepared catalysts, the H3PW12O40 (HPW) phase was observed. The FE-SEM images showed that the synthesized particles were in nanoscale. The results of TPD studies indicated that moderate acidic sites of Al2O3 supported nanocatalyst was more than the others. The ...

Mesoporous nanostructured γ-Al2O3 powders were synthesized through multi- step precipitation proc... more Mesoporous nanostructured γ-Al2O3 powders were synthesized through multi- step precipitation procedures using the pH-swing technique. Structural and morphological characteristics in addition to the thermal behavior of the procured samples were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FT-IR) spectroscopy, thermogravimetry-derivative thermal gravimetric (TG-DTG) and N2 adsorption–desorption isotherm. Plackett-Burman design was implemented as a screening method to examine the impacts of fifteen variables on physical properties of synthesized γ-Al2O3 as a response variable. Specific surface area, pore volume and average pore diameter of the prepared samples were found to be within the ranges of 72-335.7 m2/g, 0.26-1.03 cm2/g and 4.6-15.2 nm, respectively. It was determined that the variables including pH value on the acidic region, time in the alkaline region and number of pH-swing frequencies had m...

Chemical equilibria are dynamic in nature and at this condition the forward and backward reaction... more Chemical equilibria are dynamic in nature and at this condition the forward and backward reaction rates are equal. In chemical reacting systems including industrial reactors where the reversible reactions are taking place, prediction of infinity concentration or infinity pressure is practically important due to being involved in their kinetic models. Developed method can predict the infinity concentration or pressure in three steps with good accuracy. Having the limited timeconcentration data, at the first step the numerical values of the coefficients for logarithmic, power and exponential models are determined using non-linear regression technique. And the best model among them is then specified using statistical parameters. At the second step, the rate of change of concentration or pressure is computed using backward difference technique and the time required to reach equilibrium is estimated. Finally the value of infinity concentration or pressure is then computed with the aid of...

Catalysts containing copper, zinc and aluminum are widely used in hydrogenation and some other pe... more Catalysts containing copper, zinc and aluminum are widely used in hydrogenation and some other petrochemical processes. Among the latter are low temperature water - gas shift conversion and methanol synthesis at low pressure. In this paper, by using a special three-level experimental design, the effects of certain preparation parameters on crystalline phase of the catalysts for calcined and uncalcined precursors are discussed. The influence of such parameters on total surface area, copper metal surface area and also on reactor activity of the catalysts are also investigated.

Thin films of titanium dioxide with high surface area are prepared by sol-gel dip-coating techniq... more Thin films of titanium dioxide with high surface area are prepared by sol-gel dip-coating technique. In this regards, Titania nano sols with high photocatalytic activity were prepared by dissolving titanium alkoxide in alcohol and water under acidic conditions. Photocatalytic activities of titanium dioxide thin films were measured in the presence of methylene blue. Microstructure and photocatalytic activity of the films, nanopowders and titanium dioxide sols were investigated using X-ray diffraction, scanning electron microscopy, specific surface area, zeta sizer and ultraviolet-visible spectrometry techniques. Particle size analysis of sols showed that the mean particle sizes were 15 to 128 nm. X-ray diffraction analyses revealed that anatase crystal structure was produced with crystallite size below 11 nm. Increasing mass percent of anatase phase and specific surface area, enhance the photocatalytic activity. Scanning electron microscopy images showed that the addition of methylce...

Journal of Statistical Theory and Applications, 2021

AB S T R A C T The presence of the multicollinearity problem in the predictor data causes the va... more AB S T R A C T
The presence of the multicollinearity problem in the predictor data causes the variance of the ordinary linear regression coefficients
to be increased so that the prediction power of the model not to be satisfied and sometimes unacceptable results be predicted.
The ridge regression has been proposed as an efficient method to combat multicollinearity problem long ago. In application
of ridge regression the researcher uses the ridge trace and selects a value of ridge parameter in such a manner that he thinks
the regression coefficients have stabilized; this leads the ridge regression to be subjective technique. The purpose of this paper is
the conversion of the ridge regression method from a qualitative method to a quantitative one meanwhile to present a method
to find the optimum ridge regression parameter which maximizes the R-squared of prediction. We examined four well-known
case studies on this regard. Significant improvements at all of the cases demonstrated the validity of our proposed method.

Journal of Engineered Fibers and Fabrics, Jun 1, 2011

The water vapor transport properties of textile fabrics are of considerable importance in determi... more The water vapor transport properties of textile fabrics are of considerable importance in determining thermal comfort properties of clothing systems. There are different standard test methods available for measuring water vapor transport properties of fabrics. They are either time consuming or expensive methods. Objective of this work is to determine water vapor transmission resistance of the fabric using other properties of the fabric in such a manner that one can predict water vapor resistance. Both linear and nonlinear models were considered and different measures of model adequacy including residual sum of square, maximum absolute deviation and average absolute deviation were calculated. Using linear regression techniques, several statistically acceptable linear models were developed. The results revealed that several non-linear models can predict the water vapor resistance better than linear models.

Journal of the Serbian Chemical Society

In this study, the effect of calcination temperature and Si/Al mole ratio on acidity and physicoc... more In this study, the effect of calcination temperature and Si/Al mole ratio on acidity and physicochemical properties of silica SBA-15 were investigated. Silica SBA-15 samples were calcined at 350, 450 and 550?C, and then post-synthesis, the Al-grafting method was applied to incorporate aluminum species into their framework with Si/Al mole ratio of 10 and 30. Characterizations using small angle XRD and N2 adsorption?desorption techniques indicated that the hexagonal mesoporous structure was retained after performing Al-grafting even at the high aluminum loading. Moreover, FTIR results implied that the aluminum species were incorporated into the SBA-15 framework. NH3-TPD results showed that by decreasing Si/Al mole ratio at all calcination temperatures, the number of weak acid sites increased in comparison to those of the pure SBA-15 samples. Additionally, the maximum total acidity of synthesized samples was observed at the calcination temperature of 450?C with Si/Al mole ratio of 30.

Journal of Engineered Fibers and Fabrics

The journal of applied research

Scientia Iranica

In this study, Response Surface Methodology (RSM) and Artificial Neural Network (ANN) predictive ... more In this study, Response Surface Methodology (RSM) and Artificial Neural Network (ANN) predictive models are developed, based on experimental data of the Oxidative Coupling of Methane (OCM) over Na–W–Mn/ SiO2 at 0.4 MPa, which was obtained in an isothermal fixed bed reactor. Results show that the simulation and prediction accuracy of ANN was apparently higher compared to RSM. Thus, the Hybrid Genetic Algorithm (HGA), based on developed ANN models, was used for simultaneous maximization of CH4 conversion and C2+ selectivity. The pareto optimal solutions show that at a reaction temperature of 987 K, feed GHSV of 15790 h−1, diluents amounts of 20 mole%, and methane to oxygen molar ratio of 3.5, the maximum C2+ yield obtained from ANN-HGA was 23.91% (CH4 conversion of 34.6% and C2+ selectivity of 69%), as compared to 22.81% from the experimental measurements (CH4 conversion of 34.0% and C2+ selectivity of 67.1%). The predicted error in optimum yield by ANN-HGA was 4.81%, suggesting that ...