Seyed Reza Nabavi | University of Mazandaran (original) (raw)

Papers by Seyed Reza Nabavi

Chitosan (CS) is a natural biopolymer that due to its excellent properties such as biocompatibili... more Chitosan (CS) is a natural biopolymer that due to its excellent properties such as biocompatibility and biodegradability is suitable for use in many applications. But, dependent on the molecular weight and other properties the electrospinning capability of CS is very weak. So, to solve this problem, it is recommended to blend it with a second polymer. In this work, CS/polyamide-6 (PA6) composite nanofibers were fabricated by electrospinning technique. Then different weight percentages of graphene oxide (GO) i.e. 0.1, 0.25, and 0.5 wt. % were used to improve the mechanical and thermal properties of composite nanofibers. The characterization results showed that uniform nanofibers were formed by electrospinning of the PA6/CS nanocomposites blend, and the addition of GO lead to the formation of spider-web-like morphology with decreasing of nanofibers diameter. Further, the GO can improve Young's module and thermal degradability of the PA6/CS nanofibers mat. Finally, the potential of...

رد یاه هدنیلاآ ناونع هب یصخش یاه تبقارم و ییوراد تلاوصحم تلاوصحم نیا روضح .دنا هدش هتخانش بآ عبان... more رد یاه هدنیلاآ ناونع هب یصخش یاه تبقارم و ییوراد تلاوصحم تلاوصحم نیا روضح .دنا هدش هتخانش بآ عبانم رد روهظ لاح تارثا )مرگونان ات ورکیم هدودحم رد( مک رایسب ریداقم رد یتح نونکات .دنک یم داجیا تشادهب و تسیز طیحم رب ار یبولطمان باسپ زا اهوراد فذح یارب یملع عبانم رد یدایز یاه شور شیاسکا یاهدنیآرف اه نآ نیرتمهم هک دنا هتفرگ رارق یسررب دروم یدیئورتسا یاهوراد زا %99 یلااب فذح( ینز نزا دنیآرف :ریظن هتفرشیپ ،)یباهتلادض و یبرچ هدننک میظنت ،اه کیتویب یتنآ ،یدیئورتساریغ و ،)نیلیسیسکومآ ریظن اه کیتویب یتنآ لماک بیرخت( نوتنفوتف و نوتنف ،)میرپوتمیرت و نیساسکلافا لماک فذح( یدیشروخ نوتنفوتف بیرخت( UV/H2O2 ،)نیساسکولفورپیس %100 فذح( زیلونوس شهاک یارب مه اب اهدنیآرف نیا بیکرت و )نیلیسیسکومآ لماک ینز نزا دنیآرف .تسا اه هنیزه ندرک مک هجیتن رد و شنکاو نامز یژولونکت کی ،نزا لوکلوم یلااب یگدننکدیسکا تردق لیلد هب یلومعم یاه شور اب هک تسا ییاه هدنیلاآ فذح رد هدننکراودیما ماجنا یاه شهوژپ هلاقم نیا رد .درک فذح بآ زا ار اه نآ ناوت یمن ییوراد یاه هدنیلاآ فذح یارب نزا رب ینتبم یاهدنیآرف هب طوبرم هدش ،نیا رب هولاع ...

Journal of Cleaner Production, Aug 1, 2022

Journal of Industrial and Engineering Chemistry, Sep 1, 2015

Abstract In order to attain to the higher selectivity of propylene in the process of methanol con... more Abstract In order to attain to the higher selectivity of propylene in the process of methanol conversion to propylene (MTP) over H-ZSM-5, the bi element catalysts were prepared by Mn/H-ZSM-5 and each of Ce, Cr, Fe, P and Ni promoters. The results revealed that the Ce–Mn/H-ZSM-5 demonstrated the highest selectivity to propylene. Response surface methodology was applied to optimize the preparation parameters (second metal loading, calcination temperature and calcination time) of the bimetallic Ce–Mn/H-ZSM-5 catalyst. Kinetic modeling is performed in the reaction temperature range of 440–500 °C and in the different weight hourly space velocities of methanol (i.e., 2.51, 4.18 and 8.37 h−1). A reaction mechanism based on the theory of hydrocarbon pool and conjugate methylation/cracking mechanisms is applied for the MTP. The hybrid genetic algorithm is employed to calculate the kinetic parameters.

Journal of the Taiwan Institute of Chemical Engineers, 2016

Abstract To enhance the propylene selectivity in catalytic conversion of methanol to propylene (M... more Abstract To enhance the propylene selectivity in catalytic conversion of methanol to propylene (MTP), the bimetallic catalysts were prepared by Mn/H-ZSM-5 with second metal of Ce, Cr, Fe and Ni. In order to design the bimetallic catalysts (M-Mn/H-ZSM-5; M: Ce, Cr, Fe and Ni) and to optimize the propylene selectivity, an artificial neural network (ANN) model was linked with genetic algorithm (GA). Investigation of the optimal catalyst preparation conditions (wt. % of second metal loading, calcination temperature and calcination time) and the atomic descriptors of second metal (electronegativity, melting enthalpy, atomic weight and ionization energy) were carried out by the ANN-GA model simultaneously. The model predicted that the maximum propylene selectivity was produced via Ce-Mn/H-ZSM-5 with the following catalyst preparation conditions: 2.46 wt. % of Ce loading, calcination temperature of 486 °C and calcination time of 4 h. The optimized propylene selectivity of model prediction and the experimental value were 54.3% and 54.8% respectively. The catalyst samples were characterized by XRD, FE-SEM, FT-IR, N 2 adsorption/desorption, NH 3 -TPD and ICP-AES.

The activity of the H-ZSM-5 was modified by the addition of Ca, Mn, Cr, Fe, Ni, Ag, Ce and P. The... more The activity of the H-ZSM-5 was modified by the addition of Ca, Mn, Cr, Fe, Ni, Ag, Ce and P. The highest selectivity of propylene was obtained over the Mn/H-ZSM-5 catalyst. The Mn modified catalyst was selected as the optimal catalyst and the kinetic study was carried out on it. All of the experiments were carried out in an isothermal fixed bed and plug flow reactor with the mixture of methanol and water. The temperature range was 400-550 °C and the weight hourly space velocities (WHSV) of methanol were: 2.51, 5.42, and 8.17 h-1. A reaction mechanism based on the theory of hydrocarbon pool and conjugate methylation/cracking mechanisms was proposed. The behavior of the reactor was mathematically modeled and the hybrid genetic algorithm was applied to estimate kinetic parameters. Good agreement was observed between the experimental and the calculated data. Effect of temperature on propylene selectivity was also investigated. It was found that the propylene selectivity steadily increases with temperature.

In the present study, nano zeolite A (LTA) was synthesized by the alkaline fusion method without ... more In the present study, nano zeolite A (LTA) was synthesized by the alkaline fusion method without adding an organic template. Effect of temperature and aging time were studied on the crystallinity and morphology of the final product. The synthesized LTA was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and N2 adsorption/desorption technique. The prepared nano LTA zeolite was applied to the water softening process. The main effects and interaction of factors such as pH, the amount of LTA, initial total hardness, temperature and contact time were investigated by response surface methodology (RSM). The obtained optimum values of factors were applied to hard water to remove Ca2+ and Mg2+ ions. Pseudo-first and second-order models were applied to kinetic and rate data. It was found tha...

The steam cracking reactions are always accompanied with the formation of coke which deposits on ... more The steam cracking reactions are always accompanied with the formation of coke which deposits on the walls of the tubular reactors. The investigation has attempted to control catalytic coking by the applying aluminum, zinc and ceramic coating like aluminum-magnesium by thermal spray and pack cementation method. Rate of coke formation during steam cracking of naphtha has been investigated both for uncoated stainless steel (with different alloys) and metal coating constructed with thermal Spray and pack cementation method with metal powders of Aluminum, Aluminum-Magnesium, zinc, silicon, nickel and chromium. The results of the study show that passivating the surface of SS321 with a coating of Aluminum and Aluminum-Magnesium can significantly reduce the rate of coke deposition during naphtha pyrolysis. SEM and EDAX techniques (Philips XL Series) were used to examine the coke deposits formed by the metal-hydrocarbon reactions. Our objective was to separate the different stages by identi...

This work aims to test the application of computational fluid dynamics (CFD) modeling to fixed be... more This work aims to test the application of computational fluid dynamics (CFD) modeling to fixed bed catalytic cracking reactors. Studies of CFD with a fixed bed design commonly use a regular packing with N=2 to define bed geometry. CFD allows us to obtain a more accurate view of the fluid flow and heat transfer mechanisms present in fixed bed equipment. Naphtha was used as feedstock and the reactor length was 80cm. It is divided in three sections that catalyst bed packed in the middle section of the reactor. The reaction scheme was involved one primary reaction and 24 secondary reactions. Because of high CPU times in these simulations, parallel processing have been used. In this study the coke formation process in fixed bed and empty tube reactor was simulated and coke in these reactors are compared. In addition, the effect of steam ratio and feed flow rate on coke formation was investigated.

International Journal of Hydrogen Energy, 2017

In this work, nickel oxide nanofibers (NiO-NFs) are produced by electrospinning method and calcin... more In this work, nickel oxide nanofibers (NiO-NFs) are produced by electrospinning method and calcination in air for 5 h. The thermal gravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and electrochemical impedance spectroscopy (EIS) are used for characterization of the NiO-NFs. The FE-SEM images of the precursor indicate that a large quantity of nanofibers with diameters ranging from 100 to 150 nm with tens of micrometers in length can be acquired. Also, the results show that rough NiO-NFs having large specific surface area are composed of the small nanoparticles. After calcination, the nanofibers are composed of cubic structure. The EIS study shows that the value of charge-transfer resistance of the NiO-NFs modified carbon paste electrode (NiO-NFs/CPE) is much smaller than that CPE, indicating a faster electron-transfer process. The NiO-NFs are used as potential catalysts for electro-catalytic oxidation of ethylene glycol (EG) in 0.2 M NaOH solution. The results demonstrate that the NiO-NFs/CPE reveals good electro-catalytic activity towards EG oxidation, showing a suitable stability and robustness.

Journal of the Taiwan Institute of Chemical Engineers, 2014

ABSTRACT Modeling and optimization of catalytic oxidation of 2-propanol over LaMnyCo1−yO3 nano pe... more ABSTRACT Modeling and optimization of catalytic oxidation of 2-propanol over LaMnyCo1−yO3 nano perovskites was carried out by an unreplicated mixture–process experimental design and genetic algorithm methodologies, respectively. Mixture variables were the components of perovskites in B sites: cobalt and manganese. The process variables were calcination temperature and reaction temperature. An eight term statistical model was proposed to fit the experimental data with determination coefficient of 0.982. The effect of composition and process variables on 2-propanol conversion and interaction of variables was studied by the model. It was found that the activity of nano perovskites increases with a decrease in calcination temperature and an increase in Mn mole fraction in the catalyst. Full conversion of 2-propanol was predicted to occur over LaMn0.65Co0.35O3 at calcination and reaction temperatures of 700 and 273 °C, respectively. The structure of nano perovskites was characterized by XRD and FTIR and the morphology was investigated by SEM technique.

A series of experiments were carried out by mixture of methanol and water as feed of the methanol... more A series of experiments were carried out by mixture of methanol and water as feed of the methanol to propylene (MTP) process in temperature range of 623-823 K. The H-ZSM5 catalyst with the Si/Al ratio of 200 was applied for carrying out the experiments. A novel lumped kinetic scheme was proposed for methanol to propylene (MTP) process. The reactor was mathematically modeled by assumptions of being isothermal, fixed bed, plug flow and the hybrid genetic algorithm was applied for estimating the kinetic parameters. The temperature dependency of the kinetic parameters was determined, using the modified Arrhenius relation. A good agreement was observed between the experimental and the calculated data. Effect of temperature on propylene and ethylene selectivity was investigated. It was found that the propylene selectivity increases with temperature until 773.15 K, but after that it decreases.

Journal of the Taiwan Institute of Chemical Engineers, 2013

The optimal design of new heterogeneous catalysts for developing new processes or optimization of... more The optimal design of new heterogeneous catalysts for developing new processes or optimization of available catalysts formulations for obtaining higher yields of desired products is the ultimate goal in catalyst design. But because of many parameters that affect catalyst performance, catalyst design is a tedious and complex process involving many steps, numerous variables, and complex interactions among these variables, which render the experimental studies quite expensive and time-consuming [1]. Thus soft computing techniques were used in catalyst design for guiding the selection of experiments that are most worthy of study or enabling the design of new catalysts with reducing time and operating costs. Furthermore developing new techniques that are popular and have better performance is noteworthy. Because of the capability of artificial neural networks (ANNs) in function approximation and that of genetic algorithm (GA) in searching of large, complex, poorly understood spaces, the combination of ANNs and GA has been used for the modeling and optimization of performances of catalysts by many researchers [2-11]. Baumes et al. [11] for the first time have developed the concept of virtual screening of materials using neuro-genetic approach for reducing the number of catalysts that should be tested experimentally. They introduced a new methodology for boosting primary screening in heterogeneous catalysis to discover the best promising catalysts in Water Gas Shift (WGS) reaction. After them the studies have continued for using atomic descriptors for predicting catalysts performances, since in some cases this approach was successful but because of the heterogeneity of catalysts, in some cases it was not able to get the appropriate catalyst. A comprehensive review of the literature that deals with such methods has been reported by Farrusseng [12]. Recently we used a combination of descriptors and experimental factors for design of bi-metallic Ag-ZSM-5 catalysts for catalytic oxidation of volatile organic compounds [13]. Catalytic conversion of methanol to gasoline range hydrocarbons (MTG) is considered one of the widely used technologies for production of high-octane gasoline from biomass, natural gas, and coal. Methanol is normally produced from synthesis gas (CO + H 2) through gasification of biomass, coal, or steam reforming of natural gas. The obtained methanol is then converted to hydrocarbons (gasoline, olefins, etc.) using a zeolitic catalyst. A good review of the results of many studies on methanol to hydrocarbons conversion has been given by Stö cker [14].

Petroleum Science and Technology, 2008

... Coke formation in steam crackers for ethylene production. Chem. Eng. Process., 41: 199–214. [... more ... Coke formation in steam crackers for ethylene production. Chem. Eng. Process., 41: 199–214. [CrossRef], [Web of Science ®]; 5. Das, P., Prasad, S. and Kunzru, D. 1992. Organo phosphorous compounds as coke inhibitors during naphtha pyrolysis. ...

Journal of Industrial and Engineering Chemistry, 2012

ABSTRACT A neural network model was coupled with genetic algorithm to find an optimal catalyst fo... more ABSTRACT A neural network model was coupled with genetic algorithm to find an optimal catalyst for elimination of volatile organic compounds (VOCs). The model was based on simultaneous investigation of catalyst formulation, preparation condition, and loaded metal atomic descriptors as representative of each metal, which enables us to evaluate catalyst composition with much fewer experimental data. We have investigated oxides of first transition metal series (V, Cr, Mn, Fe, Co, Ni, Cu and Zn) as a promoter for Ag-ZSM-5 catalyst. Three optimum catalysts, Fe–Ag-ZSM-5, Ni–Ag-ZSM-5, and V–Ag-ZSM-5 were found to have more catalytic activity for VOC (ethyl acetate) oxidation than Ag-ZSM-5.

Journal of Industrial and Engineering Chemistry, 2013

Optimization of 2-propanol oxidation over CuMn m Co 2Àm O 4 nanospinels was carried out by a spli... more Optimization of 2-propanol oxidation over CuMn m Co 2Àm O 4 nanospinels was carried out by a split design method. 15-term model was proposed to fit the experimental data. The model revealed that both whole plot and subplot variables have significant effects on conversion of 2-propanol. The model predicted the interaction of subplot and whole plot variables as well as their importance. The maximum conversion of 2-propanol was observed over CuMn 2 O 4 (x 1 = 0.33, x 2 = 0, x 3 = 0.67) at calcination and reaction temperatures of 800 8C (z 1 = 1) and 300 8C (z 2 = 1), respectively. The predicted response and the response obtained from experiment for optimum conditions were 93.36 and 96, respectively.

Journal of Analytical and Applied Pyrolysis, 2007

ABSTRACT A three layer perceptron neural network, with back propagation (BP) training algorithm, ... more ABSTRACT A three layer perceptron neural network, with back propagation (BP) training algorithm, was developed for modeling of thermal cracking of LPG. The optimum structure of neural network was determined by a trial and error method and different structures were tried. The model investigates the influence of the coil outlet temperature, steam ratio (H2O/LPG), total mass feed rate and composition of feed such as C3H8, C2H6, iC4, and nC4 on the thermal cracking product yields. Good agreement was found between model results and industrial data. A comparison between the results of mathematical model and designed neural networks was also conducted and ANOVA calculation was carried out. Performance of the neural network model was better than mathematical model.