http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Modeling and operating conditions optimization of Fischer–Tropsch synthesis in a fixed-bed reactor
Ali Akbar Mirzaei,Bahman Shirzadi,Hossein Atashi,Mohsen Mansouri 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
The effect of a range of operation variables such as pressure, low temperature and H2/CO molar feed ration the catalytic performance of 80%Co/20%Ni/30 wt% La2O3/1 wt% Cs catalyst was investigated. It was found that the optimum operating conditions is a H2/CO = 2/1 molar feed ratio at 260 8C temperature and 2 bar pressure. Reaction rate equations were derived on the basis of the Langmuir–Hinshelwood–Hougen–Watson (LHHW) type models for the Fischer–Tropsch reactions. The activation energy obtained was 59.69 kJ/mol for optimal kinetic model.
Akbar Zare,Mehdi Shiva,Ahad Zare,Ali Akbar Mirzaei 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6
The Co–Ni/Al2O3 catalysts prepared using impregnation procedure, were used for the Fischer–Tropsch synthesis. The effect of calcination conditions of the catalyst as well as reactor situation was studied. It was found that the catalyst calcined at 550 8C for 6 h in air atmosphere has shown the best catalytic performance for CO hydrogenation. The best operational conditions were obtained as following:T = 350 8C, P = 1 atm and H2/CO = 2/1.
ZPD-Based Dynamic Assessment and Collaborative L2 Vocabulary Learning
Azizullah Mirzaei,Leila Shakibei,Ali Akbar Jafarpour 아시아영어교육학회 2017 The Journal of Asia TEFL Vol.14 No.1
Despite growing interest in the implementation of dynamic assessment in second or foreign language learning research, few studies have attempted to incorporate the notion into real second language classrooms. This study explored the effect of cumulative Group-Dynamic Assessment on depth of vocabulary knowledge in an EFL context. To this end, 50 EFL learners were selected from a junior high school in Iran after administering the Oxford Quick Placement Test. Then, they were randomly assigned to two equal groups, namely, experimental Group-Dynamic Assessment and control Non- Dynamic Assessment. The Group-Dynamic Assessment group was instructed through interactionist cumulative Group-Dynamic Assessment procedures while the control group was taught without providing any cumulative ZPD-sensitive feedback. Before and after the instruction, a vocabulary knowledge scale (Paribakh & Wesche, 1993, 1996) was administered to measure both groups’ depth of second language vocabulary knowledge. The split-plot ANOVA results revealed that the implementation of interactionist cumulative Group-Dynamic Assessment helped the learners outperform the Non-Dynamic Assessment group on both immediate and delayed posttests. Additionally, complementary qualitative analysis showed that cumulative Group-Dynamic Assessment had both diagnostic and developmental potentials to contribute not only to individual participants but also to the whole class to increase their depth of vocabulary knowledge. The findings pointed to the use of ZPD-based collaborative frameworks in teaching second language vocabulary in meaningful contexts and thereby helping learners develop deeper word knowledge.
Amir Eshraghi,Ali Akbar Mirzaei,Rahbar Rahimi,Hossein Atashi 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.10
Mass transfer limitations and kinetics studies were performed for Fischer-Tropsch Synthesis over spherical 10 wt% Fe-10wt% Co-0.5 wt% Pt/79.5 wt% -Al2O3 catalyst in a fixed bed reactor. The external mass transfer limitation was checked by studying the effect of gas hourly space velocity (GHSV) and feed flow rate (at constant GHSV) on CO conversion. Theoretical and practical methods were applied to assess the effect of catalyst pellet size on the internal mass transfer limitation. The results indicated there is external diffusion limitation for GHSV lower than 4,200 h1. Both the theoretical and practical methods showed that the reaction is free of internal diffusion limitation with average particle sizes of 0.21 and 0.42 mm due to Thiele modulus smaller than 0.4, denoting that the rate of reaction is kinetically controlled. The kinetics results demonstrated the combined enol and carbide mechanism-based model was able to provide a good fit for the experimental data.
Development of a kinetic model for Fischer–Tropsch synthesis over Co/Ni/Al2O3 catalyst
Farhad Fazlollahi,Majid Sarkari,Akbar Zare,Ali Akbar Mirzaei,Hossein Atashi 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
In the present research an active Co–Ni/Al2O3 catalyst was prepared by impregnation method for synthesis of light olefins in Fischer–Tropsch synthesis. After studying the effects of using optimized operating conditions on catalyst performance, the kinetic experimental study was performed in a differential micro-fixed-bed-reactor by altering reaction temperature (230–270 8C), pressure (2–12 bar),gas hourly space velocity (2000–7200 h-1) and H2/CO feed molar ratio (1–3). Based on Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach, seven different two-parameter kinetic models were considered. The kinetic data of this study were fitted accurately by a simple form -rCO ¼APCOPH2 =ð1 þ bPCOP0:5H2Þ2 that assumed the following kinetically relevant steps, where CO dissociates via interaction with adsorbed hydrogen; the first hydrogenation step of the surface carbon was reversible and fast, while the second one was slow and rate determining. The kinetic parameters were determined using Levenberg–Marquardt (LM) method and the apparent activation energy and heat of adsorption were 78.70 kJ/mol and -14.16 kJ/mol, respectively.
Mehdi Shiva,Hossein Atashi,Farhad Farshchi Tabrizi,Ali Akbar Mirzaei,Maryam Arsalanfar 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.1
The study addresses an enhanced approach for study of kinetics and mechanism of CO hydrogenation over Fe–Co catalyst. Kinetic models for rate of methane, paraffin and olefin formation have been developed by LHHW approach and information that obtained from UBI_QEP calculations.
Kinetics studies of nano-structured cobalt–manganese oxide catalysts in Fischer–Tropsch synthesis
Mohsen Mansouri,Hossein Atashi,Farshad Farshchi Tabrizi,Ali Akbar Mirzaei,Ghobad Mansouri 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4
The nano-structured cobalt/manganese oxide catalyst was prepared by thermal decomposition of [Co(NH3)4CO3]MnO4 precursor, and was tested for the Fischer–Tropsch reaction (hydrocarbon forming)in a fixed-bed micro-reactor. Experimental conditions were varied as follow: reaction pressure 1–10 bar,H2/CO feed ratio of 1–2 and space velocity of 3600 h1 at the temperature range of 463.15–523.15 K. On the basis of carbide and/or enolic mechanisms and Langmuir–Hinshelwood–Hougen–Watson (LHHW)type rate equations, 30 kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The kinetic parameters were estimated with non-linear regression method and the activation energy was 80.63 kJ/mol for optimal kinetic model. Kinetic results indicated that in Fischer–Tropsch synthesis (FTS) rate expression, the rate constant (k) has been increased by decreasing the catalyst particle size. The catalyst characterization was carried out using different methods including powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements.
Intrinsic kinetics of the Fischer-Tropsch synthesis over an impregnated cobalt-potassium catalyst
Hossein Atashi,Mohsen Mansouri,Seyyed Hossein Hosseini,Mohammad Khorram,Ali Akbar Mirzaei,Masoud Karimi,Ghobad Mansouri 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
The optimal amount of 15 wt%Co/10 wt%K/Al2O3 catalyst was prepared using the impregnation technique in order to study the kinetics of the Fischer-Tropsch synthesis. The rate of synthesis was measured in a fixed-bed micro reactor with H2/CO feed ratio of 1-3 and space velocity in the range of 2,700-5,200 h−1 under reactor pressure of 8 bar and a temperature range of 210-240 oC. The experimental data were best fitted by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach rate in the form of −rCO=(k2K1PCOPH2)/(1+K1PCO). Furthermore, the data were fitted fairly well by a power law equation in the form of −rCO=kPCO 1.32PH21.42. The activation energies for LHHW approach model and power law equation were obtained as 138.5 kJ/mol and 87.39 kJ/mol, respectively.