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RISS 인기검색어
- 검색키워드
- 저자 : Mehdi Rashidzadeh (검색결과 4 건)
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Investigating the Cold Plasma Surface Modification of Kaolin- and Attapulgite-Bound Zeolite A
Mahboobeh Ejtemaei,Sepehr Sadighi,Mehdi Rashidzadeh,Sirous Khorram,Jan O. Back,Simon Penner,Michael F. Noisternig,Dariush Salari,Aligholi Niaei 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-
Hydrophilic zeolites with low catalytic activity are considered as suitable adsorbents for drying gasstreams containing olefinic compounds. In this contribution, the surface treatment of kaolin and attapulgite/zeolite A extrudates is investigated using argon glow discharge plasma. The zeolite is synthesizedfrom kaolin using the hydrothermal method. Surface and bulk characterization is performed using X-raydiffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, Fourier-transform infrared (FTIR)spectroscopy, temperature-programmed-desorption (TPD) of NH3 and X-ray photoelectron spectroscopy(XPS) techniques. Plasma treatment increases surface area and pore volume, but it decreasesthe weak acidic site density of the extrudates. The obtained results show that attapulgite/zeolite extrudatesare more affected by plasma treatment than kaolin/zeolite extrudates. The catalytic activity ofuntreated and plasma-treated extrudates are compared with respect to coke formation resulting from1-butene and 1,3-butadiene. The plasma-treated sample is more resistant to coke formation (35%decrease compared to untreated one). The potassium contents of extrudates decreased as a result of sputteringloosely bound potassium cations on the crystal surface by argon ions, which led to a decrease inwater sorption capacity (by 15% of the initial sorption capacity).
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4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption
Sepehr Sadighi,Arshad Ahmad,Mehdi Rashidzadeh 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4
A 4-lump kinetic model including hydrogen consumption for hydrocracking of vacuum gas oil in a pilot scale reactor is proposed. The advantage of this work over the previous ones is consideration of hydrogen consumption,imposed by converting vacuum gas oil to light products, which is implemented in the kinetic model by a quadratic expression as similar as response surface modeling. This approach considers vacuum gas oil (VGO) and unconverted oil as one lump whilst others are distillate, naphtha and gas. The pilot reactor bed is divided into hydrotreating and hydrocracking sections which are loaded with different types of catalysts. The aim of this paper is modeling the hydrocracking section, but the effect of hydrotreating is considered on the boundary condition of the hydrocracking part. The hydrocracking bed is considered as a plug flow reactor and it is modeled by the cellular network approach. Initially,a kinetic network with twelve coefficients and six paths is considered. But following evaluation using measured data and order of magnitude analysis, the three route passes and one activation energy coefficient are omitted; thus the number of coefficients is reduced to five. This approach improves the average absolute deviation of prediction from 7.2%to 5.92%. Furthermore, the model can predict the hydrogen consumption for hydrocracking with average absolute deviation about 8.59% in comparison to those calculated from experimental data.
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Catalytic dehydration of methanol to dimethyl ether (DME) over Al-HMS catalysts
Behrouz Sabour,Mohammad Hassan Peyrovi,Touba Hamoule,Mehdi Rashidzadeh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.1
A series of Al-HMS with different Si/Al ratio was used as a solid acid catalyst for methanol dehydration todimethyl ether (DME). The effect of temperature, feed composition, space velocity, and the catalyst Si/Alratio on the catalytic dehydration of methanol was investigated. By decreasing Si/Al, the temperaturerequired to reach equilibrium conversion of methanol decreased due to the increased number of acidicsites. Compared to commercial γ-Al2O3, Al-HMS-5 and Al-HMS-10, catalysts exhibited a high yield ofDME. Among all Al-HMS catalysts, Al-HMS-10 exhibited an optimum yield of 89% with 100% selectivityand excellent stability for methanol dehydration to DME.
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Sakaki Seyyed Alireza,Dadvand Koohi Ahmad,Rashidzadeh Mehdi,Sheykhan Mehdi 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.3
Nowadays, waste plastics made a signifi cant environmental problems. Chemical converting of the polymers to valuable liquids is a promising method to solve the problem and make excellent benefi t. This study investigates the utilization of kaolin, a natural resource, for synthesizing zeolite Na-A and signifi cance of the catalyst crystallinity on the catalytic cracking of a 50:50 mixture of polystyrene (PS) and low-density polyethylene (LDPE). This research aims to identify the optimal hydrothermal conditions for producing crystalline zeolite Na-A and evaluate the eff ect of crystallinity of synthesized zeolite Na-A on production of liquids. A central composite design (CCD) model is employed to achieve this, selecting three independent variables: hydrothermal temperature (80, 85, 90, 95 and 100 °C), the molarity of the alkaline solution (NaOH concentration = 1,2,3,4 and 5 molar), and hydrothermal time (8, 10.43, 14, 17.56 and 20 h). Fourier transform infrared spectroscopy (FTIR) determines the functional groups which proves the presence of sodium aluminosilicate in the synthesized zeolite. The crystallinity of the produced zeolite Na-A is evaluated through X-ray diff raction (XRD) analysis, optimizing the results using the CCD model. Scanning electron microscopy (SEM) reveals well-formed cubic crystalline structures of zeolite Na-A. The optimum conditions for polymer cracking are determined as hydrothermal temperature of 89 °C, a hydrothermal time of 13 h, and a NaOH molarity of 2.8, while predicted liquid production was obtained 81%. The analysis of ANOVA indicates that the designed model based on CCD calculations is valid for prediction of the process. Finally, gas chromatography with fl ame ionization detection (GC-FID) is employed to characterize the main resulting value-added components (styrene, toluene, and ethylbenzene) under optimum conditions.
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