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متن کامل


نویسنده: 

IRANI M.

اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    8
تعامل: 
  • بازدید: 

    120
  • دانلود: 

    0
چکیده: 

IN THE PRESENT WORK, STEAM METHANE REFORMING (SMR) REACTION IN MONOLITH REACTORS WAS MODELED. EXPERIMENTS OF SMR WERE CARRIED OUT IN A BENCH-SCALE MONOLITH REACTOR. A SINGLE-CHANNEL WAS CONSIDERED AND TWO AXI-SYMMETRIC CFD MODELS WERE DEVELOPED FOR MODELING. GENERAL KINETIC MODELS FOR SMR AND WATER-GAS-SHIFT (WGS) REACTION RATES BASED ON LANGMUIR-HINSHELWOOD TYPE WERE EMPLOYED. GOOD AGREEMENT WAS ACHIEVED BETWEEN BENCH EXPERIMENTAL DATA AND THE MODEL. THE VALIDATED CFD MODEL WAS CONSIDERED AS NUMERICAL LABORATORY .A SENSITIVITY ANALYSIS WAS RUN IN ORDER TO FIND THE EFFECT OF TEMPERATURE, PRESSURE AND INLET H2O/CH4 MOLAR RATIO ON THE REACTOR PERFORMANCE. IT WAS CONCLUDED THAT OBTAINED RESULTS FROM CFD ANALYSIS GIVES PRECISE GUIDELINES FOR FURTHER STUDIES ON OPTIMIZATION OF MONOLITHIC REACTOR PERFORMANCE.

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بازدید 120

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اطلاعات دوره: 
  • سال: 

    1393
  • دوره: 

    4
تعامل: 
  • بازدید: 

    523
  • دانلود: 

    2121
چکیده: 

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اطلاعات دوره: 
  • سال: 

    2021
  • دوره: 

    53
  • شماره: 

    4
  • صفحات: 

    1323-1338
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    40
  • دانلود: 

    0
چکیده: 

One of the most important issues in today's world is the pollution of water with toxic and dangerous metals. Cadmium is one of the toxic metals that enter the surface and groundwater through various industrial wastewaters. In this paper, polyethylene oxide-based silica monolith was synthesized with a uniform porous structure and was used to remove cadmium ions from the aqueous medium. The chemical and physical properties of silica monolith were characterized by SEM, BET, and FTIR techniques. The results of BET and SEM analysis showed that the monolith has a mesopore structure with a specific surface area of 543 m2g-1. The synthesized silica monolith was used as an adsorbent for cadmium removal in a batch adsorption process and the effects of operating parameters including pH, adsorbent concentration, cadmium initial concentration, and contact time were investigated. The Central Composite Design method was used to optimize the effects of operating parameters. The results of the experimental design showed the importance of pH and adsorbent concentration parameters. The analysis of equilibrium data indicated that the maximum adsorption capacity of the monolith for cadmium is 153 mg g-1. The kinetic data were analyzed with various models and results indicated the importance of chemical adsorption. The results of regeneration and reuse of monolith as an adsorbent showed that the synthesized monolith has a high ability to adsorb heavy metal ions from an aqueous solution and can be an option for water treatment at industrial scale.

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نویسندگان: 

Shehni Siamak | Tabatabaei Ghomsheh Seyed Mostafa

نشریه: 

JOURNAL OF NANOSTRUCTURES

اطلاعات دوره: 
  • سال: 

    2025
  • دوره: 

    15
  • شماره: 

    3
  • صفحات: 

    1151-1167
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    28
  • دانلود: 

    0
چکیده: 

In this study, we investigated the selective production of propylene from methanol using monolith-structured ZSM-5 and germanium-modified ZSM-5 nanocatalysts within a fixed-bed reactor system. Optimal reaction conditions were established as 500 °C, 1 bar pressure, and a weight hourly space velocity (WHSV) of 15 h⁻¹, with methanol as the feedstock. To assess the physical and chemical characteristics of the pelletized parent, Ge-modified, and monolith-structured HZSM-5 nanocatalysts, we utilized various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and ammonia temperature-programmed desorption (NH3-TPD). NH3-TPD results indicated a reduction in acidity for the Ge-modified HZSM-5 nanocatalyst, attributed to the partial elimination of strong acid sites. XRD patterns confirmed the presence of the washcoat on the monolith-structured support. Additionally, SEM images of the Ge-modified and monolith-structured HZSM-5 nanocatalysts showed no change in the crystallinity of HZSM-5, while demonstrating a uniform nanocatalyst coating within the channels of the monolith-structured support. The most effective modified nanocatalyst was achieved by incorporating 0.1 wt% germanium into ZSM-5, which resulted in a substantial enhancement of propylene selectivity by 53% and yield by 22.1%. Among the monolith-structured nanocatalysts, variations with single-layer, double-layer, and triple-layer coatings of HZSM-5 were prepared. The single-layer HZSM-5 monolith-coated nanocatalyst exhibited the most significant improvements, with propylene selectivity increasing by 55% and yield by 28.4%. These improvements were attributed to enhanced internal diffusion and reduced mass transfer resistances within the monolith channels, leading to shorter residence times and reduced aromatic formation

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نویسندگان: 

اطلاعات دوره: 
  • سال: 

    2022
  • دوره: 

    56
  • شماره: 

    -
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    0
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 0

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اطلاعات دوره: 
  • سال: 

    2010
  • دوره: 

    7
  • شماره: 

    3
  • صفحات: 

    74-80
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    368
  • دانلود: 

    0
چکیده: 

An integral reactor-based kinetic model for the selective reduction of nitric oxide over Cu-Zn/ZSM-5 wash coated monolithic catalysts is reported. The active component was wash coated onto a 400 cpsi ceramic monolithic substrate at a loading of 23.6 wt. % usage 2,000 ppm iso-butane was used as the reluctant. High activity without significant pressure drop was achieved at a GHSV of 16,000 h-1. Third order polynomial satisfactorily fitted the activity versus space time data and low activation energy of +30.3 kJ/mol was obtained. The applicability of the model was demonstrated within 300-400°C and space time of 0.12-0.94 s.

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بازدید 368

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اطلاعات دوره: 
  • سال: 

    2022
  • دوره: 

    11
  • شماره: 

    2
  • صفحات: 

    252-261
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    29
  • دانلود: 

    0
چکیده: 

Background: In the field of recombinant protein production, downstream processing, especially protein purification, is critical and often the most expensive step. Carbohydrate binding module 64 (CBM64) was shown in 2011 to bind efficiently to a broad range of cellulose materials. Methods: In this study, we developed a protein purification method using nanocrystalline cellulose embedded in a polyacrylamide monolith cryogel and CBM64 affinity tag linked by intein to PD1 as a model protein. The CBM64-Intein-PD1 gene cassette was expressed in E. coli. Following cell lysis, CBM64-Intein-PD1 protein bound to the monolith PA-NCC cryogel. After washing and reducing the pH from 8. 0 to 6. 5, the intein underwent self-cleavage, resulting in the release and elution of pure PD1 protein. Results: The synthesized monolith column had a porous structure with an average pore size of 30 μ, m and a maximum binding capacity of 497 μ, g per gram of dried column. The yield of this purification method was 84%, while the yield of the His tag-acquired CBM64-Intein-PD1 method was 89%. Conclusions: We used cellulose as support for affinity chromatography, which can be used as a costeffective method for protein purification.

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نویسندگان: 

اطلاعات دوره: 
  • سال: 

    2022
  • دوره: 

    10
  • شماره: 

    1
  • صفحات: 

    0-0
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    11
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 11

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نویسندگان: 

IRANI M. | RASHIDZADEH M. | SOLTANIEH M.

اطلاعات دوره: 
  • سال: 

    2005
  • دوره: 

    2
  • شماره: 

    1
  • صفحات: 

    61-70
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    360
  • دانلود: 

    0
چکیده: 

This article presents the research results on production and performance of palladium-only catalytic converters. Monolith is used as the catalyst carrier and gamma alumina as the substrate. Dipping method is used for monolith washcoating. Palladium as the active metal is impregnated on gamma alumina using wet impregnation to produce catalyst samples. The effects of factors such as percent solids in slurry, milling time, calcination time and temperature, pH and existence of Al(NO3)3 on wash-coat characteristics were studied experimentally. SEM, XRD and BET tests were carried out on the samples. Catalyst performance was tested in an experimental reactor that was designed for this research. The results show that catalytic activity increases as calcination time increases, whereas it declines as calcination temperature increases. Furthermore, as the slurry pH decreases, the catalytic activity also decreases. It was observed that impregnation of Al(NO3)3 does not have any effect on catalytic activity.

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اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    8
تعامل: 
  • بازدید: 

    169
  • دانلود: 

    0
چکیده: 

THE OBJECTIVE OF THIS WORK IS TO DEMONSTRATE THE PERFORMANCE OF MEMBRANE REACTORS IN IMPROVING THE EFFICIENCY AND SELECTIVITY OF HYDROCARBON ISOMERIZATION. FOR THIS PURPOSE, A PROPER MODELING FOR A TYPICAL MEMBRANE REACTOR IS CONSIDERED AND THE SIMULATION RESULTS ARE COMPARED TO A CONVENTIONAL PLUG FLOW REACTOR FOR N-BUTANE ISOMERIZATION. THE SIMULATION RESULTS INDICATE THAT THE MEMBRANE REACTOR PERFORMANCE IS MUCH BETTER THAN THE PLUG FLOW REACTOR. SO THAT THE OUTLET OF MEMBRANE REACTOR HAS A HIGHER CONCENTRATION OF ISO-BUTANE AND THE MEMBRANE REACTOR HAS HIGHER SELECTIVITY THAN THE PLUG FLOW REACTOR. FOR INSTANCE, THE OUTPUT COMPOSITION OF ISO-BUTANE FOR THE MEMBRANE REACTOR IS 64% WHILE THAT IS ONLY 44% FOR THE PLUG FLOW REACTOR, I.E., MORE THAN 40% OF ISO-BUTANE CONVERSION CAN BE ACHIEVED USING THE MEMBRANE REACTOR COMPARED TO THE PLUG FLOW REACTOR AT SAME REACTOR CONDITION.

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