مقالههای Ahmadian Namini
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Synthesis of PEG Supported Palladium Nanoparticles: Simple and recyclable palladium catalytic system for Heck reaction
اطلاعات انتشار: نخستین کنگره بین المللی نانوفنآوری و کاربردهای آن در صنایع نفت، گاز و پتروشمی، سال ۱۳۸۵
تعداد صفحات: ۷
Palladium nanoparticles with narrow size distribution as a catalytic system for Heck reaction were synthesized by applying poly(ethyleneglycol) (PEG) and Pd(OAc)2. PEG acts as a reducing agent for reduction of Pd2+ to Pd and also as a stabilizer for synthesized palladium anoparticles. Both XRD and TEM results exhibit production of nanoparticles with about 7nm in diameter. This polymeric palladium catalyst is relatively inexpensive, environmentally benign, and simply functionalizable and can be easily recovered from the products.<\div>
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال ۱۳۸۶
تعداد صفحات: ۸
The polyacrylamide sol–gel method is a fast, cheap and easy to scale–up method for obtaining nanopowders of a wide variety of ceramic materials. The aim of the present work is to synthesize nanosized alumina and zirconia powders via this method and investigate the effect of initial salt on the size of the synthesized nanaopowders. The obtained results showed that the presence of nitrate or chloride ions affects the synthesized nanoparticle size via two different mechanisms: the crystallization and polymeric network degradation. In zirconia synthesis, the retarded crystallization mechanism dominated over the polymeric network degradation and powders synthesized with nitrate base salt are smaller, but in alumina synthesis, two entitled mechanisms eliminate the effects of each other and there is no obvious difference between particle sizes.<\div>
۳Synthesis and Seeding Time Effect on the Inter–Crystalline Structure of Hydroxy–Sodalite Zeolite Membranes by Single Gas (H2 and N2) Permeation
اطلاعات انتشار: Iranian Journal of Chemistry and Chemical Engineering (IJCCE)، بيست و هشتم،شماره۴(پياپي ۵۲)، ۲۰۰۹، سال ۰
تعداد صفحات: ۱۲
Microporous hydroxy–sodalite zeolite membranes with different morphologies were synthesized via secondary growth technique with vacuum seeding on tubular α–Al2O3 supports at two different synthesis conditions (i.e. two different routes). Microstructures of the synthesized membranes were characterized by X–ray diffraction (XRD), Scanning electron microscope (SEM) and single gas permeation using H2 and N2. Also, the effect of seeding time on microstructure and performance of the synthesized hydroxy–sodalite top–layers was investigated at four different levels (60, 120, 180 and 240 s). Permeation test was carried out in order to attain a more exact comparison of both applied routes and seeding times. Microstructure of the synthesized hydroxy–sodalite zeolite membrane layers and the effects of the investigated factors on the elimination of inter–crystalline pores were evaluated by the permeation of single gases (H2 and N2) under different pressure differences at ambient temperature. The permeation results confirmed the high quality of the hydroxy–sodalite zeolite membranes manufactured via the first route at seeding time of 60s for the hydrogen purification under extremely low temperatures ( 200 K) and\or extremely high pressures (> 100 bars).
۴An Optimum Routine for Surface Modification of Ceramic Supports to Facilitate Deposition of Defect–Free Overlaying Micro and Meso (Nano) Porous Membrane
اطلاعات انتشار: Iranian Journal of Chemistry and Chemical Engineering (IJCCE)، سي ام،شماره۳(پياپي ۵۹)، ۲۰۱۱، سال ۰
تعداد صفحات: ۱۲
In this work, a simple and effective way to modify the support surface is developed and a nanostructure ceramic support to facilitate deposition of a defect–free overlying micro and meso (nano) porous membrane is obtained. To achieve high performance nanocomposite membranes, average pore size of outer surface of support was reduced by dip–coating in submicron and nano α–alumina slurries. In this respect, the effects of several parameters such as: solid content, dipping time, vacuum pressure, heating rate and number of coated layers on microstructure of the fabricated layers were investigated. The obtained results showed that the optimum routine for this technique was twice coating of 5wt% submicron slurry without applying vacuum followed by vacuum dip–coating of 5wt% submicron and 1wt% nano alumina slurry. Pore size of the unmodified membrane support was calculated using permeance data and the obtained result was 540 nm. After twice modification with submicron alumina slurry without vacuum, average pore size of surface decreases significantly. More surface modification by vacuum dip–coating of alumina submicron and nano particles slurries results in decreasing of average pore size of intermediate layers to nanometric scale (100 nm), respectively. The obtained results are confirmed by mercury porosimetry measurements.
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