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SUPERVISOR
Abdol-Hossein Dabbagh
عبدالحسین دباغ (استاد راهنما)
 
STUDENT
Hossein Mortaji
حسین مرتجی

FACULTY - DEPARTMENT

دانشکده شیمی
DEGREE
Master of Science (MSc)
YEAR
1388
Amorphous high surface area Al 2 O 3 /Ni-Co was prepared using sol-gel method. The effects of vacuum and/or N 2 atmosphere on the structure and texture of alumina doped with Ni and Co ions were investigated using XRD, SEM, EDX, BET, TG/DTG, DSC and FT-IR. Also BJH and MP diagrams were plotted to determine meso and micropore distribution. It was found that vacuum reduces porosity and enhances dehydroxylation. In addition, vacuum significantly changes the structure in compare to N 2 atmosphere and produce nano-rod shaped particles. We related formation of rod shaped particles to vacuum force which causes formation of high tensile points on the surface. Two distinct reactio ethanol amination and octanol dehydration were performed using two prepared catalysts. Also in order to explanation of observed reactivity and selectivity and its relationship with catalyst catalysts then appropriate mechanisms were presented. In the case of ethanol amination, we improved the presented mechanism by C. Feng et al that not only does’nt involve hydrogenation of transitions, but also justifies their acetonitrile formation yield. Anyway by our improved catalyst we got 40% yield of acetonitrile production at 350°C by usage of only 1g catalyst. Interestigly our product distribution on two catalysts was similar which we related this to formation of NH 2 - species on catalyst surface. On other words NH 2 - species paly the main role in this type of catalytic reactions. In the case of 1-octanol reaction on catalysts the selectivity changed. Overally we got 1-octene, 2-octene, 3-octene which first one was dominant, octanal, 1, 1?-dioctylether and finally octyloctanoate ester. Formation of ester is a specific effect of doping nickel and cobalt in alumina structure because formation of ester on alumina has been reported in high pressures. Our results revealed reaction on vacuum prepared catalyst is more selective to dehydrogenationreactions: octyloctanoate ester and octanal production. In computational part, DFT was performed for the ?-alumina (100) surface doped with Ni +2 and Co +2 (considering lattice charge 0 and -1). The stability of surface structures depends upon the valence electrons and the position of doping atom. The catalyst surface is more sensitive to cobalt dopant. Finally the most sensitive and the most insensitive location based on the charge difference and characteristics of the ion were determined. In addition 15 different poses of ethanol adsorption on ?-alumina (100) surface were studied to specify the best absorption manner. In this regard changes in ethanol molecule after adsorption on the surface different places were considered and it was found that ethanol’s oxygen and then hydrogen connected to oxygen have dominant effect on ethanol adsorption. In addition we probed changes in bond lengthes and angles of ethanol molecule. Our results revealed C?O and then O?H bons are the most variable bonds of ethanol during adsorption.
در این کار تحقیقاتی تمرکز و توجه روی اثر شرایط خلاء و جو نیتروژن بر ساختار و خواص کاتالیزور آلومینا/نیکل-کبالت اکساید قرار گرفت. تاثیر این شرایط بر ویژگی های ساختاری و همچنین خصوصیات کاتالیستی آن را مورد بررسی قرار دادیم. لذا با تغییر شرایط تهیه کاتالیزور (خلاء و جو N 2 )، تغییرات ایجاد شده در بافت کاتالیزور با استفاده از روش های XRD، SEM، FT-IR، EDX، BET و آنالیز حرارتی دنبال شد. در ادامه دو واکنش مختلف یعنی آمیناسیون اتانول و آب گیری 1- اکتانول روی دو کاتالیزور انجام پذیرفت. همچنین برای توضیح واکنش پذیری و انتخاب گری مشاهده شده و ارتباط آن با ساختار کاتالیزور ها، مکانیسم های مقتضی ارائه و مورد بحث و بررسی قرار گرفت. در رویکرد محاسباتی این پروژه اثر جایگزینی یون های نیکل و کبالت به جای یون های آلومینیم سطح (100) اسپینل ?-آلومینا مطالعه شد و انرژی ساختار های حاصله مقایسه شدند تا مناسب ترین همچنین نامطلوب ترین مکان های جایگزین شده مشخص شوند. علاوه بر این مولکول اتانول در 15 حالت مختلف بر روی مکان های متفاوت همین سطح جذب شد تا مناسب ترین حالت جذبی برای مولکول اتانول مشخص شود. در این راستا تغییرات حاصل در مولکول اتانول در اثر جذب بر روی مکان های مختلف سطح مورد توجه قرار گرفت.

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