دراسة الخواص السطحية للخامات الزيوليتية السورية المحملة بالكوبالت

الموضوعات

علوم بحتة وطبيعية

روابط وملفات

التعريف والنوع

رقم الوثيقة

fd36ebeb-57c0-4083-b327-3fc8e481262a

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل ماجيستير

نوع الملف

word

أسماء الملفات

1967664_1.doc

بيانات النشر

ترجمة العنوان

Study Of The Surface Properties Co-loading On Syian Zeolite

ألقاب المؤلفين

[{"name_ar":" إبراهيم راهب","title_ar":"اشراف","title_en":"Supervision"},{"name_ar":"إبراهيم راهب","title_ar":"اشراف","title_en":"Supervision"},{"name_ar":"محمد ياسر آمنة","title_ar":"اعداد","title_en":"Preparation"}]

اللغة

Arabic

المصدر والدورية

اسم المصدر

دراسة الخواص السطحية للخامات الزيوليتية السورية المحملة بالكوبالت

المحتوى والصفحات

عدد الصفحات

0

ترجمة الملخص

Procedure : We used in this work the Syrian zeolite ores as a base samples . The base sample was washed with distilled water and dried at 1100C for 24 h and followed calcination at 5500C for 6 hr and we donat N-79 for this sample . The sample N-79 was loaded with cobalt by two methods : The first was the Ion-exchange method using aqueous solution of (0.1M) Co(NO3)2.6H2O . The mixture (solid + Nitrate solution) mixed up at room temperature for one day and then filtrated and calcinated at 5500C for 6 h and this sample donated N-79-Co-ex. The second method was the wetness impregnation : the necessary mass of cobalt (Nitrate) dissolved in minimum volume of distillated water then the solid sample of zeolite impregnated with all cobalt solution , after the mixture dried at R.T the resulted mass was calcinated at 5500C for 6 h. the ratio of cobalt in the zeolite sample was in the range (1-25%) and samples with loading with cobalt donate N-79-Co-X , where the X is the mass ratio of cobalt. II. Techniques : The chemical analysis was performed using AAS and FIS methods. X.R.D patterns in the 2 angular intended from 10 to 70 were obtained by ATOE Powder Diffraction System and cu k Radiation (λ=1.541 Ǻ). Textural characteristics of samples were determined from the analysis of N2 adsorption / desorption data at 77K using Gemini III 2375 surface analyzer instrument . Prior to adsorption measurements, the samples were out gassed at 2500C for 8 h under reduced pressure of 10-4 torr . The surface area was calculated by applying BET method and the total pore volume was calculated from the volume adsorbed at P/P0 = 0.95 in liquid form. The microporisty was determined using DR equation and the mean pore radius was calculated. The DTA-TG analysis was performed by heating 40-70 mg portion of the sample in the range of 25-10000C at 100C/min surrounded by an argon atmosphere , using SETARAM thermal system type labsysTM (TG-DTA). Acid sites types present on the surface were determined with FTIR spectra of asorbed trietylamine. Prior to the trietylamine adsorption the samples were degassed at 2000C for 6hrs , then the excess trietylamine was removed by drying its in an executor containing silica gel and CaCl2. The FTIR spectra were performed using JASCO FTIR-400 plus in the range 1400-1700cm-1 . The amount of acid sites on the surface was determined by temperature programmed desorption (TPD). The adsorbed trietylamine was removed by heating the samples in the temperature range 25-5000C. using TG-curve we determined the amount of desorbed trietylamine corresponding to every temperature , then we calculated the lost mass of trietylamine from the total TG%. Catalytic activity of cobalt loading on zeolite were measured after reduction with hydrogen at 2500C and the hydrogenation of sunflower oil was applied to determination the ability of samples to hydrogenation reaction. The yield of hydrogenation reaction determined by measuring the iodine number of oil after reaction with hydrogen at various times. The evaluation of the hydrogenation was carried out in stainless steel reactor volume 400ml with several values to inter the gas and reactants and take up the products. The reaction was carried out under conditions : 2500C and 1g of solid catalyst in 100g of oil and 5bar of hydrogen pressure . The probe was taken every 1hr to titration to determine iodine number. III. Result : The X-ray diffraction (XRD) patterns of various prepared samples were showed a changes in the crystallinity of samples. The diffraction pattern of Co-Zeolite samples was noticed in 5,10,15 and 25wt% of Co-loading , a great loss zeolite crystallinity was noticed especially for Co-loading samples up to 15wt%. The patterns demonstrated the Co3O4 phases with increasing Co-loading which was accompanied by the appearance of new peaks at 2Ѳ = 21,31.8,36,38.6 and 47.8 which are assigned to Co3O4 , and other peaks at 2Ѳ=29.3,42.4 and 56.7 which are characteristic of cobalt silicate (Co2SiO4). The addition of various amounts of cobalt ions cause an increase in the cell volume. This reflects the presences of the fraction of carbon ions inside the zeolite pores since the ionic radius of Co ions (0.65Ǻ) is larger than that of Al(0.54Ǻ) and Si(0.26Ǻ) ions. It is obvious that the solids prepared by impregnation have larger particle size, than that of the parent zeolite. The surface textural properties of Co-zeolite samples have been determined by N2 adsorption at 77K. The adsorption isotherms for all samples were found to belong to types II and IV according to sing classification. The analysis of the adsorption data and porosity before and after addition of Co showed that : 1. The surface area of the prepare samples decreased with the increasing of cobalt ratio. The decrease in SBET values was from 131.6m2/g for N-79 to 45.2m2/g for N-79-Co-25 may be due to blocking of some pores with cobalt particles formed on surface. 2. The total pore volume decrease from 0.229 to 0.076ml/g with increasing the cobalt loading to 25wt%. 3. The calculate values of mean pore radius showed a smooth changes with increasing the Co-loading. 4. The data of Microporisity showed a weak changes with increasing the Co-loading. TG-DTA curves showed that the form of these curves are similar specially to 5000C and after that appears some changes. For the N-79 samples the TG-DTA data showed indothermal effect at 7900C which attribute to destroy the crystalline structure but for Co-loading samples the effect of destroyed structure appears at 7400C and the increasing of cobalt ratio leads to be less thermal stability. Acidic properties of Co-promoted zeolite samples were examined using FTIR spectroscopy of trietylamine adsorption as a probe molecule. It is well known that trietylamine adsorbed on Lewis acid sites (L-acid) gives bands at 1447-1460,1488-1500,≈1580 and 1600-1630cm-1 , that on Bronsted acid sites (B-acid) at 1485-1500,1540 and ≈1640cm-1 and the hydrogen-bonded trietylamine at 1400-1447,1485-1490 and 1580-1600cm-1 respectively[61-63]. The spectrum recorded illustrates three peaks at 1456,1580 and 1620cm-1 detected at 1542 and 1638cm-1. L- and B-acid sites were coming together at 1490cm-1. The increasing of cobalt ratio leads to decrease the B-acid sites especially for samples containing Co-loading higher than 5wt%. The decrease of the acidity of Co-promoted zeolite samples with increasing Co-loading can be explained by hypothesizing that, at high concentration, Co+2 ions might be present as bulk oxides as well as on the surface, thus reducing coordinative unsaturated metal sites (Lewis acid sites) and absence of proton-donor OH groups which are capable of generating Bronsted acidity. Such hypothesize was confirmed by presence of Co3O4 on the surface as indicated previously by XRD and FTIR results. Catalytic activity of Co-promoted zeolite samples after reduction with hydrogen at 2500C have been applied to hydrogenation of sunflower oil. The results showed that the parent sample N-79 (without cobalt) have a catalytic effect, and the conversion of hydrogenation was 17.9% after 3hrs. On the other hand the Co-loading samples showed higher conversions than the N-79 sample in the hydrogenation reaction. We notice that the increasing of Co ratio leads to increasing of the conversion and it was maximum at 15wt%. we believe that the temperature 2500C is not enough to reduced the cobalt oxide in the pores and on the other hand the reduction process will be difficult when we have high amount of cobalt on the surface. The hydrogenation of oils is not specific reaction to examine the catalytic acidity of the prepared samples so in the future we have to examine these samples according to another reactions

إشراف وإعداد

الإشراف

إبراهيم راهب, إبراهيم راهب

الإعداد

محمد ياسر آمنة

الاقتباسات الببليوغرافية