Zagazig University Digital Repository
Home
Thesis & Publications
All Contents
Publications
Thesis
Graduation Projects
Research Area
Research Area Reports
Search by Research Area
Universities Thesis
ACADEMIC Links
ACADEMIC RESEARCH
Zagazig University Authors
Africa Research Statistics
Google Scholar
Research Gate
Researcher ID
CrossRef
Investigation of solid-solid interactions between pure and Li2O-doped cobalt and ferric oxides
Faculty
Science
Year:
1997
Type of Publication:
Article
Pages:
123-133
Authors:
ElShobaky, GA, Abdalla, FHA, Ghozza, AM
DOI:
10.1016/S0040-6031(96)03073-0
Journal:
THERMOCHIMICA ACTA ELSEVIER SCIENCE BV
Volume:
292
Research Area:
Chemistry
ISSN
ISI:A1997XG33900017
Keywords :
catalysis, CoFe2O4, doping, mobility
Abstract:
The solid-solid interactions between pure and lithium-doped cobalt and ferric oxides have been investigated using TG, DTG, DTA and XRD techniques. The catalytic activity, in CO oxidation by O-2 at 400 degrees C, was determined for each solid preheated in air at 700-1000 degrees C. The amounts of lithium, expressed as mol\% Li2O were 1.5 and 3. The results obtained showed that Fe2O3 interacted readily with Co3O4 at temperatures starting from 700 degrees C to produce CoFe2O4 phase in well crystallized form. The degree of propagation of this reaction increased by increasing the heating temperature. However, a small portion of unreacted free oxides was found in the case of pure-mixed solids heated at 1000 degrees C. Lithium oxide-doping stimulates the ferrite formation to an extent proportional to its amount present. The stimulation effect of lithium was evidenced by following up the change in the peak heights of certain diffraction lines characteristic of Fe2O3, Co3O4 and CoFe2O4 phases located at `d' spacing of 2.69, 2.44 and 2.08 Angstrom, respectively. The change of peak height of the diffraction line at 2.08 Angstrom as a function of firing temperature of pure- and doped-mixed solids enabled the calculation of the activation energy of the ferrite formation (Delta E). The computed Delta E values were 57.3, 38.4 and 28.8 kJ mol(-1) for pure-mixed solids specimen and those treated with 1.5 and 3 mol\% Li2O, respectively. The catalytic activity was found to decrease by increasing the calcination temperature and also by increasing the amount of Li2O due to the enhanced formation of CoFe2O4 phase which is less reactive than the free oxides, Co3O4 and Fe2O3. The promotion effect of lithium in the cobalt ferrite formation was attributed to an effective increase in the mobility of diffusion of reacting cations. (C) 1997 Elsevier Science B.V.
Online
PDF
جامعة المنصورة
جامعة الاسكندرية
جامعة القاهرة
جامعة سوهاج
جامعة الفيوم
جامعة بنها
جامعة دمياط
جامعة بورسعيد
جامعة حلوان
جامعة السويس
شراقوة
جامعة المنيا
جامعة دمنهور
جامعة المنوفية
جامعة أسوان
جامعة جنوب الوادى
جامعة قناة السويس
جامعة عين شمس
جامعة أسيوط
جامعة كفر الشيخ
جامعة السادات
جامعة طنطا
جامعة بنى سويف