الفهرس 
الملخص العربى
Preparation of starting materialsOnly 14 pages are availabe for public view
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Abstract
The present investigation is a trial to study the texture Jf cllromium oxide and zinc oxide as initial oxides
for the formation of the spinel zinc chromite. Furthermore
th) study of texture of mixed initial oxides as well as the spinel is performed. Such studies are conducted as fol1JWS :
1-The;arcnt material of chr-otrl.a or zinc oxide was
prepared by the addition of ammonia solution to a solution of chromium nitrate or zinc nitrate with continuous stirring. The product was dried at 1;1.9°0 in air. The doped samples were prepared b,y the addition of calculated amounts of the nitrate solution of the dopant to the host parent material. The spinel sample
was prepared by the calcination of an equimOlE>cular mixture from zinc oxide and chromium oxide at 1000° 0 for 8 days in air.
z-’:Che parent materia.ls were characterized through TGA, DTA,.and X-ray analysis. Furthermore, the ldnetics as well the mechanism of the thermal decomposition
calci;.Led
at variou~ temperatures in air up to lOOo~a •
/
The present investigation is a trial to study the texture Jf cllromium oxide and zinc oxide as initial oxides
for the formation of the spinel zinc chromite. Furthermore
th) study of texture of mixed initial oxides as well as the spinel is performed. Such studies are conducted as fol1JWS :
1-The;arcnt material of chr-otrl.a or zinc oxide was
prepared by the addition of ammonia solution to a solution of chromium nitrate or zinc nitrate with continuous stirring. The product was dried at 1;1.9°0 in air. The doped samples were prepared b,y the addition of calculated amounts of the nitrate solution of the dopant to the host parent material. The spinel sample
was prepared by the calcination of an equimOlE>cular mixture from zinc oxide and chromium oxide at 1000° 0 for 8 days in air.
z-’:Che parent materia.ls were characterized through TGA, DTA,.and X-ray analysis. Furthermore, the ldnetics as well the mechanism of the thermal decomposition
calci;.Led
at variou~ temperatures in air up to lOOo~a •
/
of tee parent materials was verformed. ,_ The parent materials as well as the doped samples were calci;.Led
at variou~ temperatures in air up to lOOo~a for
5 hours. For all the adecr-berrt s investigated, specific volume measurements were determined using alcohol as an imbibition liquid. Also, Burface er6+ ior-s concentration was determined for chromia samples, after extraction, iodometrically.
4-Adsorption of nitrogen was measured at liauid ndsr-ogen temperature. The variation of SB~ with th8 calcination temperature, were studied. Analysis
of sorption isotherms were performed. Constructing
V-t plots and carrying out pore size distribution,
a fron c1UII1ulative calculations, it was possible to
investigate the porosity of various adsorbents.
5-The sintering of the parent materials was studied
N2
through the measurements of SBm’ -temperature of calcinafion. It was found that the sintering is a chemical reaction in nature.
6-The adsorption of 02 was conducted on pure chromia and z’:”nc oxide at ... 1960 C. Ii; was concluded that the uptake of oxygen at this temperature can be considered in terms of molecular chemisorption. Moreover, it is suggested that the active sites for oxygen uptakeof ohroma and inteI’stitia.lof zinc oxide. ma~t be er6+ ions in case Zn2+ ions in case