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Catalytic Decomposition of HO over Pure and LiO-Doped CoO Solids

Authors :
Gamil A. El-Shobaky
Nagi R.E. Radwan
Farouk M. Radwan
Source :
Adsorption Science & Technology, Vol 16 (1998)
Publication Year :
1998
Publisher :
SAGE Publishing, 1998.

Abstract

Pure and doped Co 3 O 4 samples were prepared by the thermal decomposition at 500–900°C of pure and lithium nitrate-treated basic cobalt carbonate. The amounts of dopant added were varied in the range 0.75–6 mol% Li 2 O. The effects of this treatment on the surface and catalytic properties of cobaltic oxide solid were investigated using nitrogen adsorption at −196°C and studies of the decomposition of H 2 O 2 at 30–50°C. The results obtained revealed that Li 2 O doping of Co 3 O 4 followed by heat treatment at 500°C and 600°C resulted in a progressive increase in the value of the specific surface area, S BET , to an extent proportional to the amount of dopant present. However, the increase was more pronounced in the case of solid samples calcined at 500°C. This increase in the specific surface areas has been attributed to the fixation of a portion of the dopant ions on the uppermost surface layers of the solid leading to outward growth of the surface lattice. The observed increase in S BET due to Li 2 O doping at 500°C might also result from a narrowing of the pores in the treated solid as a result of the doping process. Lithium oxide doping of cobaltic oxide followed by heat treatment at 700–900°C resulted in a significant decrease in the S BET , V p and r̄ values. Pure and doped solids precalcined at 500°C and 600°C exhibited extremely high catalytic activities which were not much affected by doping with Li 2 O. On the other hand, doping followed by calcination at 700–900°C brought about a considerable and progressive increase in the catalytic activity of the treated solids. This treatment did not modify the activation energy of the catalysed reaction, i.e. doping of Co 3 O 4 solid followed by heating at 700°C and 900°C did not alter the mechanism of the catalytic reaction but increased the concentration of catalytically active constituents taking part in the catalytic process without altering their energetic nature.

Details

Language :
English
ISSN :
02636174 and 20484038
Volume :
16
Database :
Directory of Open Access Journals
Journal :
Adsorption Science & Technology
Publication Type :
Academic Journal
Accession number :
edsdoj.4e4d8adfb74534a2c26e4c14fc3d7e
Document Type :
article
Full Text :
https://doi.org/10.1177/026361749801600906