Journal of Radioanalytical and Nuclear Chemistry
Volume/Issue:
Volume 177: Issue 2
Effect of gamma-irradiation on the catalytic activity and selectivity of gamma-alumina
I. Conversion of methanol
Authors:
Nabil Amin Ain-Shams University Chemistry Department, Faculty of Education Cairo (Egypt)

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,
Gamil El-Shobaky National Research Center Department of Physical Chemistry Dokki Cairo (Egypt)

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Gehan Fagal National Research Center Department of Physical Chemistry Dokki Cairo (Egypt)

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Pages:
211–218
Online Publication Date:
14 Aug 2005
Publication Date:
17 Jan 1994
Article Category:
Research Article
DOI:
https://doi.org/10.1007/bf02061117
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Abstract  

Methanol conversion reaction was carried out in contact with a poorly crystalline -alumina pre-irradiated with different doses of -rays. The reaction was conducted at 140–440°C using a flow technique under atmospheric pressure. The results obtained revealed that -irradiation of Al2O3 resulted in drastic modifications of its activity and selectivity in methanol conversion reaction. The dose of 15 Mrad was sufficient to suppress completely the formation of dimethyl ether (DME) and stimulated the formation of methane, which started at 200°C instead of 300°C in the case of the unirradiated alumina specimen. However, the rate of CH4 formation was found to decrease as a function of the dose employed. When the dose reached 140 Mrad, DME was reproduced with a rate comparable to that measured for the unirradiated catalyst sample. These results permitted us to conclude that DME is produced on the weak acidic sites (Brönsted acidity of Al2O3) and is not necessarily an intermediate compound for methane formation that takes place directly from methanol on strong acidic sites (Lewis acidity). The doses of 15–75 Mrad expelled completely the Brönsted acidic sites from Al2O3 surface, and the doses above this limit brought about a transformation of Lewis acidic sites into Brönsted acidity that is responsible for dimethyl ether formation. This transformation occurs by the action of liberated water from the dehydration of methyl alcohol.

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Cover Journal of Radioanalytical and Nuclear Chemistry
Journal of Radioanalytical and Nuclear Chemistry
Print ISSN:
0236-5731
Online ISSN:
1588-2780

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Journal of Radionalytical and Nuclear Chemistry
Language English
Size A4
Year of
Foundation		 1968
Volumes
per Year		 1
Issues
per Year		 12
Founder Akadémiai Kiadó
Founder's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher		 Chief Executive Officer, Akadémiai Kiadó
ISSN 0236-5731 (Print)
ISSN 1588-2780 (Online)

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