Activity and selectivity of manganese oxides in alcohols Conversion as influenced by gamma-irradiation |
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Authors: | M. M. Doheim A. S. Ahmed H. A. El-Boohy G. A. El-Shobaky |
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Affiliation: | (1) Egyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt;(2) Department of Chemistry, Cairo University, Faculty of Science, Cairo, Egypt;(3) National Center for Radiation Research and Technology (NCRRT), Nasr City, Cairo, Egypt;(4) National Research Center (NRC), Dokky, Cairo, Egypt |
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Abstract: | Manganese oxide samples obtained from thermal decomposition of manganese carbonate at 400 and 600 °C were subjected to different doses of g-irradiation within the range 0.2 to 1.6 MGy. The surface and catalytic properties of the above samples were studied using nitrogen adsorption isotherms measured at -196 °C and catalytic conversion of ethanol and isopropanol at 300-400 °C using micropulse technique. The results obtained revealed that manganese oxides obtained at 400 °C consisted of a mixture of Mn2O3 and MnO2 while the samples calcined at 600 °C composed entirely of Mn2O3. Gamma-irradiation resulted in a decrease in the particle size of manganese oxide phases with subsequent increase in their specific surface areas. Gamma-irradiation with 0.2 and 0.8 MGy effected a measurable progressive decrease in the catalytic activity in dehydration and dehydrogenation of both alcohols. However, the treated catalyst retained their initial activity upon exposure to a dose of 1.6 MGy. Also, g-irradiation increased the selectivities of the investigated solids towards dehydrogenation of both alcohols. The catalyst samples precalcined at 600 °C exhibited higher catalytic activities than those precalcined at 400 °C. |
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