کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6468693 | 1362321 | 2016 | 7 صفحه PDF | دانلود رایگان |
High surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol-gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719 m2/g) mesoporous (pore size 67 à and pore volume 1.19 cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol-gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Brønsted acidity. These catalysts showed very high catalytic activity for esterification; a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost.
Very high surface area (719Â m2/g) mesoporous (pore size 67Â Ã and pore volume 1.19Â cc/g) silica has been prepared by a simple sol-gel process using ethyl silicate-40 as a novel silca precursor without using any organic template and hydrothermal treatment. Molybdena supported on this high surface area silica has yielded a solid acid catalyst efficient for esterification of di-carboxylic acids with a range of alcohols.193
Journal: Comptes Rendus Chimie - Volume 19, Issue 10, October 2016, Pages 1247-1253