Elaboration of an Easy Aqueous Sol-Gel Method for the Synthesis of Micro- and Mesoporous <i>γ</i>-Al<sub>2</sub>O<sub>3</sub> Supports

Abstract

An aqueous sol-gel method for the synthesis of γ-Al 2 O 3 supports has been developed for the use in tar reforming applications. It was determined the influences of two different aluminum precursors (aluminum sec-butoxide (Al[OCH(CH 3 )CH 2 CH 3 ] 3 ) and aluminum nitrate (Al(NO 3 ) 3 )) on the textural and crystallographic properties of Al 2 O 3 supports. Only the formation of γ-Al 2 O 3 is aimed in order to use these alumina materials as catalytic supports, because it presents high specific surface area and pore volume values. Additionally, the synthesis of γ-Al 2 O 3 was realized with the use of a functionalized silicon precursor, [3-(2-aminoethylamino)propyl]trimethoxysilane, called EDAS. By the presence of an ethylenediamine group in this molecule, it is possible to chelate metallic ions and to highly increase their dispersion at a molecular level during the synthesis of metallic catalysts supported on alumina, which is an asset for catalytic applications. So it was developed a synthesis sol-gel procedure for the cogelation between the functionalized silicon alkoxide EDAS and alumina precursor. The alumina supports synthesized with Al(NO 3 ) 3 as precursor presented higher porous values than the ones obtained with aluminium sec-butoxide precursor. Since nitrate salts are much easier to handle than alkoxides, these observations allowed validating Al(NO 3 ) 3 as aluminum source for the future synthesis procedures for metallic catalysts supported on alumina.