Elaboration of an Easy Aqueous Sol-Gel Method for the Synthesis of Micro- and Mesoporous γ-Al2O3 Supports

An aqueous sol-gel method for the synthesis of γ-Al2O3 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(CH3)CH2CH3]3) and aluminum nitrate (Al(NO3)3)) on the textural
and crystallographic properties of Al2O3 supports. Only the formation of γ-
Al2O3 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-Al2O3 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(NO3)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(NO3)3 as aluminum source for the future synthesis
procedures for metallic catalysts supported on alumina.