XD107: Abstract to poster contribution
Author: Mgr. Petr Machac
Synthesis of high surface area aluminophosphate and phosphonate
xerogels by non-hydrolytic sol-gel reactions
Petr Machaca
, Johan G. Alauzunb
, Ales Styskalika,c
, Damien P. Debeckerd
, P. Hubert Mutinb
, Jiri Pinkasa,c,*
a Masaryk University, Faculty of Science, Department of Chemistry, Kotlarska 2, 61137, Brno, Czech Republic
b Institut Charles Gerhardt Montpellier, UMR 5253, CNRS-Universit´e de Montpellier-ENSCM, Montpellier Cedex 5, 34095, France
c Masaryk University, CEITEC MU, Kamenice 5, 62500, Brno, Czech Republic
d Institute of Condensed Matter and Nanoscience (IMCN), UCLouvain, Place Louis Pasteur 1, 1348, Louvain-La-Neuve, Belgium
We disclose the preparation of high-surface-area mesoporous aluminophosphates and
aluminophosphonates by the non-hydrolytic sol-gel reactions (NHSG) of Al(NMe2)3 with
trimethylsilylated phosphate OP(OSiMe3)3, phosphonates RP(O)(OSiMe3)2 (R = Me, tBu, Ph), and
bis-phosphonates (Me3SiO)2(O)P–X–P(O)(OSiMe3)2 (X = C6H4, (C6H4)2) in dry toluene. The
reactions proceed by silylamine elimination of Me3SiNMe2 to provide organic-inorganic hybrid
xerogels with properties influenced by organic substituents and the Al:P ratio of the precursors.
Dried xerogels exhibit large surface areas (up to 1000 m2 g–1) and matrices based on condensed
Al–O–P networks. They stay stable under relatively harsh thermal conditions. 27Al, 13C, and 29Si
solid-state NMR spectroscopy was employed to characterize the aluminum coordination and the
residual amido and trimethylsilyl groups. The catalytic performance of NHSG prepared material
was examined in gas-phase dehydration of ethanol to ethylene exhibiting conversion and
selectivity comparable to weak solid acid benchmark catalysts. The number of unreacted surface
groups was determined by gravimetric measurements and by thermal analysis (TG-DSC). These
residual groups have the potential to be used in post-synthetic grafting of catalytically active
metal centers.