Olga K. Krasilnikova*, Ekaterina B. Markova, Tatiana Y. Grankina, Elena V. Khozina and Valery N. Simonov Pages 100 - 115 ( 16 )
Introduction: New nanomaterials based on porous amorphous aerogels composed of Al2O3 nanofilaments with a diameter of 5 nm were obtained by oxidation of metallic aluminum. Al2O3 nanofilaments were covered by a TiO2 monolayer to prepare a TiO2/Al2O3 composite aerogel. It has been shown that the hydrogen treatment of inactive aerogel formed by alumina nanofilaments and its composite TiO2/Al2O3 at temperatures of 923-1173 K gave rise to a catalytic activity in the cracking of propane. It was found that the hydrogen treatment at high temperatures resulted in the self-organization of Al2O3 intertwined nanofilaments (5 nm in diameter) and TiO2/Al2O3 composite into the η-Al2O3 nanocrystalline hollow nanotubes with a diameter of 33 nm and 6 nm-thick walls followed by packing these nanotubes into bundles. This transformation was evidenced by electron microscopy, transmission electron microscopy, low-temperature adsorption of nitrogen vapors, X-ray fluorescence and X-ray diffraction.
Method: The high-temperature hydrogen activation of aerogels prepared from Al2O3 and Al2O3/TiO2 nanofilaments significantly added to their efficiency in the cracking of propane compared both to the commercial platinum catalyst supported by alumina and the thermal cracking, as well.
Result & Conclusion: The mesoporous crystalline structure of alumina nanotubes ensured a high selectivity (63% ethylene) and a catalytic activity (0.3 mmol/g×s) in the cracking of propane over the temperature range of 923-1123 K. In the case of TiO2/Al2O3 nanotubes, the reaction products changed from ethylene mainly to propylene with the selectivity of 68% and the catalytic activity of 0.1 mmol/g×s in the same temperature range.
Alumina nanotubes, TiO2/Al203 nanotubes, self-organization of alumina nanofilaments, cracking of propane, ethylene, propylene.
Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Peoples' Friendship University of Russia, Moscow, Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, National Research Nuclear University, Moscow Engineering Physics Institute, Moscow