Papers by Author: Masashi Inoue

Abstract: The influence of morphology of the support particles upon the nickel-catalyzed decomposition of methane into carbon nanotubes and hydrogen was explored using a thermogravimetric apparatus. High carbon nanotube yield was attained by the Ni catalysts supported on the glycothermally synthesized ZrO2 and Er3Ga5O12 particles, which had spherical shapes. Quite high carbon yield was also obtained by the Ni catalyst supported on spherical Al2O3 particles (Nanophase Tech. Corp.). It was concluded that the most important factor governing the carbon yield is the morphology of the catalyst support, which contributes to the internal pressure of carbon nanotubes thus determining their chemical potentials.

Abstract: Solvothermal reaction of aluminum alkoxides in various alcohols at 250-300 oC yielded alkyl derivatives of boehmite (alkoxyalumoxanes; AlO(OH)1-x(OR)x) in which alkyl groups were incorporated between the boehmite layers through the covalent bondings. In the present work, pore textures of aluminas prepared by calcination of the products were examined. The alumina obtained from the ethyl derivative of boehmite had a broad pore-size distribution, while the pore-size of the alumina obtained from the dodecyl derivative of boehmite distributed in a narrow range in the mesopore region. The mode pore diameter of the latter alumina increased with the increase in calcination temperature (600 oC, 39 Å; 800 oC, 54 Å; 1000 oC, 74 Å), but narrow pore-size distribution was maintained even after calcination at high temperatures.

Abstract: The reaction of a stoichiometric mixture of aluminium isopropoxide and yttrium acetate in 1,4-butanediol (1,4-BG) at 300 °C directly yielded crystalline yttrium aluminium garnet (YAG), while the reaction in ethylene glycol (EG) afforded an amorphous product in which a large amount of EG moieties remained. The latter product exhibited an exothermic peak due to the crystallization of YAG at around 900 °C and single-phase YAG was obtained by calcination at 1000 °C. The YAG sample directly obatained in 1,4-BG had a large unit cell parameter (12.144 Å), whereas the YAG sample obtained by the latter method had a unit cell parameter (12.015 Å) essentially identical with the value (12.01 Å) reported in the JCPDS card. Rietveld analysis indicates that the former crystals had Al vacancies at 24d sites and oxygen vacancies while the latter was essentially free from these vacancies.