| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,600,000 (Direct Cost: ¥1,600,000)
|
|---|
| Research Abstract |
The present research has been attempted to design a novel type of solid acid catalysts whose active species can be highly dispersed on the support by means of chemical vapor deposition(CVD) of the precursor metal alkoxides, and to apply those solid acid catalysts to several organic processes.
The solid acid such as <B_2O_3> / <SiO_2> , <B_2O_3> / <Al_2O_3> and <TiO_2> / <SiO_2> in which active species of metal oxides were supported in a state of high dispersion could be obtained by reacting <B(OEt)_3> and <Ti(OPr)_4> with silica and alumina at 190 - 350 ゜C in the presence of oxygen. It was suggested that the metal oxides were fixed onto the support surface through repetition of the reaction between metal alkoxides and the surface hydroxy groups of support followed by the combustion of the organic moieties of the immobilized surface alkoxides.
Compared with very large metal oxide particles of 10 - 50 <mu> m found for the solid acids prepared by the ordinary impregnation method, the solid
… More
acids obtained by CVD consisted of uniformly dispersed very fine crystallites of active metal oxides to afford more uniform acid strengths, which were confirmed through the measurements of surface area, pore distribution, X-ray diffraction, temperature-programmed desorption of pyridine and differential heat of adsorption of ammonia, together through the observation by scanning electron microscope.
The <B_2O_3> / <SiO_2> and <B_2O_3> / <Al_2O_3> prepared by CVD exhibited higher catalytic activity and selectivity for the vapor-phase Beckmann rearrangement of cyclohexanone oxime at 250 - 300 ゜C (oxime conversion 98 - 100 %, <epsilon> -caprolactam selectivity 95 - 98 mol%), in comparison with the supported boron oxide catalyst obtained by the impregnation method. Moreover, the CVD <TiO_2> / <SiO_2> showed also higher catalytic activity for the esterification reactions in the gas phase.
Thus, the CVD of metal alkoxide in the presence of oxygen is confirmed to be an effective novel method for the design of solid acid catalysts. Less
|
