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31.
Flexible PVC pellets were treated at 150–250°C in 0–7M NaOH solutions for 0–12 h. The degree of dehydrochlorination of flexible PVC pellets increased with increasing reaction temperature and was about 100% at 250°C over 5 h. A porous char, 2–16 μm in pore size, was produced. The dehydrochlorination of PVC in the flexible PVC was proceeded by a first-order reaction in alkaline solution. The maximum rate of the dehydrochlorination for flexible PVC was reached at 5M NaOH. The apparent activation energies were 22–35 kcal/mol in 1–7M NaOH for flexible PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2171–2177, 1998 相似文献
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Tsugio Sato Ken-ichi Sato Yoshinobu Fujishiro Toshiaki Yoshioka Akitsugu Okuwaki 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1996,67(4):345-349
The photocatalytic activity of H2Ti4O9/CdS nanocomposites incorporating CdS particles, less than 0·8 nm thick, in the interlayer of H2Ti4O9 was evaluated for the reduction of NO3− with and without methanol. NO3− was photochemically reduced by bandgap illumination in the presence of H2Ti4O9/CdS nanocomposites with and without methanol although unsupported CdS showed no noticeable photocatalytic activity for NO3− reduction. The oxidation of CdS in H2Ti4O9/CdS to SO42- was accompanied by NO3− reduction without methanol, whereas addition of methanol was useful to promote the NO3− reduction and depress the oxidation of CdS. The catalytic activity of H2Ti4O9/CdS greatly increased with doping Pt particles in the interlayer. 相似文献
33.
Corrosion Behavior of Alumina Ceramics in Caustic Alkaline Solutions at High Temperatures 总被引:2,自引:0,他引:2
Tsugio Sato Shigeki Sato Akitsugu Okuwaki Syun-ichiro Tanaka 《Journal of the American Ceramic Society》1991,74(12):3081-3084
The corrosion rate and changes in the microstructure and fracture strength of alumina ceramics (93.0% Al2 O3 and 99.5% Al2 O3 ) were studied in 0.1 m to 25 m NaOH solutions at 150°C to 200°C, where m = mol/(kg of H2 O). The attack of the caustic alkaline solution started at the grain boundaries. Consequently, the corrosion resistance increased with decreasing SiO2 content in Al2 O3 ceramics, and the corrosion resistance of 99.5% pure Al2 O3 was similar to that of Si3 N4 ceramics. Since large pits are formed by corrosion, the surface area increased first and the apparent corrosion rate increased with time in the initial stage of the corrosion. The corrosion rate of Al2 O3 increased linearly with increasing NaOH concentration, and the activation energy was 102 kJ/mol. The fracture strength of corroded Al2 O3 decreased monotonically as the degree of dissolution of alumina increased. 相似文献
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Tsugio Sato Kenji Kato Toshiaki Yoshioka Akitsugu Okuwaki 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,55(4):385-390
The behaviour of uptake of the benzenecarboxylate ions, C6H6-n(COO)nn (n = 1–6), in aqueous solutions by rock-salt type magnesium aluminium oxide, Mg(1-x)(2+x)Al2x/(2+x)O (x = 0.17, 0.30, 0.33) was investigated at 0.70°C. All the benzenecarboxylate ions were taken up from solution competitively with OH- to form the hydrotalcite-like layered double hydroxides. The uptake rate could be adequately described by a surface chemical reaction controlled shrinking core model, and the apparent activation energy was c. 60 kJ mol?1. The selectivity of anion uptake increased with increasing the charge density of the benzenecarboxylate ions. The amount of benzenecarboxylate ions incorporated in the interlayer of hydrotalcite and the selectivity of uptake for benzenecarboxylate possessing higher electric change increased with increasing aluminium content in the magnesium aluminium oxide. 相似文献
37.
Tomohito Kameda Toshiaki Yoshioka Fumiko Yabuuchi Miho Uchida Akitsugu Okuwaki 《Bulletin of Materials Science》2008,31(4):625-629
In this study, we confirmed that the characteristics of anion intercalation into the interlayer of a hydrotalcite-like compound
(HT) during synthesis are similar to those of the anion-exchange reaction of HTs as well as the reconstruction reaction of
HTs from Mg-Al oxide. We demonstrated that (i) Cl−, which has a higher charge density than NO3−, more easily reacted with Mg and Al species to form HT structure, resulting in greater intercalation of Cl− into the HT interlayer; and (ii) for HTs with lower Mg: Al molar ratios, OH−, which has a higher charge density than Cl− and NO3−, was more likely to interact with Mg and Al species to form HT structure, blocking the intercalation of Cl− and NO3−. Furthermore, we showed that high concentrations of Cl− and NO3− in solution regulated their intercalation into the HT interlayer. The high activity of Cl− and NO3− in solution would facilitate the anions’ reactions with Mg and Al species to form HTs, resulting in a high degree of anion
intercalation into the interlayer of HTs. 相似文献
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2-Bromophenol was reacted in aqueous sodium hydroxide at 200-250 degrees C. The decomposition rate was remarkably faster at 250 degrees C than at 225 or 200 degrees C, and the percentage debromination reached almost 100% in 1M NaOH at 250 degrees C for 4h. The percentage increased with NaOH concentration over the range 0.1-1M. Aliphatic compounds, such as 2,2-dimethoxypropane and 4-hydroxy-4-methyl-2-pentanone, and aromatic compounds, such as phenol and cresol, were formed as decomposition products. The formation of carboxylic acids, such as formic, acetic, and propionic acids, in the presence of oxygen was also confirmed. Under a nitrogen atmosphere, the oxidation caused by oxygen in solution was suppressed and hydrolysis became the dominant reaction in the decomposition of 2-bromophenol. 相似文献