里川 重夫

The authors have so far demonstrated that production of fine TiO₂ powder is possible by gas phase hydrolysis of titanium tetraisopropoxide (TTIP). In this paper, the effects are discussed of the shape of reactor and operational condition, such as mixing condition on the produced particle properties especially particle diameter of produced TiO₂ fines.<BR> Our originally designed reactor was used, in which the steam vapor was fed from the bottom of the reactor then transported through an internal thin tube in the heated part of the reactor, and then mixed with TTIP fed from the top of the reactor without heating. The TiO₂ fines were produced by 1.00 ml/min of TTIP gas flow (RC I) at 200, 300, 400 and 500°C of the reactor temperature with 10.0 ml/min (at 25°C) of TTIP gas flow (RC II).<BR> The particle diameter of TiO₂ produced by gas phase synthesis was the smallest at 200°C, while the produced TiO₂ showed increased crystallinity and photochemical activity with increased reaction temperature. The photocatalytic activity of TiO₂ fines produced at 500°C was around 1/10, while that of the calcinated TiO₂ fines produced at 200°C under RC II was 1/4 compared with that of JRC-TIO-4, respectively. The results of the photocatalytic activity tests suggested the activity is expected to be increased not only with increased crystallinities but also with decreased particle size.

PEFC用の水素製造プロセスにおける微量のCO除去方法として、新たにCOメタン化反応が注目を集めている。COメタン化反応は装置の制御が簡便化できるという利点を有するが、改質ガス中に含まれるCO₂のメタン化が同時に進行すると熱暴走する危険性がある。本研究ではCOメタン化反応の選択性の向上を目的とし、担持Ru触媒を用いて、Ru粒子径や担体のCOメタン化反応選択性への影響について検討した。

改質ガス中の微量CO除去を目的とし、CO選択メタン化反応用Ru触媒について検討を行った。種々の金属酸化物を担体としたRu触媒について検討したところ、活性および選択性は担体によって大きく異なり、アルミナやチタニア、Y型およびベータ型ゼオライトを用いることで、従来の商業触媒以上に使用可能な温度域が広がった。特に低温活性の高かったRu/TiO2触媒について、チタニアの調製条件やRuの担持条件などの触媒調製条件がRu/TiO2触媒の活性選択性に与える影響について検討した。

For this study, we established and evaluated two usage scenarios of ethanol (EtOH) from biomass for transportation: direct use of ethanol and use of hydrogen produced from EtOH. As a result, we examined the effectiveness of fuel cell vehicles of the latter case. In the EtOH direct-use scenario, the EtOH-to-Tank efficiency was 63.6-81.0% (energy loss: 706-289 kJ/mol) with 30% Tank-to-Wheel efficiency of EtOH hybrid cars. In other words, in the scenario of fuel cell vehicles with 60% Tank-to-Wheel efficiency, the efficiency of EtOH-to-Tank should be more than 31.8-40.5%. From the results of the present study, it can be concluded that the two evaluated scenarios have comparative efficiencies, considering the currently published EtOH-to-Tank efficiency using steam reforming of 34.0-43.0%. For the realization of bioEtOH-oriented fuel cell vehicles, the development of higher hydrogen production efficiency is required.