Showing papers by "Naotsugu Itoh published in 2006"
TL;DR: In this paper, the authors examined the gasification of lignin biomass model compounds in the presence of magnesium oxide supported nickel catalysts (Ni/MgO) in sub-and supercritical water from 523 to 673 K.
Abstract: Gasification of lignin biomass model compounds was examined in the presence of magnesium oxide supported nickel catalysts (Ni/MgO) in sub- and supercritical water from 523 to 673 K. The main gas products were methane, carbon dioxide, and hydrogen. The amount of gases produced increased with an increase in nickel loading on magnesium oxide. The highest total gas yield in a carbon basis was 78% with 20 wt % Ni/MgO catalyst at 673 K and 0.3 g/cm3 water density. In this system, the metal and support of Ni/MgO probably play different roles in gasification that MgO decomposed lignin to reactive intermediates and nickel promoted reaction between intermediates and water to form gases. The yield of methane and carbon dioxide increased with increasing water density but then decreased and leveled out to constant values, which indicates that water density affected the reaction kinetics.
83 citations
TL;DR: In this article, the anti-Markovnikov alkylation of phenol with tert-butyl alcohol was achieved without catalyst in supercritical water at 673 K. The de-hydration gave isobutene and was fo...
Abstract: The anti-Markovnikov alkylation of phenol with tert-butyl alcohol could be achieved without catalyst in supercritical water at 673 K. The dehydration of tert-butyl alcohol gave isobutene and was fo...
9 citations
TL;DR: In this article, the reaction rates of methane steam reforming for hydrogen production at low temperatures 400-525°C were measured to establish the rate expression, and a 2wt% ruthenium supported alumina was used as a catalyst.
Abstract: Reaction rates of methane steam reforming for hydrogen production at low temperatures 400-525°C were measured to establish the rate expression. A 2wt% ruthenium supported alumina was used as a catalyst. As the measured rates were analyzed based on the Langmuir-Hinshelwood mechanism, it was found that the surface reaction between methane and water adsorbed was the rate-determining step and the following expression could well explain the kinetic data obtained experimentally.r=k/ (1+KCH4PCH4+KH2OPH2O+KH2PH2) 4/ (PCH4PH2O-PCO2PH24/KP)
7 citations
TL;DR: Cis-3-hexenal, 1-hexanol, hexanalであり，反応経路は1）cis-threehexen-1-olの脱水素
Abstract: 不飽和アルコール脱水素反応のモデル反応として，流通式反応器を用い，CuO/ZnO触媒によるcis-3-hexen-1-olの脱水素反応を行った．反応温度は438–458 Kとした．主生成物はcis-3-hexenal, 1-hexanol, hexanalであり，反応経路は1）cis-3-hexen-1-olの脱水素反応によるcis-3-hexenalの生成，2）脱水素反応で生成した水素とcis-3-hexen-1-olの水素化反応による1-hexanolの生成，3）cis-3-hexenalの水素化反応，4）1-hexanolの脱水素反応によるhexanalの生成であった．hexanal収率がもっとも高く，収率は最大80%以上となった．熱力学物性が未知であるcis-3-hexen-1-olとcis-3-hexenalの物性値を推算し，それに基づき全反応の自由エネルギーを計算した．反応平衡計算の結果，本温度領域ではhexanalが非常に安定であり，実験結果と同様の傾向であった．また，438–458 Kにおける実測値を相関する反応速度定数の実験式を提出した．
3 citations
01 Jul 2006
TL;DR: In this paper, the mixtures of methyl-cyclohexane and cyclohexanes were proposed as another chemical hydride, where the evolved hydrogen was selectively separated from the catalyst-packed reaction zone through a palladium membrane that is impervious to any gases except hydrogen.
Abstract: The mixtures of methyl-cyclohexane and cyclohexane were proposed as another chemical hydride. Addition of 10 mol% methyl-cyclohexane to cyclohexane could lead to about 25 C depressions in the solidification temperature of cyclohexane, which means that the freezing point become as low as ca. -20 C. Further, methyl-cyclohexane and a mixture consisting of 10 mol% methyl-cyclohexane and 90 mol% cyclohexane were de-hydrogenated using a membrane reactor, where the evolved hydrogen was selectively separated from the catalyst-packed reaction zone through a palladium membrane that is impervious to any gases except hydrogen. In any case, both the decrease of feed rate and the increase of the pressure of reaction side increased the amount of hydrogen recovered through membrane in the range of 250 - 300 C and 2-4 bar. (authors)
1 citations