Catalytic asymmetric allylation of aldehydes with allylic trimethoxysilanes was achieved with the p-Tol-BINAP small middle dotAgF complex as catalyst [Eq. (a); p-Tol-BINAP=2,2'-bis(di-p-tolylphosphanyl)-1,1'-binaphthyl)]. High anti and enantioselectivities were obtained in the reaction with crotyltrimethoxysilane, irrespective of the configuration at the double bond.

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The hydrogen permeability of Pd-Ag alloy membranes has been investigated over a wide temperature range between 100 C and 500 C. The hydrogen permeation coef cient, Φ, for Pd-23mol%Ag decreases with decreasing temperature above 300 C, in good agreement with the previous literature. However, Φ starts to increases below 250 C, and a peak is observed at around 180 C. Considering the silver concentration and operating temperature, the α-α phase transition never occurs in this condition. In other words, the α-α phase transition is not the reason for the anomalous peak behavior of Pd-23mol%Ag alloy at low temperature. In addition, it is con rmed that the diffusion-limiting hydrogen permeation reaction takes place from room temperature up to 500 C. To understand the reason for the peak appearance, the hydrogen permeability has been analyzed in view of the new description of hydrogen permeation based on hydrogen chemical potential. As a result, it is found that the temperature dependence of the PCT factor, f PCT , is dominant for the peak appearance, meaning that the corresponding pressure-composition-isotherms (PCT curves) are essential for the understanding of hydrogen permeability of the alloy. Dependences of the pressure condition and silver concentration on the peak behavior have also been investigated. The peak temperature increases with increasing the hydrogen pressure at feed side. In addition, the peak appears at lower temperature and becomes remarkable with decreasing silver concentration of Pd-Ag alloy membrane. In other words, the composition of Pd-Ag alloy membranes must be designed based on the operating temperature or pressure condition. Thus, this study suggests new possibilities of alloy design for Pd-Ag alloy membranes.

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A concept for alloy design of hydrogen permeable membrane with high hydrogen permeability and long-term durability has been proposed in view of the PCT factor, f PCT , and the ductile-to-brittle transition hydrogen concentration, DBTC. As an example, V-10mol%Fe alloy has been designed for low operative temperature, which exhibits excellent and stable hydrogen permeability for at least 1000 hours at 573 K without brittle fracture.In addition, the alloying effects of iron on the hydriding property and the hydrogen diffusivity have been investigated quantitatively in order to establish a way to design optimal composition of V-Fe based hydrogen permeable alloy under any given conditions. It is found that the addition of iron into vanadium increases linearly the partial molar enthalpy change, ∆H 0.2 , of hydrogen for hydrogen dissolution, but scarcely affects on the partial molar entropy change, ∆S 0.2 . It is also found that both the activation energy, E and the pre-exponential factor, B 0 , of the mobility for hydrogen diffusion decrease linearly with increasing the mole fraction of iron, meaning that the addition of iron enhances the hydrogen diffusivity at low temperature below about 700 K. The evaluation in view of the four parameters, ∆H 0.2 , ∆S 0.2 , E and B 0 , is useful for deep understanding of the property of hydrogen permeable metal membrane. Following the concept for alloy design in view of these four parameters, optimal alloy composition can be designed under any given conditions. The hydrogen permeability of the designed alloy under the condition can also be estimated quantitatively.

The alloying effects of Ru and W on the hydrogen solubility, the resistance to hydrogen embrittlement and hydrogen permeability are investigated quantitatively for Nb-based hydrogen permeable alloys. It is found that the hydrogen solubility decreases by the addition of alloying element into niobium or by increasing the temperature. As a result, the resistance to hydrogen embrittlement is improved by reducing the hydrogen concentration. On the other hand, the hydrogen flux, J, through the alloy membrane increases linearly with increasing difference of hydrogen concentration, ÁC, between both sides of the membrane. It is shown that the Nb-5 mol%X (X = Ru and W) alloys possess excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate permeation conditions, i.e. temperature and hydrogen pressures. Also, the hydrogen diffusion coefficients during the practical hydrogen permeation at high temperature are evaluated from the linear relationship between the hydrogen flux and the hydrogen concentration difference. It is found that the hydrogen diffusion coefficient of pure Nb is much lower than the reported values measured for dilute hydrogen solid solutions. Surprisingly, the hydrogen diffusion is found to be faster in Pd-26 mol%Ag alloy with fcc crystal structure than in pure niobium with bcc structure at 773 K during the hydrogen permeation. It is also interesting that the addition of Ru or W into niobium enhances the hydrogen diffusion of the practical hydrogen permeation at high temperature.

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