Yasuo Saito

Studies on catalysis by molten metal: VI. Kinetics and the reaction scheme for the dehydrogenation of isopropyl alcohol over the liquid indium catalyst

The rate of dehydrogenation of isopropyl alcohol over the molten indium (liquid indium) catalyst has been studied in a specially designed reaction apparatus. It has been shown that the rate of reaction is expressed by the following equation: r = kAKA2pA2(1 + KAPA)2, where kA = 12.7 exp (−30,600RT) in mole cm−2 sec−1 and KA = 6 × 10−2 exp (9000RT) in atm−1. In order to explain the kinetic data, reaction schemes have been discussed to indicate that the surface bimolecular collision between the adsorbed alcohol molecules is the rate controlling step. Further, kinetic evidence has been given to consider that the adsorbed alcohol behaves like a two-dimensional gas.

2-Butanol vapor adsorption and the accompanying changes in surface tension and surface composition of an InSn liquid alloy system

Abstract Surface tensions of InSn liquid alloys of various compositions were measured at high temperatures. The measurement was carried out by means of a maximum bubble pressure method. Paying particular attention to the effect of 2-butanol vapor adsorption upon the surface composition C 1 s in addition to inert gases, 2-butanol vapor was used to make the bubble. The experimental results revealed that the adsorption of 2-butanol vapor results in a great deviation of the surface composition from the bulk composition C 1 b . In addition, the C 1 s - C 1 b relation was found to exhibit an S-shaped curve with a singular point defined by C 1 s = C 1 b ⋟ 0.5 . At this point, the adsorption coefficient K a for 2-butanol was found to take a maximum value. The formation of a small amount of a complex having the composition of In Sn ⋟1 is discussed, and an especially strong interaction of the complex with 2-butanol is suggested.

Studies on the catalysis of molten metal: XII. A stereochemial study on the reaction of menthol

Abstract The conversion of dl -menthol and that of l -menthol have been measured by a rectangular duct-type reactor containing a liquid metal catalyst (Tl or In; the surface area is about 20 cm 2 ). The experimental result has shown that the total conversion of dl -menthol is higher than that of l -menthol. In order to explain this unusual result, the following reaction scheme has been assumed: With the aid of stereochemistry and molecular interaction models, comparisons among the rate constants for the elementary steps have been carried out. It has been shown that the transfer hydrogenation step proceeds faster in the dl -menthol system than in the l -menthol system and, consequently, that the difference in the total conversion of the menthol isomers becomes observable.

Studies on the catalysis by the molten metal: XI. An analysis of an anomalous catalytic activity of In-Sn liquid alloy in the dehydrogenation of 2-butanol

Abstract Measurements of the rate of 2-butanol dehydrogenation over the In-Sn liquid alloy catalyst have been carried out. In addition, the surface tension of the liquid alloy has been measured at high temperatures and under the atmosphere of 2-butanol vapor. It has been found that the catalytic activity vs catalyst composition curve has a maximum at In/Sn ≒ 1. Furthermore, interesting information about the adsorption of 2-butanol has been obtained from the surface tension data. By assuming a surface unimolecular reaction mechanism, the Hinshelwood-Lindemanns theory has been applied to analyze the experimental data. Thus, it has been shown that the curious relation between the catalytic activity and the catalyst composition is ascribed to the following reasons. (i) The admolecules at In/Sn ≒ 1 have the largest effective internal freedom. (ii) The admolecules with the largest internal freedom must have the smallest chance to be activated. (in) If activated, however, such admolecules are brought to the most strongly energized state. (iv) Hence the admolecules at In/Sn ≒ 1 are able to have the shortest lifetime and decompose with the highest rate.