Phenol is readily produced by some stoichiometric reactions of benzene with certain copper(II) salts. The main part of the reaction using copper(II) sulfate is estimated to be expressed by the following equation: This reaction was carried out in a flow system at 300 °C, where a vapor mixture of benzene and water flowed through a packed bed of copper(II) sulfate supported on silica gel. The products were mainly phenol and CO2 with a trace amount of biphenyl. The phenol yield became appreciable at temperatures higher than 250 °C, and reached a maximum at ca. 300 °C. At higher temperatures, the CO2 yield increased along with the consumption of phenol. The percentage yield of phenol based on copper(II) salt was 86% at the highest. Although copper(II) phosphate was similarly useful, it required a higher reaction temperature (ca. 500 °C).

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The performance of silica supported Pd–Cu composite catalyst developed previously for direct oxidation of benzene to phenol has been improved by changing the copper ion source from Cu(II) sulfate to Cu(II) phosphate and by additional impregnation of phosphoric acid. The reaction proceeds under the simultaneous feeding of benzene, hydrogen and oxygen at 200 °C with a rate of phenol production ca. 0.4 mmol h−1 (g-cat)−1, which is ten times greater than that we have reported previously with a catalyst prepared from Cu(II) sulfate. With this catalyst, complete oxidation to carbon dioxide is also retarded to increase the selectivity of phenol. The improvement of catalytic activity arises apparently from the diminution of the yield of water and is ascribed to the presence of a thin liquid film over the silica surface.

The present purpose is to reveal the mechanism of a flying pipe from an aerodynamic point of view. At first, we conduct field observations of a flying pipe using a pair of high-speed video cameras, together with three-dimensional motion analyses. In addition, we conduct numerical analyses by a finite difference method based on the MAC scheme. As a result, the observed orbit is approximated to be not an obvious parabolic curve but rather a straight line, after an initial instable and complicated curve. The stable flight with this approximately-straight orbit suggests the importance of aerodynamics in flying mechanism. More specifically, the model is in an unstable and complicated flight during an initial flight, afterwards becomes in a stable and approximately-straight flight. In the initial instable and complicated flight, the model flies fluctuating its posture upward, downward, left-ward and right-ward. As flight distance increases, the absolute value and the amplitude of moment becomes small to zero. During such a decaying and stabilising process, the gyroscopic effect plays a primary role balancing not angular acceleration of the model but aerodynamic fluid moment. In the stable and approximately-straight flight, the flow in the stable and approximately-straight flight is nearly the velocity-potential one, and accompanies very-small drag force. And, we could ignore the influence of model's rotation upon the flow and the orbit. In this context, the model's rotation is only to stabilise its posture, and gives negligible contribution upon its aerodynamics.

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