Water is a special liquid-and not only under "normal" conditions. Water in the supercritical state (shaded area in the phase diagram) is distinguished by special properties which are wholly at variance with those of normal water. So far these have usually been exploited for the purification of waste water, for example for the complete oxidation of poorly degradable substances. But what is the potential of supercritical water for synthesis? Answers are provided here on the basis of thermodynamic and kinetic studies as well as with reference to measurements of corrosion.

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Wasser ist ein besonderer Saft – nicht nur unter „normalen”︁ Bedingungen. Wasser im überkritischen Zustand (gerasterte Fläche im Phasendiagramm) zeichnet sich durch Eigenschaften aus, die von denen des normalen Wassers erheblich abweichen. Bisher wurden diese meistens zur Abwasserreinigung, z. B. zur Totaloxidation schwer abbaubarer Stoffe, genutzt. Doch wie sieht es mit dem Synthesepotential von überkritischem Wasser aus? Antworten werden hier anhand von thermodynamischen und kinetischen Untersuchungen sowie von Korrosionsmessungen gegeben.

Water is a special liquid-and not only under "normal" conditions. Water in the supercritical state (shaded area in the phase diagram) is distinguished by special properties which are wholly at variance with those of normal water. So far these have usually been exploited for the purification of waste water, for example for the complete oxidation of poorly degradable substances. But what is the potential of supercritical water for synthesis? Answers are provided here on the basis of thermodynamic and kinetic studies as well as with reference to measurements of corrosion.

L 0 [m] initial length of the fluid bridge L drop [m] drop length in flow direction R 0 [m] initial radius of the fluid bridge R drop [m] drop radius of the initial spherical drop g [m s ±2 ] acceleration of gravity = 9.81 t [s] measurement time v R [m s ±1 ] rate of change of the bridge radius v z [m s ±1 ] rate of change of the bridge length Greek symbols Z matrix [Pa s] matrix shear viscosity Z drop [Pa s] drop shear viscosity l [±] ratio of drop and matrix viscosity s matrix-drop [N m ±1 ] surface tension between drop and matrix fluid References [1] Hudson, N.E.; Ferguson, J.; Mackie, P., The Measurement of the