Details

Autor(en) / Beteiligte

• Turner, G.M

Titel

Solution and surface reactions of liquid

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1989

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• This thesis is divided into two parts; the first is concerned with solutions of non-metals in liquid caesium whilst the second describes the reaction of unsaturated hydrocarbons on liquid alkali metals. The caesium-dicaesium telluride system was investigated using resistometric and thermal analysis techniques. No phase changes could be detected by either technique for dilute solutions. The steel was corroded by liquid tellurium but not by dilute solutions in caesium. The caesium-caesium hydroxide system was investigated using the same techniques and the solvation enthalpy of hydroxide in caesium was determined as 404.6 kJmol-1. Caesium hydroxide caused a depression of the freezing point of caesium by 1.2oC, at the eutectic concentration of 0.7mol% OH. Caesium hydroxide may exist in solution as dimers, or there may be a solid solution formed up to a concentration of 0.34mol% OH. Ethene undergoes reduction to ethane on liquid caesium both by self hydrogenation and also catalytically. Ethene is adsorbed both associatively and dissociatively, so that hydrogen atoms from the dissociation then reduce the associatively adsorbed ethene to give ethane. The reaction was first order with an activation energy of 15.8 kJmol-1, which was determined by the rate of loss of hydrogen from the dissociative species. With ethene/hydrogen mixtures the dissociation process is supprssed and the added hydrogen now quantitatively reduces the associatively adsorbed ethene to ethane. The reaction was again first order with an activation energy of 45.5 kJmol-1, which is identical to the caesium-hydrogen reaction. Ethyne undergoes self hydrogenation on the surface of potassium, sodium-potassium alloy and caesium. The products depended on temperature and metal. Generally potassium produced KC2H and C2H4 (70-90oC) at low temperatures, at slightly higher temperatures K2C2 and C2H4 were formed (110-140oC), and these were replaced on raising the temperature (> 170oC) by C2H6 and K2C2. With sodium-potassium the reactions occurred at lower temperatures. On caesium a mixture of ethane and hydrogen was produced at all temperatures studied (35-100oC). The catalytic hydrogenation of ethyne on NaK by hydrogen occurred from 25-150oC but was complex. With 1:1 at 25-50oC some ethene and ethane were produced. With 1:2, up to 30% of ethyne is converted to ethane catalytically and no ethene is formed. In no case did the added hydrogen completely suppress the dissociative ethyne species. (D89357)