Studien zum Vorgang der Wasserstoffübertragung, 75 [1]. Elektrochemische Untersuchungen von S-und P-vergiftetem Raney-Nickel (Ra—Ni) und Versuche zu dessen Reaktivierung / Studies on the Occurrence of Hydrogen Transfer, 75 [1]. Electrochemical Investigation of Raney-Nickel (Ra—Ni) Poisoned with S and P and Experiments for the Reactivation

Abstract

Abstract Ra-Ni with an artificial rest potential of -1000 mV (vs SCE) is shifted with different rates to more positive values after the addition of thioethers and carbon disulfide. Only with Na2S·9H2O a potential of -1100 mV (constant) is observed. Ra-Ni poisoned with sulfur is not reactivated neither cathodically nor anodically nor by the corrosive degradation at constant pH. Hydrogen structurally incorporated into the lattice of Ra-Ni (structural bonded hydrogen) is consumed by poisoning with thioethers and trivalent phosphorus compounds in a stoichiometric way. Ra-Ni-powder stepwise corrosively degradated up to 30% shows the same degree of desulfuri-zation as the original Ra-Ni. Desactivated Ra-Ni (loss of structural bonded hydrogen) is reacti-vated (56%) by cathodical treatment. In competing reactions the P-S, C-S, and C -P-bond in thiophosphinic esters, thioethers and trivalent P-compounds are hydrogenolyzed by Ra-Ni, the C-P-bond faster than the C-S-bond.