Langmuir, Vol.13, No.5, 913-918, 1997
Induced Surface Heterogeneity as an Autocatalytic Way to Promote Acid-Base Heterogeneous Reactions
Alkaline hydrides MH are insoluble in all known solvents. Dispersed in strictly anhydrous solvents, KH has an extraordinary behavior with respect to Bronsted acids HA : it reacts with difficulty with strong acids, but reacts readily with weak acids. The reason for this behavior is ascribed to the fact that the reaction K+H(s-) + HA((sol)) --> K(+)A((s)(-)) + H-2(g) does not occur via an acid-base pathway, but via electron transfer from H- to HA. A model is proposed for the autocatalytic activation of acid-base reaction due to the presence of a superficial layer of adsorbed K+ A(-) ionic pairs. The effect of these ionic pairs is to reduce the activation energy for the acid-base pathway. This model predicts that in some conditions the production rate of H-2 formed via the acid-base pathway oscillates with time.
Keywords:BINUCLEAR ATOMS;PHASE