Investigation of the Degradation of Chelate Complexes in Liquid Redox Desulfurization Processes

Abstract

Metal complexes such as Fe-EDTA, which are used as pseudo-catalysts or oxygen carriers in wet oxidative desulfurization processes, are subject to a degradation mechanism that significantly influences the economics of such processes. Therefore, this study presents a methodology for determining the degree of degradation during the reactive hydrogen sulfide absorption in a Fe-EDTA solution within a continuously operating semi-batch reactor system. For this purpose, the reactive conversion of H2S in the liquid phase was used as a reference, and a clear dependence of the degradation on the pH could be shown. In addition, indicators are introduced that evaluate the observed pH dependency of the degradation and distinguish pH-induced effects such as the pH-dependent absorption performance of H2S.