Simultaneous Sulfur Dioxide Absorption and Hydrogen Sulfide Generation in an Aqueous Solution of Sodium Sulfide

Abstract

In flue gas desulfurization (FGD) processes, elemental sulfur is the desirable end product for SO2 producers located in remote areas, since it is easier to handle and transport. To convert sulfur dioxide to elemental sulfur via the Claus reaction, hydrogen sulfide is needed as a reductant. In the present work, an attempt was made to generate H2S from aqueous sodium sulfide using SO2. The behavior of the Na2S(aq)−SO2(g)−H2S(g) system was studied experimentally and by modeling. A three-stage pattern was observed in a semi flow batch reactor (SFBR) in regard to chemical properties of this system. It was concluded that aqueous Na2S solution can be used to absorb SO2 in flue gas and to generate H2S under conditions of the second stage. The simultaneous SO2 absorption and H2S generation in an aqueous Na2S solution were confirmed using a continuous flow tank reactor (CFTR). To simulate both the SFBR and the CFTR, two mathematical models were developed based on chemical equilibria of acid−base reactions and mass ...