The Kinetics of the Reaction of Hydrogen Sulfide and S u l f u r Dioxide in Organic Solvents

This reaction is equilibrium-limited to 95 to 97% conversion in 2 to 4 stages because the temperature must be kept above the dewpoint of sulfur. Additional processing must be provided to reduce the concentration of sulfurous compounds in the effluent to environmentally acceptable levels. When the reaction between H2S and SO2 is carried out in organic liquids at temperatures below 15OoC it is irreversible and goes essentially to completion. In many organic solvents, such as triethylene glycol, dimethyl ether (Triglyme) and diethylene glycol, methyl ether (DGM), the reaction is impractically slow and, at room temperature, the sulfur formed is too finely divided to be readily separated. Urban (3) found that the presence of N,N-dimethyl aniline (DMA) increased the crystal size of the precipitated sulfur. Furthermore, DMA accelerates the reaction to the extent that 99+% removal of H2S is possible with careful selection of the solvent mixture. The present work was undertaken to study the reaction between HOS and S O 2 in mixtures of DMA/Triglyme and DMA/DGM. Experiments performed by monitoring the temperature rise of this exothermic reaction in an adiabatic calorimeter show the effects of various solvent compositions on the kinetics of the reaction. Solvent selection criteria for an appropriate process scheme can then be set. This reaction system is suitable for application to a process currently being studied in this laboratory for the removal of hydrogen sulfide from industrial gas streams.