CA2309422A1 - Hydrogen sulfide removal process - Google Patents

Abstract

Hydrogen sulfide is removed from gas streams by reaction with sulfur dioxide to produce sulfur. The reaction is effected in a reaction medium comprising a non-aqueous Lewis base with a pK b value of about 6 to about 11. The reaction medium possesses a specific combination of properties: a) absorbs sulfur dioxide and reacts chemically therewith, the reaction medium containing hydrogen sulfide, sulfur and water to form complex sulfur-oxide species, including sulfate and polythionate species, whereby the resulting solution exhibits no or an insignificant sulfur dioxide vapor pressure; b) absorbs hydrogen sulfide; c) removes the hydrogen sulfide from the gas stream through contact of the gas stream with the reaction medium in the presence of the complex sulfur-oxide species; d) acts as a catalyst for the overall reaction of the hydrogen sulfide with sulfur dioxide to produce sulfur; and (e) has the capacity to absorb sulfur dioxide in sufficient quantity to remove substantially all the hydrogen sulfide from the gas stream, notwithstanding short term variations in the stoichiometric balance between the hydrogen sulfide and the sulfur dioxide in the reaction medium. The reaction medium may be preloaded with sulfur dioxide, whereby the complex sulfur-oxide species are preformed in the reaction medium before contacting with the gas stream.