Hydrogen Recovery from Hydrogen Sulfide by Oxidation and by Decomposition

Abstract

Selective oxidation of hydrogen sulfide to hydrogen and sulfur oxides in a two-step process and the catalytic decomposition of hydrogen sulfide were studied for the recovery of hydrogen from hydrogen sulfide. Platinum, when adequately dispersed on a silica support, was found to be effective in reacting with hydrogen sulfide to produce hydrogen and platinum sulfide at 500 C. The platinum sulfide could then be treated with oxygen at 400 C to release sulfur oxides and regenerate the platinum. However, oxidation of sulfur dioxide to trioxide, retention of oxygen by platinum, and adsorption of hydrogen sulfide by the silica support also occurred, which resulted in a minor loss in hydrogen yield. In the decomposition of hydrogen sulfide, platinum sulfide was found to be catalytically active. The equilibrium hydrogen yields were measured experimentally over the range 350--650 C and compared with the values calculated on the basis of a model that included the S, allotropes, the H[sub 2]S[sub n] sulfanes, and HS. The values agreed well at low temperatures but deviated from each other up to 20% at high temperatures.