Effect of the V⁵⁺ to V⁴⁺ Molar Ratio on H₂S Absorption and Conversion to Elemental Sulfur

Abstract

This study assessed V5+ concentration and V5+ to V4+ ratio effects on the H2S absorption and oxidation to elemental sulfur from H2S gas streams in simulated Stretford solutions. Laboratory-derived sulfur products were characterized by inductively coupled plasma optical emission spectrometry, X-ray diffraction (XRD), particle size distribution (PSD), and differential scanning calorimeter (DSC) analyses for probing the chemical, mineralogical, and physical properties of the sulfur products. H2S absorption and sulfur production efficiencies increase with an increase in the V5+ concentration. However, the sulfur’s PSD results are finer and the purity decreases as the V5+ concentration increases because of K/Al/Si/Mg/Fe impurities in the added technical grade sodium ammonium vanadate (SAV) to the Stretford solution. XRD and DSC results of the orthorhombic sulfur (α-S8) products indicate that these products have similar mineralogical properties and melting points compared to those of the commercial α-S8. V5+ to V4+ ratios decreased with a decrease in α-S8 production efficiency, and a total vanadium loss of 89% was achieved because of the V4+ precipitation from the Stretford solution without disodium salt of 2,6 and 2,7 isomers of anthraquinone-disulphonic acid (Na2[ADA]). Low V5+ to V4+ ratios were found to be responsible for the sulfur sol formation and subsequent dark-colloidal V4+ and fine α-S8 precipitation in the Stretford units. The Stretford process must be operated with Na2[ADA] for the V4+ oxidation in the solutions. Research outcomes as well as the total replacement for SAV with a pure V5+ salt can assist the Stretford operators to further improve α-S8 quality and its production efficiency.

Enhanced Desulfurization by Tannin Extract Absorption Assisted by Binuclear Sulfonated Phthalocyanine Cobalt Polymer: Performance and Mechanism

“…It is of great importance to remove H 2 S from COG for health and environmental concerns. The main technologies for H 2 S removal from COG in traditional coking industries include the Takahax method (TH) [ 6 ], Anthraquinone disulfonic acid method (ADA) [ 7 , 8 ], tannin extract absorption [ 9 , 10 ] and the PDS method [ 11 ]. Among them, tannin extract absorption and PDS method are promising methods due to their low cost and high efficiency.…”