Sulfur-containing chelating agents

LO-CAT A process for removing hydrogen sulfide and organic sulfur compounds from petroleum fractions by air oxidation in a cyclic catalytic process similar to the Stretford process. The aqueous solution contains iron, two proprietary chelating agents, a biocide, and a surfactant the formulation is known as ARI-310. The sulfur product is removed as a slurry. Developed in 1972 by Air Resources (now ARI Technologies) and first commercialized in 1976. Over 125 units were operating in 1996. An improved version, LO-CAT II, was announced in 1991. 

Selective adsorption may also have dramatic consequences for crystal growth if certain crystal planes can be blocked ). Trace amounts of Impurities may in this way determine the eventual crysted shape. This feature plays an Important role in the preparation of (tailor-made) colloids (Volume IV) obviously adsorption kinetics plays an Important role here. Certain substances may of course work the other way around In that they "attack the solid. Examples are some sulfur-containing compounds with silver halides, and chelating agents with haematite (a-Fe O ). 

Sulfur-Containing Chelating Agents. Perhaps the greatest interest in square planar complexes has arisen in the area of sulfur donors and the resulting discussions concerning multiple oxidation states of nickel (25, 63, 86, 87, 88). 

Figure 6. Sulfur-containing chelating agents which promote square planar geometry...

Maier, L., and Crutchfield, M.M., Organic phosphorus compounds. Part 70. Preparation and properties of new phosphorus-containing chelating agents for calcium and magnesium ions. Phosphorus Sulfur, 5, 45, 1978. 

The traditional HDS catalysts are CoMo or NiMo based catalysts. Highly dispersed molybdenum sulphide exhibits a low but stable catalytic activity in a sulfur-containing environment. By adding the promoter elements, cobalt or nickel, in an atomic Co/Mo or NiMo ratio of 0.3 to 0.5 a ten-fold increase in activity could be achieved [1], Further improvements were made by addition of chelating agents, phosphate, and fluorine [2]. 

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