Separation of thiosulfate from Stretford solution
AssigneeMobil Oil Corporation
InventorWilton F. Espenscheid
Life of this patent
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Abstract
A thiosulfate-containing purge stream generated in a Stretford-type process for purifying a hydrogen sulfide contaminated gas stream is treated with a nickel ethylenediamine complex to remove thiosulfate as a nickel ethylenediamine thiosulfate precipitate. The precipitate is treated with acid to decompose the thiosulfate and then with lime to recover the nickel ethylenediamine complex for reuse.
Claims1
In the process of purifying a hydrogen sulfide contaminated gas by indirectly oxidizing the hydrogen sulfide with oxygen gas to form elemental sulfur and purified gas, which process comprises recycling a reactive, regenerable aqueous sorbent comprising sodium salts of anthraquinone disulfonic acid and an oxyanion of vanadium as means for effecting said indirect oxidation, and wherein a stream of said recycled aqueous sorbent containing thiosulfate is purged;
- the improvement comprising removing thiosulfate from said purge stream by:
- (a) treating said purge stream with a nickel ethylenediamine complex forming a precipitate of insoluble nickel ethylenediamine thiosulfate without precipitation of anthraquinone disulfonic acid or vanadate;
- (b) separating said aqueous sorbent from said insoluble precipitate and returning said sorbent to said recycling step;
- (c) acidifying said precipitate with sulfuric or phosphoric acid whereby decomposing thiosulfate;
- (d) alkalizing the acidified precipitate whereby forming a precipitate of insoluble salts;
- (e) recovering a regenerated nickel ethylenediamine complex;
- and
- (f) recycling the regenerated nickel ethylenediamine complex to be used in treating said purge stream.
Dependencies are inferred from the claim text.