关键词: 磷钼酸钠, 硫回收, 机理, 热力学可行性

Abstract: A new method of natural gas desulfurization has been developed by employing the heteropoly compound of the rich elements of our country. This method enables hydrogen sulfide to be removed and element sulfur to be recovered simaltaneously. The thermodynamic feasibility of simultaneous desulfurization and sulfur recovery from natural gas with the solution of heteropoly compound was proved to be applicable by the experimental result of potential pH-curves. At present, no proof was given on the exact number of electron transferred during the redox reaction between sodium phosphomolybdate and reductants including hydrogen sulfide. The research here also reveals the reaction mechanism between sodium phosphomolybdate and hydrogen sulfide. With the aid of ISE, DSC and EMS, the mechanism of desulfurization reaction was studied. The reaction products contain little deposition compounds of molybdenum and vanadium, indicating that sodium phosphomolybdate is still much stable in its chemical property after many times of absorption regeneration cycles, the agent loss is much lower than that of the chelate iron method. The chemical equation of sodium phosphomolybdate and H₂S was proposed to be: H₂S+Na₂HPMo₁₂^Ⅵ O₄₀→S↓+Na₂H₃PMo₁₀^ⅥMo₂₀^Ⅴ₄₀ i.e ., there are two Mo(Ⅵ) atoms reduced to Mo(Ⅴ). Therefore, the theoretical saturation sulfur loading capacity of sodium phosphomolybdate is twice that of chelate iron with the same molar concentration.

Key words: Sodium phosphomolybdate, Sulfur recovery, Mechanism, Thermodynamic feasibility