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The LYSY complexed iron-based desulfurization technology is a wet oxidation method for removing hydrogen sulfide, using complexed iron as a catalyst. It features the direct conversion of H2S into elemental sulfur, with the H2S content in the treated gas being less than 10 ppm. It represents a new type of desulfurization technology that is simple to operate, has a high sulfur handling capacity, and is environmentally friendly and non-toxic. It overcomes the shortcomings of traditional desulfurization processes, such as low sulfur handling capacity, complex operation, high formation of by-products, and severe environmental pollution. The sulfur recovery rate achieved using this system can reach 99.9%. 2.2 Process principle of the LYSY complexed iron-based desulfurization technology: The complexed iron desulfurization technology is a complete set of solutions for removing hydrogen sulfide using complexed iron; it offers various cooperation models such as provision of process packages, chemical reagents and related components, as well as EPC services for hydrogen sulfide removal. Tangshan Lvyuan Environmental Protection provides a constant-temperature, low-cost method for eliminating hydrogen sulfide. The chemical reaction principle involves using oxygen in the air to oxidize hydrogen sulfide in the gas phase, thereby converting hydrogen sulfide into elemental sulfur. Its chemical reaction equation is as follows: H2S + 1/2O2 → H2O + S. The absorption-oxidation reaction equation for aqueous solutions containing complexed iron ions is: H2S(g) + 2Fe3+(L) → 2H+(L) + S↓ + 2Fe2+(L). The overall reduction-regeneration reaction equation is: 1/2O2(g) + H2O(L) + 2Fe2+(L) → 2OH-(L) + 2Fe3+(L). In the overall reaction, the role of the complexed iron ions is to release the electrons generated in the absorption reaction into the regeneration reaction; since the formation of each molecule of elemental sulfur requires the consumption of two iron atoms, at least two iron atoms must be provided during the reaction process. Thus, iron ions serve as reactants. However, iron ions are not consumed in the overall reaction; they act as a catalyst for the reaction between hydrogen sulfide and oxygen. Due to this dual function, iron ion complexes are generally defined as catalysts. In the complexed iron desulfurization process, the pH value of the circulating aqueous solution is a very important variable operating factor, as the total amount of H2S gas that can be absorbed by the aqueous solution depends entirely on its pH value. The overall reaction equation shows that no net products of H+ ions or OH- ions are formed as a result of this reaction, so the pH value of the aqueous solution does not change. Since the gas phase being processed contains carbon dioxide (CO2), and especially at higher pressures, carbon dioxide dissolves easily in water, forming bicarbonate (HCO3-) and carbonate (CO32-) ions; subsequent side reactions then reduce the pH of the aqueous solution. To stabilize the pH of the aqueous solution, potassium hydroxide needs to be added to the system. Generally, a higher pH value can improve reaction efficiency, promote the formation of thiosulfate ions, and reduce oxygen absorption; however, it also hinders the aggregation of elemental sulfur ； Too low a pH value will hinder the absorption of H2S gas. Therefore, use a weakly alkaline aqueous solution with a pH of 8.0–9.0. 2.3 Advantages of the LYSY complexed iron-based desulfurization technology (1) The treatment process is simple; a one-step process is sufficient to rapidly oxidize hydrogen sulfide directly into elemental sulfur ； For various concentrations of H2S, the H2S content after desulfurization can be reduced to below 10 ppm. (2) The system has strong resistance to fluctuations. (3) Low operating costs. (4) The complexed iron catalyst has high selectivity, with no by-product salts discharged. (5) The desulfurization working fluid has a high sulfur capacity. (6) It can remove organic sulfur compounds such as COS and thiols. (7) The equipment has a small size, allowing for effective skid-mounted installation. (8) The catalyst has high safety; the catalyst used in the system is non-toxic and harmless to the environment and human health, offering excellent environmental benefits.