Complete Removal Of H₂S From Biogass By Wet Catalytic Oxidation To Sulfur On Zinc/Iron Catalyst

Along with our country new energy construction carring on, as a new energy, biogas is becoming important increasingly in its exploiture, and has the vital Significanc to the ecological protection which cannot be substituted, especially in the extensive rural areas.But biogas contains a certain amount of hydrogen sulfide, which is corrosive, toxic, could contaminate environmentl, rust metal and endangering human health and life, must controlled strictly.However,there is no practical economic desulfurization systems for the rural domestic gas system which size is small and distributing abroad at present So the study of domestic biogas desulfurization process has the certain practical meaning..According to the principle of metallic ions M2+ and S2- can generate low solubility product MS deposition, proposed in this paper to absorb H₂S with Zn²⁺ solution, which generate ZnS deposition for efficient desulfurization, and then use the Fe³⁺ oxidate ZnS, release desulfur precipitating agent Zn²⁺for the recycling of Zn²⁺ and obtains sulfur resource simultaneously. Regenerated Fe³⁺ which consumed during the absorption process with electrolytic oxidation, recycling desulfur agent.The first part, Absorbing experiments were done in a self-manufacture bubble sieve absorbing reactor with ZnCl2, FeCl3 and certain additives mixed solution as the absorbent. Investigated the single factor affecting the efficiency of the desulfurization, ascertained the Zn / Fe system's apropriate make up. In the limited laboratory conditions, the desulfurization efficiency reached 99.6 percent, after desulfurization, hydrogen sulfide content inbiogas is less than 20 mg/m3, reached the state standards about hydrogen sulfide content in coal gas. The Zn/Fe system's absorbing selectivity is big to S, the sulphur generated size is large, separate easily and high purity.The second part, analysised the desulfur mechanism with thermodynamics and electrochemical .Thermodynamic analysis indicated that Zn²⁺ can remove H₂S fast, effectively, is an ideal H₂S precipitating agent. And ZnS/S's electrochemical analysis indicated that Fe³⁺ can oxidate the production of ZnS rapidly and realization sulfur resourced. The shudy of absorbing kinetic with dual-use film theory show, the reaction of Zn²⁺ and H₂S is an irreversible instant reaction, controlled by gas film. The third part, studied the regeneration of Fe³⁺ with electrolytic process.The effect of voltage, H+ concentration in the cathode liquid, stirring rate and temperature on the electrolytic current were discussed singly. And analysis the experimental datas, the electrolysis reaction dynamic equation can be expressed by:After regeneration, the composition of absoring agent return to the initial level, can be circle use repeatly.