Acidity Controlled Desulfurization of Biogas by Using Iron (III) and Ferrosoferric (II, III) Oxide

Abstract

Removal of hydrogen sulfide (H2S) from raw biogas is essential for feeding the refined gas with high methane (CH4) content in engines and combustion units. In small-scale farmhouses and power plants, a cheap, inexpensive, and facile desulfurization process is needed. Herein, the desulfurization process of biogas by treating with Fe2O3 and nanoscaled Ferrosoferric oxide (FeF) suspension is presented. The treatment process includes both the chemical reaction and physical adsorption phenomena. With variable pH and treatment duration, efficient desulfurization of the biogas was achieved. The optimum pH for H2S removal was 5 at which the removal efficiency was 97% for Fe2O3 solution and 95% for FeF solution. Respectively, CH4 content increased above 75%. The H2S-concentration dropped by 50 ppm from the initial value. The H2S content in the purified gas is thus reduced below the recommended limit for running internal combustion engines. We suggest some physicochemical elimination of the H2S fraction. The process might be feasible to utilize in small farmhouses and power units.