It is difficult to selectively remove H2S and simultaneously avoid SO2 emission in biogas purification process
with a low-cost and efficient method. In this study, an efficient hybrid adsorbent/photocatalytic
composite (TiO2/zeolite) was synthesized for the H2S removal and SO2 capture by coating TiO2 on the surface
of cheap natural zeolite with an ultrasonic-calcination way. The TiO2/zeolite showed the highest H2S
removal capacity and lowest SO2 emission, compared with the single zeolite adsorption and TiO2 photocatalysis.
H2S removal capacity and SO2 capture capacity of TiO2/zeolite were affected little by the high
level of CO2 in biogas, and were favored with the presence of moisture in the biogas. Moreover, the regeneration
of the TiO2/zeolite could be easily achieved by a weakly basic washing and calcination. The results
indicated that the TiO2/zeolite was economically promising, sustainable and nontoxic material for the
direct elimination of H2S from biogas.