Hydrogen sulfide (H2S) is a toxic gas abundant in industrial gases such as ammonia synthesis tail gas, methanol synthesis tail gas, coke oven gas and refinery gas. Carbon dioxide always exists along with hydrogen sulfide in industrial gases. Hence, there is a growing interest in the selective removal of H2S from gas streams with high concentration of CO2, compared to H2S.
However, a considerable amount of CO2 can also be absorbed during the conventional desulfurization process by the wet oxidation method because both H2S and CO2 are acidic and similar in their physical and chemical properties. Consequently, it can increase the consumption of absorption liquid and aggravate the energy load of solution regeneration units. Therefore, absorbents for industrial gas sweetening processes should be able to selectively absorb hydrogen sulfide against carbon dioxide, which will then greatly intensify the process efficiency and bring social and economic benefits.
Ri Jin Hyok, a researcher at the Faculty of Chemical Engineering, has investigated the selective removal of H2S from high-concentration CO2 by using Na2CO3+NaHCO3 solution doped with “888” catalyst in a microporous tube-in-tube microchannel reactor (MTMCR).
As a result, he has found that the removal efficiency and selectivity of H2S are significantly affected by catalyst concentration, alkalinity of adsorbent, NaHCO3 content and gas–liquid ratio. In other words, with increasing alkalinity and liquid flow rate, the removal efficiency of H2S increases but its selectivity decreases, and the selectivity increases with increasing NaHCO3 contents.
For more information, please refer to his paper “Selective removal of H2S from high concentration CO2 by catalytic wet oxidation in microporous tube-in-tube microchannel reactor” in “Brazilian Journal of Chemical Engineering” (SCI).