Characteristics of activated carbon in elevated-temperature pressure swing adsorption desulfurization
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Elevated-temperature pressure swing adsorption could potentially replace wet methods in the field of syngas purification. However, the reversibility of sulfur removal in this technique needs to be validated. In this study, the H2S adsorption reversibility of two types of activated carbon sorbents were evaluated on a fixed-bed reactor. The effects of desorption method and desorption temperature were studied. Elevated-temperature vacuum desorption was found to be effective for regenerating adsorbents saturated with H2S. The necessities of both vacuum desorption and elevated temperature were reported. The findings were explained on the basis of the characterization results obtained using pore distribution analysis, inductively coupled plasma, and X-ray photoelectron spectroscopy. The oxidative functional groups or adsorbed O2 reacted with H2S on the surface of the adsorbents and the resultant, i.e., elemental sulfur, damaged the pore structure. The richness of the pores with a diameter range of 0.7–0.8 nm decreased by nearly 50% after several adsorption–desorption cycles. At high temperatures and under vacuum atmosphere, element sulfur could be easily distilled and removed from the fixed bed. Thus, element sulfur would not accumulate on the adsorbent, thus ensuring the reversibility of H2S.
KeywordsDesulfurization Activated carbon Pressure swing adsorption Reversibility
This research was financed by National Key R&D Program of China (Grant No. 2017YFB0601900), the National Natural Science Foundation of China (Grant No. 51806120) and Shanxi Province Science and Technology Major Projects (Grant No. MH2015-06).
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