Effect of carbon dioxide on methane adsorption on coconut shell activated carbon in a packed bed column

Abstract

The investigation of methane adsorption with the presence of carbon dioxide on the coconut shell activated carbon (CSAC) was studied in a packed bed column. The adsorption kinetics of methane and carbon dioxide were examined at atmospheric pressure and room temperature. The dynamic adsorption of 75 to 85 vol% methane and 5 to 20 vol% carbon dioxide were first carried out in a packed bed column with approximately 5.0 g of the CSAC. The competitive adsorption of the two species on the CSAC was then studied at 10 vol% methane and 10 to 30 vol% carbon dioxide. After that, the comparison of competitive adsorption on different adsorbents including the untreated CSAC, the CSAC treated by sulfuric acid, the CSAC treated by potassium hydroxide, and the untreated palm shell activated carbon (PSAC) were studied at 10 vol% methane and carbon dioxide. Moreover, the 3-cycle adsorption-desorption was used to investigate the adsorbent stability. BET and SEM techniques were used to characterize the adsorbents. The composition of methane and carbon dioxide was determined by gas chromatography. Results show that carbon dioxide significantly affects the adsorption of methane. The breakthrough time of carbon dioxide is longer than that of methane, and the methane roll up increases with the increase in the concentration of carbon dioxide because carbon dioxide is more selectively adsorbed on all adsorbents than that of methane. For the adsorbent stability, results show that the increase in the adsorption-desorption cycle from 1 to 3 times slightly affects the adsorbent stability.