Amine-Grafted MCM-48 and Silica Xerogel as Superior Sorbents for Acidic Gas Removal from Natural Gas

In an effort to develop selective solid sorbents for acidic gas (CO2 and H2S) removal from natural gas mixtures, we synthesized amine-surface-modified silica xerogel and MCM-48 materials. With large amounts of basic amine groups on the surface, the sorbents are able to selectively bind the acidic gases CO2 and H2S. High adsorption capacities and adsorption rates were obtained for both gases. The adsorption−desorption isotherms of the gases and thermogravimetric analysis of the sorbents showed that these sorbents can be regenerated completely under mild conditions such as those used in pressure swing or temperature swing adsorption processes. We have also investigated the effect of moisture on the adsorption of CO2 and H2S by TPD-MS and infrared spectroscopy. The results indicated that the presence of water vapor doubled the amount of CO2 adsorbed and barely affected the H2S adsorption.