Adsorption and regeneration study of the mesoporous adsorbent SBA-15 adapted to the capture/separation of CO2 and CH4

Carbon dioxide (CO2) and methane (CH4) are considered to be major greenhouse gases that have a direct impact on the world's atmosphere. It is critical that effective separation and capture technologies be developed to reduce the amount of greenhouse gases into our environment. Present liquid and solid capture and separation technologies cannot realize the regeneration of the saturated solution/adsorbent at ambient temperature (25 degrees C), which is a critical feature for the proper operation of these types of pressure swing systems. The present study uses triethanolamine (TEA) to modify the surface of SBA-15 and the resulted adsorbent showed promising performance in separating CO2 from its mixture with CH4. TEA did not change the ordered structure of SBA-15, but to enhance its selectivity for CO2. The modification enlarged the difference between the equilibrium adsorption of CO2 and that of other gases. The separation coefficient between CO2 and CH4, evaluated on the basis of breakthrough curves, enlarged to as much as more than seven times due to the modification. In addition, the modification allowed the adsorption of CO2 reversible, and the saturated adsorbent was regenerated at the ambient temperature either by purging it with the purified gas or by vacuuming. Repeated adsorption/regeneration experiments proved the stability of the separation performance of the adsorbent. (c) 2006 Elsevier Ltd. All rights reserved.