Adsorption application of tetraethylenepentamine (TEPA) modified SBA-15@MIL-101(Cr) in carbon capture and storage (CCS)

Abstract

To design a better carbon capture material, a SBA-15@MIL-101(Cr) composite is prepared by an in situ synthesis method, and its adsorption performance is enhanced by TEPA modification. The SBA-15 with well-ordered mesopores acted as a carrier, which regulated the growth of MIL-101(Cr) crystals. The silicon hydroxyl group in SBA-15 stably binds to TEPA in the form of hydrogen bond, and the Lewis acid site (CUS) in MIL-101(Cr) makes it bind to TEPA in coordination bond. The unique pore cage structure of MIL-101(Cr) and the basic site provided by TEPA make the material contain both physical and chemical adsorption forces in the process of adsorption of CO2 molecules. The good thermal stability of SBA-15 improves the thermal stability of MIL-101(Cr) and TEPA in the SBA-15 channel. Compared with the original MIL-101(Cr), the composite and modified materials showed higher CO2 absorption capacity at 298K and 100 kPa. By fitting the Langmuir equation and Freundlich equation, it can be found that the adsorption behavior of the materials after TEPA loading has the non-uniformity of surface binding. The adsorption behavior is a typical exothermic process, so the adsorption capacity of the material is inversely proportional to the temperature. Compared with other similar materials, the materials designed in this work have good CO2 adsorption energy per unit area, and also have good reusability. Therefore, this study opens a new way for the design of graded porous amine-modified MOF-based materials with advanced gas adsorption properties.