(537i) Generating Mesoporous Skins on Clay Nanotubes for Carbon Capture

Amine-functionalized high surface area porous supports are of significant interest as they serve as solid adsorbents for CO2 capture. The premise of our research is to develop such solid adsorbents as alternatives to commercial liquid amine solution-based technologies that are tremendously energy intensive. Thus, we discuss the use of an inexpensive and widely available clay nanotube (halloysite, HNT) and its modifications to serve as effective adsorbents. Halloysite nanotubes are natural aluminosilicate hollow tubular clay materials with inner diameter (lumen) of 15 − 30 nm and length of 0.5 − 3 μm. The tubular interior can be used to sequester polymeric amines. While HNT is intrinsically not a high surface area material with a surface area of about 50 m2/g, ordered mesoporous MCM-41 have high surface areas (> 1200 m2/g). In this study, we show a concept of creating a skin of mesoporous silica MCM-41 on the exterior surface of HNT. Thus, we can create a material that can have the big pore volume of HNT in the tubular interior and a high surface area skin on the exterior which can be used in CO2 capture studies. Characterization results show that the structural properties of the HNT remain intact after the generation of MCM-41 skin. The generation of such mesoporous skins allows both encapsulation of polymeric amines such as polyethyleneimine in the pores (class I adsorbents) and the functionalization of surfaces with aminosilanes (class II adsorbents). The method of generating mesoporous skins is done through a one-step facile aerosol assisted route. The morphology of the materials shows the potential for creating mesoporous plugs on the nanotubes potentially allowing encapsulation of the nanotube lumen with polymeric amines that do not leach out under humid conditions.