Novel carbon molecular sieves (CMS) prepared using a green approach

Carbon molecular sieves (CMS) are carbonaceous materials with a narrow pore size distribution, with pore sizes in the range of 3 - 5 Å and surface areas in the range of 250-400 m2/g. The pore size in CMS is in the range of gas molecular dimensions. CMS are used for the separation of permanent gases (hydrogen, oxygen, nitrogen, carbon monoxide, and the inert gases) and low molecular weight linear- and branched-chain hydrocarbons. Potential applications of CMS include large-scale, energy-efficient gas separators. CMS are traditionally prepared by the controlled pyrolysis of a thermosetting polymeric precursor such as poly(vinylidene chloride) or sulfonated polymers. In order to fabricate environmentally friendly gas separators, several authors have studied the use of carbonized biopolymers for the preparation of CMS. In this project, we propose to use nanostructured biopolymers as precursors for the preparation of CMS. We will take advantage of both, the naturally occurring nanostructure of some natural biopolymers and the nanostructure of nano-objects prepared from biopolymers. We will use the cellulose synthetized by bacteria, known as bacterial cellulose (BC) as a precursor. BC is synthetized as a network of nano-sized cellulose fibers. In addition, we will use nanocomposites prepared with nanoparticles from a variety of biopolymers such as starch, chitin, and carrageenan. By controlling the parameters of pyrolysis and the biopolymeric-based precursors, we will aim at controlling the final properties of CMS and prepare tailor-made flat carbon molecular sieves. With the understanding of CMS structure and separation performance, we will determine which of these systems are promising for environmentally friendly gas separators.