A Review on Polymer Precursors of Carbon Molecular Sieve Membranes for Olefin/Paraffin Separation

Abstract

Carbon molecular sieve (CMS) membranes have been developed to replace or support energy-intensive cryogenic distillation for olefin/paraffin separation. Olefin and paraffin have similar molecular properties, but can be separated effectively by a CMS membrane with a rigid, slit-like pore structure. A variety of polymer precursors can give rise to different outcomes in terms of the structure and performance of CMS membranes. Herein, for olefin/paraffin separation, the CMS membranes derived from a number of polymer precursors (such as polyimides, phenolic resin, and polymers of intrinsic microporosity, PIM) are introduced, and olefin/paraffin separation properties of those membranes are summarized. The effects from incorporation of inorganic materials into polymer precursors and from a pyrolysis process on the properties of CMS membranes are also reviewed. Finally, the prospects and future directions of CMS membranes for olefin/paraffin separation and aging issues are discussed.

Analysis of Influencing Factors on the Gas Separation Performance of Carbon Molecular Sieve Membrane Using Machine Learning Technique

“…In order to broaden the application of the technology, it is important to develop novel membrane materials with excellent gas separation performance [3]. Carbon molecular sieve (CMS) membrane is a carbon-based membrane fabricated from the pyrolysis of polymeric precursor film [4,5]. As a novel membrane for gas separation with a broad development prospect, CMS membrane has the advantages of excellent gas permeability and selectivity, high thermal and chemical stability, and anti-plasticization.…”

Polyethyleneglycol-Modified Cellulose Acetate Membrane for Efficient Olefin/Paraffin Separation

“…Carbon molecular sieve membranes made by pyrolysis of their polymeric precursors include a selective layer with an inorganic support. In the case of olefin paraffin separation, they are fabricated from polyimide-based precursors with high separation factors for ethylene/ethane and propylene/propane. − Still, despite their favorable advantages, such as their good mechanical strength, their fabrication process is complicated. Polymeric membranes are the most widely used simplest subclass of membranes due to their scalability, low fabrication cost, and processability with no drawbacks, such as carrier poisoning or high fabrication costs. , Polymeric membranes normally can be divided into rubbery and glassy categories.…”

Fluorinated Polybenzimidazole as a Novel Precursor for Carbon Molecular Sieve Membranes with Enhanced Gas Separation Properties

“…Aromatic polyimides have been the most studied precursors due to their good thermochemical stability and elevated carbon yield. 11,12,17,18 Additionally, they are easy to produce with high molecular weights, and a large variety of polyimide structures have been synthesized to date. 19 Several studies on the relationship between the precursor polyimide structure, pyrolysis conditions, and properties of the final CMSMs have been published.…”

“…Recently a new family of membrane materials obtained by the controlled pyrolysis of the polymeric precursors, so-called carbon molecular sieve membranes (CMSMs), has been developed. − In contrast to the conventional polymeric membranes, CMSMs demonstrate both high permeability and selectivity for challenging gas separations, such as N 2 /CH 4 , CO 2 /CH 4 , and olefin/paraffin overpassing the upper-bound limit. − Additionally, these membranes exhibit excellent thermochemical stability and resistance to plasticization caused by CO 2 , which is another important drawback of many conventional polymeric materials . All these features make CMSMs quite promising candidates for membranes operating under high temperature and aggressive conditions.…”

“…Besides, the precursors should be thermally stable and of high molecular weight in order to sustain the high temperature pyrolytic conditions eliminating the possibility of resulting in extremely brittle materials. Aromatic polyimides have been the most studied precursors due to their good thermochemical stability and elevated carbon yield. ,,, Additionally, they are easy to produce with high molecular weights, and a large variety of polyimide structures have been synthesized to date . Several studies on the relationship between the precursor polyimide structure, pyrolysis conditions, and properties of the final CMSMs have been published. , It has been demonstrated that the pore size distribution in CMSMs depended on the precursor structure, pyrolysis inert atmosphere used, and pyrolysis regime. , Thus, a careful choice of pyrolysis conditions opens the possibility of forming pores of desirable sizes suitable for the separation of specific gas pairs.…”