Top-Down Polyelectrolytes for Membrane-Based Post-Combustion CO2 Capture

Abstract

Polymer-based CO2 selective membranes offer an energy efficient method to separate CO2 from flue gas. ‘Top-down’ polyelectrolytes represent a particularly interesting class of polymer materials based on their vast synthetic flexibility, tuneable interaction with gas molecules, ease of processability into thin films, and commercial availability of precursors. Recent developments in their synthesis and processing are reviewed herein. The four main groups of post-synthetically modified polyelectrolytes discern ionised neutral polymers, cation and anion functionalised polymers, and methacrylate-derived polyelectrolytes. These polyelectrolytes differentiate according to the origin and chemical structure of the precursor polymer. Polyelectrolytes are mostly processed into thin-film composite (TFC) membranes using physical and chemical layer deposition techniques such as solvent-casting, Langmuir-Blodgett, Layer-by-Layer, and chemical grafting. While solvent-casting allows manufacturing commercially competitive TFC membranes, other methods should still mature to become cost-efficient for large-scale application. Many post-synthetically modified polyelectrolytes exhibit outstanding selectivity for CO2 and some overcome the Robeson plot for CO2/N2 separation. However, their CO2 permeance remain low with only grafted and solvent-casted films being able to approach the industrially relevant performance parameters. The development of polyelectrolyte-based membranes for CO2 separation should direct further efforts at promoting the CO2 transport rates while maintaining high selectivities with additional emphasis on environmentally sourced precursor polymers.

Polyelectrolytes as Building Blocks for Next-Generation Membranes with Advanced Functionalities

“… 220 , 288 Such oxygen barrier properties, also point to the relevance of these materials for the fabrication of advanced gas separation membranes, which are relevant for, for example, CO separation and storage. 289 We, thus, foresee a very bright future for polyelectrolyte-based advanced functional membranes, for applications in water treatment, but also in industrial processes that require the separation of organic solvents and gases.…”

A Review on Ionic Liquid Gas Separation Membranes

“…In this work, the term PIL is referring to both polymerized ILs and post-synthesis modified polymers to resemble them. Recently, several contributions have reviewed approaches for PIL synthesis [ 125 , 126 ].…”

“…Alternatively, PILs can be prepared from existing polymers available on the market or custom-made polymers by their post-functionalization. These polymer precursors are attributed to three different groups based on the presence of a charged group in their backbone or as side groups: (a) Neutral with no chargeable groups (i.e., chitosan (CHI), poly(ethyleneimide) (PEI), poly(4-vinylpyridine) (P4VP), poly( N , N -dimethyl aminoethylmethacrylate) (PDMAEMA)), (b) anionic polyelectrolytes with anions (i.e., sodium polyacrylate (PAA), sodium polystyrene sulphonate (PSS), sodium hyaluronate (HA)), (c) cationic polyelectrolytes with cations poly(diallyldimethylammonium) chloride (PDADMAC), poly(allylamine) hydrochloride (PAH), and poly(4-vinylbenzyltrimethylammonium) chloride (PVBTMAC)) [ 126 , 198 , 199 ]. The post-functionalization of neutral polymer precursors is most often conducted via one of the four methods depicted in Figure 6 : (i) Ionization, (ii) quaternization to obtain cationic PIL, (iii) sulphation to obtain anionic PIL, and (iv) cross-linking.…”

Industrial Application of Bottom–Blown CO2 in Basic Oxygen Furnace Steelmaking Process

“…[22,24] At present, the methods of CO 2 capture can be categorized into the absorption method, [25,29] adsorption method, [30,33] and membrane separation method. [34,36] The absorption method includes the chemical absorption method and physical absorption method. The chemical absorption method has the advantages of fast absorption rate, high absorption efficiency, and low cost.…”