The AEROPILs Generation: Novel Poly(Ionic Liquid)-Based Aerogels for CO2 Capture.

Raquel V Barrulas,Clara López-Iglesias,Manuela Ribeiro Carrott,Marcileia Zanatta,Marta C Corvo,Carlos A García-González,Gonzalo Mármol,Teresa Casimiro

doi:10.3390/ijms23010200

Abstract

CO2 levels in the atmosphere are increasing exponentially. The current climate change effects motivate an urgent need for new and sustainable materials to capture CO2. Porous materials are particularly interesting for processes that take place near atmospheric pressure. However, materials design should not only consider the morphology, but also the chemical identity of the CO2 sorbent to enhance the affinity towards CO2. Poly(ionic liquid)s (PILs) can enhance CO2 sorption capacity, but tailoring the porosity is still a challenge. Aerogel’s properties grant production strategies that ensure a porosity control. In this work, we joined both worlds, PILs and aerogels, to produce a sustainable CO2 sorbent. PIL-chitosan aerogels (AEROPILs) in the form of beads were successfully obtained with high porosity (94.6–97.0%) and surface areas (270–744 m2/g). AEROPILs were applied for the first time as CO2 sorbents. The combination of PILs with chitosan aerogels generally increased the CO2 sorption capability of these materials, being the maximum CO2 capture capacity obtained (0.70 mmol g−1, at 25 °C and 1 bar) for the CHT:P[DADMA]Cl30% AEROPIL.

Highlights

In light of the urgent climate change mitigation strategies, the development of a material capable of performing direct CO2 capture (CC) is highly desirable
It is possible to observe that there was a volume shrinkage from the hydrogel to the aerogel varying between 58.1–74.7%, which was smaller for the aerogels with Poly(ionic liquid)s (PILs) and glutaraldehyde
Since the shrinkage can be attributed to the flexibility of the polymeric chains of the chitosan that are brought closer after solvent extraction [45], it can be inferred that the cross-linker is preventing this flexibility through the formation of imine bonds with the amine residues from chitosan, stabilizing the network structure

Summary

Introduction

In light of the urgent climate change mitigation strategies, the development of a material capable of performing direct CO2 capture (CC) is highly desirable. CC commonly focuses on solvent scrubbing for CO2 chemical absorption. This process has several disadvantages which interfere with the energy efficiency and overall cost, like solvent losses through evaporation, the formation of corrosive by-products, and high energy consumptions during solvent regeneration. CC can use solid physical adsorbers like zeolites, activated carbon, metal organic frameworks (MOFs), covalent organic frameworks (COFs), and organic/inorganic membranes, which have a diminished performance in the presence of impurities [1,2,3]. Ionic liquids (ILs), i.e., organic salts with melting points below 100 ◦ C, result from the combination of organic cations with organic or inorganic anions, and have been proposed as alternative solvents for CC since they are stable, highly selective for CO2, and recyclable.

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Results

Conclusion