(696a) Development of Highly Compatible and High-Performance Mixed Matrix Membranes for CO2 Separation

Development of highly compatible
and high-performance mixed matrix membranes for CO₂ separation

Zhi
Wang*, Xiaochang Cao, Zhihua Qiao, Jixiao Wang, Shichang Wang

Chemical Engineering
Research Center, School of Chemical Engineering and Technology, Tianjin
University, Tianjin 300350, PR China

Tianjin Key
Laboratory of Membrane Science and Desalination Technology, State Key
Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical
Science and Engineering, Tianjin University, Tianjin 300350, PR China

wangzhi@tju.edu.cn
*Corresponding author

Global energy and
environmental problems create an urgent need
for new and environmental friendly strategies that
can be used to capture CO₂ energy-efficiently. Membrane-based CO₂ separation
technology exhibits potential applications for greenhouse gas control (CO₂
capture from flue gas) and clean energy supply (natural gas purification and
hydrogen production). Currently, great efforts have been devoted to membranes
that preferentially permeate CO₂ with high permeances and
selectivities for CO₂/N₂, CO₂/CH₄
and CO₂/H₂ gas pairs. Mixed matrix membranes (MMMs) offering a number of
benefits, become one of the most popular membrane morphologies for efficient CO₂ separation applications for
the past few years. MMMs, consisting of organic
polymers as the continuous phase and filler particles
as the disperse phase, not only could circumvent the trade-off limit of the continuous
phase as well as the inherent obstacles of brittleness associated with the
disperse phase, but also could
combine their advantages such as good processability of polymers and excellent
gas separation property of fillers.

One of the
critical factors that restrict achieving high separation performance of MMMs is
the poor compatibility between the filler and polymer matrix leading to
non-selective interface voids formation. To systematically explore polymer-filler
interface and its influence, a series of MMMs have been fabricated by coating
the mixture comprised of same polymer and different inorganic fillers. The size of interface voids is connected to the property
of fillers¹. Under the direction of this work, a series of nanofillers
with good interface compatibility towards polymer chains and high
permselectivity for CO₂separation have been synthesized and
incorporated into polymers to fabricate highly compatible and high-performance MMMs by our group
(presented in Fig. 1).

Polymeric nanofillers possess apparent favorable
affinities toward polymer continuous phase based on the
theory of similarity and intermiscibility. Two kinds of polymeric nanofillers
have been designed. Polyaniline
(PANI) nanorod² containing amino carrier, constructs the CO₂-facilitated
transport highway in the MMM (presented
in Fig. 1(a)). Covalent organic framework (COF)³
containing amino carrier, obtains CO₂ preferential adsorption channels in the MMM (presented in Fig. 1(b)).

Coupling of polymer chains and nanofillers is an
effective way to improve the interface compatibility between polymer continuous phase and coupled
nanofillers. Therefore,
our group has coupled hydrotalcite (HT)'s channels
in a polyethyleneimine-epichlorohydrin copolymer (PEIE)⁴,
in which contains abundant amino-groups and moderate hydroxyl groups, to
establish high-speed CO₂ facilitated transport channels in the MMM (presented in Fig. 1(c)).

The as-developed MMMs display outstanding
CO₂ separation performance.

(a)

(b)

(c)

Figure
1. Scheme illustration of highly compatible and high-performance
MMMs for CO₂ separation: (a) membrane with PANI nanorod; (b) membrane with COF; (c) membrane with HT-PEIE.

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