Novel Inorganic Two-dimensional Materials for Gas Separation Membranes

doi:10.15541/jim20190548

Abstract

Abstract:

Membrane-based gas separation is one of the critical technologies in filtration and separation industry, since it is more efficient, energy-saving and environmentally friendly compared with traditional separation technologies. Novel inorganic two-dimensional materials (2DMs) for gas separation are expected to achieve both high selectivity and high permeability, breaking through the trade-off between selectivity and permeability of commercial polymer membranes. This review begins with a brief explanation of gas separation mechanisms for membranes. Afterwards, special attention will be given to the recent advances in novel inorganic 2DMs including graphene and their derivatives, TMDs and MXene, about their design, fabrication and application in gas separation. The gas separation characteristics of different materials, their challenges and directions for future research are summarized. Moreover, the application of other novel inorganic 2DMs, such as LDH, h-BN and mica nanosheets in gas separation technology is also discussed. Finally, the perspectives and challenges for future research of novel inorganic 2DMs in gas separation field are outlined.

Key words: membrane, gas separation, inorganic material, two-dimensional material, review

CLC Number:

TQ174

YANG Liuxin,LUO Wenhua,WANG Changan,XU Chen. Novel Inorganic Two-dimensional Materials for Gas Separation Membranes[J]. Journal of Inorganic Materials, 2020, 35(9): 959-971.

Figures/Tables 13

Fig. 1 Schematic representation of transport mechanisms in membranes, where Dc is the location of carbon centers, and the pore diameter is defined as Dp = Dc - Dvdw/$\sqrt{2}$, where Dvdw is the van der Waals diameter of a carbon atom[1,10,11,14-17]

Fig. 2 Schematic of pores in graphene sheet (a-b) and pore electron density isosurfaces of porous graphene (c-d)[28] (a) Creation of a nitrogen-functionalized pore within a graphene sheet; (b) An all-hydrogen passivated pore in graphene; (c) Pore electron density isosurface of the nitrogen-functionalized porous graphene; (d) The all-hydrogen passivated porous grapheme Color code: C-black; N-green; H-cyan (isovalue is at 0.2 e/nm)

Fig. 3 Snapshots of passing-through events of gas molecules[29] (a, d) CO2; (b, e) N2; (c, f) CH4. (a-c) Top view; (d-f) Side view

Fig. 4 Schematic of fabrication of a large-area graphene membrane by the nanoporous carbon film-assisted transfer method (a) and high-resolution TEM images of the intrinsic defects in graphene lattice (b)[33]

Fig. 5 Photo of a 1-μm-thick GO film (a), electron micrograph of the film’s cross section (b), schematic view for possible permeation through the laminates (c), and examples of He-leak measurements for a freestanding submicrometer-thick GO membrane and a reference PET film (d)[40] (1 mbar=100 Pa)

Fig. 6 Schematic illustration of two different GO coating methods (Method one and Method two) (a), schematic illustration of possible gas transport through graphene membrane (b), AFM images of GO membrane surfaces with insert images showing depth profiles of GO membrane surfaces: (c) method one [root mean square roughness (Rq) = 0.8 nm, average roughness (Ra) = 0.614 nm] and (d) method two (Rq = 0.608 nm, Ra = 0.467 nm)[19]

Fig. 7 Schematic representation of the assembly of GO nanosheets in polymeric environment (a), digital photographs of the membrane with 0.1wt% GO (b), overview (the yellow dashed lines are eye-guiding lines indicating the GO laminates in these regions) (c) and expanded TEM image of the cross section of GO-1 membrane (d)[17]

Fig. 8 Force analysis for one 2D channel unit consisting of GO nanosheets and polymer chain (a), schematic illustration of intrinsic force induced disordered structure (left) and highly ordered laminar structures (right) driven by introduced synergistic external forces (b)[54]

Fig. 9 Schematic illustration of the gas solution-diffusion transport pathway through a GO-SILM (a), molecular structures of [BMIM][BF4] IL confined in the GO nanochannels (b), the cross section of the GO membrane (c) and GO-SILM (d), respectively[55]

Table 1 Graphene-based membranes for gas separation

Materials^a	Preparation method	Feed condition	Selectivity	Permeate rate/ permeance/permeability	Ref.
Porous graphene monolayer	Simulation All-H passivation	H₂/CH₄	10²³	10^-20 mol?s^-1?Pa^-1	[28]
Porous graphene bilayer	Ultraviolet-induced oxidative etching	H₂/CH₄	104	4.5×10^-23 mol?s^-1?Pa^-1	[30]
Porous graphene bilayer	Focused ion beam perforation	H₂/CO₂	4.6	5.0×10³ mol?m^-2?s^-1?Pa^-1	[32]
Porous graphene	Ozone functionalization-based pore-etching	H₂/CH₄	25	4.1×10^-7 mol?m^-2?s^-1?Pa^-1	[33]
GO/PES	Spin coating	H₂/CO₂	30	4.02×10^-17 mol?m?m^-2?s^-1?Pa^-1	[19]
GO/PES	Dip and spin coating	H₂/CO₂	20	5.69×10^-17 mol?m?m^-2?s^-1?Pa^-1	[19]
GO/AAO	Vacuum filtration	H₂/CO₂	3400	10^-7 mol?m^-2?s^-1?Pa^-1	[20]
GO/AAO	Vacuum filtration	H₂/CO₂	22.5	1.14×10^-7 mol?m^-2?s^-1?Pa^-1	[41]
TU-GOF	Hydrothermal Self-assembly synthesis	H₂/CO₂	225	10^-7 mol?m^-2?s^-1?Pa^-1	[42]
GO/AAO	Spin coating	H₂/CO₂	240	3.4×10^-7 mol?m^-2?s^-1?Pa^-1	[44]
PEBA-GO	Drop casting	CO₂/N₂	91	3.35×10^-14 mol?m?m^-2?s^-1?Pa^-1	[17]
SPEEK/S-GO	Drop casting	CO₂/CH₄	72.2	4.44×10^-13 mol?m?m^-2?s^-1?Pa^-1	[53]
EFDA-GO	Vaccum-spin	H₂/CO₂	29-33	2.8-4.0×10^-13 mol?m?m^-2?s^-1?Pa^-1	[54]
GO-[BMIM][BF₄]	Vacuum filtration	CO₂/ H₂	24	2.29×10^-8 mol?m^-2?s^-1?Pa^-1	[55]
		CO₂/ CH₄	234
		CO₂/N₂	382

Fig.10 Schematic of gas permeation pathway across MoS2 membranes before and after heating at 160 ℃(a)[63], cross section SEM images of the membrane (b-e)[64], and synthesis process for MoS2-SILM (f)[69](b) GO membrane; (c) MoS2 membrane; (d) GO-MoS2 (50/50) hybrid membrane; (e) GO-MoS2 (75/25) hybrid membrane

Fig. 11 SEM image of the delaminated MXene nanosheets on porous anodic aluminum oxide (AAO) (a) with insert showing the Tyndall scattering effect in MXene colloidal solution in water, cross-sectional SEM image of the MXene membrane (b) with insert showing a tweezer bent membrane, AFM image of the Mxene nanosheet on cleaved mica (c), illustration of the spacing between the neighboring MXene nanosheets in the membrane (d)[77], structures and gas transport of H2-selective and CO2-selective Mxene nanofilms (e)[78]

Table 2 Other novel inorganic 2DMs for membrane gas separation

Materials^a	Preparation method	Feed Condition	Selectivity	Permeate rate/permeance/ permeability	Ref.
MoS₂/AAO	Vacuum filtration	H₂/CO₂	3.4	9.19×10^-6 mol?m^-2?s^-1?Pa^-1	[62]
MoS₂	Vacuum filtration	H₂/CO₂	8.29	3.94×10^-13 mol?m?m^-2?s^-1?Pa^-1	[63]
GO/MoS₂	Vacuum filtration	H₂/CO₂	26.7	8.04×10^-7 mol m^-2 s^-1 Pa^-1	[64]
MoS₂-Pebax	Spin coating	CO₂/N₂	93	2.14×10^-14 mol?m?m^-2?s^-1?Pa^-1	[68]
MoS₂-[BMIM][BF₄]	Vacuum filtration and drop	CO₂/N₂	131.42	1.60×10^-8 mol?m^-2?s^-1?Pa^-1	[69]
WS₂-[BMIM][BF₄]	Vacuum filtration and spin-coating	CO₂/N₂	153.21	1.58×10^-8 mol?m^-2?s^-1?Pa^-1	[70]
Ti₂C₃T_x	Vacuum filtration	H₂/CO₂	160	7.37×10^-13 mol?m?m^-2?s^-1?Pa^-1	[77]
Ti₂C₃T_x/borate-PEI	Vacuum filtration and spin-coating	CO₂/CH₄	15.3	1.17×10^-7 mol?m^-2?s^-1?Pa^-1	[78]
MgAl-CO₃ LDH	Electrophoretic deposition	CO₂/N₂	1.53	2.34×10^-7 mol?m^-2?s^-1?Pa^-1	[83]
MgAl-CO₃ LDH	Vacuum-suction	CO₂/N₂	34.4	5.5×10^-10 mol?m^-2?s^-1?Pa^-1	[83]
NiAl-CO₃ LDH	In situ growth	H₂/CH₄	80	4.5×10^-8 mol?m^-2?s^-1?Pa^-1	[84]
h-BN-XTR	Drop casting	H₂/CH₄	24.1	7.03×10^-14 mol?m?m^-2?s^-1?Pa^-1	[85]
mica-[BMIM][BF₄]	Vacuum filtration and drop-casting	CO₂/N₂	87	2.68×10^-8 mol?m^-2?s^-1?Pa^-1	[89]

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