A mechanistic study of molecular sieving inorganic membranes for gas separations. Final report, [August 1, 1992--July 31, 1993]

The development of inorganic membranes has mainly found applicability in liquid separation technologies. However, only a few reports cite the permeation and separation of liquids through inorganic nanofiltration membranes compared with the more popular microfiltration membranes. Herein, we prepared silica membranes using 3,3,3-trifluoropropyltrimethoxysilane (TFPrTMOS) to investigate its liquid permeance performance using four different ion solutions (i.e., NaCl, Na2SO4, MgCl2, and MgSO4). The TFPrTMOS-derived membranes were deposited above a temperature of 175 °C, where the deposition behavior of TFPrTMOS was dependent on the organic functional groups decomposition temperature. The highest membrane rejection was from NaCl at 91.0% when deposited at 200 °C. For anions, the SO42− rejections were the greatest. It was also possible to separate monovalent and divalent anions, as the negatively charged groups on the membrane surfaces retained pore sizes >1.48 nm. Ions were also easily separated by molecular sieving below a pore size of 0.50 nm. For the TFPrTMOS-derived membrane deposited at 175 °C, glucose showed 67% rejection, which was higher than that achieved through the propyltrimethoxysilane membrane. We infer that charge exclusion might be due to the dissociation of hydroxyl groups resulting from decomposition of organic groups. Pore size and organic functional group decomposition were found to be important for ion permeation.

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Synthesis of Porous Inorganic Membranes

MRS Bulletin ◽

10.1557/s0883769400051885 ◽

1999 ◽

Vol 24 (3) ◽

pp. 30-35 ◽

Cited By ~ 33

Author(s):

Michael Tsapatsis ◽

George R. Gavalas

Keyword(s):

Molecular Sieves ◽

Activated Carbons ◽

High Surface ◽

Sol Gel ◽

Adsorption Properties ◽

Air Separation ◽

Inorganic Membranes ◽

Carbon Molecular Sieves ◽

Functional Composites ◽

Molecular Sieving

Here we will attempt a brief overview of recent synthetic efforts for micropore and lower-end mesopore membranes. We will not address the very important classes of nonporous membranes, such as dense metals and solid electrolytes with applications in H2 and O2 separations, or meso- and macroporous membranes, which find applications in food processing and water treatment. Microporous materials provide high permselectivities for molecules encountered in the chemical-processing industry but suffer from low intrinsic permeabilities. Therefore, in order to bring microporous membrane materials to commercial applications, functional composites with small effective thicknesses (in the micron or submicron range) must be developed. For example, to achieve economical membrane-reactor sizes, fluxes as high as 0.1 mol/(m2 s) are desirable. Approaches to microporous membranes include modification of mesoporous membranes by sol-gel and chemical-vapor-deposition (CVD) techniques, carbonization of polymers to form molecular-sieve carbon, and polycrystalline-film growth of zeolites and other molecular sieves.Microporous carbon is widely used for liquid or gas purification because of its strong adsorptive properties and high surface area. It is also used for air separation by pressure swing adsorption (PSA), relying on its adsorptive and molecular-sieving properties. From the standpoint of applications, microporous carbons are classified into activated carbons with pore size 0.8–2 nm, and ultramicroporous carbons or carbon molecular sieves with pores 0.3–0.6 nm. Activated carbons are used because of their strong adsorption properties, while carbon molecular sieves are useful on account of their molecular-sieving as well as adsorption properties.

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A highly permeable polyimide with enhanced selectivity for membrane gas separations

Journal of Materials Chemistry A ◽

10.1039/c4ta00564c ◽

2014 ◽

Vol 2 (14) ◽

pp. 4874-4877 ◽

Cited By ~ 114

Author(s):

Yulia Rogan ◽

Richard Malpass-Evans ◽

Mariolino Carta ◽

Michael Lee ◽

Johannes C. Jansen ◽

...

Keyword(s):

Gas Separations ◽

Gas Selectivity ◽

Intrinsic Microporosity ◽

Molecular Sieving ◽

Enhanced Selectivity

Introducing the highly rigid ethanoanthracene unit into polyimides of intrinsic microporosity provides an impressive enhancement of gas selectivity by molecular sieving.

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Gas separations using inorganic membranes

10.2172/10150064 ◽

1992 ◽

Author(s):

B.Z. Egan ◽

S.P.N. Singh ◽

D.E. Fain ◽

G.E. Roettger ◽

D.E. White

Keyword(s):

Gas Separations ◽

Inorganic Membranes

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