| | | Polymeric membranes | Inorganic membranes |
| | Materials | Present in either rubbery or glassy type which depends on the operating temperature [12]. | Made from inorganic-based material like glass, aluminium, and metal [13]. |
| | Characteristics | (i) Polymer is more rigid and hard in glassy state while in rubbery state it is more soft and flexible.
(ii) Glassy polymeric membranes exhibit higher glass transition temperature compared to rubbery membranes, and glassy types tend to have higher CO2/CH4 selectivity [14]. | (i) Able to withstand with solvent and other chemicals and also susceptible to microbial attack.
(ii) Comprise significantly higher permeability and selectivity, but they are also more resistant towards higher pressure and temperature, aggressive feeds, and fouling effects [15]. |
| | Disadvantages | (i) May have plasticization problem when handling high CO2.
(ii) Presence of CO2 may result in membrane performance reduction at certain elevated pressure.
(iii) As the membranes expose to CO2, polymer network in the membrane will swell, and segmental mobility will also increase which consequently cause a rise in permeability for all gas components [16].
(iv) The components with low permeability characteristic will experience more permeability increment; thus, the selectivity of the membrane will definitely decrease [17–19]. | (i) Inherent brittleness characteristic.
(ii) Performed well under low pressure which does not suit the natural gas well which required high pressure for the exploration.
(iii) High production cost which seems not practical for large industrial applications [20]. |
| | Examples | Polyethylene (PE), poly(dimethylsiloxane) (PDMS), polysulfone (PSU), polyethersulfone (PES), polyimide (PI) [21], polycarbonate [22], polyimide [23], polyethers [24], polypyrrolones [25, 26], polysulfones [27], and polyethersulfones [28]. |
Aminoslicate membrane [29], carbon-silicalite composite membrane [30], MFI membranes [31], and microporous silica membranes [32]. |
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