Membrane assembly for gas separation, method for producing the membrane assembly and method of separating gases
The present invention concerns gas-separation membranes. In some embodiments, the membranes comprise nano- or microislands or non-continuous metal layers suitable to adsorb, react with and/or otherwise retain at least one of the gases to be separated from a mixture of gases. In one embodiment, the membrane comprises a porous graphene membrane on which Pt or Pd nanoislands are deposited using a mesh, while the nanoislands are suitable to retain and bind to H 2 while letting helium pass in a H 2 /He gas mixture. In another embodiment CO 2 is separated from a H 2 /CO 2 mixture. The membranes exhibit both, high selectivity and permeance and can be operated at room temperature.
1 . A gas-separation membrane assembly comprising a porous membrane and a gas-affinity material deposited on the porous membrane,
wherein said gas-affinity material is non-continuously deposited so as to form separated, raised areas of said gas-affinity material, wherein said separated raised areas are operatively deposited on said porous membrane to adsorb, absorb and/or dissolve a first gas to be separated from a mixture of gases comprising said first gas and at least a second gas, wherein said porous membrane is permeable to said second gas, such that said gas-separation membrane is suitable to separate said first gas from said second gas by adsorbing, absorbing and/or dissolving said first gas and thereby preventing said first gas from passing through said gas-separation assembly, and
wherein said gas-affinity material does not adsorb, absorb and/or dissolve said second gas, or does adsorb, absorb and/or dissolve said second gas to a lesser extent than said first gas.
2 . The membrane assembly of claim 1 , further comprising a porous substrate, wherein said porous membrane is in contact with said porous substrate.
3 . The membrane assembly of claim 2 , which comprises first and second sides wherein at the first side, the membrane assembly comprises said gas-affinity material, and wherein at the second side, said the membrane assembly comprises said porous substrate, and wherein said porous membrane is provided between said gas-affinity material and said porous substrate, and wherein said first side is intended for exposure to said mixture of gases.
4 . The membrane assembly of claim 1 , which exhibits saturation when a specific amount of the gas to be separated is adsorbed, absorbed and/or dissolved by said gas-affinity material and wherein, when said saturation is reached, a permeate ratio of said membrane during operation changes in that the gas to be separated is no longer separated by said membrane and/or is less efficiently separated by said membrane.
5 . The membrane assembly of claim 1 , wherein said separated raised areas have a thickness of 5-300 nm.
6 . The membrane assembly of claim 1 , wherein said separated, raised areas of said gas-affinity material are areas of 1-90,000 μm 2 .
7 . The membrane assembly of claim 1 , wherein said separated, raised areas form micro- or nanoislands on said porous membrane or on an optional intermediate layer.
8 . The membrane assembly of claim 1 , wherein said porous membrane comprises pores having an average diameter of 2 nm to 200 nm.
9 . The membrane assembly of claim 1 , wherein said porous membrane comprises a porous two-dimensional membrane material.
10 . The membrane assembly of claim 9 , wherein said porous two-dimensional membrane material is selected from the group consisting of carbon-based two-dimensional membrane materials, hybrid two-dimensional membrane materials, organic two-dimensional membrane materials and inorganic two-dimensional membrane materials.
11 . The membrane assembly of claim 1 , wherein said porous membrane comprises a material selected from the group consisting of: graphene, graphene oxide, metal organic frameworks (MOFs), covalent organic frameworks (COFs), MXene, layered double hydroxide, zeolite, layered silicate, transition metal dichalcogenides (TMDs), and hexagonal-Boron Nitride (h-BN).
12 . The membrane assembly of claim 1 , wherein said porous substrate comprises or consists essentially of a material selected from the group consisting of holey silicon nitride, silicon oxide materials, aluminium oxide materials, and polymers.
13 . The membrane assembly of claim 1 , wherein said gas-affinity material comprises and/or consists essentially of a material selected from the group consisting of: palladium (Pd), platinum (Pt), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), and alloys comprising one or more of the aforementioned.
14 . The membrane assembly of claim 1 , wherein said first gas is hydrogen (H 2 ) gas, and wherein said gas-affinity material is suitable to adsorb, absorb and/or dissolve said hydrogen gas, and wherein said membrane is permeable to said second gas.
15 . The membrane assembly of claim 1 , which exhibits, during operation, a permeance with respect to the permeating gas or gases of 10 5 GPU or higher and a separation factor of 5 (Knudsen Selectivity) or higher.
16 . A method for separating one or more gases from a mixture of gases, the method comprising:
exposing the mixture of gases to a first side of a gas-separation membrane assembly comprising a porous membrane and a gas-affinity material deposited on the porous membrane, wherein said gas-affinity material is non-continuously deposited, wherein said gas-affinity material is suitable to adsorb, absorb and/or dissolve a first gas to be separated from said mixture of gases,
collecting one or more gases that are separated from the mixture of gases on a second side of the membrane assembly,
wherein said mixture of gases comprises said first gas and a second gas, wherein said gas-affinity material adsorbs, absorbs and/or dissolves said first gas, wherein said porous membrane is permeable to said second gas, wherein said second gas is collected on said second side of the membrane assembly, and
wherein said gas-separation membrane is suitable to separate said first gas from said second gas by adsorbing, absorbing and/or dissolving said first gas and thereby preventing said first gas from passing through said gas-separation assembly.
17 . The method of claim 16 further comprising:
restoring at least partially an initial separation capacity of said gas-separation membrane assembly by exposing the gas-separation membrane assembly to a temperature above 100° C.
18 . A method for producing the gas-separation membrane assembly of claim 1 , the method comprising:
providing a precursor assembly comprising a nonporous membrane on a porous substrate;
if necessary; providing pores in said nonporous membrane, thereby obtaining the porous membrane; and,
depositing the gas-affinity material on said porous membrane, wherein said gas-affinity material is non-continuously deposited.
19 . The method of claim 18 , wherein depositing said gas-affinity material on said porous membrane comprises:
providing a grid on said porous membrane; and,
depositing said gas-affinity material on the grid placed on the porous membrane, thereby obtaining separated areas of said gas-affinity material on said porous membrane.
20 . The method of claim 17 , wherein exposing said gas-separation membrane assembly to said temperature is done under vacuum.
21 . The membrane assembly of claim 1 , wherein said first gas is carbon dioxide (CO 2 ) gas, and wherein said gas-affinity material is suitable to adsorb, absorb and/or dissolve said CO 2 gas and wherein said membrane is permeable to said second gas.
22 . The membrane assembly of claim 1 , wherein gas-affinity material is deposited using focused ion beams or deposition through a grid or mesh on said porous membrane material so as to form said separated, raised areas of said gas-affinity material.