US 2014/0209533 A1 · MULTILAYER, MICRO- AND NANOPOROUS MEMBRANES WITH CONTROLLED PORE SIZES FOR WATER SEPARATION AND METHOD OF MANUFACTURING THEREOF

Abstract

The present invention relates to design and manufacture of multilayer sintered membranes made from metals and inorganic compounds (ceramics, silicate, clay, zeolites, phosphates, etc.). The membranes are designated for separation of water. They comprise at least one layer having nanopores commensurable with the size of water molecules. The membranes comprise: (a) supporting metallic layer having pore size 1-500 microns, (b) metallic interlayer having pore size <2 micron, (c) sublayer with local regular protrusions of the interlayer into the supporting layer to increase service life of the membrane, and (d) one nanoporous ceramic or metallic top layer having pore size in the range of 1-15 angstroms. The invented design and method allow the manufacture of cost-effective multilayer membranes containing nanoporous layer with controlled pore sizes in each layer and optimal morphology of pores that provides selective transport of molecules during filtration and separation of liquids.

Claims16

Dependent claims

A multilayer, micro- and nanoporous membrane with controlled pore sizes for water separation comprising the following components:

(a) a porous supporting metallic layer having pore size in the range of 1-500 microns,
(b) at least one porous metallic interlayer having pore size less than 1 micron,
(c) a sublayer between the supporting metallic layer and interlayer with local regular protrusions of the interlayer into the supporting metallic layer in order to improve adhesive strength between these layers, which increases service life of the multilayer membrane because the adhesive strength is now greater than stresses that appear during the back flow of liquid through the membrane, and
(d) at least one nanoporous ceramic or metallic or aluminosilicate layer having pore size in the range of 1-15 angstroms,
wherein pores in the supporting layer and interlayer have an ellipse-like morphology at the ratio of a short axis A to a long axis B in the range from A:B=1:1.5 to A:B=1:2.3 in order to improve the permeance of water molecules through the membrane.

2 more elements

A method of manufacturing multilayer, micro- and nanoporous membranes with controlled pore sizes for water separation comprising of the following operational steps:

(a) manufacturing a porous supporting layer from metal powders selected from titanium, zirconium, niobium, and their alloys, by at least one process selected from direct powder rolling, tape casting, and loose powder sintering at the temperature 700-1000° C., to provide pore sizes in the range of 1-500 microns;
(b) cleaning metal particles during sintering of the supporting layer from residual oxygen by cyclic heating to 600-700° C. accompanied by hydrogenation-dehydrogenation processes of the porous support layer repeated at least two times to intensify diffusion processes during sintering;
(c) cold rolling of the supporting layer in as-sintered condition to reduce its thickness by 30-70% while controlling the thickness of said supporting layer to provide tolerances within the range of ±0.0001 inch (±2.5 microns)) and surface roughness to N7 to N9 according to ISO 1302;
(d) hydrogenation of the supporting layer up to 3% wt. of hydrogen;
(e) manufacturing of fine metal hydride powders selected from hydrides of titanium, zirconium, niobium, and alloys thereof having particle size from 0.5-10 microns with average particle size being about 2 microns by attrition of said metal hydrides in alcohol;
(f) partial dehydrogenation of obtained metal hydride powders in vacuum at the temperature of about 350° C. to reach the content of residual hydrogen in the range of 0.3-0.5 wt. %;
(g) manufacturing a suspension by mixing partially-dehydrogenated metal hydride powders with isopropyl alcohol in presence of ceramic ground bodies having diameter of about 3 mm, whereby the volume ratio of alcohol to the metal hydride powder is about from 1:10 to 1:15;
(h) coating this supporting layer with fine metallic powder having particle size from 0.5-10 microns with average particle size being about 2 microns using at least one process selected from powder spraying, impregnation from the suspension, painting and tape casting of this powder in the form of a multilayer tape with at least two layers deposited over the sintered supporting layer whereby both layers have different hydrogen content;
(i) sintering the coated support layer at 570-870° C. under a protective controlled atmosphere in order to form a double-layer structure comprising the porous supporting layer bonded to the porous interlayer;
(j) re-rolling the sintered double-layer structure for optimization of pore morphology and sizes and controlling the thickness of this double-layer structure in order to provide tolerances within the range of ±0.0001 inch (±2.5 microns), thickness reduction of at least 5%, and surface roughness from N5 to N6 according to ISO 1302;
(k) annealing of sintered and re-rolled multilayer membrane in the vacuum or protective atmosphere at 500° C. to release micro-stresses,
(l) coating with inorganic compound nanoparticles over the interlayer with at least one of the following, titanium, zirconium, niobium, and their alloys particles, their oxides, carbides, or combinations thereof, providing the required nanopores having the size in the range of 1-15 angstroms, and
(m) coating of the molecular sieve layer by coarse particles selected from titanium, zirconium, niobium, and their alloys for the purpose of preventing destruction of this molecular sieve layer.

10 more elements

Dependencies are inferred from the claim text.

Multilayer, micro- and nanoporous membranes with controlled pore sizes for water separation and method of manufacturing thereof

Life of this patent

Multilayer, micro- and nanoporous membranes with controlled pore sizes for water separation and method of manufacturing thereof

Life of this patent

Abstract

Claims16