| 摘要 |
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. |
| 主权项 |
1. A multilayer, micro- and nanoporous membrane with controlled pore sizes for water separation comprising:
(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 porous supporting metallic layer and the porous metallic interlayer with local regular protrusions of the porous metallic interlayer into the porous supporting metallic layer, which improves adhesive strength between these layers, wherein service life of the multilayer membrane is increased because the adhesive strength is greater than stresses that occur during 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, disposed over the porous metallic interlayer;wherein pores in the porous supporting metallic layer and the porous metallic 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, wherein the multilayer, micro- and nanoporous membrane is manufactured by a method comprising:
(a) manufacturing a porous supporting metallic layer from metal powders selected from titanium, zirconium, niobium, and their alloys, by at least one process selected from the group consisting of direct powder rolling, cold rolling, and tape casting, followed by vacuum sintering, or loose powder sintering at the temperature 700-1000° C., to provide pore sizes in the range of 1-500 microns; (b) cleaning the metal powders during the vacuum or loose powder sintering of the porous supporting metallic layer of residual oxygen by cyclic heating of the porous supporting metallic layer to 600-700° C. accompanied by a hydrogenation-dehydrogenation process of the porous supporting metallic layer that is repeated at least two times; (c) cold rolling of the sintered porous supporting metallic layer to reduce its thickness by 30-70% while maintaining the thickness of said porous supporting metallic layer to provide tolerances in thickness within a range of ±0.0001 inch (±2.5 microns) and surface roughness to N7 to N9 according to ISO 1302; (d) hydrogenating the sintered porous supporting metallic layer to a hydrogen content of up to 3% wt. of hydrogen; (e) manufacturing fine metal hydride powders, selected from the group consisting of hydrides of titanium, zirconium, niobium, and alloys thereof, having particle size from 0.5-10 microns, with an average particle size of about 2 microns, by attrition of said metal hydrides in alcohol; (f) partially dehydrogenating the obtained metal hydride powders in vacuum at a temperature of about 350° C. to reach a content of residual hydrogen in the range of 0.3-0.5 wt. %; (g) manufacturing a suspension by mixing the partially-dehydrogenated metal hydride powders with isopropyl alcohol in the presence of ceramic ground bodies having diameter of about 3 mm, wherein the volume ratio of alcohol to the partially-dehydrogenated metal hydride powder is about from 1:10 to 1:15; (h) coating the porous supporting metallic layer with partially-dehydrogenated metal hydride powder having a particle size from 0.5-10 microns with an average particle size of about 2 microns using at least one process selected from the group consisting of powder spraying of the suspension, impregnation from the suspension, painting of the suspension, and tape casting of this powder in the form of a multilayer tape with at least two layers deposited over the sintered porous supporting metallic layer, thereby forming a porous metallic interlayer and a sublayer between the porous supporting metallic layer and the porous metallic interlayer; (i) sintering the coated porous supporting metallic layer at a temperature of 570-870° C. under a protective controlled atmosphere, and forming a structure comprising the porous supporting metallic layer bonded to the porous metallic interlayer; (j) re-rolling the sintered structure for optimization of pore morphology and sizes and maintaining the thickness of this 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 the sintered and re-rolled multilayer membrane in a vacuum or a protective atmosphere at 500° C. to release micro-stresses; (l) coating inorganic compound nanoparticles over the interlayer wherein the inorganic compound nanoparticles comprise at least one of the following, titanium, zirconium, niobium, and their alloys, their oxides, carbides, and combinations thereof, wherein at least one nanoporous layer having nanopores in the size range of 1-15 angstroms is formed, and (m) optionally coating the nanoporous layer with coarse particles selected from the group consisting of titanium, zirconium, niobium, and their alloys. |
