Sintered clay mineral matrix doped with rare earth metals, transition metals, or post-transition metals
A porous sintered clay mineral matrix that contains aluminum and is doped with 0.1-20 mol %, based on the amount of the aluminum, one or more transition metals, one or more post-transition metals, one or more rare earth metals, or a combination thereof. An example is a kaolinite matrix. The matrix can be made from a calcined clay mineral powder that contains aluminum and is doped with at least one of these metals. Also disclosed are methods of preparing the above-described matrix and powder.
1. A sintered clay mineral matrix, wherein the matrix is porous, contains aluminum, and is doped with 0.1-20 mol %, based on the amount of the aluminum, one or more transition metals, one or more post-transition metals, one or more rare earth metals, or a combination thereof, in which at least zinc or lanthanum is a dopant.
2. The sintered clay mineral matrix of claim 1 , wherein the transition metal is titanium, chromium, iron, cobalt, manganese or yttrium, the post-transition metal is zinc, and the rare earth metal is lanthanum.
3. The sintered clay mineral matrix of claim 2 , wherein the matrix is a membrane.
4. The sintered clay mineral matrix of claim 3 , wherein the matrix is doped with lanthanum or zinc.
5. The sintered clay mineral matrix of claim 4 , wherein the matrix is doped with lanthanum 5-15 mol %.
6. The sintered clay mineral matrix of claim 4 , wherein the sintered clay mineral matrix is a sintered kaolinite matrix.
7. The sintered clay mineral matrix of claim 6 , wherein the matrix is doped with lanthanum and the pores in the matrix have two distinctive diameter distributions, one in a range of 4 to 11 inn and the other less than 3 μm.
8. The sintered clay mineral matrix of claim 6 , wherein the matrix is doped with lanthanum and has a mechanical strength rate of greater than 5 MPa and a Darcy's permeability rate of greater than 5.00E-014 m 2 .
9. The sintered clay mineral matrix of claim 4 , wherein the matrix is doped with zinc 5-20 mol %.
10. The sintered clay mineral matrix of claim 6 , wherein the matrix is doped with zinc and has a mechanical strength rate of greater than 30 MPa.
11. A calcined clay mineral powder, wherein the powder contains aluminum and is doped with 0.1-20 mol %, based on the amount of the aluminum, one or more transition metals, one or more post-transition metals, one or more rare earth metals, or a combination thereof, in which at least zinc or lanthanum is a dopant.
12. The calcined clay mineral powder of claim 11 , wherein the transition metal is titanium, chromium, iron, cobalt, manganese or yttrium, the post-transition metal is zinc, and the rare earth metal is lanthanum.
13. The calcined clay mineral powder of claim 12 , wherein the powder is doped with lanthanum or zinc.
14. The calcined clay mineral powder of claim 13 , wherein the powder is doped with lanthanum 5-15 mol %.
15. The calcined clay mineral powder of claim 13 , wherein the powder is doped with zinc 5-20 mol %.
16. The calcined clay mineral powder of claim 13 , wherein the calcined clay mineral powder is a calcined kaolinite powder.
17. A method of preparing a clay mineral material, the method comprising:
dissolving one or more salts of transition metals, one or more salts of post-transition metals, one or more salts of rare earth metals, or a combination thereof in water to form a solution;
adding an organic solvent to the solution to form a second solution;
mixing clay mineral with the second solution to form a homogenous mixture;
heating the homogenous mixture at 50-150° C. for 12-72 hours to obtain a dried lump;
calcining the dried lump at 500-800° C. for 1-10 hours, and then cooling it to an ambient temperature, wherein both the heating and cooling are each conducted at a rate of 1-20° C./min; and
grinding the calcined lump to obtain a metal-doped clay mineral powder.
18. The method of claim 17 , wherein the transition metal is titanium, chromium, iron,
cobalt, manganese or yttrium, the post-transition metal is zinc, and the rare earth metal is lanthanum.
19. The method of claim 18 , wherein the clay mineral is kaolinite.
20. The method of claim 18 , wherein the salt is lanthanum nitrate or zinc nitrate.
21. The method of claim 17 , further comprising:
mixing the metal-doped clay mineral powder with a solution to form a second homogenous mixture, wherein the solution is prepared by dissolving 1-10 wt % polymeric binder in a pure or mixed organic solvent and includes 0.1 to 1 wt % additives that is a non-ionic surfactant, a deflocculating agent, and a plasticizer;
drying the second homogenous mixture at an ambient temperature for 1-10 hours to form a cake;
grinding the cake to obtain a powder;
molding the powder to form a ceramic green body by forming techniques of compression molding, extrusion, slip casting or tape casting; and
sintering the green body at 1000-1400° C. for 2-10 hours, and then cooling it to an ambient temperature, wherein both the heating and cooling are each conducted at a rate of 1-20° C./min, to obtain a metal-doped clay mineral matrix.
22. The method of claim 21 , wherein the clay mineral is kaolinite.