The present invention provides a layered double hydroxide with improved conductivity, a layered double hydroxide and a composite material containing the layered double hydroxide. The layered double hydroxide is represented by the general formula: [Mg.sup.2+.sub.(1-y)M1.sup.+.sub.y].sub.1-x[Al.sup.3+.sub.(1-z)M2.sup.+.sub.z].sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O, wherein 0.1x0.4, 0y0.95, and 0z0.95, provided that both y and z are not 0 at the same time; =1 or 2; =2 or 3; A.sup.n is an n-valent anion, provided that n is an integer of 1 or greater; m0; M1.sup.+ is a cation of at least one substituent element selected from monovalent elements, transition metal elements, and other elements with an ionic radius greater than that of Mg.sup.2+; and M2.sup.+ is a cation of at least one element selected from divalent elements, transition metals, and other elements with an ionic radius greater than that of Al.sup.3+.

Processes for making magnesium-containing layered double hydroxides from a magnesium phosphate-containing mineral are disclosed, as well as a magnesium-containing layered double hydroxides and their uses.

Processes for making magnesium-containing layered double hydroxides from a magnesium phosphate-containing mineral are disclosed, as well as a magnesium-containing layered double hydroxides and their uses.

The invention presented concerns a process for the manufacture of coated, nano-scale, hydrotalcites, where the individual, primary, nano-scale hydrotalcite particles are coated. In order to obtain the corresponding hydrotalcite particles in coated, nano-scale form, the additive precipitation reaction is employed invention-related. Every primary particle indicates its own coating in this case. In a further aspect, the registration is directed toward coated primary, nano-scale, hydrotalcite particles, in particular obtainable in accordance with the invention-related process. A further aspect of the invention is directed toward composites containing nano-scale hydrotalcites, in particular hydrotalcites manufactured in accordance with the invention presented. Finally the registration presented is directed towards compositions containing mixtures of magnesium hydroxide and hydrotalcite.

Provided is a method of forming a layered double hydroxide (LDH) dense membrane on the surface of a porous substrate. The LDH dense membrane is composed of an LDH represented by the formula: M.sup.2+.sub.1-xM.sup.3+.sub.x(OH).sub.2A.sup.n.sub.x/n.Math.mH.sub.2O where M.sup.2+ represents a divalent cation. M.sup.3+ represents a trivalent cation, A.sup.n represents an n-valent anion, n is an integer of 1 or more, and x is 0.1 to 0.4. This method includes (a) providing a porous substrate, (b) evenly depositing, on the porous substrate, a nucleation material capable of providing a nucleus from which the crystal growth of the LDH starts; and (c) hydrothermally treating the porous substrate in an aqueous stock solution containing a constituent element of the LDH to form the LDH dense membrane on the surface of the porous substrate. The method of the present invention can form a highly-densified LDH membrane evenly on the surface of a porous substrate.

The present invention provides and produces a high-grade layered double hydroxide (LDH) dense body having a relative density of 88% or greater in a simple and stable manner. The present invention provides a LDH dense body including a layered double hydroxide as a main phase and having a relative density of 88% or greater, the LDH being represented by general formula: M.sup.2+.sub.1-xM.sup.3+.sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O wherein M.sup.2+ is a divalent cation, M.sup.3+ is a trivalent cation, A.sup.n is an n-valent anion, n is an integer of 1 or greater, and x is 0.1 to 0.4. This LDH dense body can be produced by compacting and firing a raw material powder of a LDH to obtain an oxide fired body, retaining this oxide fired body in or immediately above an aqueous solution comprising an n-valent anion to reproduce the LDH, and removing excessive water from the resulting water-rich LDH solidified body.

Provided is a layered-double-hydroxide-containing composite material including a porous substrate and a functional layer disposed on and/or in the porous substrate, the functional layer containing a layered double hydroxide represented by the formula M.sup.2+.sub.1xM.sup.3+.sub.x(OH).sub.2A.sup.n.sub.x/n.mH.sub.2O, where M.sup.2+ represents a divalent cation, M.sup.3+ represents a trivalent cation, A.sup.n represents an n-valent anion, n is an integer of 1 or more, and x is 0.1 to 0.4, and the functional layer further containing sulfur (S) at the interface between the functional layer and the porous substrate and in the vicinity of the interface. In the LDH-containing composite material of the present invention, the LDH-containing functional layer disposed on and/or in the porous substrate exhibits significantly improved conductivity.

The present invention relates to a method for extracting magnesium and lithium and also producing layered double hydroxides (LDH) from brine, comprising the steps of: adding an aluminum salt to brine, to prepare a mixed salt solution A for preparing MgAl-LDH; adding an alkaline solution to carry out co-precipitation, followed by crystallization; after the crystallization is complete, performing solid-liquid separation to obtain a solid product of MgAl-LDH and a filtrate; concentrating the filtrate by evaporation to obtain a lithium-rich brine, adding an aluminum salt thereto to prepare a mixed salt solution B for preparing LiAl-LDH; adding the mixed salt solution B to an alkaline solution to carry out precipitation; after the precipitation is complete, performing solid-liquid separation to obtain a solid product of LiAl-LDH and a filtrate; and concentrating the filtrate by evaporation, returning the solution concentrated by evaporation to the lithium-rich brine for recycled use. This method uses mild reaction and simple equipment, has a small loss of Li, can achieve isolation of resources from salt lakes, and can also obtain functional materials having a high added value.

Layered double hydroxides having a high surface area (at least 125 m.sup.2/g) and the formula (I)

[M.sup.z+.sub.1-xM.sup.y+.sub.x(OH).sub.2].sup.a+(X.sup.n-).sub.a/n.sup.+bH.sub.2O.c(AMO-solvent)(I)

wherein M and M are different and each is a charged metal cation (and must be present), z=1 or 2; y=3 or 4, 0<x<0.9, b is 0 to 10, c=0 to 10, X is an anion, n is the charge on the anion, and a=z(1x)+xy2; AMO-solvent is aqueous miscible organic solvent, may be prepared by a method which comprises a) precipitating a layered double hydroxide having the formula

[M.sup.z+.sub.1-xM.sup.y+.sub.x(OH).sub.2].sup.a+(X.sup.n-).sub.a/n.sup.+bH.sub.2O wherein M, M, z, y, x, a, b and X are as defined above from a solution containing the cations of the metals M and M and the anion X.sup.n-; b) ageing the layered double hydroxide precipitate obtained in step a) in the original solution; c) collecting, then washing the layered double hydroxide precipitate; d) dispersing the wet layered double hydroxide in an AMO solvent so as to produce a slurry of the layered double hydroxide in the solvent; e) maintaining the dispersion obtained in step d); and f) recovering and drying the layered double hydroxide.

The high surface area products have low particle size and are particularly suitable for use as catalysts, catalyst supports, sorbents and coatings.

Disclosed are a catalyst composition for oxidative dehydrogenation and a method of preparing the same. More particularly, disclosed is a catalyst composition comprising a multi-ingredient-based metal oxide catalyst and a mixed metal hydroxide. The catalyst composition and the method of preparing the same according to the present disclosure may prevent loss occurring in a filling process due to superior mechanical durability and wear according to long-term use, may inhibit polymer formation and carbon deposition during reaction, and may provide a superior conversion rate and superior selectivity.