| abstract |
Layered double hydroxides having a high surface area (at least 125 m 2 /g) and the formula (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 ( 1-x )+ xy -2; 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 z+ n 1- n x M ' n y n + n x (OH) 2 ] a+ (X n- ) a/n ' b H 2 O 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 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. |