PROCESS FOR PREPARING SMALL SIZE LAYERED DOUBLE HYDROXIDE PARTICLES

摘要

A process for preparing particles of a layered double hydroxide of the general formula [M_p^z+ M'_q^y+ (OH)₂]^a+(X^n-)_a/n⋅bH₂O (I) wherein M^z+ and M'^y+ are metal cations or mixtures of metal cations, z = 1 or 2; y = 3 or 4; p + q = 1; b = 0 to 10, X^n- is an anion, n is 1 to 5 and a is determined by p, q, y and z such that a = zp+yq-2 comprises (a) mixing, in aqueous solution, M^z+ cations, M'^y+ cations and X^n- anions, with a base; and (b) allowing the layered double hydroxide of formula (I) to precipitate from the solution mixed in step (a). Preferably, M is Li, Mg, Zn, Fe, Ni, Co, Cu, Ca, or a mixture of two or more. Preferably, y is 3 and M' is Al, Ga, In, Fe or a mixture of two or more thereof. Also provided are particles obtainable by the process, especially wherein M is Ca, M' is Al and X^n- is NO₃-. Particles of a layered double hydroxide wherein the particles have a particle size of not greater than 2000 nm, preferably not greater than 300 nm and especially not greater than 100 nm, are also provided. The layered double hydroxides according to the invention are useful in certain applications, for example, as adsorbents, coatings and catalyst supports.