Patent ID: 8435910

Claim:
A preparation method for preparing an anion-exchangeable, layered double hydroxide, comprising: dispersing a starting material in an aqueous solution mixed with a salt containing minus monovalent anions (X − ) in an amount sufficient to substitute a carbonate ion site thereby substituting the carbonate ion site while maintaining pH (hydrogen ion exponent) of the aqueous solution 4-7, wherein the starting material is a carbonate ion type layered double hydroxide (LDH) having a composition represented by a general formula: Q x R(OH) z (CO 3 2− ) 0.5-y/2 (X − ) y ·nH 2 O, where x is indicative of a numeral range of 1.8≦x≦4.2, z is indicative of 2(x+1), y is indicative of a minimum value of at least 0 that increases to less than 1 when anions (X − ) remain or a part of anions is introduced, Q is a divalent metal ion, R is a trivalent metal ion, and n is 2±2, and y in said general formula increases to a maximum of 1 by substitution of the minus monovalent anion (X −1 ) at the carbonate ion site.