Patent ID: 8088349

Claim:
A clean method for preparing layered double hydroxides comprising: adding hydroxides of M 2+ and M 3+ with a molar ratio of M 2+ / M 3+ =2˜4 into water to obtain a mixture in which the weight ratio of H 2 O to the hydroxides is 0.25˜999, wherein M 2+ represents one or two divalent cations selected from Mg 2+ , Zn 2+ , Ca 2+ , Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cd 2+ , and Be 2+ , and M 3+ represents one or two trivalent cations selected from Al 3+ , Co 3+ , Fe 2+ , Mn 3+ , Cr 3+ , V 3+ , In 3+ , and Ga 3+ ; adding the mixture into a reactor; feeding H n A n in such an amount that the molar ratio of M 3+ /A n− =n into the reactor, wherein H n A n is an acid containing any of the following anions: (1) inorganic anions: F − , Cl − , Br − , I − , NO 3 − , ClO 3 − , ClO 4 − , IO 3 − , H 2 PO 4 − , CO 3 2− , SO 3 2− , S 2 O 3 2− , HPO 4 2− , WO 4 2− , CrO 4 2− , and PO 4 3− ; (2) organic anions: terephthalate, adipate, succinate, dodecyl sulfonate, p-hydroxybenzoate, and benzoate; and (3) isopolyacid and heteropolyacid anions: Mo 7 O 24 6− , V 10 O 28 6− , PW 11 CuO 39 6− , and SiW 9 V 3 O 40 7− , H n A n is a source of an intercalated anion in the layered double hydroxide, and n represents the charge number of the anions and is an integer of 1˜7, wherein the product is made is (1-x)M 2+ (OH) 2 +xM 3+ (OH) 3 +x/nH n A+(m-x)H 2 O→[M 2+ 1-x M 3+ x (OH) 2 ]A n− x/n ·mH 2 O; and reacting the contents in the reactor to obtain the layered double hydroxide with A n− as the intercalated anion.