Clean method for preparing layered double hydroxides
AssigneeBeijing University of Chemical Technology
InventorsXue Duan, Dianqing Li, Zhi Lv, Yanjun Lin, Xiangyu Xu
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Abstract
Disclosed is a clean method for preparing layered double hydroxides (LDHs), in which hydroxides of different metals are used as starting materials for production of LDHs by atom-economical reactions. The atom efficiency of the reaction is 100% in each case because all the atoms of the reactants are converted into the target product since only M2+(OH)2, M3+(OH)3, and CO2 or HnAn− are used, without any NaOH or other materials. Since there is no by-product, filtration or washing process is unnecessary. The consequent reduction in water consumption is also beneficial to the environment.
Claims4
A clean method for preparing layered double hydroxides comprising:
- adding hydroxides of M2+ and M3+ with a molar ratio of M2+/ M3+=2˜4 into water to obtain a mixture in which the weight ratio of H2O to the hydroxides is 0.25˜999, wherein M2+represents one or two divalent cations selected from Mg2+, Zn2+, Ca2+, Cu2+, Ni2+, Co2+, Fe2+, Mn2+, Cd2+, and Be2+, and M3+ represents one or two trivalent cations selected from Al3+, Co3+, Fe2+, Mn3+, Cr3+, V3+, In3+, and Ga3+;
- adding the mixture into a reactor;
- feeding HnAn in such an amount that the molar ratio of M3+/An−=n into the reactor, wherein HnAn is an acid containing any of the following anions:
- (1) inorganic anions:
- F−, Cl−, Br−, I−, NO3−, ClO3−, ClO4−, IO3−, H2PO4−, CO32−, SO32−, S2O32−, HPO42−, WO42−, CrO42−, and PO43−;
- (2) organic anions:
- terephthalate, adipate, succinate, dodecyl sulfonate, p-hydroxybenzoate, and benzoate;
- and (3) isopolyacid and heteropolyacid anions:
- Mo7O246−, V10O286−, PW11CuO396−, and SiW9V3O407−, HnAn 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)M2+(OH)2+xM3+(OH)3+x/nHnA+(m-x)H2O→[M2+1-xM3+x(OH)2]An−x/n·mH2O;
- and
- reacting the contents in the reactor to obtain the layered double hydroxide with An− as the intercalated anion.
Dependencies are inferred from the claim text.