Polyoxometalate intercalated layered double hydroxides
AssigneeBoard of Trustees operating Michigan State University
InventorsThomas J. Pinnavaia, Taehyun Kwon, Emmanuel D. Dimotakis, Jayantha Amarasekera
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Abstract
This disclosure describes the synthesis of layered double hydroxide compositions interlayered by polyoxometalate anions with Keggin-type structures and having the formula [M.sub.1-x.sup.ll M.sub.x.sup.lll (OH).sub.2 ]A.sub.x/n.sup.n-.yH.sub.2 O, wherein, M.sup.ll is a divalent metal and M.sup.lll is a trivalent metal, A is an anionic polyoxometalate of negative charge n, x range between 0.12 to 0.8, and y is a positive number. The products exhibit well-defined XRD peaks corresponding to uniformly crystalline layered products with basal spacing values.gtoreq.14 .ANG..
Claims23
An intercalated uniform crystalline layered double hydroxide clay composition conforming to the formula [M.sub.1-x.sup.II M.sub.x.sup.III (OH).sub.2 ]A.sub.x/n.sup.n-.yH.sub.2 O wherein M.sup.II is a divalent metal and M.sup.III is a trivalent metal, A is polyoxometalate anion of charge n-, x is between 0.12 and 0.8, and provides pillar height greater than about 9 Angstroms and an X-ray diffraction basal spacing value greater than about 14 Angstroms.
A process for preparing an intercalated crystalline layered double hydroxide clay composition conforming to the formula [M.sub.1-x.sup.II M.sub.x.sup.III (OH).sub.2 ]A.sub.x/n.sup.n-.yH.sub.2 O wherein M.sup.II is a divalent metal and M.sup.III is a trivalent metal, A is polyoxometalate anion charge n-, and x is between 0.14 and 0.8, and y is a positive number comprising:
- (a) adding a hot slurry with a temperature between about 50.degree. and 100.degree. C. containing a layered double hydroxide material conforming to the formula, [M.sub.1-z.sup.II M.sub.z.sup.III (OH).sub.2 ]B.sub.z. yH.sub.2 O, wherein B is a monovalent anion selected from the group consisting of NO.sub.3.sup.-, Cl.sup.-, and z is between 0.14 and 0.8, wherein the layered double hydroxide material is formed and used without drying in water which contains the dissolved polyoxometalate anion A.sup.n- whereby B is substituted by the polyoxymetalate anion;
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- (b) recovering the composition.
A process for the preparation of an LDH of the formula [Mg.sub.1-x Al.sub.x (OH).sub.2 ](OH).sub.x. yH.sub.2 O, wherein x is between 0.12 to 0.8 and y is a positive number, comprising:
- (a) calcining the hydrotalcite material with the composition conforming to the formula [Mg.sub.1-x Al.sub.x (OH).sub.2 ](CO.sub.3).sub.x/2. yH.sub.2 O at an elevated temperature preferably to a temperature up to about 500.degree. C. to provide a calcined material;
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- (b) hydrolyzing the calcined material in degassed water under a CO.sub.2 free atmosphere to form the LDH having a gallery anion which is hydroxide ion.
A process for the preparation of a LDH sorbent conforming to the formula, [M.sub.1-x.sup.II M.sub.x.sup.III (OH).sub.2 ]A.sub.x/n.sup.n-.yH.sub.2 O wherein M.sup.II is a divalent metal and M.sup.III is a trivalent metal, A is a polyoxometalate anion of charge n-, and x is between 0.14 and 0.18 and y is between 0 to 8, comprising:
- (a) exchanging a gallery OH.sup.- ion in an LDH of the formula [Mg.sub.1-x Al.sub.x (OH).sub.2 ](OH).sub.x.yH.sub.2 O, wherein the intermediate LDH is formed and used without drying, with polyoxoanions in an aqueous solution by mixing an aqueous slurry of the LDH in water and an aqueous solution of polyoxomatalate anion A, wherein the process is conducted in the absence of carbon dioxide;
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- (b) isolating the LDH sorbent.
Dependencies are inferred from the claim text.