# US 5,348,725 A · Method of making pillared hydrotalcites and associated products

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- Number: US 5,348,725 A
- Document ID: US5348725A
- Status: Granted
- Kind: A
- Application number: 07/754,770
- Filed: 1991-09-04
- Granted: 1994-09-20
- Earliest claimed: 1990-03-20
- Assignees: Aluminum Company of America
- Inventors: Chanakya Misra; Anthony J. Perrotta
- Web page: https://patentgrep.com/patent/US5348725A

## CPC

- B01J 29/049: {Pillared clays}
- C01B 13/145: {After-treatment of oxides or hydroxides, e.g. pulverising, drying, decreasing the acidity}
- C01G 37/006: {Compounds containing chromium, with or without oxygen or hydrogen, and containing two or more other elements}
- C01G 49/009: {Compounds containing iron, with or without oxygen or hydrogen, and containing two or more other elements}
- C01G 53/84: Hydroxides
- C01P 2002/22: layered hydroxide-type, e.g. of the hydrotalcite-type
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2002/74: by peak-intensities or a ratio thereof only
- C01P 2002/78: by stacking-plane distances or stacking sequences
- C01P 2006/12: Surface area
- C01P 2006/16: Pore diameter
- C01P 2006/80: Compositional purity
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

A method of making a pillared hydrotalcite and an associated products. The pillared hydrotalcite is made by calcining a hydrotalcite having the formula A.sub.w B.sub.x (OH).sub.y [C].sub.z .multidot.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion and w, x, y, z and n satisfy the following: 0<z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x). The method further comprises combining the calcined compound with a salt solution of an anion to make the pillared derivative of the compound and then separating the pillared derivative from the salt solution. A method of intercalating inorganic anions and resulting product is also disclosed.

## Claims

### Claim 1

A method of making a pillared derivative of a compound having the formula A.sub.w B.sub.x (OH).sub.y [C].sub.z .multidot.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion, and w, x , y, z and n satisfy the following:
0<z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x).
said method comprising:
(a) calcining the compound;
(b) combining said calcined compound with a salt solution of an anion to make a pillared derivative of said compound; and
(c) separating said pillared derivative from said salt solution.

### Claim 2 (depends on 1)

The method of claim 1, wherein employing as said compound one having the formula:
A.sub.6 B.sub.2 (OH).sub.16 [C].sub.z .multidot.4H.sub.2 O
where 1/2.ltoreq.z.ltoreq.2.

### Claim 3 (depends on 2)

The method of claim 2, wherein employing: A selected from the group consisting of Mg.sup.2+, Ni.sup.2+, Fe.sup.2+ and Zn.sup.2+ ; B selected from the group consisting of Al.sup.3+, Fe.sup.3+ and Cr.sup.3+ ; and C selected from the group consisting of OH.sup.-, Cl.sup.-, Br.sup.-, NO.sub.3.sup.-, CH.sub.3 COO.sup.-, CO.sub.3.sup.2-, SO.sub.4.sup.2-, PO.sub.4.sup.3-, Fe(CN).sub.6.sup.3- and Fe(CN).sub.6.sup.4-.

### Claim 4 (depends on 1)

The method of claim 1, wherein employing as said compound one selected from the group consisting of natural hydrotalcite, synthetic hydrotalcite, pyroaurite and takovite.

### Claim 5 (depends on 1)

The method of claim 1, wherein recitation (a) includes:
heating said compound to one or more temperatures within about 400.degree.-800.degree. C. (752.degree.-1472.degree. F.) for at least about 20 minutes.

### Claim 6 (depends on 5)

The method of claim 5, wherein
heating said compound to one or more temperatures within about 450.degree.-550.degree. C. (842.degree.-1022.degree. F.).

### Claim 7 (depends on 5)

The method of claim 5, wherein recitation (b) includes:
(i) agitating said calcined compound and said anion salt solution for at least about 20 minutes; and
(ii) forming said pillared derivative at one or more temperatures above about 20.degree. C. (68.degree. F.).

### Claim 8 (depends on 1)

The method of claim 1, which further includes:
(d) rinsing the separated derivative; and
(e) drying said rinsed derivative.

### Claim 9 (depends on 8)

The method of claim 8, wherein recitation (d) includes rinsing the pillared hydrotalcite with distilled water having a temperature between about 20.degree. C. to 50.degree. C. (68.degree.-122.degree. F.).

### Claim 10 (depends on 1)

The method of claim 1, wherein employing as said salt solution of the anion one selected from the group consisting of Cr.sub.2 O.sub.7.sup.2-, Mo.sub.7 O.sub.24.sup.6-, SiO.sub.3.sup.2-, VO.sub.3.sup.- and WO.sub.4.sup.2-.

### Claim 11 (depends on 1)

The method of claim 1, wherein creating said pillared derivative having brucite layers and having an X-ray diffraction [d(001)] value below about twelve Angstroms (12 .ANG.) for the distance between the brucite layers.

### Claim 12

A method for intercalating anions into a compound having the formula A.sub.6 B.sub.2 (OH).sub.16 [C].sub.z .multidot.4H.sub.2 O wherein A is selected from the group consisting of Mg.sup.2+, Ni.sup.2+, Fe.sup.2+ and Zn.sup.2+ ; B is selected from the group consisting of Al.sup.3+, Fe.sup.3+ and Cr.sup.3+ ; and C is selected from the group consisting of OH.sup.-, Cl.sup.-, Br.sup.-, NO.sub.3.sup.-, CH.sub.3 COO.sup.-, CO.sub.3.sup.2-, SO.sub.4.sup.2-, PO.sub.4.sup.3-, Fe(CN).sub.6.sup.3- and Fe(CN).sub.6.sup.4- ; and 1/2.ltoreq.z.ltoreq.2, said method comprising:
(a) heating the compound to one or more temperatures between about 400.degree.-800.degree. C. (752.degree.-1472.degree. F.) for at least about 20 minutes
(b) combining said heated compound with an anionic salt solution to form a pillared hydrotalcite containing said an ion; and
(c) separating said pillared hydrotalcite from the solution.

### Claim 13 (depends on 12)

The method of claim 12, wherein employing as said compound one selected from the group consisting of natural hydrotalcite, synthetic hydrotalcite, pyroaurite and takovite.

### Claim 14 (depends on 12)

The method of claim 12, wherein recitation (a) includes heating said compound to one or more temperatures within about 450.degree.-550.degree. C. (842.degree.-1022.degree. F.) for about 4 or more hours.

### Claim 15 (depends on 12)

The method of claim 12, wherein employing as said salt solution of said anion one selected from the group consisting of Cr.sub.2 O.sub.7.sup.2-, Mo.sub.7 O.sub.24.sup.6-, SiO.sub.3.sup.2-, VO.sub.3.sup.- and WO.sub.4.sup.2-.

### Claim 16 (depends on 12)

The method of claim 12, which further includes:
(d) rinsing said separated compound with distilled water; and
(e) drying said rinsed compound.

### Claim 17 (depends on 12)

The method of claim 12, wherein creating said pillared derivative having brucite layers and having an X-ray diffraction [d(001)] value between about seven and twelve Angstroms (7 .ANG.-12 .ANG.) for the distance between the brucite layers.

### Claim 18

A method for intercalating one or more inorganic anions selected from the group consisting of Cr.sub.2 O.sub.7.sup.2-, Mo.sub.7 O.sub.24.sup.6-, SiO.sub.3.sup.2-, VO.sub.3.sup.- and WO.sub.4.sup.2- into a compound having the structure of a hydrotalcite to produce a pillared derivative of said compound having brucite layers and having an X-ray diffraction [d(001)] value of between about seven to twelve Angstroms (7 .ANG.-12 .ANG.) for the distance between the brucite layers, said method comprising:
(a) providing the compound having the structure of a hydrotalcite in an activated calcined form;
(b) combining said activated calcined compound with a salt solution of said inorganic anion to produce said pillared derivative; and
(c) separating said pillared derivative from said salt solution.

### Claim 19 (depends on 18)

The method of claim 18, wherein employing Cr.sub.2 O.sub.7.sup.2- as said inorganic anion and creating said pillared derivative having an X-ray diffraction [d(001)] value below about 8.6 Angstroms (8.6 .ANG.) for the distance between the brucite layers.

### Claim 20 (depends on 18)

The method of claim 18, wherein employing Mo.sub.7 O.sub.24.sup.6- as the inorganic anion and creating said pillared derivative having an X-ray diffraction [d(001)] value between about 9.4-10.6 Angstroms (9.4 .ANG.-10.6 .ANG.) for the distance between the brucite layers.

### Claim 21 (depends on 18)

The method of claim 18, wherein employing SiO.sub.3.sup.2- as the inorganic anion and creating said pillared derivative having an X-ray diffraction [d(001)] value below about 8 Angstroms (8 .ANG.) for the distance between the brucite layers.