|Publication number||USRE34164 E|
|Application number||US 07/650,730|
|Publication date||Jan 19, 1993|
|Filing date||Feb 4, 1991|
|Priority date||Mar 30, 1974|
|Publication number||07650730, 650730, US RE34164 E, US RE34164E, US-E-RE34164, USRE34164 E, USRE34164E|
|Original Assignee||Aluminum Company Of America|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (21), Non-Patent Citations (14), Referenced by (13), Classifications (17), Legal Events (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation-in-part of U.S. patent application Ser. No. 595,374, filed Mar. 30, 1984, now abandoned.
This invention relates to a method for producing synthetic hydrotalcite.
Hydrotalcite is a naturally occurring mineral having the formula 6 MgO.Al2 O3.CO2.12 H2 O or Mg6 Al2 (OH)16 CO3.4 H2 O. Known deposits of natural hydrotalcite are very limited and total only about 2,000 or 3,000 tons in the whole world. Natural hydrotalcite has been found in Snarum, Norway and in the Ural Mountains. Typical occurrences are in the form of serpentines, in talc schists, and as an alteration product of spinel where, in some cases, hydrotalcite has formed as pseudomorphs after spinel.
The upper stability temperature of hydrotalcite is lower than the lower limit for spinel. Spinel and hydrotalcite theoretically never would appear together in stable condition. If equilibrium has been established, the spinel would be completely changed to hydrotalcite. However, naturally occurring hydrotalcite is intermeshed with spinel and other materials.
Natural hydrotalcite is not present as pure product and always contains other minerals such as penninite and muscovite and potentially undesirable minerals such as heavy metals. Conventional practice recognizes that it is practically impossible to remove such impurities from a natural hydrotalcite.
Previous attempts to synthesize hydrotalcite have included adding dry ice or ammonium carbonate (a) to a mixture of magnesium oxide and alpha-alumina or (b) to a thermal decomposition product from a mixture of magnesium nitrate and aluminum nitrate and thereafter maintaining the system at temperatures below 325° C. at elevated pressures of 2,000-20,000 psi. Such a process is not practical for industrial scale production of synthetic hydrotalcite by reason of the high pressures. Furthermore, the high pressure process forms substances other than hydrotalcite, such as brucite, boehmite, diaspore, and hydromagnesite.
Ross and Kodama have reported a synthetic mineral prepared by titrating a mixed solution of MgCl2 and AlCl3 with NaOH in a CO2 free system and then dialyzing the suspension for 30 days at 60° C. to form a hydrated Mg-Al carbonate hydroxide. The mineral product has been associated with the formula Mg6 Al2 CO3 (OH)16.4 H2 O while having the properties of manasseite and hydrotalcite. X-ray diffraction powder patterns have indicated that the mineral more closely resembles manasseite than hydrotalcite, while the differential thermal analysis curve of the precipitate has been characterized as similar to that given for hydrotalcite.
Kerchle, U.S. Pat. No. 4,458,026, discloses a preparation of Mg/Al/carbonate hydrotalcite which involves the addition of mixed magnesium/aluminum nitrates, sulphates or chlorides as an aqueous solution to a solution of a stoichiometric amount of sodium hydroxide and carbonate at about 25°-35° C. with stirring over a several-hour period producing a slurry. The slurry is then heated for about 18 hours at about 50°-200° C. (preferably 60°-75° C.) to allow a limited amount of crystallization to take place. After filtering the solids, and washing and drying, the dry solids are recovered.
Kumura et al. U.S. Pat. No. 3,650,704, reports a synthetic hydrotalcite preparation by adding an aqueous solution of aluminum sulfate and sodium carbonate to a suspension of magnesium hydroxide. The suspension then can be washed with water until the presence of sulfate radical becomes no longer observable. The suspension is heated at 85° C. for three hours and dried. The magnesium component starting material is reported as any member of the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate, and water-soluble magnesium salts, e.g., such as mineral acid salts including magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium dicarbonate, and bittern.
It is an object of the present invention to produce synthetic hydrotalcite in high purity.
It is another object of this invention to produce hydrotalcite in high yield at atmospheric pressure.
The present invention includes a method for producing hydrotalcite including reacting an activated magnesia with an aqueous solution of aluminate, carbonate, and hydroxyl ions. The method can be carried out at atmospheric pressure to form hydrotalcite in high purity and high yield. Activated magnesia is formed by heating a magnesium compound such as magnesium carbonate or magnesium hydroxide to a temperature between about 500°-900° C.
FIG. 1 is a graphical depiction of a powder X-ray diffraction pattern obtained from synthetic hydrotalcite produced by the method of the present invention.
FIG. 2 is a graphical depiction of the differential thermal analysis of synthetic hydrotalcite obtained by the method of the present invention.
FIG. 3 is a photographic representation of synthetic hydrotalcite obtained by the method of the present invention.
The present invention produces synthetic hydrotalcite by reacting activated magnesia with an aqueous solution of aluminate, carbonate, and hydroxyl ions. The magnesia must be activated to produce hydrotalcite in high purity. Otherwise, i.e., in the event that an unactivated magnesia is used, the resulting product will include substantial amounts of mineral forms other than hydrotalcite.
The activated magnesia can be formed by activating magnesium compounds such as magnesium carbonate or magnesium hydroxide at temperatures of between about 500°-900° C. Below 500° C., the magnesium salt will not activate sufficiently and will contain inhibiting amounts of the starting material. Above 900° C., the resulting magnesium oxide takes on a form which is insufficiently active. The insufficiently active magnesia could be characterized as dead burnt. Such a form of magnesia will not form hydrotalcite predominantly over other mineral forms. The insufficiently active form of magnesia which is nonspecific to forming hydrotalcite will be avoided by heating the magnesium salt starting materials to elevated activating temperatures, but which must not exceed about 900° C., to form the activated magnesia or magnesium oxide (MgO).
The activated magnesium oxide is added to a solution containing ions of aluminate, carbonate, and hydroxl. Preferably the activated magnesium oxide is added to an aqueous solution having a pH above about 13. For example, a suitable solution may contain alkali hydroxide, alkali carbonate, and aluminum oxide. Industrial Bayer process liquor used for the production of alumina from bauxite is a suitable solution containing sodium hydroxide, sodium carbonate, and aluminate ions. A Bayer process liquor containing excess alumina also is suitable.
By way of example, 5-25 grams per liter of activated MgO can be added to 120-250 g/l NaOH (expressed as Na2 CO3), 20-100 g/l Na2 CO3, and 50-150 g/l Al2 O3 in an aqueous solution. The mixture should be agitated at a temperature of about 80°-100° C. for 20-120 minutes.
It has been found that magnesium compounds other than the activated magnesia of the present invention produce less than desirable results. For example, MgSO4, MgCl2, or MgNO3 added to Bayer liquor yields Mg(OH)2 and Al(OH)3. Similarly, Mg(OH2 added to Bayer liquor remains mostly unreacted.
The process of the present invention produces hydrotalcite in high yield. By high yield is meant a conversion yield greater than about 75% and preferably greater than about 90%.
The mineral produced by the method of the present invention can be analyzed by powder X-ray diffraction. The product formed by Example 2 of this specification was analyzed in powder form in a Siemens X-ray diffractometer having Model No. D-500 supplied by Siemens AG (W. Germany). The resulting X-ray diffraction pattern is depicted in FIG. 1. The diffraction pattern indicates that the product is hydrotalcite at high purity. The dÅ spacing obtained by X-ray diffraction is shown in Table I for the mineral obtained from the method of Example 2 and is compared to (1) the ASTM standard for hydrotalcite and (2) natural hydrotalcite as reported by Roy et al. American Journal of Science, Vol. 251, at page 353. By these indications, the process of the present invention produces hydrotalcite in high purity.
High purity in the context of the present invention is established by the absence of diffraction lines attributable to compounds other than hydrotalcite. The absence of diffraction lines indicates that such other compounds are not present in any significant amount. By way of contrasting example, the material produced in Example 1 described hereinbelow using a non-activated magnesium oxide contains lines or peaks indicating the presence of compounds other than hydrotalcite. These lines are observed in the data in Table I for the dÅ spacing of the product from Example 1.
TABLE I______________________________________X-RAY DIFFRACTION Natural HydrotalciteASTM (Snarum,(22-700) Norway) Example 1 Example 2I/I I/I I/I I/IdÅMax. dÅ Max. dÅ Max. dÅ Max.______________________________________7.84 100 7.63 100 12.4676 4.3 8.8729 3.73.90 60 3.82 50 12.3128 4.8 7.7348 99.22.60 40 2.56 10 12.1094 4.2 7.6746 100.02.33 25 2.283 5 11.8579 5.5 6.0944 5.01.99030 1.941 10 11.5907 4.2 6.0194 4.71.950 6 1.524 5 11.3070 4.7 5.9257 5.91.54135 1.495 5 11.1268 4.2 4.0786 8.61.49825 10.9421 4.2 3.9498 30.01.419 8 10.5889 4.1 3.8387 60.91.302 6 4.7678 45.7 3.8192 64.51.26510 4.6131 6.9 2.6644 4.01.172 2 4.5742 6.0 2.5765 80.10.994 4 4.5429 3.9 2.5204 25.20.976 6 4.5093 5.3 2.5102 21.7 4.4645 4.9 2.4960 14.9 4.4154 3.3 2.4840 13.0 4.3161 3.3 2.4643 10.8 4.2944 3.0 2.4526 11.4 4.2552 3.2 2.4364 10.0 4.2163 5.9 2.0677 3.7 4.1814 5.4 2.0530 5.7 4.1349 7.4 2.0477 3.3 4.1009 6.9 2.0467 3.9 4.0676 9.7 2.0401 4.9 3.9759 13.9 2.0318 7.4 2.7284 5.4 2.0221 6.7 2.6458 4.1 2.0191 6.6 2.5774 30.4 2.0041 12.4 2.4920 7.3 1.9976 10.3 2.4800 6.6 1.5239 38.8 2.4660 8.0 1.5115 18.4 2.4372 19.9 1.4963 34.1 2.3703 100.0 1.3209 2.0 2.3191 15.5 1.3180 2.8 2.2869 17.1 1.3161 4.1 1.9616 5.2 1.3114 4.1 1.9465 9.7 1.3099 3.3 1.9372 8.3 1.2771 4.1 1.9302 8.2 1.2722 5.2 1.9244 7.3 1.2692 4.3 1.8194 5.0 1.2689 5.6 1.7953 27.1 1.2662 6.8 1.5740 29.2 1.2632 4.1 1.5614 3.0 1.5557 4.2 1.5347 4.7 1.5225 18.2 1.5102 7.9 1.4918 87.7 1.3745 4.9 1.3719 5.2 1.3692 3.0 1.3176 2.2 1.3121 7.8 1.3089 8.4______________________________________
The product of Example 2 was analyzed by differential thermal analysis (DTA). FIG. 2 presents a graphical illustration of the DTA for the product of Example 2 which represents hydrotalcite in a high purity.
The synthetic hydrotalcite produced by the present invention is a highly porous mineral. A photograph by scanning electron micrograph was taken of the product of the process carried out in Example 2 and is presented as FIG. 3. The photograph illustrates the mineral product at a 5,000X magnification. The mineral can be seen to have a high surface area and high porosity.
Synthetic hydrotalcite produced by the process of the present invention has utility in one aspect in purification applications such as a filter aid. The synthetic hydrotalcite is adaptable in other aspects as a fire retardant material which releases water and CO2 on heating. Other applications include a filler material for paper or as a drying, bleaching, or absorbent material after activation by heating to over about 500° C. Synthetic hydrotalcite produced by the process of the present invention also is useful in purification and catalytic applications by virtue of an anion exchange capability wherein carbonate anion can be replaced with other anions without destroying the structure of the compound.
Magnesium carbonate in an amount of 25 grams was heated to about 1,100° C. for about 45 minutes and allowed to cool. The resulting magnesium oxide was added to a Bayer liquor prepared by digesting Suriname bauxite in a ratio of about 0.65 (defined as Al2 O3 /caustic expressed as Na2 CO3 as used in industrial practice) at blow off and then filtered. One liter of Bayer liquor was heated to about 95° C. Ten grams of the magnesium compound treated at 1,100° C. were added. The mixture was agitated for one-half hour and then filtered. The residue was washed and dried at 105° C. overnight.
The resulting product weighed about 16.7 grams which indicates a yield of less than 67%. The product of this Example 1 was analyzed by powder X-ray diffraction and was found to contain predominant amounts of Mg(OH)2 and MgO.
Activated magnesia was produced by heating 25 grams magnesium carbonate to about 600° C. for 45 minutes. The heating period of 45 minutes was selected to facilitate complete activation. For varying amounts and temperatures, the heating period should be adjusted to achieve an active product. Typical heating periods will range from about 30 to about 120 minutes.
Ten grams of the activated MgO were added to one liter of the same Bayer liquor used in Example 1. The mixture was heated to about 95° C. and agitated for about one-half hour. The mixture was filtered, and the residue was washed and dried at 105° C. overnight. The resulting precipitate had a white appearance, weighed about 22.5 grams, and had a refractive index of 1.50. The precipitate was a fine, free-flowing crystalline powder insoluble in water and organic solvents.
The precipitate was analyzed by powder X-ray diffraction and found to be hydrotalcite in high purity.
The 22.5 grams compares to a theoretical yield of 24.95 grams and indicates a high yield conversion of over 90%.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US201208 *||Jan 25, 1878||Mar 12, 1878||Improvement in trace trimming and creasing machines|
|US3320029 *||Dec 21, 1964||May 16, 1967||Method of preparing magnesia|
|US3539306 *||Jul 21, 1967||Nov 10, 1970||Kyowa Chem Ind Co Ltd||Process for the preparation of hydrotalcite|
|US3650704 *||Jan 6, 1970||Mar 21, 1972||Hasui Katuyuki||Novel synthetic hydrotalcite and antacid comprising said synthetic hydrotalcite|
|US3796792 *||Dec 8, 1970||Mar 12, 1974||Kyowa Chem Ind Co Ltd||Composite metal hydroxides|
|US3879523 *||Dec 8, 1970||Apr 22, 1975||Kyowa Chem Ind Co Ltd||Composite metal hydroxides|
|US4046855 *||Apr 14, 1976||Sep 6, 1977||Gebruder Giulini Gmbh||Method for removing harmful organic compounds from aluminate liquors of the Bayer process|
|US4145400 *||Apr 12, 1977||Mar 20, 1979||Imperial Chemical Industries Limited||Process for the preparation of plural metal crystalline compounds|
|US4229309 *||Jul 18, 1977||Oct 21, 1980||Petrolite Corporation||Magnesium-containing dispersions|
|US4351814 *||Dec 18, 1980||Sep 28, 1982||Kyowa Chemical Industry Co., Ltd.||Hydrotalcites having a hexagonal needle-like crystal structure and process for production thereof|
|US4443433 *||Nov 1, 1982||Apr 17, 1984||Warner-Lambert Company||Antacid material based on magnesium aluminum hydroxide and preparation thereof|
|US4447417 *||Feb 15, 1979||May 8, 1984||Anphar S.A.||Basic aluminium magnesium carbonate|
|US4482542 *||Jul 12, 1983||Nov 13, 1984||Warner-Lambert Company||Antacid material based on magnesium aluminium hydroxide and the preparation thereof|
|US4539195 *||Feb 23, 1984||Sep 3, 1985||Giulini Chemie Gmbh||Basic magnesium aluminum hydroxycarbonate|
|US4560545 *||Mar 5, 1984||Dec 24, 1985||Anphar S.A.||Basic aluminum magnesium carbonate|
|US4591633 *||Jul 8, 1985||May 27, 1986||Chisso Corporation||Deodorized polyolefins and process for the preparation thereof|
|US4593343 *||Nov 5, 1984||Jun 3, 1986||Sprague Electric Company||Electrolytic capacitor and spacer therefor|
|US4642193 *||Jan 25, 1985||Feb 10, 1987||Kyowa Chemical Industry Co. Ltd.||Method for purification of the cooling water used in nuclear reactors|
|US4735987 *||Jun 30, 1986||Apr 5, 1988||Osaka Yuki Kagaku Kogyo Kabushiki Kaisha||Method for manufacture of high-expansion type absorbent polymer|
|US4774212 *||Dec 22, 1987||Sep 27, 1988||Amoco Corporation||Pillared hydrotalcites|
|US4915930 *||Nov 23, 1988||Apr 10, 1990||Aluminum Company Of America||Process for producing aluminum hydroxide of improved whiteness|
|1||"Synthesis of Hydrotalcite-Like Compounds & Their Physicochemical Properties . . . ", Clay & Clay Minerals, vol. 25, pp. 14-18, 1977.|
|2||"Synthesis of New Hydrotalcite-Like Compunds & Their Physico Chemical Properties . . . ", Chemistry Letters, pp. 843-848, 1973.|
|3||*||Hand Book of Chemical Synonyms & Trade Names, 1978, p. 365.|
|4||*||Neoformation of Hydrotalcite Due to Industrial Inputs in Marine Sediments, American Mineralogist, vol. 62, pp. 1173 1179, 1977, Stoffyn et al.|
|5||Neoformation of Hydrotalcite Due to Industrial Inputs in Marine Sediments, American Mineralogist, vol. 62, pp. 1173-1179, 1977, Stoffyn et al.|
|6||*||Physico Chemical Properties of Synthetic Hydrotalcites in Relation to Composition Clay and Clay Minerals, vol. 28, 1, pp. 50 56, 1980.|
|7||Physico-Chemical Properties of Synthetic Hydrotalcites in Relation to Composition Clay and Clay Minerals, vol. 28, #1, pp. 50-56, 1980.|
|8||*||Properties of a Synthetic Magnesium Aluminum Carbonate Hydroxide and its Relationship to Magnesium Aluminum Double Hydroxide Manasseite and Hydrotalcite, The American Mineralogist, vol. 52, Jul., Aug. 1967.|
|9||*||Synthesis of Hydrotalcite Like Compounds & Their Physicochemical Properties . . . , Clay & Clay Minerals, vol. 25, pp. 14 18, 1977.|
|10||*||Synthesis of New Hydrotalcite Like Compunds & Their Physico Chemical Properties . . . , Chemistry Letters, pp. 843 848, 1973.|
|11||*||The Syntheses of Hydrotalcite like Compouds & Their Structures & Physico Chemical Properties, Clay & Clay Minerals, vol. 23, pp. 369 375, 1975.|
|12||The Syntheses of Hydrotalcite-like Compouds & Their Structures & Physico Chemical Properties, Clay & Clay Minerals, vol. 23, pp. 369-375, 1975.|
|13||*||The System MgO Al 2 O 3 H 2 O & The Influence of Carbonate and Nitrate Ions on the Phase Equilibria, American Journal of Science, vol. 251, pp. 337 361, May 1953.|
|14||The System MgO--Al2 O3 --H2 O & The Influence of Carbonate and Nitrate Ions on the Phase Equilibria, American Journal of Science, vol. 251, pp. 337-361, May 1953.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5474715 *||Sep 9, 1993||Dec 12, 1995||Tdk Corporation||Photochromic material, photochromic thin film, clay thin film, and their preparation|
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|US5624646 *||Feb 2, 1995||Apr 29, 1997||Aluminum Company Of America||Method for improving the brightness of aluminum hydroxide|
|US5645810 *||Jun 7, 1995||Jul 8, 1997||Aluminum Company Of America||High surface area meixnerite from hydrotalcites|
|US5750453 *||Dec 20, 1996||May 12, 1998||Aluminum Company Of America||High surface area meixnerite from hydrotalcites infiltrated with metal salts|
|US5843862 *||Oct 25, 1996||Dec 1, 1998||Amoco Corporation||Process for manufacturing an absorbent composition|
|US5882622 *||Apr 9, 1997||Mar 16, 1999||Aluminum Company Of America||Carbon dixide adsorption of synthetic meixnerite|
|US6322885 *||Dec 13, 2000||Nov 27, 2001||Isela Laminate Systems Corp.||Talc particles as fillers for improved epoxy laminates|
|US6803401||Sep 21, 2001||Oct 12, 2004||Reheis, Inc.||Halogen scavenger for olefin formulations|
|US20030100647 *||Sep 21, 2001||May 29, 2003||Parekh Jawahar C.||Halogen scavenger for olefin formulations|
|WO1995029874A1 *||Jan 6, 1995||Nov 9, 1995||Aluminum Company Of America||Synthetic meixnerite product and method|
|WO1996005140A1 *||Jan 6, 1995||Feb 22, 1996||Aluminum Company Of America||Two powder synthesis of hydrotalcite and hydrotalcite-like compounds|
|WO2014074596A1||Nov 6, 2013||May 15, 2014||Equistar Chemicals, Lp||Stabilized high-density polyethylene composition with improved resistance to deterioration and stabilzer system|
|U.S. Classification||423/115, 423/179, 423/630, 423/430, 423/420.2, 423/600, 424/686|
|International Classification||C01F7/00, C01F5/02|
|Cooperative Classification||C01P2004/03, C01P2002/72, C01F5/02, C01P2002/88, C01F7/005, C01P2002/22|
|European Classification||C01F7/00D2H, C01F5/02|
|Jul 12, 1993||FPAY||Fee payment|
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