# US 10,118,831 B2 · Method of producing magnesium aluminate spinels > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,118,831 B2 - Document ID: US10118831B2 - Status: Granted - Kind: B2 - Application number: 15/545,920 - Filed: 2016-01-05 - Published: 2018-01-11 - Granted: 2018-11-06 - Earliest claimed: 2015-01-28 - Assignees: Sasol (USA) Corporation - Applicants: Sasol (USA) Corporation - Inventors: Brian C. Peoples; Allison L. Hann - Web page: https://patentgrep.com/patent/US10118831B2 ## CPC - C01F 7/162: Magnesium aluminates - C01P 2002/32: spinel-type (AB2O4) - C01P 2006/12: Surface area - C01P 2006/14: Pore volume - C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; 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 cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00}) - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS ## Abstract The invention provides for a method of making a magnesium aluminate spinel including an alumina compound and a magnesium compound, the method including the steps of; dispersing the alumina compound by dispersing it in a aqueous solution, to form an alumina dispersion, the aqueous solution having a pH of between 2 and 5; preferably between 2 and 4, flocculating the alumina by increasing the pH of the alumina dispersion to a pH of between 8 and 10 by adding a base; adding the alumina dispersion to an aqueous dispersion of the magnesium compound to form a slurry; drying the slurry to produce a dried spinel precursor; and calcining the dried spinel precursor to produce the magnesium aluminate spinel. Dispersing at such a low pH results in a conversion to spinel as well as allows for the control of the surface area of the spinel. ## Claims ### Claim 1 A method of making a magnesium aluminate spinel including an alumina compound and a magnesium compound, the method including the steps of: a) dispersing the alumina compound in an aqueous solution, to form an alumina dispersion, the aqueous solution having a pH of between 2and 5; b) flocculating the alumina by adding a base to increase the pH of the alumina dispersion to a pH of between 8 and 10; c) adding the alumina dispersion having a pH of between 8 and 10to an aqueous dispersion of the magnesium compound to form a slurry; d) drying the slurry to produce a dried spinel precursor; and e) calcining the dried spinel precursor to produce the magnesium aluminate spinel. ### Claim 2 (depends on 1) The method of claim 1 wherein the alumina is dispersed in step a) at a pH of between 2 and 4. ### Claim 3 (depends on 1) The method of claim 1, wherein the alumina compound includes aluminum oxyhydroxide, aluminum oxide, aluminum hydroxide or mixtures thereof. ### Claim 4 (depends on 1) The method of claim 1, wherein the alumina compound is selected from the group consisting of boehmite, bayerite, gibbsite gamma-alumina, transitional aluminas and mixtures thereof. ### Claim 5 (depends on 4) The method of claim 4, wherein the alumina compound is selected from the group consisting of boehmite and gamma-aluminas. ### Claim 6 (depends on 5) The method of claim 5, wherein the alumina compound is ultra high purity boehmite. ### Claim 7 (depends on 1) The method of claim 1, wherein, the pH of the aqueous solution in step a) is modified by addition of an acid. ### Claim 8 (depends on 7) The method of claim 7, wherein the acid includes formic acid, acetic acid, citric acid, nitric acid, hydrochloric acid, oxalic acid, butanoic acid, and sulfuric acid. ### Claim 9 (depends on 7) The method of claim 7, wherein the acid is added in an amount of 0.001 wt % to 10 wt % to the aqueous solution. ### Claim 10 (depends on 7) The method of claim 7, wherein the acid is added before the dispersal of the alumina compound or after the dispersal of the alumina compound. ### Claim 11 (depends on 10) The method of claim 10, wherein the acid is added before dispersing the alumina compound in the aqueous solution. ### Claim 12 (depends on 1) The method of claim 1, wherein the magnesium compound includes magnesium oxides and salts. ### Claim 13 (depends on 12) The method of claim 12, wherein the magnesium oxides and salts include magnesium hydroxide, magnesium hydrate, magnesium oxide, magnesium acetate, magnesium nitrate, magnesium chloride, and magnesium formate. ### Claim 14 (depends on 13) The method of claim 13, wherein the magnesium compound is magnesium oxide or magnesium hydroxide. ### Claim 15 (depends on 14) The method of claim 14, wherein the magnesium compound is magnesium hydroxide.