Rutile titanium dioxide microspheres and ordered botryoidal shapes of same

Abstract

Rutile TiO 2 microspheres and microparticles in a botryoidal morphology which form from ordered acicular aggregates of elongated TiO 2 crystallites that resemble nano-sized flower bouquets and/or triangular funnels, and process for their preparation by thermally hydrolyzing a soluble TiO 2 precursor compound in aqueous solution in the presence of a morphology controlling agent selected from carboxylic acids and amino acids.

1 - 7 . (canceled) 
     
     
         8 . Rutile TiO 2  microparticles which comprise generally spherical structures in the range of from 1 to 2 microns in diameter, said spherical structures comprising ordered acicular aggregates of elongated TiO 2  crystallites having a thickness in the range of from 3 nm to 5 nm in which one end of each of said elongated TiO 2  crystallites are joined into a cluster such that the opposite ends of each of said elongated TiO 2  crystallites extend outwardly and terminate at an angle normal to the outer surface forming said spherical structure. 
     
     
         9 . Rutile TiO 2  microparticles which comprise generally spherical structures in the range of from 1 to 2 microns in diameter, said spherical structures comprising ordered acicular aggregates of elongated TiO 2  crystallites, produced by the process comprising:
 (a) forming an aqueous solution of a soluble titanium compound at a titanium concentration of from 0.5 to 1.0 moles per liter;   (b) introducing a morphology controlling agent selected from the group consisting of an α-hydroxy carboxylic acid of the formula R—CH(OH)COOH, an α-hydroxy carboxamide of the formula R—CH(OH)CONH 2  or an α-amino acid of the formula R—CH(NH 2 )COOH, wherein R is an alkane, alkene, alkyne, arene, or cycloalkane group having 4 or fewer carbon atoms, into the solution at an acid- or carboxamide-to-titanium molar ratio of from 0.02 to 0.2 while simultaneously heating the solution to a temperature in the range of from 75° C. to 80° C. with constant stirring;   (c) maintaining the stirred solution at a temperature in the range of from 75° C. to 80° C. for a period of from one to 3 hours;   (d) elevating the temperature of the stirred solution to a value of from 100° C. to the refluxing temperature and maintaining said temperature for a period of from 2 hours to 4 hours to form a reaction product;   (e) optionally neutralizing the reaction mixture which results from step (e);   (f) cooling the reaction mixture to room or ambient temperature; and   (h) separating and drying the reaction product.   
     
     
         10 . The rutile TiO 2  microparticles of  claim 9  wherein said elongated TiO 2  crystallites have a length of from 20 nm to 50 nm and a thickness of from 3 nm to 5 nm. 
     
     
         11 . The rutile TiO 2  microparticles of  claim 10  wherein one of the ends from each of said elongated TiO 2  crystallites assemble into a cluster whereby the opposite ends of each of said crystallites extend outwardly and terminate at an angle normal to the outer surface forming said spherical structure. 
     
     
         12 . The rutile TiO 2  microparticles of  claim 9  wherein said morphology controlling agent is selected from lactic acid (CH 3 CH(OH)COOH); 2-hydroxybutyric acid (C 2 H 5 CH(OH)COOH); 2-hydroxypentanoic acid (C 3 H 7 CH(OH)COOH); 2-Hydroxyhexanoic acid (C 4 H 9 CH(OH)COOH); 2-Hydroxyisocaproic acid (CH 3 CH(CH 3 )CH 2 CH(OH)COOH); alanine (CH 3 CH(NH 2 )COOH); valine (CH 3 CH(CH 3 )CH(NH 2 )COOH); norvaline (C 3 H 7 CH(NH 2 )COOH); isoleucine (C 2 H 5 CH(CH 3 )CH(NH 2 )COOH); leucine (CH 3 CH(CH 3 )CH 2 CH(NH 2 )COOH); and norleucine (C 4 H 9 CH(NH 2 )COOH) and mixtures thereof. 
     
     
         13 . The rutile TiO 2  microparticles of  claim 9  wherein said soluble titanium compound is selected from titanium oxychloride (TiOCl 2 ), titanium oxybromide (TiOBr 2 ), titanium oxyiodide (TiOI 2 ), titanium oxynitrate (TiO(NO 3 ) 2 ), titanium trichloride (TiCl 3 ), titanium tribromide(TiBr 3 ), titanium oxalate (Ti 2 (C 2 O 4 ) 3 ), potassium hexafluorotitanate(K 2 TiF 6 ), ammonium hexafluorotitanate ((NH 4 ) 2 TiF 6 ), potassium titanyloxolate (K 2 TiO(C 2 O 4 ) 2 ), ammonium titanyloxolate ((NH 4 ) 2 TiO(C 2 O 4 ) 2 ), titanium bis(ammonium lactate) dihydroxide ([CH 3 CH(O)COONH 4 ] 2 Ti(OH) 2 ) and mixtures thereof. 
     
     
         14 . The rutile TiO 2  microparticles of  claim 12  wherein said soluble titanium compound is selected from titanium oxychloride (TiOCl 2 ), titanium oxybromide (TiOBr 2 ), titanium oxyiodide (TiOI 2 ), titanium oxynitrate (TiO(NO 3 ) 2 ), titanium trichloride (TiCl 3 ), titanium tribromide(TiBr 3 ), titanium oxalate (Ti 2 (C 2 O 4 ) 3 ), potassium hexafluorotitanate(K 2 TiF 6 ), ammonium hexafluorotitanate ((NH 4 ) 2 TIF 6 ), potassium titanyloxolate (K 2 TiO(C 2 O 4 ) 2 ), ammonium titanyloxolate ((NH 4 ) 2 TiO(C 2 O 4 ) 2 ), titanium bis(ammonium lactate) dihydroxide ([CH 3 CH(O)COONH 4 ] 2 Ti(OH) 2 ) and mixtures thereof. 
     
     
         15 . The rutile TiO 2  microparticles of  claim 14  wherein said morphology controlling agent is lactic acid (CH 3 CH(OH)COOH), and said soluble titanium compound is titanium oxychloride (TiOCl 2 ). 
     
     
         16 . A method for preparing rutile TiO 2  particles which comprise structures in a botryoidal morphology having a size in the range of from 10 to 20 microns, said structures being aggregates of elongated TiO 2  crystallites having a thickness of from 3 nm to 5 nm, said method comprising:
 (a) forming an aqueous solution of a soluble titanium compound at a titanium concentration of from 0.5 to 1.0 moles per liter;   (b) introducing a morphology controlling agent selected from an α-hydroxy carboxylic acid of the formula R—CH(OH)COOH, an a-hydroxy carboxamide of the formula R—CH(OH)CONH 2  or an a-amino acid of the formula R—CH(NH 2 )COOH, wherein R is an alkane, alkene, alkyne, arene, or cycloalkane group having 4 or fewer carbon atoms, into the solution at an acid- or carboxamide-to-titanium molar ratio of from 0.02 to 0.2 while simultaneously heating the solution to a temperature in the range of from 75° C. to 80° C. with constant stirring;   (c) introducing TiO 2  seeds into the stirred solution at a seed-to-TiO 2  molar ratio of from 0.0005 to 0.0015 and maintaining the stirred solution at a temperature in the range of from 75° C. to 80° C. for a period of from one to 3 hours;   (d) elevating the temperature of the stirred solution to a value of from 100° C. to the refluxing temperature and maintaining said temperature for a period of from 2 hours to 4 hours to form a reaction product;   (e) optionally neutralizing the reaction mixture resulting from step (d);   (f) cooling the reaction mixture to room or ambient temperature; and   (g) separating and drying the reaction product.   
     
     
         17 . The method of  claim 16  wherein said morphology controlling agent is selected from lactic acid (CH 3 CH(OH)COOH); 2-hydroxybutyric acid (C 2 H 5 CH(OH)COOH); 2-hydroxypentanoic acid (C 3 H 7 CH(OH)COOH); 2-Hydroxyhexanoic acid (C 4 H 9 CH(OH)COOH); 2-Hydroxyisocaproic acid (CH 3 CH(CH 3 )CH 2 CH(OH)COOH); alanine (CH 3 CH(NH 2 )COOH); valine (CH 3 CH(CH 3 )CH(NH 2 )COOH); norvaline (C 3 H 7 CH(NH 2 )COOH); isoleucine (C 2 H 5 CH(CH 3 )CH(NH 2 )COOH); leucine (CH 3 CH(CH 3 )CH 2 CH(NH 2 )COOH); and norleucine (C 4 H 9 CH(NH 2 )COOH) and mixtures thereof. 
     
     
         18 . The method of  claim 16  wherein said soluble titanium compound is selected from titanium oxychloride (TiOCl 2 ), titanium oxybromide (TiOBr 2 ), titanium oxyiodide (TiOI 2 ), titanium oxynitrate (TiO(NO 3 ) 2 ), titanium trichloride (TiCl 3 ), titanium tribromide(TiBr 3 ), titanium oxalate (Ti 2 (C 2 O 4 ) 3 ), potassium hexafluorotitanate(K 2 TiF 6 ), ammonium hexafluorotitanate ((NH 4 ) 2 TiF 6 ), potassium titanyloxolate (K 2 TiO(C 2 O 4 ) 2 ), ammonium titanyloxolate ((NH 4 ) 2 TiO(C 2 O 4 ) 2 ), titanium bis(ammonium lactate) dihydroxide ([CH 3 CH(O)COONH 4 ] 2 Ti(OH) 2 ) and mixtures thereof. 
     
     
         19 . The method of  claim 17  wherein said soluble titanium compound is selected from titanium oxychloride (TiOCl 2 ), titanium oxybromide (TiOBr 2 ), titanium oxyiodide (TiOI 2 ), titanium oxynitrate (TiO(NO 3 ) 2 ), titanium trichloride (TiCl 3 ), titanium tribromide(TiBr 3 ), titanium oxalate (Ti 2 (C 2 O 4 ) 3 ), potassium hexafluorotitanate(K 2 TiF 6 ), ammonium hexafluorotitanate ((NH 4 ) 2 TiF 6 ), potassium titanyloxolate (K 2 TiO(C 2 O 4 ) 2 ), ammonium titanyloxolate ((NH 4 ) 2 TiO(C 2 O 4 ) 2 ), titanium bis(ammonium lactate) dihydroxide ([CH 3 CH(O)COONH 4 ] 2 Ti(OH) 2 ) and mixtures thereof. 
     
     
         20 . The method of  claim 19  wherein said morphology controlling agent is lactic acid (CH 3 CH(OH)COOH), and said soluble titanium compound is titanium oxychloride (TiOCl 2 ). 
     
     
         21 . Rutile TiO 2  microparticles comprising structures in a botryoidal morphology having a size in the range of from 10 to 20 microns and formed by the process of:
 (a) forming an aqueous solution of a soluble titanium compound at a titanium concentration of from 0.5 to 1.0 moles per liter;   (b) introducing a morphology controlling agent selected from an α-hydroxy carboxylic acid of the formula R—CH(OH)COOH, an α-hydroxy carboxamide of the formula R—CH(OH)CONH 2  or an α-amino acid of the formula R—CH(NH 2 )COOH, wherein R is an alkane, alkene, alkyne, arene, or cycloalkane group having 4 or fewer carbon atoms, into the solution at an acid- or carboxamide-to-titanium molar ratio of from 0.02 to 0.2 while simultaneously heating the solution to a temperature in the range of from 70° C. to 80° C. with constant stirring;   (c) introducing TiO 2  seeds into the stirred solution at a seed-to-TiO 2  molar ratio of from 0.0005 to 0.0015 and maintaining the stirred solution at a temperature in the range of from 70° C. to 80° C. for a period of from one to 3 hours;   (d) maintaining the stirred solution at a temperature in the range of from 70° C. to 80° C. for a period of from one to 3 hours;   (e) elevating the temperature of the stirred solution to a value of from 100° C. to the refluxing temperature and maintaining said temperature for a period of from 2 hours to 4 hours to form a reaction product;   (f) optionally neutralizing the reaction mixture resulting from step (e);   (g) cooling the reaction mixture to room or ambient temperature and separating and drying the reaction product.   
     
     
         22 . The rutile TiO 2  microparticles of  claim 21  wherein:
 (a) said morphology controlling agent is selected from lactic acid (CH 3 CH(OH)COOH); 2-hydroxybutyric acid (C 2 H 5 CH(OH)COOH); 2-hydroxypentanoic acid (C 3 H 7 CH(OH)COOH); 2-Hydroxyhexanoic acid (C 4 H 9 CH(OH)COOH); 2-Hydroxyisocaproic acid (CH 3 CH(CH 3 )CH 2 CH(OH)COOH); alanine (CH 3 CH(NH 2 )COOH); valine (CH 3 CH(CH 3 )CH(NH 2 )COOH); norvaline (C 3 H 7 CH(NH 2 )COOH); isoleucine (C 2 H 5 CH(CH 3 )CH(NH 2 )COOH); leucine (CH 3 CH(CH 3 )CH 2 CH(NH 2 )COOH); and norleucine (C 4 H 9 CH(NH 2 )COOH) and mixtures thereof, and 
 (b) said soluble titanium compound is selected from titanium oxychloride (TiOCl 2 ), titanium oxybromide (TiOBr 2 ), titanium oxyiodide (TiOI 2 ), titanium oxynitrate (TiO(NO 3 ) 2 ), titanium trichloride (TiCl 3 ), titanium tribromide(TiBr 3 ), titanium oxalate (Ti 2 (C 2 O 4 ) 3 ), potassium hexafluorotitanate(K 2 TiF 6 ), ammonium hexafluorotitanate ((NH 4 ) 2 TiF 6 ), potassium titanyloxolate (K 2 TiO(C 2 O 4 ) 2 ), ammonium titanyloxolate ((NH 4 ) 2 TiO(C 2 O 4 ) 2 ), titanium bis(ammonium lactate) dihydroxide ([CH 3 CH(O)COONH 4 ] 2 Ti(OH) 2 ) and mixtures thereof. 
 
     
     
         23 . Rutile TiO 2  microparticles in a botryoidal morphology having a size in the range of from 10 to 20 microns which comprise an assembly of generally spherical structures in the range of from 1 to 2 microns in diameter, said spherical structures comprising ordered acicular aggregates of elongated TiO 2  crystallites having a thickness in the range of from 3 nm to 5 nm in which one end of each of said elongated TiO 2  crystallites are joined into a cluster such that the opposite ends of each of said elongated TiO 2  crystallites extend outwardly and terminate at an angle normal to the outer surface forming said spherical structure.