FO, 2. by Ed ATTORNEYS 3,485,583 United States Patent Office Patented Dec

Dec. 23, 1969 W. L. WILSON PROCESS FOR PREPARING IMPROVED TITANIUM DIoxIDE Filed Oct. 8, 1965

?zzzzzzzzzzzzzzzzzz§<<<<<<<<<<<<<<< 24227

INVENTOR WillLIAM L. WILSON FO, 2. BY ed ATTORNEYS 3,485,583 United States Patent Office Patented Dec. 23, 1969

2 More particularly, there is produced a raw, uncoated 3,485,583 pigmentary titanium oxide particle hawing improved dis PROCESS FOR PREPARING IMPROVED TITANIUM DOXOE persion, a tinting strength of at least 1600, usually at William L. Wilson, Barberton, Ohio, assignor to PPG least 1700, a blue undertone (tint tone), and a particle Industries, Inc., Pittsburgh, Pa., a corporation of size distribution range below 1.0 micron in mean diameter, Pennsylvania preferably 0.2 to 0.5 micron, with a final tinting strength Filed Oct. 8, 1965, Ser. No. 494,175 of at least 1780, usually above 1800, when the raw pig Int. C. C01g23/04 ment is wet treated or coated as disclosed, for example, by U.S. C. 23-202 4 Claims U.S. Letters Patent 3,146,119 issued to Dr. Hartien S. 10 Ritter; copending U.S. patent application Ser. No. 469,881, filed July 6, 1965 by Dr. Harry Lott, Jr. and Dr. Albert Dietz; and copending U.S. patent application Ser. No. ABSTRACT OF THE DISCLOSURE 469,864, filed July 6, 1965 by Dr. Albert Dietz and Dr. Pigmentary titanium dioxide of improved optical prop Harry Lott, Jr. erties is prepared by vapor phase reaction of titanium 15 Sources of the metals noted hereinbefore include, not tetrahalide in the combined presence of a source of by way of limitation, each metal in elemental state, alloys thorium and a source of at least one member selected containing one or more of the metals, and organic and/or from the group consisting of potassium, rubidium, cesium, inorganic compounds containing one or more of the vari sodium, lithium and zinc. ous metals. 20 Preferably, each metal source is one which will react -namuwumulu with an oxidizing agent and form an oxide of the metal This invention relates to a process for producing pig at the vapor phase reaction temperature although it is mentary titanium oxide by a vapor phase reaction. More not intended to represent that the source material actually particularly, this invention relates to a process for pro forms such oxide; that is, the source should in this instance ducing titanium oxide pigment having Superior optical 25 be capable of forming such oxide whether or not such properties by the vapor phase oxidation of a titanium oxide actually is formed during the vapor phase reaction. halide, e.g., a titanium tetrahalide such as TiCl4, TiBra, To more specifically describe the process of this in and Ti4. vention, reference is made to the drawing, and FIGURES Typical vapor phase reaction processes are disclosed 1 to 3, inclusive, which depict apparatus for practicing by U.S. Letters Patents 2,450,156 to Pechukas; 2,240,343 30 the process invention. to Muskat; 2,937,928 to Hughes et al.; 2,968,529 to Wil FIGURE 1 describes a diagrammatic cross-section view son; 3,069,281 to Wilson; Canadian Patent 517,816 to of a concentric orifice-annulus burner fitted in a furnace. Krchma et al.; Canadian Patent 609,804 to Wilson; Cana FIGURE 2 further illustrates the construction of the dian Patent 639,659 to Wilson; Canadian Patent 631,871 burner of FIGURE 1, representing a view along line to Wilson; British Patent 979,564 to Wilson; British 35 I-I of FIGURE 1. Patent 876,672; British Patent 726,250; and British Patent FIGURE 3 illustrates a diagrammatic cross-section 922,671. The vapor phase reaction may also be conducted view of a burner which may be fitted in the furnace of in a fluidized bed, e.g., as disclosed in U.S. Letters Patent FIGURE 1 to produce pigmentary titanium dioxide ac 2,760,846 to Richmond. cording to the process of this invention. In accordance with the practice of this invention, titan 40 Referring to FIGURES 1 and 2, reaction zone chamber ium oxide is produced by a vapor phase reaction in the of furnace A comprises a concentric steel shell 1 and an presence of a thorium source and a source of at least one internal lining of firebrick 5 (or other heat resistant in metal selected from the group consisting of potassium, Sulation). At the lower part of furnace A is a conical rubidium, cesium, sodium, lithium, and zinc. bottom terminating at outlet 7. At the upper part of In one embodiment of this invention, it is contemplated furnace A' is a burner A. producing titanium oxide pigment by a vapor phase re Burner A is composed of three concentric tubes, 2, 3, action in the presence of at least one source of thorium, and 4. Tube 3 is arranged so as to circumscribe tube 4 zinc, and at least one alkali metal of the group consisting (forming annulus 6) and tube 2 is arranged so as to cir of potassium, rubidium, cesium, sodium, and lithium. cumscribe tubes 3 and 4 (forming annulus 9). Each of Specific combination contemplated in the practice of 50 the tubes 2 and 3 are evenly spaced from the wall of the this invention include, not by way of limitation, tube it circumscribes. This is more clearly shown in FIG URE 2, which shows the tube arrangement taken along Th and Li Th, Zn and Li line II of FIGURE 1. Th and Na Th, Zn and Na In the operating of the reactor of FIGURES 1 and 2, Th and K Th, Zn and K 55 an oxygenating or oxidizing gas typically preheated to at Th and Rb Th, Zn and Rb least 900 C., usually at least 1750° C., is fed to the upper Th and Cs Th, Zn and Cs opening in tube 4, while an inert gas at room tempera Th and Zn ture up to the temperature of the oxygenating gas is fed to the opening at the top of tube 3. The oxygenating or It has been discovered that when titanium oxide is pre 60 inert gas may be preheated with the products of com pared in accordance with the present invention, there is bustion of a selected material, or with a high energy produced a titanium oxide particle having optimum pig source, e.g., a plasma arc or laser beam. mentary properties, particularly tint tone and tinting The inert gas may comprise, not by way of limitation, strength, for a given particle size distribution range. chlorine, nitrogen, bromine, iodine, argon, helium, kryp 3,485,583 3 4 ton, xenon, carbon dioxide, SO or mixtures thereof. The selected metallic source (or sources) of zinc and/ Concurrently therewith, titanium tetrahalide is fed to the or alkali metals may be added to the vapor phase oxida opening at the upper part of tube 2. The titanium tetra tion reaction in amounts ranging from 0.01 to 10,000 halide has a temperature of 140° C. to about 1200° C. parts by weight of each selected metal per million parts Referring to FIGURE 3, burner B, which may be fit by weight of titanium oxide produced by the oxidation ted in furnace A" of FIGURE 1 in replacement of Burner reaction. A, is composed of three concentric tubes annularly ar Generally, there is added less than 6,000 parts by ranged. Central oxygenating gas tube 12 is circumscribed weight of the metal with best results being obtained with by tube 11, which in turn is circumscribed by tube 10, 5 to 5000 parts by weight of the metal per million parts such that there is formed annuli 17 and 16. Tube 11 is 0 by weight of titanium oxide formed by the oxidation re provided with an annular lip 13 at its lower end and tube action. 10 is provided with annular lip 14, such that the titanium With certain of the alkali metals such as potassium, it tetrahalide and inert gas streams are emitted from the may be more desirable to add substantially less than 1,000 annuli 17 and 16 in a direction substantially perpendicul parts by weight per million parts by weight titanium lar to the direction of flow of the oxygenating gas from 5 oxide. tube 12. In operation, burner B is fed in the same man Thus, it has been discovered that effective results are ner as burner A of FIGURE 1. obtained when potassium is present in an amount rang The source or sources of the various additives, e.g., ing from 1 to 500 parts by weight per million parts by thorium, zinc, and the alkali metals, can be introduced to weight titanium oxide produced in the vapor phase oxida the vapor phase reaction together or separately. 20 tion zone. Furthermore, such sources can be introduced directly In the practice of this invention, it is contemplated that or indirectly to the vapor phase reaction of the titanium sources of other metals may be added to the reaction tetrahalide and oxygen. Zone, particularly sources of rutile promoting agents such Thus, in the practice of this invention, one or more as aluminum, zirconium, and/or water, or sources of par sources of one or more of the aforementioned additives 25 ticle size control agents such as silicon and/or water. may be added in conjunction with an inert gas, or one or The aluminum source may be added to the vapor phase more of the reactants, or both. reaction in an amount sufficient to insure the presence of When the process is heated by the combustion of a 0.01 to 10.0 percent by weight aluminum based on the fuel, one or more sources may be added to the fuel or weight of the titanium oxide formed. the products of combustion thereof, e.g., a combustible 30 The zirconium source may be added to the vapor phase carbon-containing or sulfur-containing fuel or the com reaction in an amount sufficient to insure the presence of bustion products thereof when a process is operated in 0.001 to 10.0 percent by weight zirconium based on the accordance with U.S. Letters Patents 3,069,282 and weight of the titanium oxide formed. 3,105,742. The water source may be added to the vapor phase re The source of each selected additive may also be added 35 action in an amount Sufficient to insure the presence of directly to the reaction zone 30 independently of the re 0.001 to 5.0 percent by weight water based on the weight actants, inert gases, or combustible fuels; e.g., one or of the titanium oxide formed. more sources may be added directly to the reaction zone The silicon source may be added to the vapor phase as an atomized spray in a solid, liquid, or gaseous state. reaction in an amount sufficient to insure the presence of Furthermore, one or more metallic additives may be 40 0.0001 to 5.0 percent by weight silicon based on the added to the zone 30 by employing an inner furnace wall weight of the titanium oxide produced. It has been dis 5 constructed of a ceramic or firebrick material which covered that best results are obtained with 0.01 to 1.0, contains one or more sources of one or more additives, particularly 0.02 to 0.50, percent by weight silicon based e.g., one or more compounds of thrium, zinc, or alkali on the titanium oxide produced. metal. Such surce material is gradually eroded into the When the silicon is used in conjunction with potas reaction zone due to the high temperature and corrosive sium, there is employed about 25 to 50 parts by weight nature of the environment in zone 30, as noted, for ex silicon per part by weight potassium, e.g., 500 parts by ample, in British patent specification 672,753. weight silicon for 10 to 20 parts by weight potassium One or more additives, particularly potassium, may based on the titanium oxide pigment produced by the also be introduced into the reaction zone by employing a 50 vapor phase reaction. ceramic dedusting edge, as disclosed in copending U.S. The total of the various metals added to the vapor patent application Ser. No. 379,825, filed July 2, 1964, phase reaction (e.g., Th, Zn, alkali metals, Al, Zr, and which contains a source of the particular additive, e.g., Si) should be less than 10.0 percent by weight of the lava stone containing about 0.5 to 1.5 percent by weight titanium oxide produced with effective results being ob potassium. tained below about 6.0 percent by weight. Likewise, the additive may be introduced to the zone The thorium source can be elemental thorium, ThH. 30 by using a baffle as disclosed in copending U.S. appli (thorane), Thhs, ThH2, tetra-1,1-diethylpropoxy thorane, cation Ser. No. 376,980, filed June 22, 1964, now U.S. ThCl4, Thbra, ThF, ThI, ThC, thorium nitrate, thori Patent 3,382,042, which is constructed out of the selected um Sufate, ThS2, ThCS, ThCF2, thorium nitride, thorium additive or a source of the additive. 60 nitrite, Th(PO4)4, thorium oxalate, ThoCO, Th(OH)4, Such sources may also be added directly to the zone ThO2, Th(CO), hydrates such as ThF-8HO, 30 or to one or more inert or reactant gas streams by Thg (PO4)4 4H2O, Th(SO4)29HO, Th(CO)6HO, emitting the source from one or more plasma arc elec ThoCO38H2O, NasTh(CO)5-12H2O, thorium iodate, trodes as disclosed, for example, in copending U.S. pat thorium chlorate, thorium bromate, KThCle, RbThCls, ent application Ser. No. 354,597, filed Mar. 25, 1964. 65 CsThCl6, NaThCls, tetramethoxy thorane, tetraethoxy The thorium source is added to the vapor phase oxida thorane, tetrapropoxy thorane, tetraisopropoxy thorane, tion reaction in an amount sufficient to insure the pres and tetrabutoxy thorane. When the source is thorium ox ence of 0.0001 to 15.0 percent by weight thorium based ide, the oxide should have a small mean diameter of less on the weight of the titanium oxide formed in the reaction than 1.0 micron, usually less than 0.5 micron, preferably ZOle. 70 less than 0.15 micron. Preferably, the source of thorium is added in a small, The source of the zinc is defined as any organic or in effective amount equivalent to less than 5.0 percent by organic compound of zinc including metallic zinc and Weight thorium based on the titanium oxide pigment Zinc alloys, preferably a source of zinc which will react formed, with best results being obtained in the range of with oxygen at the vapor phase reaction temperature to 0.001 to 1.0 percent by weight thorium. form a corresponding oxide of zinc although it is not 3,485,583 5 intended to indicate that the source material actually ZnCO (zinc oxalate), forms such oxide; that is, the source should in this in zinc oleate, stance be capable of forming a corresponding oxide of ZnSiO2 (zinc metasilicate), zinc whether or not such oxide actually is formed during zinc stearate, the vapor phase oxidation reaction. In addition, source ZnSO, (zinc sulfate), as herein employed, is further defined as also including hydrates of zinc sulfate, any oxide of zinc providing such oxide has a mean par ticle size diameter of less 1.0 micron, usually less than ZnSO (zinc sulfite). 0.5 micron, preferably less than 0.15 micron, as noted Likewise, zinc alloys may be used. hereinbefore. 10 The potassium source can be elemental potassium, a Typical zinc compounds contemplated herein include, potassium compound, or a potassium ally. Examples, not not by way of limitation, both organic and inorganic com by way of limitation, of potassium compounds include pounds such as both organic and inorganic compounds such as Zn(CH3O2)2 (zinc acetate), KHC6H3O8 (potassium saccharate acid), Zn(C2H5O)22H2O, KOCHNO" 2HO ZnAlO4 (zinc aluminate), Zn(NH2)2 (zinc amide), (potassium - m - nitrophen oxide or potassium - p - ni Zn(CH5O2)2 (zinc benzoate), trophen oxide), KHCH4O4 CH6O4 (potassium hydro 3ZnO2BO3 (zinc borate), gen succinate), K2SO4 (potassium sulfate), KHSO4 (po Zn(BrO3)2' 6H2O (zinc bromate), 20 tassium hydrogen sulfate), K2S2O (potassium pyrosul ZnBr (zinc bromide), fate), K2S2O8 (potassium peroxydisulfate), KS (potas Zn(CHO)22H2O (zinc butyrate), sium monosulfide), KS 5H2O, KHS (potassium hydro Zn(C6H1102)2 (zinc caproate), sulfide), KS (potassium disulfide), K2S2'3H2O, K2S3 ZnCO (zinc carbonate), (potassium trisulfide), KS4 (potassium tetrasulfide), Zn(ClO3)2.4H2O (zinc chlorate), 25 K2S2H2O, K2S5 (potassium pentasulfide), K2SO3.2H2O, ZnCl2 (zinc chloride), KHSO3, KSO5 (potassium pyrosulfite), ZnCrO4 (zinc chromate), ZnCrO3H2O (zinc dichromate), Zn3 (C6H5O)2 2H2O (zinc citrate) s (potassium d-tartrate), K2C4H4O6, KHCH4O6 (potas Zn(CN)2 (zinc cyanide), 30 sium hydrogen di-tartrate), K2HTeO6'3H2O (po Zn(H2O)6GaF55H2O (zinc fluogallate), tassium orthotellurate), KCS (potassium trithiocarbo ZnF (zinc fluoride), nate, KSCN (potassium thiocyanate), K2S2O6 (potas ZnSiF6' 6H2O (zinc fluosilicate), sium dithionate), KSOs (potassium trithionate), K2S4O6 Zn(HSO CHO)2, (potassium tetrathionate), 2K2S5Os3H2O (potassium Zn(OH)HSO CH2O (zinc formaldehydesulfoxylate), pentathionate), KSn33H2O, 3K2S2O3.H2O (potassium Zn(CHO)2 (zinc formate), thiosulfate), 3K2SO 5H2O, KHCH2N4O (potassium ZnC4H4O6 H2O, acid urate), KCHO (potassium acetate), ZnCH4O6'2H2O (zinc tartrate), KCHO HCH O Zn(SCN)2 (zinc thiocyanate), 40 (potassium acid acetate), KCHO4.2H2O (potassium Zn(C5H8O2)22H2O (zinc valerate), acetylsalicylate), KNH. (potassium amide) KNH4CH4O6 Zn(NH3)2]Cl2 (zinc diamminezinc chloride), Zn(CH2CH2CH2CH3)2 (zinc di-n-butylzinc), (potassium ammonium tartrate), Zn(C2H5)2 (zinc diethylzinc), KAuOxH2O Zn(CH3)2 (zinc dimethylzinc), KN (potassium azide), KCH5O2.3H2O (potas Zn(C6H5)2 (zinc diphenylzinc), sium benzoate), K2B2H6 (potassium diborane), K2B2H6O2 Zn(CH2CH2CH3)2 (zinc di-n-propylzinc), (potassium dihydroxy diborane), KaBs Hg (potassium pen Zn(C6H4CH3)2 (zinc di-o-tolylzinc), taborane), KBO (potassium metaborate), K2B4O78H2O Zn(CHO)22H2O (zinc formate), (potassium tetraborate), KBO'4H2O (potassium penta ZnCa2O4 (zinc gallate), 50 borate), KBO /2 H2O (potassium peroxyborate), ZnC3H7O6P (zinc glycerophosphate), KCAHBO (potassium borotartrate), KBrO3 (potassium Zn(OH)2 (zinc hydroxide), bromate), KBr (potassium bromide), KAuBri, Zn(IO) (zinc iodate), Zn(IO)22H2O, K2Cr O4 2Cr ( OH ) CrO4 Zn (zinc iodide), 55 (potassium chromium chromate, basic), Zn(CH3O2)2.3H2O (zinc di-lactate), Zn(CH3O2)22H2O (Zinc di-lactate), KCr(SO4)2- 12H2O (potassium chromium sulfate) Zn(CHO) (zinc aurate), KCH5OHO (potassium citrate), KHC6H5O1 (potas Zn(MnO4)28H2O (zinc permanganate), sium citrate, monobasic), KOCN (potassium cyanate), Zn(NO3)2.3H2O (zinc nitrate), 60 KCN (potassium cyanide), KC2H5SO4 (potassium ethyl ZnN (zinc nitride), sulfate), K2GeF6 (potassium fluogermanate), K2C20H10Os ZnO (zinc oxide), (potassium fluoroescein derivatives), KPF6 (potassium Zn(CHO)2 (zinc acelylacetonate), Zn(CHsO4)2 (zinc 1-phenol-4-sulfonate), KAuOxH2O Zn3(PO4)2 (zinc orthophosphate), 65 hexafluorophosphate), KF (potassium fluoride), Zn(PO4)2.4H2O, KF•2H2O Zn3(PO4)22H2O, KHF, KAu(CN), KBFA (potassium fluororate).KHPO3 Zn2PO (zinc pyrophosphate), (potassium mono hydrogen orthophosphite) KH2PO3 Zn2P (zinc phosphide), 70 (potassium di hydrogen orthophosphite), KHCH4O4 Zn(H2PO4)2-H2O (zinc hypophosphite), (potassium hydrogen phthalate), KCHNO (potassium zinc picrate, picrate), KC12HsO4 (potassium piperate), KCH5O2H2O Zn(CH5O)2.3H2O (zinc salicylate), (potassium propionate), KCHSO4 (potassium propyl ZnSeO4.5H2O (zinc selenate), sulfate), KHCH3O8 (potassium acid-d-saccharate, 3,485,583 7 8 (potassium salicylate), KC5H18O4 (potassium santoninate), rubidium alloys, or a rubidium compound, e.g., similar KC18H350 (potassium Stearate), K2C4H4O4.3H2O (potas to the potassium and cesium compounds noted herein sium succinate), before. Examples, not by way of limitation of rubidium compounds, include both organic and inorganic com KHCH4O4 (potassium hydrogen succinate) pounds such as RbC2H8O. (rubidum acetate), KHCHO-2H2O, KFSO (potassium fluorosulfonate), KThF4H2O (potassium fluorothorate), KTiF6H2O RbAl(SO4) g 12H2O (potassium fluotitanate), KCHO (potassium formate), (rubidium aluminum sulfate), RbBrO (rubidium bro KCHPOs (potassium glycerophosphate), KH (potas mate), RbBr (rubidium bromide), RbBra (rubidium tri sium hydride), KOH (potassium hydroxide), KO (po O bromide), RbBrCl (rubidium bromochloroiodide), tassium iodate), KIOHIO (potassium acid iodate), RbIBr (rubidium dibromoiodide), RbBrCl (rubidium KIO-2HEO, KIO (potassium metaperiodate), KI, KI dichlorobromide), RbBraCl (rubidium chlorodibromide), (potassium triiodide), KCl, KCl3, KF, KF, KBr, KBr, Rb2CO3 (rubidium carbonate), RbHCO3, RbClO3 (rubid KCHOXH2O (potassium lactate), KC12H2O (potas ium chlorate), RbClO4 (rubidium perchlorate), RbCl sium laurate), K2C4H4O5 (potassium malate), 5 (rubidium chloride), RbCl (rubidium dichloroiodide), RbCrO4 (rubidium chromate), RbCr2O (rubidium (potassium methionate), 2KCHSO4H2O (potassium dichromate), RbR (rubidium fluoride), Rb2SiF (rubid ium fluosilicate), RbFSO (rubidium fluosulfonate), RbH methyl sulfate), K2C10Hs (SO3)2.2H2O (potassium naph (rubidium hydride), RbCH (rubidium hydroxide), RbC) thalene-1,5-disulfonate), KIBR2 (potassium dibromoio 20 dide), KSnBre, KC10H1404.5H2O (potassium di-cam (rubidium iodate), RblO4 (rubidium metaperiodate), Rb phorate), KCO (potassium carbonate), K2CO3" xH2O, (rubidium iodide), RbI (rubidium triiodide), Rb 4SO2, KHCO (potassium hydrogen carbonate), K2COs (po RbMnO4 (rubidium permanganate), RbNO3 (rubidium tassium peroxycarbonate), (KCO)6 (potassium carbon nitrate), RbnOHNO (rubidium hydrogen nitrate), yl), KClO (potassium chlorate), KClO4 (potassium per 25 RbNO-2HNO3, Rb2O (rubidium monoxide), Rb2O3, chlorate), KCl, KClO, KICl (potassium chloroiodate), RbOs (rubidium trioxide), RbC), (rubidium superoxide), KICl2, KOSCls (potassium chloroosmate), K2RhCls (po RbSO (rubidium sulfate), RbHSO4 (rubidium hydro tassium pentachlorohodite), KCrO4 (potassium chro gen sulfate), Rb2S (rubidium monosulfide), Rb2S 4H2O, mate), KCr2O (potassium dichromate), KCrO3 (po RbS (rubidium disulfide), Rb2S3 (rubidium trisulfide), tassium peroxychromate), KNO3 (potassium nitrate), 30 Rb2S5 (rubidium pentasulfide), Rb2S6 (rubidium hexa KN (potassium nitride), KNO2 (potassium nitrite), sulfide), RbHCHOs, Rb2O, (rubidium peroxide). KC18H33O2 (potassium oleate), KC18H38O2C18H34O2 (po Specific sources of sodium or lithium would include tassium acid oleate), KOsO4.2H2O (potassium osmate), elemental sodium and lithium and alloys of same as well KCO-H2O (potassium oxalate), KHC2O4 (potassium as compounds of all the classes listed for potassium, hydrogen oxalate), KHCO /2 H2O, KHCO'H2O, 35 cesium, and rubidium hereinbefore, particularly NaCl, KHCO'H2C2O4.2H2O, K2O, K2O2, K2O3, KO2, NaBr, NaI, NaF, NaSO4, NaHSO, NaS, NaHS, NaNH2, KCHSO4 (potassium phenyl sulfate), KPO, K2HPO4, NaBH, NaH, NaOH, Na2CO3, NaHCO3, NaNO3, KPO3H2O (potassium pyrophosphate), KPO3. NaNO, NaN, NaO, NaO, LiCl, LiI, LiBr, LiF, Likewise, the corresponding compounds of other alkali LiSO4, LiHSO4, LiS, LiHS, LiNH2, Li2B2H6, Li H, LiOH, metals such as sodium and lithium as well as cesium and 40 LiCO, LiHCO3, LiNO3, LiNO2, LiaN, Li2O, and Li2O2. rubidium may be used as sources of the respective alkali Alloys or ceramics may also be used as a source of metal, e.g., sodium, lithium, cesium, and rubidium. one or more of the aforementioned alkali metals. Although Thus, the cesium source can be elemental cesium, ce it is particularly desirable that alkali oxides be in a sium alloys, or a cesium compound similar to the K con finely-divided state, e.g., less than 1.0 micron in mean pounds noted hereinbefore. Examples, not by Way of 45 diameter, a ceramic or alloy source does not have to be limitation of cesium compounds, include both organic in a finely-divided state, particularly when a ceramic or and inorganic compounds as CsCH3O3 (cesium acetate), metal reactor Wall is the source. CsCHO (cesium benzoate), CsBrO3 (cesium bromate), Rutile promoting agents as contemplated herein include CsBr (cesium monobromide), CsBr3 (cesium tribromide), sources of aluminum, zirconium, and/or water. CsBrCII (cesiurn bromochloroiodide), CsIBr2 (cesium di 50 Rutile promoting sources of aluminum and zirconium bromoiodide), CsIBr (cesium bromodiiodide), Cs2CO3 include any organic or inorganic compound of aluminum, (cesium carbonate), CsHCO3 (cesium carbonate hydro zirconium, or both, including metallic aluminum or Zir gen), CsClO3 (cesium chlorate), CcClO4 (cesium per conium, which will react with oxygen at the vapor phase chlorate), CsCl (cesium chloride), CSAuCl4 (cesium reaction temperature (of the titanium tetrahalide and chloroaurate), CsBrCl (cesium chlorodibromide), 55 oxygen) to form the corresponding metal oxide although CsBrCl (cesium dichlorobromide), CsICl2 (cesium di it is not intended to indicate that the source material chloroiodide), Cs2SnCls (cesium chlorostannate), actually forms such oxide; that is, it is preferred that the CsCrO, (cesium chromate), CsCn (cesium cyanide), source should in this instance be capable of forming the CsF (cesium fluoride), CsCHO2 (cesium formate), corresponding aluminum or zirconium oxide whether or CsCHOHO, CSFH (cesium hydride), CsOH (cesium hy 60 not such oxides actually are formed during the vapor droxide), CsIO (cesium iodate), CsIO4 (cesium meta phase oxidation reaction. In addition, source as herein periodate), CsI (cesium monoiodide), CsI (cesium tri employed is further defined as also including the oxides of iodide), CsIs (cesium pentaiodide), CsCls, CsBris, CSNO3 aluminum or zirconium providing such oxide is finely (cesium nitrate), CsNO3HNO3 (cesium hydrogen ni divided, as noted hereinbefore, e.g., having a mean parti trate), CSNO2HNO (cesium dihydrogen nitrate), 65 cle size diameter of less than 1.0 micron, generally less CsNO (cesium nitrite), CsCO4 (cesium oxalate), Cs2O than 0.5 micron, with best results obtained below 0.15 (cesium monoxide), Cs2O3 (cesium peroxide), Cs2O3 micron. (cesium trioxide), CsO3 (cesium Superoxide), CsCsh4O4 Specific sources of aluminum include, not by way of (cesium hydrogen phthalate), CsRh(SO4)2' 12H2O (ce limitation, metallic aluminum, organic and inorganic com sium rhodium sulfate, CsCH5O3 (cesium salicylate), 70 pounds containing aluminum including oxides, hydrox CsSO, (cesium sulfate), CshSO4 (cesium hydrogen Sul ides, nitrates, nitrides, sulfides, sulfates, and halides such fate), Cs.S. 4H2O (cesium sulfide), Cs2S2 (cesium disul as Al(CHO) (aluminum acetate), Al(OH) (C2H3O2)2 fide), CsS H2O, Cs2S3 (cesium tetrasulfide), Cs2S5 (ce (aluminum acetate, basic), AlC6H5O1 (aluminum cit sium pentasulfide), Cs2S6 (cesium hexasulfide). rate), AlCl3, AlCl, AlBr, AlBr, Ala, AII, AlF3, AlF, The rubidium source can be elemental rubidium, 75 Al(CIO)6H2O (aluminum chlorate), Al(OH)3 3,485,583 9 10 AlO3, Al(NO3)3'9H2O, AlN2, Al(SO4)3, Al2S3, H3AlF6, (cesium aluminum sulfate), KSiF6 (potassium fluosili AN, the aluminum ammonium holides Such as cate), K2SiO3 (potassium metasilicate), K2SiO5 (potas AiCl3 NH sium disilicate), KHSi2O5 (potassium hydrogen disili cate), KZrF6 (potassium fluozirconate), CsSiF6 (cesium NH4Al(SO4)2, and aluminum containing esters, for fluosilicate), AlTi, and AlCl3-34ZnCl2. example, aluminum compounds containing one or more Furthermore, there may be employed alloys containing organic ester radicals with one to ten carbon atoms per one or more of the aforementioned additives. radical, e.g., Al(OCH)3 (aluminum isopropylate or iso Examples of alloys contemplated herein include, not propoxide). by Way of limitation, thorium aluminum, thorium titan Likewise, there may be employed, not by way of limi 10 ium, thorium zirconium, thorium boron, thorium cerium, tation, aluminum compounds containing other organic thorium hydrogen, thorium nitrogen, thorium silicon, radicals such as hydrocarbons, e.g., paraffins, cycloparaf thorium sodium thorium sulfur, thorium zinc, and fins, olefins, acetylenes, aromatics, alcohols, phenols, thorium tin. ethers, carbonyls, amines, and benzene rings. Further Among the above sources listed for thorium, zinc, more, there may be used alloys of aluminum providing 5 alkali metals, aluminum, zirconium, and silicon, there are such alloys are capable of being oxidized. It may in Some certain advantages which will accrue from the use of cer instances be necessary to use particular alloys in a finely tain classes of material, for example, the halides, particu divided state, e.g., of a particle size below 3.0 microns, in larly the chlorides. order to enhance oxidation. It is particularly advantageous to conduct the vapor Specific sources of zirconium include, not by Way of 20 phase oxidation in the presence of sources which will react limitation, metallic zirconium, organic and inorganic with oxygen at the temperature of the vapor phase oxida compounds containing zirconium including oxides, hy tion to form the corresponding metal oxide. It is not droxides, oxalates, nitrates, nitrides, sulfides, sulfates, intended to indicate that the source materials herein listed halides, and oxyhalides such as ZrBra, ZrCl4, ZrF4, Zrl4, for thorium, zinc, alkali metals, aluminum, zirconium, Zr(OH)4, Zr. (NO3)4.5H2O, ZrO2, Zr(CO4)22Zr(OH)4 25 and silicon must actually form the corresponding metal (zirconium oxalate, basic), Zr(SO4)2.4H2O, oxide during the vapor phase oxidation. However, it is advantageous if the source material in this instance is capable of forming a metal oxide, regardless of whether ZrF(OH)3HO, ZrBr(OH)3H2O, ZrI(OH)3.3H2O, such oxide is formed. ZrOCl. 8HO, ZrOF8H2O, ZrOBr28H2O, ZrOI28H2O, 30 Where a metallic source is a high ionizable salt such as and zirconium compounds containing one or more or KCl, NaCl, LiCl, RbCl, CsCl, it is not necessary for ganic radicals, e.g., hydrocarbons, esters, benzene rings, such compound to be capable of forming an oxide at the alcohols, olefins, etc., as listed for aluminum. There may vapor phase oxidation temperature; that is, good results also be used alloys of zirconium, providing such alloys are obtained by the addition of a highly ionizable source are capable of being oxidized. Such alloys may necessarily 35 which is not oxidized at the reaction temperature and have to be employed in a finely-divided state as noted for which remains substantially unchanged chemically, e.g., the aluminum alloys. as analyzed in an effiuent stream from the reactor. Thus, In addition to additives of aluminum, zirconium, tho when KCl is added to the vapor phase reaction of TiCl rium, zinc, and the alkali metals noted hereinbefore, and O2, it is not oxidized but may be recovered as KCl. there may be further added a source of silicon. 40 Furthermore, it is also feasible to employ sources which Silicon source is defined as any organic or inorganic are not highly ionizable and which do not form oxides compound of silicon including elemental metallic silicon at the vapor phase oxidation temperature, particularly which will react with oxygen at the vapor phase reaction if such sources are heated to a high temperature by pas temperature to form the corresponding metal oxide al Sage through a plasma arc, e.g., in the presence of an though it is not intended to indicate that the source ma 45 inert gas or one of the reactants such as oxygen. terial actually forms such oxide; that is, the source should The sources listed hereinbefore may be introduced be capable in this instance of forming the corresponding into the reaction chamber 30 very effectively as solutions silicon oxide, e.g., SiO2, whether or not such oxide ac in a solvent, e.g., in the form of a spray. Thus, water tually is formed during the vapor phase oxidation reaction. Soluble metal sources of the type herein contemplated In addition, source is further defined as including the 50 can be used in water solutions. Organic metal sources may oxides of silicon, such as silica, providing such oxide has be used in many cases where they are liquids or gases, or a mean particle size below 1.0 micron in diameter as noted may be used in solutions in common organic solvents hereinbefore. which are not adverse to the vapor phase oxidation. Specific silicon sources contemplated herein include, Typical Solvents are chloroform, methylene chloride, not by way of limitation, organic and inorganic com 55 or like chlorinated aliphatic or aromatic solvents. Other pounds such as the silicon hydrides (or silanes), organo typical Slovents include acetones, ketones, benzenes, and silicon halides, alkylhalosilanes, alkylalkoxy-silanes, and alcohols. Such solvents may also be used as a source of silicon halides, particularly SiCl4. A typical list of silicon Water. sources is disclosed in my copending U.S. patent appli It is also advantageous to use materials which vaporize cation Ser. No. 474,075, filed July 22, 1965, now U.S. 30 readily and can be introduced in a vapor state. Thus, zinc Patent 3,356,456, and is incorporated herein by refer metals and various zinc halides are advantageous which enceS. are volatile at the vapor phase reaction temperature. Specific sources of water include water, ice, steam, The following is a typical working example represent water of hydration such as AlCls' 6H2O, hydrogen, organic ing the best mode contemplated by the inventer in the compounds which decompose to form hydrogen or water 65 carrying out of this invention. including the hydrocarbons such as CH4, natural gas, and propane, alcohols such as CHOH, C2H5OH, aldehydes EXAMPLE such as formaldehyde, ketones such as acetone and methyl ethyl ketone, polyols such as sugars, glycols, carbohy A burner having the configuration of Burner B in drates such as starch, cotton, and wood, phenol, aromatic 70 FIGURE 3 is employed in conjunction with reaction hydrocarbons such as benzene, and organic halides Such chamber A' of FIGURE 1. aS CHCl, CHBr, and C6H4Cl2. Titanium tetrachloride (TiCl) at 1000 C. and 14.7 Likewise, one or more compounds may be employed as pounds per square inch absolute pressure is flowed at the a source of one or more metal additives, for example, rate of 80 millimoles per minute through annulus 17 into Al(SiF) (aluminum silicofluoride), CSAl(SO4)2.12H2O 75 reaction zone 30. The TiCl4 contains 2 mole percent of 3,485,583 11 12 AlCl and 0.13 mole percent SiCIA based on the total the optical properties of a paint prepared from the pig moles of TiCl4. ment. Conversely, the more brown the pigment, the less Simultaneously, oxygen at 1000 C. and 14.7 pounds pleasing the optical properties of the paint. per square inch absolute pressure is flowed at 96 milli The undertone scale to be used ranges from a Brown moles per minute through passage 15 (tube 12) into the 10 to a Blue 6 as shown hereinafter in Table II. reaction zone 30. A 30 mole percent chlorine shroud (based on the total TABLE II moles of TiCl) at 1000 C. and 14.7 pounds per square Brown 10 Brown 1 inch absolute pressure is flowed through annulus 16. Brown 9 Neutral The reaction zone 30 is preheated and maintained at 10 Brown 8 Blue 1 1000 C. Brown 7 Blue 2 (Standard) Varying amounts of thorium and metals selected from Brown 6 Blue 3 zinc and the alkali metals are added to the oxygen stream. Brown 5 Blue 4 The AICl and SiCl4 additions to the TiCl4 are held con Brown 4 Blue 5 stant at 2 mole percent and 0.13 mole percent respectively. 5 Brown 3 Blue 6 All metals are added as inorganic chlorides, e.g., KCl, Brown 2 CsCl, RbCl, ZnCl2, and ThCla. While the invention has been described by reference to The titanium oxide pigment formed in zone 30 is with specific details of certain embodiments, it is not intended drawn at exit 7 entrained in a gaseous effluent stream. that the invention be construed as limited to such details, The raw pigment is recovered and is wet coated with 20 except insofar as they appear in the appended claims. hydrous alumina and titania in accordance with the proc I claim: ess of U. S. Letters Patent 3,146,119 issued to Dr. Har 1. In a process for producing pigmentary titanium di tien S. Ritter. oxide by vapor phase reaction of titanium tetrahalide Se The results are tabulated in Table I. All additives are lected from the group consisting of titanium tetrachlo expressed in parts by weight of the particular metal per 25 ride, titanium tetrabromide and titanium tetraiodide, the million parts by weight titanium oxide pigment formed. improvement which comprises conducting said reaction in Both raw and coated tinting strength (T.S.) are given the presence of: for the pigment, as well as raw and uncoated tint tone (a) from 0.0001 to 5.0 weight percent, based on titanium (T.T.). dioxide, of thorium, and The tinting strength of pigmentary titanium dioxide 30 (b) from 0.01 to 10,000 parts, per million parts of may be determined by any of several methods known in titanium dioxide, of at least one member selected from the paint industry. One such method is the Reynold's the group consisting of potassium, rubidium, cesium, Blue Method, A.S.T.M. D-332-26, "1949 Book of sodium, lithium and zinc. A.S.T.M. Standards,” Part 4, page 31, published by 2. A process according to claim 1 wherein said reaction American Society for Testing Material, Philadelphia 3, 35 is conducted in the presence of from 0.0001 to 5.0 weight Pa. percent, based on titanium dioxide, of thorium, and from TABLE I 5 to 5,000 parts, per million parts of titanium dioxide, of at Pigment least one member selected from the group consisting of Metal additives to potassium, rubidium and cesium. O2, p.p.m. titanium Raw Coated Raw Coated 40 3. A process according to claim 1 wherein the total Run No. Oxide T.S. T.S. T.T. T.T. amount of metals added to the vapor phase reaction is less 1------None------1,600 1,690 Brown 6- Brown2. 2------4,000Zn, 200 Th---- 1,670 1,740 Neutral--- Blue 2. than 10.0 weight percent, based on titanium dioxide. 3------3,000Zn, 50 Th------1,680 1,760 Blue 1.---- Do. 4. In a process for producing pigmentary titanium di 4------3,500 Zn, 100 Th----- 1,670 l,750 ---do------Do. 5------8.8%, 100 Th, 1,690 l,780 ---do------Blue 3. 45 oxide by vapor phase oxidation of titanium tetrachloride, 50 K, the improvement which comprises conducting said oxida 6------200 Rb, 100 Th--- 1,660 1,740 Neutral--- Blue 1. 7------200 Rb, 100 Th, 50 K. 1,680 1,770 ---do------Blue 2. tion in the presence of: 8------200 Cs, 100 Th.------1,650 1,740 Brown 1... Blue 1. (a) from 0.0001 to 5.0 weight percent, based on titanium 9------4's, St. 100 Th, 1,670 1,750 Blue 1.----. Blue 3. dioxide, of thorium, and (b) from 0.01 to 10,000 parts, per million parts of 50 titanium dioxide, of potassium. Tint tone or undertone of a titanium dioxide pigment sample is determined by visually comparing a paste of References Cited the pigment with a paste of a selected standard. In the example hereinbefore, a paste of a sample from UNITED STATES PATENTS each run and a paste of a standard is prepared in accord 55 3,105,742 10/1963 Allen et al. ------23-202 ance with A.S.T.M. D-332-26 using carbon black to tint 3,208,866 9/1965 Lewis et al. ------106-300 each Sample paste to the same depth of grey as the stand 3,228,887 1/1966 Evans et al. 106-300 XR ard. 3,304,265 2/1967 Evans et al. 106-300 XR The standard used has an oil absorption rating of 20.9 3,306,760 2/1967 Zirngibl et al. 106-288 as determined by A.S.T.M. D-281-31, an average particle 60 3,329,483 7/1967 Evans et al. 106-300 XR size of 0.25 micron as determined with an electron micro 3,337,300 8/1967 Hughes et al. ------23-202 graph, and an assigned undertone value of Blue 2. 3,356,456 12/1967 Wilson ------23-202 The samples obtained from the runs in the example are compared with the standard and an undertone value as EDWARD STERN, Primary Examiner signed to the sample by stating whether the sample is bluer 65 or browner than the designated standard. U.S. Cl. X.R. The more blue a pigment is, the more pleasing are 23-345; 106-288, 292, 300