Methods for production of titanium oxide particles, and particles and preparations produced thereby

TECHNICAL FIELD The present invention relates to a method for preparing titanium oxide nanoparticles, and more specifically to the preparation of titanium oxide nanoparticles having a desired particle size in an industrially and economically practical manner. The method of particle size distribution and habit of titanium oxide particles. In the present invention, the term titanium oxide means and includes the chemical formula TixOy (such as TiO, Ti0₂. Ti2 (h and Ή3Ο5) titanium oxide, chemical formula is Ti_p(OH) _Q0_rTitanium spasm-based oxides such as Ti(OH)J, titanic acid, various hydrated forms of these compounds, and compositions in which these compounds are the main components, where X, y, p, q, and r are all integers.

BACKGROUND OF THE INVENTION At present, titanium oxide is widely used in various industrial applications: paint pigments, opacifiers, welding electrode fluxes, optical coatings, as catalysts (for example, adsorption of NOx from flowing gas), ceramic modified coatings, plastic elastomers , Printing inks, roof granular materials, glass and glazes. In 2006, it is predicted to increase by 2.0% per year.

Titanium oxide has at least four crystal forms: titanic acid, anatase, brookite, and rutile. Among them, the rutile form has the greatest density, hardness and refractive index. The titanium oxide crystals are characterized by the diversity of size, color, density, porosity, surface area and shape. These parameters have a great influence on their use and performance. The properties of the final product depend on the development process of product deposition and aging. There is great interest in the production of titanium oxide particles with excellent properties such as nanocrystallinity, narrow particle size distribution, and the preparation of metastable phases.

As proposed in U.S. Patent Nos. 6,830, 742 and 6, 653, 356, a liquid phase method is generally used to produce titanium oxide, where titanium tetrachloride or titanium oxysulfate is used as a starting material, and the starting material is in a hydrophilic solvent. Hydrolysis occurs in a gas phase process, in which a volatile starting material such as titanium tetrachloride is vaporized and then combined with an oxidizing gas such as oxygen or steam at high temperature in a gaseous state.

200680049411.3 The first steam to react.

Generally, the titanium oxide powder produced by the liquid or gas phase method disadvantageously undergoes severe agglomeration and has a wide range of particle size distribution. In the case of the titanium oxide produced by the gas phase method, the same problems occur in the method as those that occur in the production by the liquid phase method. That is, although ultrafine particles of titanium oxide can be obtained by the conventional gas phase method, only particles of titanium oxide with grain growth can be obtained. Therefore, there is great interest in the production of titanium oxide materials with excellent properties such as nanocrystallinity, narrow particle size distribution, and the preparation of metastable phases.

The main objective of the present invention is to provide an industrial and economical method for producing titanium oxide particles characterized by the desired particle size, size distribution, and crystal habit.

Another object of the present invention is to provide an industrial and economical method for producing titanium oxide particles characterized by a low level of hydration.

Another object of the present invention is to provide an industrial and economical method for producing titanium oxide particles characterized by high porosity and desired morphology and habit.

SUMMARY OF THE INVENTION In consideration of this state of the art, a method for forming titanium oxide particles in an aqueous solution is now provided in accordance with the present invention, the method comprising: maintaining an aqueous solution of titanium salt defined as a starting aqueous solution at less than 70°C The temperature is maintained for a certain time, which is sufficient to reduce the acidity of the solution due to hydrolysis. Then the resulting solution (defined as the retention solution) is adjusted for temperature and/or dilution and/or addition of reagents, so as to adjust the pH value of the solution to form an adjustment system. The preferred way of adjusting the parameters is at a high rate.

In the second aspect of the present invention, there is provided a raw material for preparing other titanium oxide particles by conventional methods, such as thermal transformation, ignition or aging of the obtained particles.

More specifically, according to the present invention, a method for forming small-sized titanium oxide particles is now provided. The method includes the following steps: a) preparing a starting aqueous solution containing tetravalent titanium (titanic) ions and their complexes At least one of the concentration of titanium is at least 0.1% w/w; b) maintaining the solution at a temperature lower than 70°C for a certain residence time, which

200680049411.3 Hydrolysis occurs during the second period, and the degree of hydrolysis is sufficient to generate 0.1 mmol protons for every mmol of titanium present in the solution, wherein the time does not exceed 14 days in order to form a system containing a retention solution; and

c) Adjust the conditions in the system through at least one of the following steps:

I) heating the retention solution to increase its temperature by at least It; ii) changing the pH of the retention solution by at least 0.1 unit; and iii) diluting the retention solution by at least 20%.

There are thus formed particles, where most of the formed particles have a size between about 2 nm and about 500 nm.

The term titanium oxide used in this article refers to Ti0₂.Titanium hydroxides such as titanium(II) hydroxide (Ti(0H)2); titanium(III) hydroxide (Ti(OH) ₃); Titanium hydroxide (IV) (Ti(OH)J; Titanium oxide (TiO(OH) ₂); and titanic acid such as α-titanic acid (ortho titanic acid (HJiOJ), β-titanic acid (meta titanic acid (H₂TiO₃)) and combinations thereof.

In a preferred embodiment of the present invention, the solution is maintained under the adjusted conditions for at least 0.5 minutes.

The condition adjustment is preferably performed within a period of at most 2 hours.

In a preferred embodiment of the invention, the method produces at least 50 kilograms of particles per hour.

The condition adjustment is preferably performed at a pressure of at most 100 atmospheres.

In a preferred embodiment of the invention, the method is further characterized in that most of the formed particles have a crystallinity greater than 50%.

Preferably, the method is further characterized in that the size ratio between the smallest and largest particles in the middle 50% (by weight) of the formed particles is less than about 10, and in a particularly preferred embodiment, it is less than about 5.

The term intermediate 50% by weight used herein refers to 50% by weight of particles including 25% by weight of particles with a size larger than the average particle size and 25% of particles with a size smaller than the average particle size, and the larger 25% and the The smaller 25% of the particles are those particles whose size is closest to the average size in the graph depicting the size distribution of the formed particles.

Preferably, the method is further characterized in that most of the formed particles have elongated

200680049411.3 The outer configuration.

In a preferred embodiment of the present invention, the method is further characterized in that most of the formed particles have a configuration such that the ratio between one size and any other size is less than about 3.

In other preferred embodiments of the invention, most of the formed particles have an elongated configuration.

Preferably most of the particles formed have at least 30 m²/gr surface area.

It is preferred that most of the formed particles have at least 100 m²/gr surface area.

In a particularly preferred embodiment of the present invention, the method further includes an ignition step, that is, heating the formed particles to a temperature between about 90°C and about 900°C to form dehydrated particles.

In another preferred embodiment, the ignition step includes dehydration of the prepared particles.

In the preferred embodiment, the method preferably further includes the step of removing part of the water in the particle suspension after the condition adjustment step (and before, at the same time or after the dehydration).

In the preferred embodiment, the dehydration is preferably performed under superatmospheric pressure.

In the preferred embodiment, the temperature of the particle suspension is preferably increased to the dehydration temperature within a period of at most 4 hours.

In the particularly preferred embodiment, most of the dehydrated particles preferably have a configuration other than elongated.

In the particularly preferred embodiment, most of the dehydrated particles preferably have a surface area of at least 30 m7gr.

Preferably the particles are selected from anatase, rutile or brookite.

It is particularly preferred to have the chemical formula Ti0₂particle.

Also preferred are particles of the chemical formula Ti (0H) 4.

Preferably, the pH of the aqueous solution is about 0 to about 7 during at least part of the adjusting step.

A particularly preferred method is wherein the pH of the aqueous solution is about 0.5 to about 2 during at least part of the adjusting step.

200680049411.3 In a preferred embodiment of the present invention, the preparation of the aqueous solution includes dissolving the titanium compound, adding an alkali, and acidifying the titanium salt solution.

In the preferred embodiment, the titanium compound is preferably selected from titanium salts, titanium oxides, titanium hydroxides, titanium minerals, and combinations thereof. In the present invention, the term titanium complex includes titanium salt, complex and titanium hydroxide.

Preferably, the titanium compound is selected from titanium oxide, titanium hydroxide, minerals containing them, and mixtures thereof, and the compound is dissolved in an acidic solution containing an acid selected from sulfuric acid, nitric acid, Hydrochloric acid, phosphoric acid, their acid salts and combinations thereof.

In a preferred embodiment of the present invention, the prepared aqueous solution contains anions selected from the group consisting of sulfate, chloride, nitrate, phosphate, organic acid and mixtures thereof.

In a preferred embodiment of the present invention, the adjustment includes at least two heating steps.

In the preferred adjustment step, at least one heating step is preferably performed by contact with a warmer stream selected from the group consisting of hot aqueous solution, hot gas and steam.

In a preferred embodiment, the method preferably further comprises grinding the formed particles.

In a preferred embodiment, the method preferably further includes sieving the formed particles.

The present invention is also directed to titanium oxide particles formed in accordance with the method defined above and their transformed products at any time.

The present invention is also directed to articles containing the particles.

In a preferred embodiment of the article, the particles are preferably dispersed in a liquid, supported on a solid compound, or agglomerated into larger particles.

In another aspect of the present invention, there is provided a method for manufacturing an article as defined above, the method comprising steps selected from the group consisting of dispersing the particles, adding a carrier, heat treatment, mixing, water evaporation spray drying, thermal spraying, and Its combination.

In a particularly preferred embodiment of the invention, the particles and articles are used in the manufacture of coatings.

In other preferred embodiments of the invention, the particles and articles are used to prepare catalysts.

In another preferred embodiment of the present invention, a method for forming small-sized titanium oxide particles is now provided, which includes the steps:

200680049411.3 Section a) Preparation of a starting aqueous solution containing at least one of tetravalent titanium ions and their complexes at a concentration of at least 0.1% w/w titanium, the pH of the solution is lower than 2;

b) Prepare the conditioning aqueous solution; c) Contact the starting solution with the conditioning solution in the mixing chamber in a continuous manner to form the conditioning system; d) Remove the conditioning system from the mixing chamber in a plug flow manner; and the method is characterized by: i ) The residence time in the mixing chamber is less than about 5 minutes; ii) There are formed particles or agglomerates thereof, most of which have a size of about 2nm to about 500nm; and iii) The formed particles contain titanic acid Or Ti0₂Or a combination thereof.

Adjust the conditions of the system by adjusting the solution using at least one of the following conditions: a) heating the starting aqueous solution at least 10°C, b) changing the pH value of the starting aqueous solution by at least 0.1 unit; and c) changing the initial The aqueous solution is diluted by at least 20% or a combination thereof, wherein the adjustment system is maintained under the adjustment conditions for at least 0.5 minutes. In a particularly preferred embodiment of the present invention, the residence time of the adjustment system in the mixing chamber is less than 5 seconds, and in a more preferred embodiment, the residence time of the adjustment system in the mixing chamber is less than 0.5 seconds.

In a preferred embodiment of the present invention, mixing is performed in the mixing chamber by using the flow rate of the incoming solution or by using a mechanical mixing method or other mixing methods.

In a preferred embodiment of the invention, the conditioning system leaves the mixing chamber in a plug flow manner. In a more preferred embodiment, the plug flow lasts more than 0.1 second, and in the most preferred embodiment, the plug flow lasts more than 5 seconds.

In a preferred embodiment of the invention, the solution leaving the plug flow enters the container. In a more preferred embodiment of the invention, the solutions in the container are mixed.

Detailed description of the invention

200680049411.3 The present invention will now be described in detail below.

First, the method for preparing titanium oxide particles according to the present invention is described.

The starting titanium salt aqueous solution used in the present invention is preferably a titanium salt aqueous solution containing a tetravalent titanium ion or a complex thereof, and the concentration of titanium is at least 0.1% w/w.

According to a preferred embodiment, the titanium w/w concentration in the starting solution is at least 2%, more preferably at least 5%, most preferably at least 10%. There is no upper limit to the concentration of the starting solution. However, according to a preferred embodiment, the concentration is below the saturation level. According to another preferred embodiment, high viscosity is undesirable. According to a preferred embodiment, the OH/Ti ratio in the solution is less than 2. According to a preferred embodiment, the temperature of the prepared starting solution is lower than 70°C_o Any titanium source is suitable for preparing the starting solution of the present invention, including titanium-containing ores, fillings of such ores, their processed products, titanium salts, or titanium-containing solutions such as aqueous solutions leaving the titanium-containing ores.

According to a preferred embodiment, step (b) is performed shortly after obtaining both the desired concentration and pH value. According to another preferred embodiment, the solution used in step (b) is prepared in a short time and does not contain tetravalent titanium ions or their complexes, and the tetravalent titanium ions or their complexes are different Time to prepare and then mix together. For similar reasons, an extended preparation time is not desired. According to a preferred embodiment, the preparation time is shorter than 20 hours, preferably shorter than 10 hours, most preferably shorter than 2 hours. In the case where there is an older solution (for example a recirculation solution) and it is mixed with a new solution to form a starting solution, as described below, the older solution is first subjected to acid treatment.

The freshly prepared tetravalent titanium salt solution can contain any anion, including chloride, sulfate, nitrate, phosphate, carboxylate, organic acid anions, and various mixtures thereof. According to a preferred embodiment, the freshly prepared solution contains titanium sulfate. According to another preferred embodiment, the salt is a salt of an organic acid.

The newly prepared salt solution used in the method of the present invention may be a solution generated under natural conditions (for example, a solution leaving a mineral with titanium-containing ore), or a solution prepared by artificial methods including chemical or biological oxidation. Such solutions can be prepared by various methods or combinations thereof, including dissolution of tetravalent titanium salt, dissolution of titanium salt, dissolution of double salt, dissolution of ores containing titanium oxide in acidic solutions, and dissolution of waste titanium in oxidizing solutions (such as Tetravalent titanium salt, nitrate

200680049411.3 The dissolution of acid and other solutions and the leaching of titanium-containing minerals (such as anatase, rutile or brookite, etc.).

According to a preferred embodiment, the preparation of the aqueous solution is performed in a single step. According to alternative embodiments, the preparation includes two or more steps. According to another embodiment, a concentrated solution of the tetravalent titanium salt is prepared by, for example, the dissolution of the salt in water or an aqueous solution. During dissolution, when the required starting solution pH and concentration are reached instantaneously and/or locally, usually after at least partial homogenization, the pH of the resulting concentrated solution is lower than the ideal starting solution. According to a preferred embodiment, this instantaneous achievement of the desired conditions is not considered as preparing the starting solution. The pH of the concentrated solution is then brought to the desired level by any suitable method, such as acid removal, addition of alkaline compounds and/or increasing its concentration, or a combination of these methods. In this case, according to a preferred embodiment, the formation of the starting solution is regarded as being adjusted to a selected range. According to another preferred embodiment, the pH of the starting solution is obtained after at least partial homogenization.ofpH value. According to yet another preferred embodiment, a concentrated solution is prepared and the pH is adjusted to a level slightly below the ideal value. The starting solution is then prepared by solution dilution, which increases the pH to the desired level. Here again, according to a preferred embodiment, the pH value of the starting solution is the pH value obtained after at least partial homogenization. The same is true for other methods of preparing the starting solution in multiple stages, for example in the case of the formation of a tetravalent titanium salt solution.

According to a preferred embodiment, the starting solution is freshly prepared. According to another preferred embodiment, the solution does not contain ions and/or complexes prepared at different times, as in the case of mixing a recycled solution with a freshly prepared solution. According to a preferred embodiment, when the pH is lower than 0, high concentration (for example, higher than 10% titanium) and low temperature (for example, lower than 40), the solution keeps its freshness for a longer period of time and can be used as a stock solution. According to another preferred embodiment, under other conditions, the solution is not considered fresh after a few hours or days. According to a preferred embodiment, the freshness of the solution is restored by acid treatment. Acidify this less fresh solution to a pH below 0.5, preferably to a pH below 0, and preferably mix, stir or shake at least 5 before increasing the pH back above 0 to form a fresh solution again minute. According to a preferred embodiment, this reformed fresh solution is mixed with other fresh solutions.

200680049411.3 In the next step of the method, it is preferable to keep the tetravalent titanium solution at a temperature lower than 70°C for a retention time of no more than 14 days. During this holding time, hydrolysis occurs. According to a preferred embodiment, the holding time is to produce at least 0.1 mmol of H for every mmol of titanium present in the solution⁺ (Proton) The time required. According to another preferred embodiment, in the case where a base or a basic compound is added to the solution during the holding time, the holding time is the time required to form these amounts of protons without adding a base.

According to a preferred embodiment, the holding time decreases as the pH of the prepared solution increases. Therefore, for example, when the pH is lower than 1, the retention time is preferably 20 minutes to several days. At a pH value of 1.5 to 5.0, the retention time is preferably less than 1 day. In the case of changing the pH value during the holding time, the holding time is affected by the maximum pH value reached. Generally, the holding time decreases as the temperature of the solution increases.

The third step required to achieve the above-mentioned precipitation is to adjust the conditions of the solution so as to achieve at least one of an increase in pH and/or temperature and or dilution of the solution.

The adjustment of the conditions is preferably performed in a short time and the adjusted conditions are maintained for a short time. The duration under the adjusted conditions is less than 24 hours. According to an exemplary embodiment, it is preferably less than 4 hours, more preferably less than 2 hours, and most preferably less than 10 minutes. In other preferred embodiments of the present invention, the adjustment of the conditions is performed within 2 hours, preferably within 10 minutes, more preferably within 1 minute.

The increase in pH in step (c) can be achieved by any known method, such as acid removal, or addition of alkaline compounds or increasing the concentration of alkaline compounds. Acid removal can be performed by known methods, such as extraction or steaming. Any basic compound can be added. According to a preferred embodiment, the basic compound is a compound that is more basic than titanium sulfate, as measured by comparing the pH of its equimolar solutions. Therefore, such a basic compound is preferably at least one of inorganic or organic bases or base precursors, such as oxides, hydroxides, carbonates, bicarbonates, ammonia, urea, and the like. Therefore, these methods of increasing the pH value are also applicable to the step (a) of preparing the starting solution. According to a preferred embodiment, an alkaline pH value is avoided in most of the process, so that the pH value is acidic or weakly acidic during most of the duration of the increase in the pH value in step (c).

According to another preferred embodiment, the pH value in step (a) is reduced by adding acid.

200680049411.3 According to a preferred embodiment, the anion of the acid is the same as the anion present in the titanium salt, but other anions can also be used.

According to another preferred embodiment, the solution is diluted in step (C). According to a preferred embodiment, the solution is diluted by at least 20%, more preferably at least 100% and most preferably at least 200%. According to another preferred embodiment, the temperature of the solution is increased. According to yet another embodiment, the temperature is increased by at least 10°C, more preferably by at least 30°C, more preferably by at least 50°C, and most preferably by at least 80°C_oThe temperature increase can be achieved by any known method, such as contacting a hot surface, contacting a hot liquid, contacting a hot vapor, infrared radiation, microwaves, or a combination of these methods.

According to another preferred embodiment, two or all three of said adjustments are performed sequentially or simultaneously. Therefore, according to a preferred embodiment, in an aqueous solution, the basic compound is added to the tetravalent titanium salt solution after the residence time, which also dilutes the tetravalent titanium salt. According to another preferred embodiment, the tetravalent titanium salt solution is contacted with a diluted solution containing water and/or an aqueous solution. According to a first preferred embodiment, the temperature of the diluted solution is at least 50 °C higher than the tetravalent titanium salt solution, And it is preferably at least 100C higher. According to an alternative embodiment, the temperature of the diluted solution is between about 100°C and 250°C, and according to another preferred embodiment, between 150°C and 250°C. According to another preferred embodiment, the diluted solution contains agents that interact with tetravalent titanium ions, their complexes and/or their particles.

According to another preferred embodiment, in step (c), the tetravalent titanium salt solution after the residence time is combined with an adjustment aqueous solution, the adjustment aqueous solution contains a solute whose alkalinity is greater than the tetravalent salt, and the temperature of the adjustment aqueous solution Higher than the tetravalent titanium salt solution. According to a preferred embodiment, the tetravalent titanium salt solution and the conditioning aqueous solution are mixed together (for example mechanically) in a suitable device that provides strong mixing in order to quickly obtain a homogeneous system. In the case where the temperature of at least one of these solutions is higher than the boiling point, it is preferable to select the mixing equipment so that it can withstand superatmospheric pressure. According to a preferred embodiment, mixing is performed by contacting the flowing tetravalent titanium salt solution with the flowing conditioning aqueous solution in, for example, a plug flow manner. The mixed stream is preferably kept at the forming temperature or another temperature obtained by cooling or heating for a short period of time. According to typical embodiments, the short period of time is less than 1 day, preferably between 1 and 60 minutes, more preferably between 0.5 and 15 minutes. minute.

200680049411.3 When used as a single means of adjustment or performed in combination, the degree of heating, pH increase and dilution affect the chemical properties of the particles formed. For example, generally, the higher the temperature, the lower the degree of hydration of the particulate components. Crystal shape and shape are also affected.

According to a preferred embodiment, the final product oxide is formed in step (c) of the method. According to another preferred embodiment, the product of step (c) is further processed and transformed into the desired final product.

According to a preferred embodiment, such further treatment includes heating. It is preferably heated to a temperature in the range of about 90°C to 900°C. According to a preferred embodiment, the particle-forming solution containing the particles obtained in step (c) is heated, or after some treatment, such as partial or complete water removal. According to another preferred embodiment, the particles formed are first separated from the solution. The separated particles can be treated as they are or after further treatment (eg washing and/or drying). The heating in the solution is preferably carried out under superatmospheric pressure and in equipment suitable for such pressure. According to a preferred embodiment, external pressure is applied. The nature of heating is also a controlling factor, so in some cases the result of gradual heating is different from the result of rapid heating. According to a preferred embodiment, step (c) and further heating are preferably performed sequentially in the same container.

According to a preferred embodiment, the crystal habit of the transformed particle generally has the general habit of the initial particle from which it was produced. For example, rod-shaped anatase particles can be transformed into elongated rutile particles, or in another embodiment of the present invention, amorphous titanic acid particles with a low particle size ratio can be transformed into anatase particles with a high particle size ratio. . In another embodiment of the present invention, the agglomerates with rod-shaped habit or the agglomerates with spherical habit can be respectively transformed into anatase or rutile particles with rod-shaped habit or agglomerates with spherical habit.

As will be realized, the present invention provides conditions for producing precipitates that are easy to transform and provides a transformed product with excellent characteristics.

According to a preferred embodiment, at least one dispersant is present in at least one of the processing steps. As used herein, the term "dispersant" means and includes dispersants, surfactants, polymers, and rheological agents. Therefore, according to a preferred embodiment, the dispersant is introduced into the solution in which the tetravalent titanium salt is dissolved or to be dissolved, or added to the solution precursor, such as a mineral ore. According to another preferred embodiment, the dispersant is added to the solution during or after the residence time. According to an alternative embodiment, the dispersal is performed before or after the adjustment step

200680049411.3 The first agent is added to the solution. According to yet another preferred embodiment, the dispersant is added before, during or after the conversion step. According to another preferred embodiment, the method further comprises the step of adjusting the concentration and/or properties of the dispersing agent and/or adding another dispersing agent during the treatment. According to a preferred embodiment, a suitable dispersant is a compound capable of being adsorbed on the surface of the nanoparticles and/or core. Suitable dispersants include cationic polymers, anionic polymers, nonionic polymers, surfactant polyions, and mixtures thereof. In this context, the term "dispersant" refers to a molecule that has the ability to stabilize the dispersion of formed particles, and/or adjust the formation mechanism of nanoparticles, and/or adjust any formation during the nanoparticle formation process. The structure, characteristics, and dimensions of species.

According to a preferred embodiment, the dispersant is selected from the group consisting of polydimethyldiallyl ferric chloride, sodium methylcellulose, polyacrylate, polyethylene glycol and such as Solsperse grade, Efka grade, Disperbyk or Byk grade, Commercial dispersants of Daxad grade and Tamol grade (trade name).

According to a preferred embodiment, during or after at least one of the treatment steps, the method further comprises a step of sonicating the solution.

According to a preferred embodiment, during or after at least one of the treatment steps, the method further comprises a step of microwave treatment of the solution.

According to a preferred embodiment, the further processing includes partial fusion of the particles into larger size particles. According to another preferred embodiment, the agglomerates of particles are mechanically treated for comminution.

The product of the present invention, such as the product formed in step (c) or after further transformation, is preferably small-sized titanium oxide particles. According to a preferred embodiment, the particle size is in the range of 2 nm to 500 nm. According to another preferred embodiment, the size distribution range of the product particles is narrow, so that the size ratio between the smallest and largest particles in the middle 50% (by weight) of the formed particles is less than about 10, more preferably less than 5, and most preferably less than 3. .

According to a preferred embodiment, separate particles are formed. According to another embodiment, the particles formed are at least partially agglomerated.

According to a preferred embodiment, most of the formed particles have a crystallinity of more than 50% as determined by X-ray analysis.

200680049411.3 According to a preferred embodiment, the shape of the particles formed in step (C) or after further transformation is elongated, for example needle-shaped, rod-shaped or raft-shaped.

According to another preferred embodiment, the particles are spherical or nearly spherical, so that most of the formed particles have a configuration with a ratio of one size to any other size of less than about 3.

According to a preferred embodiment, most of the particles formed have a surface area of at least 30 nf/gr, more preferably at least 100 m7gr. The high surface area particles of the present invention are suitable for catalyst preparation.

The method of the present invention is capable of forming high-purity titanium oxide from relatively low-purity precursors such as titanium ore. According to a preferred embodiment, the purity of the titanium oxide product relative to the other metals mixed with it is at least 95%, more preferably at least 99%.

According to another preferred embodiment, the titanium oxide particles are doped with ions or atoms of other transition metals.

According to a preferred embodiment, the form of the obtained particles is selected from particles dispersed in a liquid, particles supported on a solid compound, particles agglomerated into larger particles, partially fused particles, coated particles, or combinations thereof.

The particles, their products and/or their conversion products are suitable for many industrial applications, such as the manufacture of pigments, catalysts, coatings, thermal coatings, and the like. In the first embodiment, the particles are used as is for these and other applications. According to another preferred embodiment, the particles are further processed, and according to another preferred embodiment, the particles are formed as part of the preparation material for this application.

Many methods described in the literature are suitable for use in the laboratory and are not very practical for commercial applications. They start with highly pure precursors, utilize highly diluted solutions and/or operate at low volumes and rates. The method of the present invention is very suitable for economically attractive industrial scale production. According to a preferred embodiment, the method is performed with a productivity of at least 50 Kg/hour, more preferably at least 500 Kg/hour.

According to a preferred embodiment, the pH of the solution drops during the treatment due to the hydrolysis of the tetravalent titanium salt and thus the formation of acid (for example sulfuric acid) is achieved. According to a preferred embodiment, such an acid is reused, for example for the formation of a tetravalent titanium salt solution, for example for the dissolution of titanium-containing minerals. According to another preferred embodiment, the acid formed is partially or completely

200680049411. 3 The first neutralization to form the acid salt. According to a preferred embodiment, the salt has industrial use, for example in the case of neutralization with ammonia in order to form a salt suitable for use as a fertilizer.

According to an alternative method, small-sized titanium oxide particles that are at least partially dehydrated are formed. The method includes the following steps: preparing a starting aqueous solution containing tetravalent titanium ions or complexes thereof, a concentration of at least 0.1% w/w titanium, the pH of the solution is at least 0; the preparation temperature is greater than 80 °C adjustment aqueous solution; contact the starting solution with the adjustment solution to form an adjustment system and maintain the adjustment system at a temperature greater than 80°C for at least 0.5 minutes. Most of the particles formed are between about 2nm and about 500nm in size and contain titanic acid or TiO2 or a combination thereof.

A method similar to the above-mentioned method can be used to prepare the starting solution. According to a preferred embodiment, the concentration of titanium in the starting solution is greater than 2%. According to a preferred embodiment, the pH of the starting solution is at least 0, more preferably the pH is at least 0.5. According to an alternative embodiment, the molar ratio of OH/Ti in the starting solution is at least 0.05. According to a preferred embodiment, the temperature of the solution is adjusted to 100-300°C.

According to a preferred embodiment, at least one of the starting solution and/or the adjustment solution contains an agent capable of interacting with tetravalent titanium ions, their complexes, or with particles containing them. According to a preferred embodiment, the agent is a dispersant or a basic compound. When used, the basic compound is preferably ammonia, carbolic acid, ferric hydrogen acid, or urea. According to a preferred embodiment, an alkaline pH value is avoided in the adjustment system. Preferably, the OH/Ti molar ratio in the solution of the adjustment system is less than 3, more preferably 0.5-4.

The temperature of the adjustment system is determined by the temperature of the starting solution and the temperature of the heat adjustment solution, by their heat capacities and their relative amounts. According to a preferred embodiment, the temperature of the adjustment system maintains a minimum change, for example, no change in either direction greater than 20°C. According to a preferred embodiment, the adjustment system is maintained at this temperature for 1-30 minutes, more preferably 3-15 minutes.

According to another preferred embodiment, the starting solution is maintained for a preliminary retention time before said contact with the conditioning solution. Preferably, during the preliminary retention time, the solution is maintained at a temperature lower than 80°C and a pH value greater than 0. According to a preferred embodiment, the duration of the initial retention is sufficient to generate 0.1 mmol of protons for every mmol of titanium present in the solution, but not more than 14 days. In some cases where the raw material is obtained in the form of an aqueous solution with a long retention time,

200680049411. 3 The raw material can be used but will produce a slightly lower quality product.

According to a preferred embodiment, the particles formed in the process are subjected to a step selected from the following: dispersing the particles, adding a carrier, heat treatment, mixing, water evaporation, spray drying, thermal spraying, and combinations thereof.

According to a preferred embodiment of the present invention, the starting aqueous solution contains at least one of tetravalent titanium ions and their complexes at a concentration of at least 0.1% w/w of titanium.

The adjustment aqueous solution with a temperature higher than 80°C and the starting solution are contacted in a continuous manner in the mixing chamber to form an adjustment system. The mixing chamber is constructed in a way that ensures rapid and efficient mixing of the solution. The adjustment system is removed from the mixing chamber in a plug flow manner. During plug flow, precipitation is complete. In another preferred embodiment, the solution is not consumed during the plug flow, and precipitation continues in another container.

It is preferable to use the flow rate of the incoming solution, or to perform the mixing in the mixing chamber by using a mechanical mixing device or other mixing means.

In a preferred embodiment, the temperature in the mixing chamber is similar to the temperature during plug flow. In another preferred embodiment, the temperature of the solution during the plug flow is higher than the temperature in the mixing chamber, and in another preferred embodiment, the temperature of the solution during the plug flow is lower than the temperature in the mixing chamber.

In a preferred embodiment of the present invention, a solution containing a compound selected from acids and bases is added to at least one solution selected from the starting solution, adjustment solution, and adjustment system.

In a preferred embodiment of the invention, the residence time in the mixing chamber is less than about 5 minutes, and more preferably the residence time is less than 1 minute. In a more preferred embodiment, the residence time in the mixing chamber is less than about 5 seconds, and in a particularly preferred embodiment, the residence time is less than 0.5 seconds.

In a preferred embodiment of the invention, the solution leaving the plug flow enters the container. In a more preferred embodiment of the present invention, the solution is mixed in the container.

In a preferred embodiment of the present invention, the solution leaving the plug flow or the produced particles present in the solution leaving the plug flow are introduced into the crystallizer.

In another preferred embodiment of the present invention, the temperature inside the crystallizer is maintained in the range of about 100-300°C.

200680049411.3 In the preferred embodiment of the present invention, the titanium salt solution is also introduced into the crystallizer. In another preferred embodiment of the present invention, titanic acid is also introduced into the crystallizer.

It is clear to those skilled in the art that the present invention is not limited to the details of the foregoing description and can be implemented in other specific forms without departing from the basic attributes of the present invention. Therefore, it is desirable to refer to the appended claims instead of the foregoing, in all respects. The embodiments and examples of the present invention are considered in an exemplary rather than restrictive manner, and therefore, the present invention intends to include all changes within the meaning and scope of equivalents of the claims.