A method for preparing nanometer titanium with catalytic activity by using waste by-product titanium dichloride oxide

Abstract

The application discloses a method for preparing nano titanium with catalytic activity by using waste by-product titanium oxychloride, and comprises the following steps: S1, refluxing reaction of waste by-product titanium oxychloride solution and aluminum hydroxide at 103-108 DEG C; S2, adding waste by-product titanium oxychloride to continue the reaction, then adding a phosphorus source, and cooling to 65-75 DEG C; S3, then adding a cerium source; S4, adding a silicon source and an aluminum source, and reacting to deposit aluminum oxide and silicon oxide to form an aluminum oxide and silicon oxide composite framework structure, and obtaining an intermediate product through solid-liquid separation; S5, then calcining the intermediate product to obtain a nano titanium product; the mass percentage of anatase titanium dioxide in the nano titanium product is greater than or equal to 40%, and the mass percentage of rutile titanium dioxide is less than or equal to 10%. Through the method, the waste by-product titanium oxychloride is successfully prepared into a nano titanium product with high catalytic activity, and the waste by-product titanium oxychloride is recycled and utilized, and the nano titanium product with high catalytic activity is prepared.

Description

Technical Field

[0001] This invention belongs to the field of nano-titanium production technology, specifically relating to a method for preparing catalytically active nano-titanium using waste byproduct titanium oxychloride. Background Technology

[0002] Titanium dioxide, a high-performance white pigment, is widely used in coatings, plastics, papermaking, and inks. There are two main production processes for titanium dioxide: the sulfuric acid process and the chlorination process. Compared to the sulfuric acid process, the chlorination process is more efficient and environmentally friendly. The chlorination process involves chlorinating enriched titanium raw materials to form TiCl4, followed by oxidation and surface treatment to produce titanium dioxide for various applications. The tail gas generated during the chlorination process contains a certain amount of titanium tetrachloride, which needs to be scrubbed with hydrochloric acid, thus producing a waste titanium oxychloride solution. This waste titanium oxychloride solution has high acidity (generally with a hydrochloric acid content between 20% and 28% by mass) and contains titanium (generally 6.8% to 9.8% by mass as titanium dioxide), and cannot be directly discharged, increasing the pressure on water treatment and wasting titanium resources.

[0003] Regarding the utilization of titanium oxychloride, some studies have explored its use in the preparation of high-purity TiO2. However, because waste titanium oxychloride contains high levels of impurities such as Fe, V, and Si, the cost of impurity removal is high. On the other hand, failing to remove impurities results in a product with high impurity content and low quality, making it unsuitable for recycling. Other studies have investigated its use in the coating process of pigment titanium dioxide, but it also faces the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing catalytically active nano-titanium using waste titanium oxychloride.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preparing catalytically active nano-titanium from waste titanium oxychloride includes the following steps:

[0007] S1. The waste titanium dioxide solution was refluxed with aluminum hydroxide at 103-108℃ to obtain a titanium dioxide mixture doped with aluminum oxide;

[0008] S2. Add waste titanium oxychloride to continue the reaction, then add a phosphorus source and cool to 65-75℃. The reaction forms a uniformly dispersed phase of TiO2, P2O5 and Al2O3.

[0009] S3. Then, a cerium source is added, and the reaction forms a uniformly dispersed phase of TiO2, P2O5, CeO2, and Al2O3;

[0010] S4. Add silicon source and aluminum source, react to deposit aluminum oxide and silicon oxide, form aluminum oxide and silicon oxide composite framework structure, and after solid-liquid separation, obtain intermediate product with cerium oxide doped titanium oxide uniformly coated on the surface of the aluminum oxide and silicon oxide composite framework structure.

[0011] S5. The intermediate product is then calcined to obtain a nano-titanium product; the nano-titanium product contains ≥40% anatase titanium dioxide and ≤10% rutile titanium dioxide by mass.

[0012] Preferably, the mass percentage of titanium in the waste titanium oxychloride solution in steps S1 and S2 is 6.8-9.8% (calculated as titanium dioxide), and the mass percentage of hydrochloric acid is 20-28%; the mass ratio of the waste titanium oxychloride solution in step S1 to the waste titanium oxychloride solution in step S2 is 1.5-3.0:1.

[0013] Preferably, the amount of aluminum hydroxide used in step S1, calculated as aluminum oxide, is 6 to 10% of the mass of titanium element in the sum of the waste titanium dioxide solutions in steps S1 and S2, calculated as titanium dioxide.

[0014] Preferably, the reflux reaction time in step S1 is 1 to 1.5 hours.

[0015] Preferably, in step S2, the waste titanium oxychloride is first added at 103-108°C and stirred for 0.5-1.0 h to mix thoroughly. Then, the phosphorus source is added, and the temperature is lowered to 65-75°C after adding the phosphorus source. The reaction is carried out for 1.0-1.5 h.

[0016] Preferably, the amount of phosphorus source, calculated as P2O5, is 3.5% to 8% of the mass of titanium element in the sum of the waste titanium dioxide solutions in steps S1 and S2.

[0017] Preferably, the amount of cerium source used in step S3, calculated as CeO2, is 1.5 to 3.5% of the mass of titanium element in the sum of the waste titanium dioxide solutions in steps S1 and S2.

[0018] Preferably, the reaction temperature in step S3 is 65–75°C and the reaction time is 0.5–1.0 h.

[0019] Preferably, the amount of silicon source used in step S4, calculated as SiO2, is 6-15% of the mass of titanium element in the sum of the waste titanium oxychloride solutions in steps S1 and S2, calculated as titanium dioxide; the amount of aluminum source used, calculated as Al2O3, is 4-15% of the mass of titanium element in the sum of the waste titanium oxychloride solutions in steps S1 and S2, calculated as titanium dioxide.

[0020] Preferably, the reaction time in step S4 is 2.0 to 3.5 hours.

[0021] Preferably, before the solid-liquid separation in step S4, the material pH is adjusted to 6.5-7.5 for 0.5-1.5 hours, followed by maturation for 2-3 hours.

[0022] Preferably, before calcination in step S5, the material is dried until the moisture content is ≤1.5%, where the moisture content is expressed as a percentage by mass; the drying temperature is 105-150℃, the heating rate is 30-80℃ / min, and the drying time is controlled within ≤10min, with the heating time calculated within the drying time.

[0023] Preferably, the calcination temperature is 450–680°C, the calcination time is controlled between 3 and 4.5 h, the heating rate is 15–25°C / min, and the heating time is calculated within the calcination time.

[0024] The method provided in this application successfully prepared waste titanium oxychloride into a highly catalytically active nano-titanium product, realizing the recycling of waste titanium oxychloride and the preparation of highly catalytically active nano-titanium products. Detailed Implementation

[0025] The typical waste titanium oxychloride processed in this application is waste titanium oxychloride formed after hydrochloric acid spraying of chlorination tail gas. Its titanium element mass percentage is 6.8-9.8% (calculated as titanium dioxide), hydrochloric acid mass percentage is 20-28%, and the total amount of trace elements vanadium, Fe, Mo, Mn and Sn is ≤320ppm.

[0026] This invention provides a method for preparing catalytically active nano-titanium using waste titanium oxychloride, specifically comprising the following steps:

[0027] S1. The waste titanium dioxide solution is refluxed with aluminum hydroxide at 103–108 °C to obtain a titanium dioxide mixture doped with aluminum oxide. Reflux is used to avoid the volatilization of hydrochloric acid in the waste titanium dioxide solution. Under high temperature conditions, due to the high hydrogen ion content of the waste titanium dioxide, it readily reacts with the hydroxyl groups in the alkaline aluminum hydroxide, and a portion of the aluminum hydroxide is converted to Al. 3+ As hydrogen ions are consumed, titanium oxychloride gradually hydrolyzes under high temperature conditions, precipitating TiO2 particles. With further decreases in acidity, Al... 3+ Ions generate alumina, which is deposited on the surface of TiO2 particles. As the reaction proceeds, a hybrid material with abundant pores, consisting of titanium oxide-alumina-titanium oxide-alumina, is formed, providing a good foundation for high photocatalytic activity.

[0028] S2. Add fresh waste titanium oxychloride solution to continue the reaction, then add a phosphorus source and cool to 65-75℃. The reaction forms a uniformly dispersed phase of TiO2, P2O5, and Al2O3. Because the newly added waste titanium oxychloride solution contains a large number of hydrogen ions, it continues to react with the hydroxyl groups in aluminum hydroxide to form Al... 3+ As hydrogen ions in the waste titanium oxychloride are consumed, TiO2 particles precipitate out (suspended in the solution without precipitating). With further decreases in acidity, Al... 3+ Ions are generated as A2O3 and deposited on TiO2 particles to form a uniform mixture. A large amount of A2O3 adsorbed on the TiO2 particles in the mixture is prone to precipitation. Therefore, a phosphorus source is added to utilize the dispersing effect of phosphate ions in the phosphorus source to make the mixed particles uniformly dispersed and prevent precipitation, thus providing a basis for subsequent doping. The dispersing effect of the phosphorus source is optimal at 65-75℃. Therefore, after adding the phosphorus source, the temperature needs to be lowered to 65-75℃.

[0029] Waste titanium oxychloride is added in two steps, allowing it to react with aluminum hydroxide in stages. In the first step, some of the aluminum hydroxide reacts to form the intermediate titanium-aluminum substrate, preventing all aluminum hydroxide and titanium oxychloride from reacting and forming a precipitate. In the second step, new waste titanium oxychloride is added, which continues to react with aluminum hydroxide and utilizes the bonding effect between the newly generated titanium dioxide and the titanium element in the titanium-aluminum substrate from step S1. This facilitates the formation of a uniformly dispersed phase between P2O5, and subsequently CeO2, and the titanium-aluminum substrate, thus better releasing photocatalytic activity.

[0030] This application uses aluminum hydroxide as the aluminum source. Compared with soluble aluminum sources such as sodium aluminate and aluminum sulfate, aluminum hydroxide has poor solubility. In the initial reaction with hydrochloric acid in titanium dichloride, only a portion of solid aluminum hydroxide is converted into Al. 3+ Subsequently, as the acidity decreased, titanium dioxide particles and Al gradually precipitated from titanium oxychloride. 3+ It is then converted into alumina and deposited on the surface of titanium dioxide particles. As the reaction proceeds, solid aluminum hydroxide gradually dissolves and participates in the reaction, forming a titanium oxide-alumina-titanium oxide-alumina material. The titanium oxide and alumina are uniformly mixed. However, if a soluble aluminum source such as sodium aluminate is used, sodium aluminate reacts rapidly with titanium dioxide, and the alumina and titanium oxide particles precipitate out quickly, resulting in uneven mixing. Moreover, compared with aluminum hydroxide, more salt and impurities are introduced into the system.

[0031] S3. Then, a cerium source is added, and the reaction forms a uniformly dispersed phase of TiO2, P2O5, CeO2, and Al2O3; cerium oxide is an n-type semiconductor, because the outer electrons of cerium are filled in a 4f configuration. 1 5d 1 6s 1Cerium oxide possesses two stable valence states, +3 and +4. During the interconversion of these two valence states, it generates a large number of oxygen vacancies that enhance visible light absorption, thus exhibiting catalytic performance. However, the excessively wide band gap of cerium oxide limits its absorption to less than 5% of ultraviolet light from sunlight, with a maximum wavelength of only 400 nm, hindering its practical application. This invention addresses this by adding a cerium source to a uniformly dispersed phase of TiO2, P2O5, and Al2O3, forming a uniformly dispersed phase of TiO2, P2O5, CeO2, and Al2O3. Cerium oxide is uniformly distributed among TiO2, P2O5, and Al2O3, increasing its specific surface area and providing a larger contact area for subsequent photocatalytic reactions. Furthermore, the doping with titanium and phosphorus sources alters the crystal structure of cerium oxide, creating lattice defects that improve its reduction efficiency and oxygen storage capacity, thereby achieving high photocatalytic performance.

[0032] S4. Add silicon and aluminum sources. The reaction causes alumina and silica to deposit, forming an alumina-silica composite framework structure. TiO2, P2O5, CeO2 and Al2O3 uniformly dispersed phases are also uniformly adsorbed and deposited on the alumina-silica composite framework structure, eventually forming a precipitate. After solid-liquid separation, cerium oxide-doped titanium oxide is obtained as an intermediate product uniformly coated on the surface of the alumina-silica composite framework structure. Silica and alumina do not participate in the photocatalytic reaction and are relatively stable as a framework structure. Moreover, silica has good hydrophilicity and alumina has good oleophilicity. The combination of the two results in good hydrophilicity and oleophilicity, which can provide good dispersibility in subsequent applications.

[0033] S5. The intermediate product is then calcined to obtain nano-titanium products; the mass percentage of anatase titanium dioxide in the calcined product is ≥40%, and the content of rutile titanium dioxide is ≤10%.

[0034] This application first reacts waste titanium oxychloride with aluminum hydroxide to form a uniformly doped titanium dioxide mixture. By adding a phosphorus source, the mixture is uniformly dispersed, forming a uniformly dispersed phase of TiO2, P2O5, and Al2O3, which provides a basis for the subsequent addition of CeO2. After the addition of Ce source, a uniformly dispersed phase of TiO2, P2O5, CeO2, and Al2O3 is formed. Then, silicon oxide and aluminum oxide are co-deposited to form a framework structure composed of aluminum oxide and silicon oxide. The TiO2, P2O5, CeO2, and Al2O3 dispersed phases are uniformly coated on the aluminum oxide and silicon oxide framework structure, increasing the photocatalytic contact area of ​​titanium dioxide and improving the photocatalytic efficiency.

[0035] In conventional techniques, cerium is typically coated onto the surface of titanium dioxide particles in the form of a film. However, in this application, cerium is first uniformly doped into a dispersed phase of TiO2, P2O5, and Al2O3, and then co-deposited with the dispersed phase onto a silicon-aluminum framework structure. The uniform doping of cerium among the titanium elements is beneficial for further enhancing the photocatalytic activity of both titanium dioxide and cerium oxide. The uniformly dispersed phase used in this application also facilitates better control over product morphology and particle size compared to conventional film coating.

[0036] Finally, the drying and calcination conditions were adjusted to convert titanium dioxide into a mixed crystal of anatase and rutile, which has a stronger catalytic effect. Specifically, the mass percentage of anatase titanium dioxide in the calcined product was controlled to be ≥40%, and the content of rutile titanium dioxide was ≤10%, thereby improving the overall photocatalytic activity. More preferably, the mass percentage of anatase titanium dioxide in the product is ≥40% and <80%, and the content of rutile titanium dioxide is ≥5% and ≤10%.

[0037] Titanium dioxide used in coatings, papermaking, and other fields has high requirements for color. Impurities in waste titanium oxychloride have a significant impact on color, limiting the recycling of waste titanium oxychloride. This application uses waste titanium oxychloride to prepare a photocatalytic system. The photocatalytic system has lower requirements for color; therefore, impurities in waste titanium oxychloride have a smaller impact on product performance.

[0038] In summary, the method provided in this application successfully prepared waste titanium oxychloride into a highly catalytically active nano-titanium product, realizing the recycling and utilization of waste titanium oxychloride and the preparation of highly catalytically active nano-titanium products.

[0039] After calcination, the product is ground and pulverized using conventional methods. The resulting product has a grain size of 10–150 nm, which is nanoscale, and the proportion of powder particles with a diameter of 0.3–0.9 μm is >95%.

[0040] Preferably, the mass percentage of titanium in the waste titanium oxychloride solution from steps S1 and S2, calculated as titanium dioxide, is 6.8–9.8%, and the mass percentage of hydrochloric acid is 20–28%. The mass ratio of the waste titanium oxychloride solution from steps S1 and S2 is 1.5–3.0:1.

[0041] Preferably, the aluminum hydroxide solid content used in step S1 is above 95%.

[0042] Preferably, the reflux reaction time in step S1 is 1 to 1.5 hours.

[0043] Preferably, in step S2, waste titanium dichloride is first added at 103–108°C and stirred for 0.5–1.0 h to mix thoroughly. Then, a phosphorus source is added, and the temperature is lowered to 65–75°C, and the reaction is carried out for 1.0–1.5 h. The phosphorus source can be one or more of sodium hexametaphosphate, sodium monohydrogen phosphate, sodium phosphate, potassium pyrophosphate, etc., and is added in solution form with a concentration of 30–45 g / L (based on P2O5).

[0044] Preferably, the amount of phosphorus source used in step S2, calculated as P2O5, is 3.5 to 8% of the mass of titanium element in the sum of the waste titanium dioxide solutions from steps S1 and S2.

[0045] Preferably, the amount of cerium source used in step S3, calculated as CeO2, is 1.5–3.5% of the mass of titanium element in the sum of the waste titanium dioxide solutions from steps S1 and S2; the reaction time is preferably 0.5–1.0 h. The cerium source can be cerium salts such as cerium ammonium nitrate or cerium oxysulfate, added in solution form, with a solution concentration of 25–55 g / L based on Ce2O4 content.

[0046] Preferably, in step S4, the amount of silicon source (based on SiO2) is 6-15% of the mass of titanium (based on titanium dioxide) in the sum of the waste titanium oxychloride solutions from steps S1 and S2; the amount of aluminum source (based on Al2O3) is 4-15% of the mass of titanium (based on titanium dioxide) in the sum of the waste titanium oxychloride solutions from steps S1 and S2; the preferred reaction temperature is 65-75℃, and the preferred reaction time is 2.0-3.5 h. The preferred aluminum source is a soluble alkaline aluminum source such as sodium aluminate or potassium aluminate, added in solution form with a concentration of 250-320 g / L (based on alumina); the preferred silicon source is sodium silicate or potassium silicate, added in solution form with a concentration of 280-350 g / L (based on silicon oxide). The use of a soluble aluminum source allows for rapid precipitation of alumina, forming a composite framework structure of silicon oxide and alumina.

[0047] Preferably, before solid-liquid separation in step S4, the pH of the material is adjusted to neutral (6.5-7.5) to facilitate calcination. The adjustment time is 0.5-1.5 hours, and the material is then matured for 2-3 hours after adjustment.

[0048] Preferably, before calcination in step S5, the material is dried until the moisture content is ≤1.5%, which is expressed as a percentage by mass. The drying temperature is 105-150℃, the drying time is controlled within ≤10 min, the heating rate is 30-80℃ / min, and the heating time is included in the drying time.

[0049] Preferably, the calcination temperature is 450–680℃, the calcination time is controlled between 3 and 4.5 h, and the heating rate is 15–25℃ / min, with the heating time included in the calcination time. If the calcination temperature is too high, the rutile titanium dioxide content will increase significantly.

[0050] By employing rapid dehydration and slow calcination, the rapid dehydration allows the composite framework structure of alumina and silica to have more pores, while the slow calcination facilitates the transformation of titanium dioxide into anatase and rutile mixed crystals with strong catalytic effects.

[0051] Example 1

[0052] Add 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 6.8%, acidity 20%, total vanadium, Fe, Mo, Mn, Sn 50 ppm) and 8.59 g of aluminum hydroxide (95% solids content), react at 103 °C for 1 h, then add another 0.5 kg of waste titanium oxychloride and stir for 0.5 h to mix thoroughly; add 0.1587 L of 30 g / L sodium hexametaphosphate solution, cool to 65 °C, and react for 1.0 h; add another 0.0816 L of 25 g / L ammonium cerium nitrate solution, and mature the reaction for 0.5 h; finally, add 21.76 mL of 250 g / L sodium aluminate and 29.14 mL of 280 g / L sodium cerium nitrate solution. The sodium silicate solution was reacted at 70℃ for 2.0 h; the pH of the material was adjusted to 6.5 for 0.5 h, and then matured for 2 h; subsequently, the material was filtered and washed, and dried at 105℃ for 10 min at a drying rate of 30℃ / min. After drying, the water content was measured to be 1.5%; then, it was calcined at 450℃ for 3 h at a calcination rate of 15℃ / min. After calcination, the content of A-type anatase titanium dioxide was measured to be 70%, and the content of rutile titanium dioxide was measured to be 10%; then, the material was ground and pulverized. The grain size was measured to be 10 nm, and the proportion of powder particles with a diameter of 0.3-0.9 μm was 95.1%, resulting in sample 1.

[0053] Example 2

[0054] Add 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 9.8%, acidity 28%, total vanadium, Fe, Mo, Mn, Sn 320 ppm) and 20.42 g of aluminum hydroxide (96% solids content), react at 108 °C for 1.5 h, then add another 0.5 kg of waste titanium oxychloride and stir for 1.0 h to mix thoroughly; add 0.3484 L of 45 g / L sodium hexametaphosphate solution, cool to 75 °C, and react for 1.5 h; add another 0.1247 L of 55 g / L ammonium cerium nitrate solution, and mature the reaction for 1.0 h; finally, add 91.88 mL of 320 g / L sodium aluminate and 84 mL of 350 g / L sodium cerium nitrate solution. Sodium silicate solution was reacted at 75℃ for 3.5h; the pH of the material was adjusted to 7.5 for 1.5h, and then matured for 3h; subsequently, the material was filtered and washed, dried at 150℃ for 2min at a drying rate of 80℃ / min, and the water content after drying was measured to be 1.0%; then calcined at 680℃ for 4.5h at a calcination rate of 25℃ / min, and the content of A-type anatase titanium dioxide in the calcined product was measured to be 40% and the content of rutile titanium dioxide was 8%; then the material was ground and pulverized, and the grain size was measured to be 150nm, with 95.1% of the powder particles having a diameter of 0.3-0.9μm, resulting in sample 2.

[0055] Example 3

[0056] Add 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 8.8%, acidity 25%, total vanadium, Fe, Mo, Mn, Sn 100 ppm) and 15.97 g of aluminum hydroxide (97% solids content), react at 103 °C for 1.0 h, then add another 0.5 kg of waste titanium oxychloride and stir for 0.75 h to mix thoroughly; add 0.2011 L of 35 g / L sodium hexametaphosphate solution, cool to 70 °C, and react for 1.25 h; add another 0.176 L of 30 g / L ammonium cerium nitrate solution and mature for 0.75 h; finally, add 50.29 ml of 280 g / L sodium aluminate and 48 ml of 330 g / L sodium cerium nitrate solution. Sodium silicate solution was reacted at 65℃ for 3.0 h; the pH of the material was adjusted to 7.0 for 1.0 h, and then matured for 2.5 h; subsequently, the material was filtered and washed, dried at 125℃ for 5 min at a drying rate of 70℃ / min, and the water content after drying was measured to be 1.2%; then calcined at 550℃ for 4.0 h at a calcination rate of 20℃ / min, and the content of A-type anatase titanium dioxide in the calcined product was measured to be 65% and the content of rutile titanium dioxide was 5%; then the material was ground and pulverized, and the grain size was measured to be 80 nm, with 95.1% of the powder particles having a diameter of 0.3–0.9 μm, resulting in sample 3.

[0057] Example 4

[0058] Add 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 8.8%, acidity 25%, total vanadium, Fe, Mo, Mn, Sn 100 ppm) and 20.41 g of aluminum hydroxide (97% solids content), react at 105 °C for 1.0 h, then add another 1.0 kg of waste titanium oxychloride and stir for 0.75 h to mix thoroughly; add 0.3771 L of 35 g / L sodium hexametaphosphate solution, cool to 70 °C, and react for 1.25 h; add another 0.1467 L of 30 g / L cerium ammonium nitrate solution and mature for 0.75 h; finally, add 50.29 ml of 280 g / L sodium aluminate and 48 ml of 330 g / L sodium silicate. The solution was reacted at 65℃ for 3.0 h; the pH of the material was adjusted to 7.0 for 1.0 h, and then aged for 2.5 h; subsequently, the material was filtered and washed, dried at 125℃ for 5 min at a drying rate of 70℃ / min, and the water content after drying was measured to be 1.1%; then calcined at 550℃ for 4.2 h at a calcination rate of 20℃ / min, and the content of A-type anatase titanium dioxide in the product after calcination was measured to be 63% and the content of rutile titanium dioxide was 5.6%; then the material was ground and pulverized, and the grain size was measured to be 20 nm, with 96.0% of the powder particles having a diameter of 0.3–0.9 μm, resulting in sample 4.

[0059] Example 5

[0060] Add 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 8.4%, acidity 25%, total vanadium, Fe, Mo, Mn, Sn 100 ppm) and 15.23 g of aluminum hydroxide (96.5% solids content), react at 105 °C for 1.0 h, then add another 1.0 kg of waste titanium oxychloride and stir for 0.75 h to mix thoroughly; add 0.42 L of 35 g / L sodium hexametaphosphate solution, cool to 70 °C, and react for 1.25 h; add 0.175 L of 30 g / L ammonium cerium nitrate solution and mature for 0.75 h; finally, add 52.5 ml of 280 g / L sodium aluminate and 48 ml of 330 g / L silicon dioxide solution. The sodium carbonate solution was reacted at 65℃ for 3.0 h; the pH of the material was adjusted to 7.0 for 1.0 h, and then matured for 2.5 h; subsequently, the material was filtered and washed, dried at 125℃ for 5 min at a drying rate of 70℃ / min, and the water content after drying was measured to be 1.1%; then, it was calcined at 550℃ for 3.8 h at a calcination rate of 20℃ / min, and the content of A-type anatase titanium dioxide in the calcined product was measured to be 68% and the content of rutile titanium dioxide was 5.6%; then the material was ground and pulverized, and the grain size was measured to be 28 nm, with 95.8% of the powder particles having a diameter of 0.3–0.9 μm, resulting in sample 5.

[0061] Example 6

[0062] Add 1.67 kg of waste titanium oxychloride solution (titanium dioxide content 8.4%, acidity 25%, total vanadium, Fe, Mo, Mn, Sn 100 ppm) and 15.23 g of aluminum hydroxide (96.5% solids content), react at 105 °C for 1.0 h, then add 0.83 kg of waste titanium oxychloride and stir for 0.75 h to mix thoroughly; add 0.42 L of 35 g / L sodium hexametaphosphate solution, cool to 70 °C, and react for 1.25 h; add 0.175 L of 30 g / L ammonium cerium nitrate solution and mature for 0.75 h; then add 52.5 ml of 280 g / L sodium aluminate and 48 ml of 330 g / L sodium cerium nitrate solution. Sodium silicate solution was reacted at 65℃ for 3.0 h; the pH of the material was adjusted to 7.0 for 1.0 h, and then matured for 2.5 h; subsequently, the material was filtered and washed, dried at 125℃ for 5 min at a drying rate of 70℃ / min, and the water content after drying was measured to be 1.1%; then calcined at 550℃ for 3.8 h at a calcination rate of 20℃ / min, and the content of A-type anatase titanium dioxide in the calcined product was measured to be 68% and the content of rutile titanium dioxide was 5.6%; then the material was ground and pulverized, and the grain size was measured to be 28 nm, with 95.8% of the powder particles having a diameter of 0.3–0.9 μm, resulting in sample 6.

[0063] Comparative Example 1

[0064] 2.0 kg of waste titanium oxychloride solution (titanium dioxide content 6.8%, acidity 20%, total vanadium, Fe, Mo, Mn, Sn 50 ppm) was adjusted to pH 6.5 for 0.5 h, and then aged for 2 h. The material was then filtered and washed. It was calcined at 450℃ for 3 h. After calcination, the content of A-type anatase titanium dioxide in the product was measured to be 100%. The material was then ground and pulverized, with a grain size of 10 nm and a powder particle size of 0.3-0.9 μm accounting for 96.1%, to obtain control sample 1.

[0065] Comparative Example 2

[0066] 2.0 kg of waste titanium oxychloride solution (titanium dioxide content 6.8%, acidity 20%, total vanadium, Fe, Mo, Mn, Sn 50 ppm) was adjusted to pH 6.5 for 0.5 h, followed by aging for 2 h. The material was then filtered and washed, and calcined at 950℃ for 3 h at a calcination rate of 15℃ / min. After calcination, the rutile titanium dioxide content of the product was measured to be 97.5%. The material was then ground and pulverized. The grain size was measured to be 280 nm, and the proportion of powder particles with a diameter of 0.3–0.9 μm was 96.8%, resulting in control sample 2.

[0067] Comparative Example 3

[0068] 21.76 ml of 250 g / L sodium aluminate and 29.14 ml of 280 g / L sodium silicate solution were added to 2.0 kg of waste titanium oxychloride solution (titanium dioxide content 6.8%, acidity 20%, total vanadium, Fe, Mo, Mn, Sn 50 ppm). The mixture was reacted at 70 °C for 2.0 h. The pH of the material was adjusted to 6.5 for 0.5 h, followed by aging for 2 h. The material was then calcined at 450 °C for 3 h at a heating rate of 15 °C / min. After calcination, the content of A-type anatase titanium dioxide in the product was determined to be 80%. The material was then ground and pulverized, with a grain size of 10 nm and a particle size of 0.3–0.9 μm accounting for 96.0%, resulting in control sample 3.

[0069] Comparative Example 4

[0070] 21.76 mL of 250 g / L sodium aluminate and 29.14 mL of 280 g / L sodium silicate solution were added to 1.5 kg of waste titanium oxychloride solution (titanium dioxide content 6.8%, acidity 20%, total vanadium, Fe, Mo, Mn, Sn 50 ppm). The mixture was reacted at 70 °C for 2.0 h. The pH of the material was adjusted to 6.5 for 0.5 h, followed by aging for 2 h. The material was then calcined at 950 °C for 3 h. After calcination, the rutile titanium dioxide content of the product was determined to be 80%. The material was then ground and pulverized, with a grain size of 300 nm and a particle size of 0.3–0.9 μm accounting for 96.1%, resulting in control sample 4.

[0071] The physicochemical properties of the samples from Examples 1-6 and Comparative Examples 1-4, as well as the commercially available domestic samples 1-3 and foreign samples 1-3, were tested and evaluated using conventional methods. The results are shown in Tables 1-2.

[0072] Table 1. Sample physicochemical properties test

[0073] Sample Name <![CDATA[Specific surface area m 2 / g]]> Grain size / nm Domestic Sample-1 125 55 Domestic Sample-2 250 25 Domestic Sample-3 300 135 Foreign Sample-1 225 35 Foreign Samples-2 285 65 Foreign Samples-3 315 150 Comparison Sample 1 308 10 Comparison Sample 2 9 280 Comparison Sample 3 280 10 Comparison Sample 4 8 300 Sample 1 385 10 Sample 2 305 150 Sample 3 315 80 Sample 4 380 20 Sample 5 326 28 Sample 6 316 23

[0074] Table 2 Catalytic performance of samples under natural light irradiation.

[0075]

[0076] As shown in Tables 1 and 2, the photocatalytic nano-titanium prepared in this invention has high catalytic activity compared with the comparative sample and domestic and foreign samples, indicating that the nano-titanium prepared in this invention has high photocatalytic activity.

[0077] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for preparing nanometer titanium having catalytic activity using waste by-product titanium oxychloride, characterized by, The method comprises the following steps: S1. refluxing the waste side titanium dichloride solution with aluminum hydroxide at 103-108℃ to obtain a titanium dioxide mixed solution doped with aluminum oxide; S2. adding the waste side titanium dichloride solution to continue the reaction, then adding a phosphorus source, and cooling to 65-75℃ to form a uniformly dispersed phase of TiO2, P2O5 and Al2O3; S3. then adding a cerium source to form a uniformly dispersed phase of TiO2, P2O5, CeO2 and Al2O3; S4. adding a silicon source and an aluminum source to deposit aluminum oxide and silicon oxide and form an aluminum oxide and silicon oxide composite skeleton structure, and then separating the solid and liquid to obtain an intermediate product in which cerium oxide doped titanium oxide is uniformly coated on the surface of the aluminum oxide and silicon oxide composite skeleton structure; S5. then calcining the intermediate product to obtain a nano-titanium product; the mass percentage of anatase titanium dioxide in the nano-titanium product is ≥40%, and the mass percentage of rutile titanium dioxide is ≤10%.

2. The method according to claim 1, wherein the mass percentage of titanium in the waste side titanium dichloride solution is 6.8-9.8% in terms of titanium dioxide, and the mass percentage of hydrochloric acid is 20-28%; and the mass ratio of the waste side titanium dichloride solution in step S1 to the waste side titanium dichloride solution in step S2 is 1.5-3.0:

1.

3. The method according to claim 1, wherein the amount of aluminum hydroxide in step S1 is 6-10% of the total amount of titanium in the waste side titanium dichloride solution in steps S1 and S2 in terms of titanium dioxide.

4. The method according to claim 1, wherein the refluxing time in step S1 is 1-1.5 h.

5. The method according to claim 1, wherein the waste side titanium dichloride solution in step S2 is first added at 103-108℃, and after stirring for 0.5-1.0 h to mix thoroughly, the phosphorus source is added; and after the phosphorus source is added, the temperature is lowered to 65-75℃, and the reaction is carried out for 1.0-1.5 h.

6. The method according to claim 1, wherein the amount of the phosphorus source is 3.5-8% of the total amount of titanium in the waste side titanium dichloride solution in steps S1 and S2 in terms of titanium dioxide.

7. The method according to claim 1, wherein the amount of the cerium source in step S3 is 1.5-3.5% of the total amount of titanium in the waste side titanium dichloride solution in steps S1 and S2 in terms of titanium dioxide; and the reaction time in step S3 is 0.5-1.0 h.

8. The method according to claim 1, wherein the amount of the silicon source in step S4 is 1.5-3.5% of the total amount of titanium in the waste side titanium dichloride solution in steps S1 and S2 in terms of titanium dioxide; and the amount of the aluminum source in step S4 is 1.5-3.5% of the total amount of titanium in the waste side titanium dichloride solution in steps S1 and S2 in terms of titanium dioxide. ​ ​ ​ ​ ​ ​ ​ The amount of the silicon source in step S4 is 6-15% of the amount of titanium in the sum of the waste by-product titanium dichloride oxide solution in steps S1 and S2, calculated as titanium dioxide; the amount of the aluminum source is 4-15% of the amount of titanium in the sum of the waste by-product titanium dichloride oxide solution in steps S1 and S2, calculated as titanium dioxide; The reaction temperature in step S4 is 65-75°C, and the reaction time is 2.0-3.5 h.

9. The method according to claim 1, wherein, Before the solid-liquid separation in step S4, the pH of the material is adjusted to 6.5-7.5, the adjustment time is 0.5-1.5 h, and the material is aged for 2-3 h after the adjustment.

10. The method according to claim 1, wherein, Before the calcination in step S5, the material is dried to a water content of ≤1.5%, calculated as mass percentage; the drying temperature is 105-150°C, the temperature rising rate is 30-80°C / min, the drying time is controlled to be ≤10 min, and the temperature rising time is calculated within the drying time; The calcination temperature is 450-680°C, the calcination time is controlled to be 3-4.5 h, the temperature rising rate is 15-25°C / min, and the temperature rising time is calculated within the calcination time.

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