Iron oxide-doped titanium oxide composite, preparation method therefor and use thereof
Patent Information
- Application Number
- PCT/CN2025/089541
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-28
- Filing Date
- 2025-04-17
- Publication Date
- 2026-10-01
Smart Images
Figure CN2025089541_01102026_PF_FP_ABST
Abstract
Description
An iron oxide-doped titanium oxide composite, its preparation method and application
[0001] This invention claims priority to Chinese Patent Application No. 2025103842014, filed on March 28, 2025, entitled "An iron oxide-doped titanium oxide composite and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This invention belongs to the field of inorganic chemistry technology, specifically relating to an iron oxide-doped titanium oxide composite, its preparation method, and its application. Background Technology
[0003] Nano-titanium dioxide is a polycrystalline powder, mainly existing in three crystalline forms in nature: anatase, rutile, and brookite. Among these, the brookite and anatase structures are not stable crystal forms and can both transform into the rutile form at high temperatures. The transformation temperature from anatase to rutile titanium dioxide is generally around 550℃, but as the size of the titanium dioxide particles decreases, their transformation temperature decreases. Nano-sized titanium dioxide begins to undergo crystal transformation at as low as 400℃.
[0004] Nano-titanium dioxide prepared by different methods exhibits different crystal structures and properties. Nano-titanium dioxide is typically prepared via gas-phase methods, commonly including high-temperature oxidation and high-temperature hydrolysis. High-temperature oxidation involves the reaction of titanium tetrachloride with oxygen to obtain nano-titanium dioxide; while high-temperature hydrolysis involves the high-temperature hydrolysis of titanium tetrachloride with hydrogen and oxygen. Their reaction mechanisms are as follows: TiCl₄ + O₂ = TiO₂ + Cl₂ TiCl₄ + H₂ + O₂ = TiO₂ + HCl
[0005] High-temperature oxidation produces chlorine as a byproduct, and its post-treatment process is complex and poses safety hazards. High-temperature hydrolysis, on the other hand, has relatively easy tail gas treatment, so it is the more common method. Relevant patents include ZL201711119459.3; US 3735000; US7686881B2, etc.
[0006] Nano-titanium dioxide maintains excellent performance at high temperatures and is a widely used heat-resistant agent for preparing heat-resistant materials. However, the effect of nano-titanium dioxide prepared by existing methods on improving the thermal stability of some polymer materials such as silicone rubber is still not ideal. Summary of the Invention
[0007] Based on this, the present invention provides a method for preparing an iron oxide-doped titanium oxide composite, which can prepare an iron oxide-doped anatase-type vapor phase titanium oxide composite. When applied to polymer materials, this composite can significantly improve their thermal stability.
[0008] The following technical solutions are used to achieve the above objectives.
[0009] The first aspect of this invention provides a method for preparing an iron oxide-doped titanium oxide composite, the method comprising the following steps:
[0010] Vaporized titanium tetrachloride, hydrogen, and combustion-supporting gas are mixed in a reactor and ignited, then introduced into a reaction furnace to obtain gas-phase titanium dioxide. The temperature inside the reaction furnace is 280℃~400℃.
[0011] The obtained gas-phase titanium dioxide and iron oxide precursor are fed into an aggregator for mixing, and the reaction generates a gas-solid mixture.
[0012] The powder in the gas-solid mixture is separated and fed into a deacidification device for deacidification treatment to obtain an iron oxide-doped titanium oxide composite. The temperature inside the deacidification device is 400-500℃.
[0013] In some embodiments, the temperature inside the reactor is 280°C to 380°C; preferably 300°C to 380°C, more preferably 300°C to 350°C, and even more preferably 310°C to 330°C.
[0014] In some embodiments, the temperature inside the deacidification device is 400°C to 480°C.
[0015] In some embodiments, the deacidification device includes two deacidification furnaces connected in sequence, wherein the powder is subjected to segmented heating and deacidification in the deacidification furnace, and the temperature of each segment in the deacidification furnace increases sequentially from the powder inlet to the powder outlet.
[0016] Preferably, the deacidification furnace performs three-stage heating deacidification on the powder sequentially. The first stage heating temperature is 400℃~410℃, the second stage heating temperature is 445℃~455℃, and the third stage heating temperature is 475℃~485℃. More preferably, the first stage heating temperature is 400℃~405℃, the second stage heating temperature is 448℃~452℃, and the third stage heating temperature is 478℃~482℃. The deacidification time is 20min~25min.
[0017] In some embodiments, the flow rate of titanium tetrachloride input into the reactor is 13 kg / h to 17 kg / h, the flow rate of hydrogen input into the reactor is 0.1 kg / h to 0.8 kg / h, and the flow rate of combustion-supporting gas input into the reactor is 30 kg / h to 50 kg / h.
[0018] In some embodiments, the temperature inside the aggregator is 250°C to 400°C; preferably 280°C to 380°C; more preferably 300°C to 380°C; and even more preferably 360°C to 380°C.
[0019] In some embodiments, the aggregator includes a pipe, a drive device, and a ribbon stirring blade; the pipe has a first inlet and multiple second inlets, the vapor-phase titanium dioxide enters the pipe through the first inlet, the iron oxide precursor enters the pipe through the second inlets, the ribbon stirring blade is disposed inside the pipe, and the output end of the drive device is connected to the ribbon stirring blade and drives the ribbon stirring blade to rotate.
[0020] In some embodiments, the iron oxide precursor is ferric chloride; preferably, the ferric chloride is an aqueous solution of ferric chloride or anhydrous ferric chloride; more preferably, the ferric chloride is an aqueous solution of ferric chloride, and the aqueous solution of ferric chloride, after atomization, is introduced into the aggregator at a flow rate of 100 g / h to 200 g / h, preferably 100 g / h to 150 g / h, more preferably 110 g / h to 130 g / h; and / or,
[0021] The combustion-supporting gas is air or oxygen.
[0022] The second aspect of the present invention provides an iron oxide-doped titanium oxide composite prepared by the method described above.
[0023] A third aspect of the present invention provides an iron oxide-doped titanium dioxide composite, wherein the iron oxide-doped titanium dioxide composite is iron oxide-doped titanium dioxide; the titanium dioxide has a mixed crystal form of anatase and rutile, and the proportion of anatase titanium dioxide in the titanium dioxide is more than 75%.
[0024] The iron oxide-doped titanium oxide composite is prepared into a suspension with a mass concentration of 4% and has a pH value of 3.2–4.5, preferably 3.3–4, and more preferably 3.3–3.5. The iron content in the iron oxide-doped titanium oxide composite is 0.6%–1.3%, preferably 0.6%–1.1%, and more preferably 0.6%–0.7%.
[0025] In some embodiments, the specific surface area of the iron oxide-doped titanium oxide composite is 35 m². 2 / g~50m 2 / g, preferably 40m 2 / g~45m 2 / g, more preferably 40m 2 / g~43m 2 / g.
[0026] The fourth aspect of the present invention provides the application of the iron oxide-doped titanium oxide composite as described above as a heat-resistant agent in the preparation of heat-resistant materials.
[0027] The fifth aspect of the present invention provides a silicone rubber, which, by weight, comprises the following components:
[0028] The iron oxide-doped titanium oxide composite is the iron oxide-doped titanium oxide composite as described above.
[0029] In some embodiments, the silicone rubber comprises the following components:
[0030] A sixth aspect of the present invention provides a method for preparing the silicone rubber described above, the method comprising the following steps:
[0031] Methyl vinyl silicone rubber, fumed silica, iron oxide-doped titanium oxide composite, bis(2,5)-hydroxyl silicone oil are mixed evenly in a two-roll mill, and then vulcanized for 8 min to 12 min at 175℃ to 185℃ in a flat vulcanizing mill. After standing at room temperature for 24 h, a second vulcanization is carried out at 195℃ to 205℃ for 1.5 h to 2.5 h.
[0032] In this invention, nanoscale fumed titanium dioxide particles of mixed anatase-rutile crystal form are first obtained by controlling the temperature inside the reactor to 280℃~400℃. Then, the fumed titanium dioxide particles are reacted with iron oxide, and the product obtained from the reaction is deacidified at a specific deacidification temperature (400~500℃) to finally obtain an iron oxide-doped titanium dioxide composite. The titanium oxide and iron oxide in the iron oxide-doped titanium dioxide composite can produce a synergistic effect, which can effectively improve the thermal stability of the polymer material. Attached Figure Description
[0033] Figure 1 is a schematic diagram of the overall structure of the apparatus used in the preparation method of iron oxide-doped titanium oxide composite;
[0034] Figure 2 is a schematic diagram of the deacidification furnace in Figure 1;
[0035] Figure 3 shows the XRD test results of the sample.
[0036] Explanation of reference numerals in the attached drawings: 1. Reactor; 2. Connector; 21. Cooling gas inlet; 3. Reactor; 4. Collector; 41. Pipeline; 42. Drive unit; 43. Spiral agitator blades; 44. First feed inlet; 45. Second feed inlet; 46. Cooling jacket; 5. Cyclone separator; 6. Buffer tank; 7. Bag filter; 8. Crushing device; 9. Deacidification furnace; 91. Heating device; 92. Annular gas outlet pipe. Detailed Implementation
[0037] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.
[0038] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.
[0039] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.
[0040] This invention provides a method for preparing an iron oxide-doped titanium oxide composite, the method comprising the following steps:
[0041] Vaporized titanium tetrachloride, hydrogen, and combustion-supporting gas are mixed in a reactor and ignited, then introduced into a reaction furnace to obtain gas-phase titanium dioxide. The temperature inside the reaction furnace is 280℃~400℃.
[0042] The obtained gas-phase titanium dioxide and iron oxide precursor are fed into an aggregator for mixing, and the reaction generates a gas-solid mixture.
[0043] The powder in the gas-solid mixture is separated and fed into a deacidification device for deacidification treatment to obtain an iron oxide-doped titanium oxide composite. The temperature inside the deacidification device is 400-500℃.
[0044] The inventors discovered through long-term research that the most stable crystal structure of titanium dioxide is rutile. However, in certain functionalities, such as its role as a heat-resistant agent in polymer materials, titanium dioxide with a mixed crystal structure of anatase and rutile exhibits better performance, especially when doped with other metal oxides. However, the proportions of different mixed anatase and rutile crystal structures, as well as the different metal oxides used for doping, significantly affect the thermal stability of polymer materials. This makes it difficult to achieve significant improvements in the thermal stability of polymer materials using existing methods for preparing metal oxide-doped titanium dioxide composites. Therefore, in this invention, by controlling the temperature inside the reactor to be 280℃~400℃, nanoscale gas-phase titanium dioxide particles with an anatase-rutile mixed crystal form, where the proportion of anatase titanium dioxide is controlled to be more than 80%, are first prepared. Then, the gas-phase titanium dioxide particles are reacted with iron oxide, and the product obtained from the reaction is deacidified at a specific deacidification temperature (400~500℃) to finally obtain an iron oxide-doped titanium dioxide composite. The titanium oxide and iron oxide in the iron oxide-doped titanium dioxide composite can produce a synergistic effect, which can effectively improve the thermal stability of the polymer material.
[0045] In some embodiments, the apparatus used in the preparation method of the above-mentioned iron oxide-doped titanium dioxide composite of the present invention is shown in Figures 1 and 2 below. The gas-phase titanium dioxide generation reaction is carried out in a reactor 3, wherein a reactor 1 connected to the reactor 3 is provided above the reactor 3. The vaporized raw material TiCl4, dried air, and hydrogen enter the reactor 1 together, are sprayed out through the nozzle of the reactor 1 and ignited to carry out the reaction. The reaction flame enters the reactor 3 and carries out a high-temperature hydrolysis reaction under specific temperature control to generate titanium dioxide particles with specific particle size and specific crystal form. In this case, by controlling the temperature in the reactor 3 to be 280°C to 400°C, a gas-solid mixture of gas-phase titanium dioxide with an anatase crystal form ratio of more than 80% is obtained. More preferably, a connector 2 is provided between the reactor 1 and the reaction furnace 3. Cooling gas inlets 21 are located on opposite sides of the connector 2, and these inlets are inclined. Cooling gases such as hydrogen, oxygen, or air entering from these inlets on opposite sides of the connector 2 enter the reaction furnace 3 and form a downward spiral airflow within the furnace. This rapidly reduces the temperature of the reaction products to a specific temperature, thereby decreasing the concentration of the reaction products. This prevents particle collisions and condensation into large particles, as well as preventing crystal transformations at high temperatures, thus achieving control over particle size and crystal structure.
[0046] The products obtained from the reaction in reactor 3 are a mixture of TiO2, HCl, and excess air. The resulting titanium dioxide particles are very small (<100 nm) and have a very low concentration, making them difficult to collect. Therefore, they need to pass through an aggregator 4 to allow the particles to collide and form aggregates (0.2-5 μm in diameter) for easier collection. Specifically, in some embodiments, the aggregator 4 includes a pipe 41, a drive device 42, and a ribbon stirring blade 43. The pipe 41 has a first inlet 44 and multiple second inlets 45. The vapor-phase titanium dioxide enters the pipe 41 through the first inlet 44, and the iron oxide precursor enters the pipe 41 through the second inlets 45. The ribbon stirring blade 43 is disposed within the pipe 41, and the output end of the drive device 42 is connected to the ribbon stirring blade 43 and drives it to rotate. Specifically, the multiple second feed ports 45 are distributed along the length of the pipe 41. The iron oxide precursor can enter the pipe 41 in an atomized or vaporized state through the second feed ports 45, reacting to generate iron oxide particles. The iron oxide particles collide with titanium dioxide particles and adhere to the surface and interior of the titanium dioxide aggregates. Inside the aggregator 4, a spiral stirring blade 43 is provided. The driving device 42, such as a rotary motor, drives the blade to rotate, propelling the powder forward, which is beneficial for powder mixing. At the same time, during the rotation, the inner wall of the pipe 41 is scraped to prevent particles from depositing on the pipe wall.
[0047] Furthermore, a cooling jacket 46 is provided on the outer peripheral wall of the pipe 41. Under the action of the cooling jacket 46, the temperature inside the pipe 41 is controlled between 250°C and 400°C, preferably between 280°C and 380°C; more preferably between 300°C and 380°C, and even more preferably between 360°C and 380°C.
[0048] The gas-solid mixture exiting the collector 4 needs further separation to obtain solid powder, which is then subjected to deacidification. In this embodiment, this separation process is carried out through a cyclone separator 5, a buffer tank 6, a bag filter 7, and a pulverizing device 8. Specifically, the top of the cyclone separator 5 is connected to the bag filter 7, and the bottom of the cyclone separator 5 is connected to the buffer tank 6. The top of the buffer tank 6 is provided with an exhaust port, which is connected to the bag filter 7. The bottom of the bag filter 7 is connected to the buffer tank 6, and the buffer tank 6 is connected to the pulverizing device 8. Understandably, the gas-solid mixture enters the cyclone separator 5 for gas-solid separation. Under the action of centrifugal force, the gas separated in the cyclone separator 5 enters the bag filter 7 from the top, and the powder exits from the bottom and enters the buffer tank 6. The top of the buffer tank 6 is equipped with an exhaust port that connects to the bag filter 7. The gas exiting the exhaust port carries entrained powder, which is collected by the bag filter 7. The powder collected in the bag filter 7 exits from the bottom and re-enters the buffer tank 6. The powder in the buffer tank 6 then enters a pulverizing device 8, where it is further homogenized and large particles are crushed. The pulverizing device 8 can be an air jet mill or a mechanical mill, preferably an air jet mill. This further pulverizes and homogenizes the powder, allowing iron oxide particles to be more evenly dispersed within titanium dioxide. The pulverized powder then enters a deacidification device, such as a fluidized bed deacidification furnace, for deacidification treatment.
[0049] In some embodiments, the temperature inside the deacidification device is 400°C to 480°C.
[0050] In some embodiments, the deacidification device includes two deacidification furnaces 9 connected in series, i.e., the deacidification device includes two deacidification furnaces 9 arranged in series, and the deacidification furnace 9 is a fluidized bed deacidification furnace. The powder is subjected to segmented heating and deacidification in the deacidification furnace 9, and the temperature of each segment in the deacidification furnace 9 increases sequentially from the powder inlet to the powder outlet; preferably, the deacidification furnace 9 performs three-stage heating and deacidification on the powder, with the first stage heating temperature being 400℃~410℃, the second stage heating temperature being 445℃~455℃, and the third stage heating temperature being 470℃~480℃; the deacidification time is 20min~25min. Specifically, the deacidification furnace 9 adopts a two-stage series structure. The powder enters from the top of the deacidification furnace 9 and flows out from the bottom. Understandably, the first, second, and third sections of the deacidification furnace 9 correspond to the top, middle, and bottom sections, respectively, and these sections are interconnected. This allows the deacidification temperature to increase sequentially as the powder flows downwards, further improving the deacidification effect. After deacidification in the deacidification furnace 9, most of the HCl gas adsorbed on the powder surface can be removed. The deacidification furnace 9 is equipped with a heating device 91, such as heating elements installed around its perimeter, to control the temperature range of different sections within the furnace 9. Simultaneously, multiple gas inlets are provided on the furnace wall of the deacidification furnace 9 to introduce deacidification auxiliary gas to assist in the deacidification process. An exhaust port is located at the top of the deacidification furnace 9, connected to a bag filter 7, to collect the powder entrained in the airflow. The collected powder is returned to the first-stage deacidification furnace 9 for recycling. Large particles of powder that fall from the bottom of the deacidification furnace 9 via air flotation can be returned to the crushing device 8 for recycling.
[0051] In some embodiments, the deacidification furnace 9 is provided with multiple annular gas outlet pipes 92, each with multiple micropores. The gas inlet of the deacidification furnace 9 is connected to the annular gas outlet pipes 92, and the deacidification auxiliary gas enters through the gas inlet and is transported into the deacidification furnace 9 through the annular gas outlet pipes 92. Furthermore, the gas inlet of the deacidification furnace 9 is connected to a pipeline heater via an input pipe. The pipeline heater heats the gas before it is input into the deacidification furnace 9 through the input pipe and the annular gas outlet pipes 92. Together with the heating device 91 of the deacidification furnace 9, the temperature inside the deacidification furnace 9 is maintained at 400-500℃, preferably 400-480℃. At this temperature, the HCl gas adsorbed on the powder surface is effectively desorbed, and the unreacted iron oxide precursor reacts completely. Simultaneously, at this temperature, some anatase titanium oxide is converted into rutile titanium oxide, allowing iron oxide particles to embed within the iron oxide grains. Iron oxide-doped titanium oxide composite powder was obtained, which has a stronger synergistic effect in improving the heat resistance of polymer materials.
[0052] The iron oxide-doped titanium oxide composite powder prepared by this method can significantly improve the thermal stability of silicone rubber when added in small amounts, showing good market prospects as a heat stabilizer for polymer materials.
[0053] Gas-phase titanium dioxide, due to its small particle size and high specific surface area, readily adsorbs HCl gas generated during production. However, the deacidification process requires high-temperature assisted desorption, which often leads to the conversion of anatase titanium dioxide to rutile titanium dioxide. Therefore, temperature control is crucial in preparing titanium dioxide products with a high anatase content. Existing technologies require the deacidification temperature to be controlled below 400℃ (because nano-titanium dioxide begins its crystal transformation at this temperature). In this embodiment, the inventors discovered that by introducing iron oxide particles after titanium dioxide particles are formed, and controlling the temperature between 400 and 500℃ during the deacidification process of the composite powder, a better synergistic effect can be achieved, resulting in improved thermal stability of the polymer material. This is because the introduction of iron oxide increases the crystal transformation temperature of titanium dioxide, thus raising the deacidification temperature and efficiency without causing excessively high crystal transformation. In addition, after the titanium dioxide particles are formed, an iron oxide precursor is introduced. Then, at a specific deacidification temperature, a small portion of the anatase titanium dioxide undergoes a crystal transformation, allowing iron oxide to enter the titanium dioxide lattice, thus obtaining iron oxide-doped titanium dioxide composite powder. This iron oxide-doped titanium dioxide composite powder has significantly different properties from the titanium oxide / iron oxide hybrid material obtained by mixing iron oxide precursor and titanium dioxide precursor together for combustion reaction in the prior art, as well as the physically mixed titanium oxide / iron oxide mixture. The iron oxide-doped titanium dioxide composite powder obtained by the process of this embodiment can achieve good synergistic effects even with low iron oxide content.
[0054] In some embodiments, the iron oxide precursor is ferric chloride. The ferric chloride can be anhydrous ferric chloride or an aqueous solution of ferric chloride. When ferric chloride is used, it is heated to 300-350°C via a raw material vaporizer, causing the ferric chloride to sublimate and enter the aggregator. Preferably, an aqueous solution of ferric chloride is used, which is atomized by hot nitrogen gas and introduced into the aggregator. The atomized ferric chloride solution is introduced into the aggregator at a flow rate of 100 g / h to 200 g / h, preferably 100 g / h to 130 g / h, based on the mass of ferric chloride.
[0055] In some embodiments, the flow rate of titanium tetrachloride input into the reactor is 13 kg / h to 17 kg / h, the flow rate of hydrogen input into the reactor is 0.1 kg / h to 0.8 kg / h, and the flow rate of combustion-supporting gas input into the reactor is 30 kg / h to 50 kg / h.
[0056] In some embodiments, the temperature inside the reactor 3 is 280°C to 380°C; preferably 300°C to 380°C, more preferably 300°C to 350°C, and even more preferably 310°C to 330°C.
[0057] This invention also provides an iron oxide-doped titanium dioxide composite, wherein the iron oxide-doped titanium dioxide composite is iron oxide-doped titanium dioxide; the titanium dioxide has a mixed crystal form of anatase and rutile, wherein the proportion of anatase titanium dioxide is 75% or more, preferably 78% or more.
[0058] The iron oxide-doped titanium oxide composite is prepared into a suspension with a mass concentration of 4% and has a pH value of 3.2 to 4.5, preferably 3.3 to 4, and more preferably 3.3 to 3.5; the iron content in the iron oxide-doped titanium oxide composite is 0.6% to 1.3%, preferably 0.6% to 1.1%, and more preferably 0.6% to 0.7%.
[0059] The present invention will be further described in detail below with reference to specific embodiments.
[0060] Example 1
[0061] This embodiment provides a method for preparing an iron oxide-doped titanium oxide composite, and the apparatus used is shown in Figures 1 and 2. The preparation method specifically includes the following steps:
[0062] Vaporized titanium tetrachloride is introduced into the reactor at a flow rate of 15 kg / h, reaction hydrogen 0.4 kg / h, and reaction air 45 kg / h. After being mixed evenly, the reaction is ignited. The reaction flame enters the reactor. The temperature inside the reactor is adjusted to 320°C by introducing cooling air into the reactor to obtain gas-phase titanium dioxide.
[0063] An aqueous solution of FeCl3, an iron oxide precursor, is introduced into the aggregator. The solution is atomized into the aggregator at a flow rate of 120 g / h based on the mass of FeCl3, and the temperature of the aggregator is controlled at 380℃.
[0064] The powder, after being pulverized by airflow, enters the deacidification furnace from the top and undergoes a three-stage heating and deacidification process. After deacidification, it flows out from the bottom of the furnace. The temperatures in the three stages of the deacidification furnace from bottom to top are 480℃, 450℃, and 400℃, respectively. The residence time of the powder in the two stages of the deacidification furnace is 25 minutes each. Finally, the deacidified sample #1 is obtained.
[0065] Example 2
[0066] This embodiment provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0067] The reaction temperature inside the reactor is 280℃.
[0068] An aqueous solution of iron oxide precursor FeCl3 is introduced into the atomizer at a total mass of 200 g / h.
[0069] The powder after air jet milling was fed into a deacidification furnace for deacidification treatment. The temperature in the deacidification furnace was 420℃, 410℃, and 400℃ in three sections from bottom to top, respectively, and the residence time of the powder in the two stages of the deacidification furnace was 25 minutes. Finally, sample #2 after deacidification was obtained.
[0070] Comparative Example 1
[0071] This comparative example provides a method for preparing titanium dioxide by gas phase method, which is the same as that in Example 1, except that:
[0072] Without introducing iron oxide precursor into the aggregator, and controlling the temperature inside the aggregator at 380℃, a gas-solid mixed powder is obtained.
[0073] The powder after air jet milling was fed into a deacidification furnace for deacidification treatment. The temperature inside the deacidification furnace was 380℃, 350℃, and 320℃ in three sections from bottom to top, respectively, and the residence time of the powder in the two stages of the deacidification furnace was 25 minutes. Finally, sample #3 after deacidification was obtained.
[0074] Comparative Example 2
[0075] This comparative example provides a method for preparing titanium dioxide by gas phase method, which is the same as that in Example 1, except that:
[0076] Without introducing iron oxide precursor into the aggregator, and controlling the temperature inside the aggregator at 380℃, a gas-solid mixed powder is obtained.
[0077] The temperatures in the deacidification furnace were 480℃, 450℃, and 400℃ from bottom to top, respectively, and the residence time of the powder in the two-stage deacidification furnace was 25 minutes. Finally, sample #4 was obtained after deacidification.
[0078] Comparative Example 3
[0079] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0080] The vaporized titanium tetrachloride was introduced into the reactor at a flow rate of 15 kg / h, 0.4 kg / h of reaction hydrogen, and 45 kg / h of reaction air. After being mixed evenly, the reaction was ignited and the reaction flame entered the reactor. At the same time, an aqueous solution of iron oxide precursor FeCl3 was introduced into the reactor at a total mass of 120 g / h of FeCl3. Cooling air was introduced to adjust the temperature inside the reactor to 320°C for the reaction.
[0081] Finally, sample #5 was obtained after deacidification.
[0082] Comparative Example 4
[0083] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0084] The powder after air jet milling was fed into a deacidification furnace for deacidification treatment. The temperature in the deacidification furnace was 380℃, 350℃, and 320℃ in three sections from bottom to top, respectively, and the residence time of the powder in the two stages of the deacidification furnace was 25 minutes. Finally, sample #6 was obtained after deacidification.
[0085] Comparative Example 5
[0086] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0087] The powder after air jet milling was fed into a deacidification furnace for deacidification treatment. The temperature in the deacidification furnace was 580℃, 550℃, and 550℃ in three sections from bottom to top, respectively, and the residence time of the powder in the two stages of the deacidification furnace was 25 minutes. Finally, sample #7 was obtained after deacidification.
[0088] Comparative Example 6
[0089] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0090] An aqueous solution of FeCl3, a precursor of iron oxide, was introduced into the aggregator at a rate of 300 g / h (total FeCl3 mass). The final product was sample #8 after deacidification.
[0091] Comparative Example 7
[0092] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0093] The temperature inside the reactor was adjusted to 250℃. Finally, sample #9 after deacidification was obtained.
[0094] Comparative Example 8
[0095] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite, which is the same as that in Example 1, except that:
[0096] The temperature of the aggregator was adjusted to 450℃. Finally, sample #10 after deacidification was obtained.
[0097] The specific surface area of the samples prepared in the examples and comparative examples was tested using a specific surface area analyzer.
[0098] The crystal form and its proportion of the sample were determined by XRD.
[0099] The deacidification effect was characterized by testing the pH value of a 4% suspension solution.
[0100] The Fe content in the sample was tested using ICP-OES.
[0101] The test results are shown in Table 1.
[0102] Table 1 shows the test results of the samples, and Figure 3 shows the XRD test results of samples 1-3#.
[0103] Table 1. Test results of basic indicators of the samples
[0104] The reaction temperatures and deacidification temperatures of Examples 1 and 2 are different, as are the amounts of iron oxide precursors used. The reaction temperature and deacidification temperature of Example 1 are relatively higher, the pH value of Sample 1 is higher, the iron content is lower, and the proportion of anatase crystals in Sample 1 is also lower.
[0105] Comparative Examples 1 and 2 differ in their deacidification temperatures, with Comparative Example 2 having a higher deacidification temperature. Sample #4 has a lower proportion of anatase crystals, but the product has a higher pH value. This indicates that a crystal form transformation occurred during the deacidification process.
[0106] The difference between Comparative Example 3 and Example 1 is that the iron oxide precursor is introduced at a different location. In Comparative Example 3, iron oxide and titanium oxide precursors are introduced into the reactor at the same time, and a hybrid material of titanium oxide and iron oxide is generated. Iron oxide does not enter the titanium oxide lattice.
[0107] The difference between Comparative Example 4 and Comparative Example 1 is the introduction of an iron oxide precursor. Compared with the examples, the deacidification temperature is lower. Comparing Examples 1 and 2 with Comparative Examples 1, 2, and 4, it can be found that the addition of the iron oxide precursor makes the deacidification of the fumed titanium dioxide product more difficult. The deacidification temperature in Comparative Example 4 was insufficient, resulting in a very low pH value for sample #6.
[0108] Compared with Example 1, Comparative Example 5 increased the deacidification temperature and the pH value of sample #7 increased, but the proportion of anatase crystals decreased.
[0109] Compared with Example 1, Comparative Example 6 increased the amount of iron oxide precursor, so the iron oxide content of sample #8 increased, but its pH value decreased, and the product appearance also became darker.
[0110] Compared to Example 1, Comparative Example 7 reduced the temperature inside the reactor, which would hinder the conversion of the precursor into iron oxide and its entry into the titanium oxide lattice, resulting in a lower iron content in the product.
[0111] Compared to Example 1, Comparative Example 8 increased the aggregator temperature, which also hindered the conversion of the precursor into iron oxide and its entry into the titanium oxide lattice. This resulted in a lower iron content in the product and a decrease in the proportion of anatase crystals.
[0112] To verify the effect of the samples obtained in the above embodiments and comparative examples on the heat resistance of silicone rubber, the samples were added to silicone rubber, and the specific formulation is as follows:
[0113] After the above materials were mixed evenly in a two-roll mill, they were vulcanized at 180℃ for 10 minutes in a flat vulcanizing mill. After standing at room temperature for 24 hours, a second vulcanization was carried out at 200℃ for 2 hours. Mechanical properties were tested after standing at room temperature for 24 hours. At the same time, 10 samples were placed in a forced-air drying oven at a constant temperature of 300℃ for 24-120 hours to test their thermal stability. At regular intervals, one sample was taken out, stood at room temperature for 24 hours, and then its performance was tested. The films obtained by adding samples 1-10# correspond to samples 1-10# of the above examples and comparative examples, respectively. The test results are shown in Table 2-11.
[0114] Table 2 Performance of Sample 1# in Silicone Rubber
[0115] Table 3 Performance of Sample #2 in Silicone Rubber
[0116] Table 4 Performance of Sample #3 in Silicone Rubber
[0117] Table 5 Performance of Sample #4 in Silicone Rubber
[0118] Table 6 Performance of Sample #5 in Silicone Rubber
[0119] Table 7 Performance of Sample 6# in Silicone Rubber
[0120] Table 8 Performance of Sample 7# in Silicone Rubber
[0121] Table 9 Performance of Sample #8 in Silicone Rubber
[0122] Note: The film has a reddish tint.
[0123] Table 10 Performance of Sample 9# in Silicone Rubber
[0124] Table 11 Performance of Sample 10# in Silicone Rubber
[0125] Comparative performance test results show that, as indicated in Tables 4 and 5, fumed titanium dioxide helps improve the thermal stability of silicone rubber. The fumed titanium dioxide obtained in Comparative Example 1 has better thermal stability for silicone rubber than that obtained in Comparative Example 2. This suggests that the thermal stability of silicone rubber is closely related to the proportion of anatase crystals in fumed titanium dioxide. When the proportion of anatase crystals is less than 80%, it has no significant effect on improving the heat resistance of silicone rubber.
[0126] As shown in Tables 1 and 2, the iron oxide-doped titanium oxide composites obtained in Examples 1 and 2 significantly improved the thermal stability of silicone rubber. Example 1, compared to Example 2, increased the reaction temperature and deacidification temperature, allowing the anatase titanium dioxide portion to undergo crystal transformation. This resulted in a better synergistic effect between the two components in the prepared iron oxide-doped titanium oxide composite, significantly improving the thermal stability of silicone rubber. The data also show that after aging at 300℃, the hardening rate of silicone rubber was significantly reduced, while the retention of tensile strength and elasticity (elongation at break) was significantly improved.
[0127] Compared with Example 1, Comparative Example 3 shows, as can be seen from Tables 6 and 1, the introduction of iron oxide precursor at different positions leads to different product structures. In Comparative Example 3, the proportion of iron oxide embedded in the titanium oxide lattice may be relatively low, resulting in a decrease in the synergistic effect between the two.
[0128] Compared with Comparative Example 4 and Example 1, as shown in Tables 7 and 1, a lower deacidification temperature leads to a lower pH value in the product, which also reduces its effect on improving the heat resistance of silicone rubber.
[0129] Compared with Comparative Example 5 and Example 1, as shown in Tables 8 and 1, when the deacidification temperature is increased, the crystal form of titanium dioxide will change, the proportion of anatase crystal form will decrease, resulting in a decrease in its effect on improving the heat resistance of silicone rubber.
[0130] Compared with Comparative Example 6 and Example 1, as shown in Tables 9 and 1, increasing the amount of iron oxide precursor increases the difficulty of deacidification, resulting in a lower pH value for the product. Furthermore, excessively high iron oxide content leads to a darker product appearance. A pH value that is too low is detrimental to improving the heat resistance of silicone rubber.
[0131] The difference between Comparative Examples 7 and 8 and Example 1 lies in the reaction temperature. As shown in Tables 10, 11, and 1, excessively high or low temperatures are not conducive to the entry of iron oxide into the titanium oxide lattice, resulting in a low iron content and affecting performance.
[0132] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0133] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing an iron oxide-doped titanium oxide composite, characterized in that, The preparation method includes the following steps: Vaporized titanium tetrachloride, hydrogen, and combustion-supporting gas are mixed and ignited in a reactor and then introduced into a reaction furnace to obtain gas-phase titanium dioxide. The temperature inside the reaction furnace is 280℃~400℃. The obtained gas-phase titanium dioxide and iron oxide precursor are fed into an aggregator for mixing, and the reaction generates a gas-solid mixture. The powder in the gas-solid mixture is separated and fed into a deacidification device for deacidification treatment to obtain an iron oxide-doped titanium oxide composite. The temperature inside the deacidification device is 400-500℃.
2. The preparation method according to claim 1, characterized in that, The temperature inside the reactor is 280℃~380℃.
3. The preparation method according to claim 2, characterized in that, The temperature inside the reactor is 310℃~330℃.
4. The preparation method according to claim 1, characterized in that, The temperature inside the deacidification device is 400℃~480℃.
5. The preparation method according to claim 4, characterized in that, The deacidification device includes two deacidification furnaces connected in sequence. The powder is subjected to segmented heating and deacidification in the deacidification furnace, and the temperature of each segment in the deacidification furnace increases sequentially from the powder inlet to the powder outlet.
6. The preparation method according to claim 5, characterized in that, The deacidification furnace sequentially heats the powder in three stages: the first stage is heated at 400℃~410℃, the second stage at 445℃~455℃, and the third stage at 475℃~485℃; the deacidification time is 20min~25min.
7. The preparation method according to any one of claims 1-6, characterized in that, The flow rate of titanium tetrachloride input into the reactor is 13 kg / h to 17 kg / h, the flow rate of hydrogen input into the reactor is 0.1 kg / h to 0.8 kg / h, and the flow rate of combustion-supporting gas input into the reactor is 30 kg / h to 50 kg / h.
8. The preparation method according to any one of claims 1-6, characterized in that, The temperature inside the aggregator is 250℃~400℃.
9. The preparation method according to claim 8, characterized in that, The temperature inside the collector is 280℃~380℃.
10. The preparation method according to claim 9, characterized in that, The temperature inside the aggregator is 360℃~380℃.
11. The preparation method according to any one of claims 1-6, characterized in that, The aggregator includes a pipe, a drive device, and a ribbon stirring blade. The pipe has a first inlet and multiple second inlets. The vapor-phase titanium dioxide enters the pipe through the first inlet, and the iron oxide precursor enters the pipe through the second inlets. The ribbon stirring blade is disposed inside the pipe. The output end of the drive device is connected to the ribbon stirring blade and drives the ribbon stirring blade to rotate.
12. The preparation method according to any one of claims 1-6, characterized in that, The iron oxide precursor is ferric chloride.
13. The preparation method according to claim 12, characterized in that, The ferric chloride is an aqueous solution of ferric chloride or anhydrous ferric chloride.
14. The preparation method according to claim 13, characterized in that, The ferric chloride is an aqueous solution of ferric chloride. Based on the mass of ferric chloride, the aqueous solution of ferric chloride is atomized and introduced into the aggregator at a flow rate of 100 g / h to 200 g / h.
15. The preparation method according to any one of claims 1-6, characterized in that, The combustion-supporting gas is air or oxygen.
16. The iron oxide-doped titanium oxide composite prepared by the method according to any one of claims 1-15.
17. An iron oxide-doped titanium oxide composite, characterized in that, The iron oxide-doped titanium dioxide composite is iron oxide-doped titanium dioxide; the titanium dioxide has a mixed crystal form of anatase and rutile, and the proportion of anatase titanium dioxide in the titanium dioxide is more than 75%. The iron oxide-doped titanium oxide composite is prepared into a suspension with a mass concentration of 4% and a pH value of 3.2 to 4.5; the iron content in the iron oxide-doped titanium oxide composite is 0.6% to 1.3%.
18. The iron oxide-doped titanium oxide composite according to claim 17, characterized in that, The iron oxide-doped titanium oxide composite was prepared into a suspension with a mass concentration of 4% and a pH value of 3.3-4.
19. The iron oxide-doped titanium oxide composite as described in claim 18, characterized in that, The iron oxide-doped titanium oxide composite was prepared into a suspension with a mass concentration of 4% and a pH value of 3.3 to 3.
5.
20. The iron oxide-doped titanium oxide composite according to claim 17, characterized in that, The iron content in the iron oxide-doped titanium oxide composite is 0.6% to 1.1%.
21. The iron oxide-doped titanium oxide composite according to claim 20, characterized in that, The iron content in the iron oxide-doped titanium oxide composite is 0.6% to 0.7%.
22. The iron oxide-doped titanium oxide composite according to claim 17, characterized in that, The specific surface area of the iron oxide-doped titanium oxide composite is 35 m². 2 / g~50m 2 / g.
23. The iron oxide-doped titanium oxide composite according to claim 22, characterized in that, The specific surface area of the iron oxide-doped titanium oxide composite is 40 m². 2 / g~45m 2 / g.
24. The iron oxide-doped titanium oxide composite according to claim 23, characterized in that, The specific surface area of the iron oxide-doped titanium oxide composite is 40 m². 2 / g~43m 2 / g.
25. The use of the iron oxide-doped titanium oxide composite according to any one of claims 17-24 as a heat-resistant agent in the preparation of heat-resistant materials.
26. A type of silicone rubber, characterized in that, The silicone rubber, by weight, is made of the following components: Wherein, the iron oxide-doped titanium oxide composite is the iron oxide-doped titanium oxide composite according to any one of claims 17-24.