Iron oxide doped titanium oxide compound as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of inorganic chemistry, and discloses an iron oxide doped titanium oxide compound and a preparation method and application thereof.The preparation method of the iron oxide doped titanium oxide compound comprises the following steps that vaporized titanium tetrachloride, hydrogen and combustion-supporting gas are mixed in a reactor and then ignited; carrying out a reaction in a reaction furnace to obtain gas phase method titanium dioxide, wherein the temperature in the reaction furnace is 280-400 DEG C; introducing the obtained gas-phase method titanium dioxide and an iron oxide precursor into a collector for mixing, and reacting to generate a gas-solid mixture; powder in the gas-solid mixture is separated, the powder is input into a deacidification device to be subjected to deacidification treatment, the ferric oxide doped titanium oxide compound is obtained, and the temperature in the deacidification device is 400-500 DEG C. The iron oxide doped titanium dioxide compound prepared by the preparation method can generate a synergistic effect, so that the thermal stability of a high polymer material can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic chemistry, and particularly relates to an iron oxide-doped titanium oxide composite, a preparation method thereof, and an application thereof. Background Art

[0002] Nano-titanium dioxide is a polycrystalline structure powder, and there are mainly three crystalline forms in nature: anatase type, rutile type, and brookite type. Among them, the brookite type and anatase type structures are not stable crystal forms and can be converted into the rutile type at high temperatures. The conversion temperature of anatase-type titanium dioxide to rutile-type titanium dioxide is generally around 550 °C. However, as the particles of titanium dioxide decrease, their conversion temperature will decrease. Nano-scale titanium dioxide begins to undergo crystal form conversion at 400 °C.

[0003] Nano-titanium dioxide prepared by different methods has different crystal structures and properties. Nano-titanium dioxide is usually prepared by the gas phase method. Commonly used methods for preparing nano-titanium dioxide by the gas phase method include the high-temperature oxidation method and the high-temperature hydrolysis method. The high-temperature oxidation method uses titanium tetrachloride to react with oxygen to obtain nano-titanium dioxide; while the high-temperature hydrolysis method uses titanium tetrachloride to perform high-temperature hydrolysis with hydrogen and oxygen to obtain nano-titanium dioxide. Their reaction mechanisms are as follows.

[0004] TiCl 4 +O 2 =TiO 2 +Cl 2

[0005] TiCl 4 +H 2 +O 2 =TiO 2 +HCl

[0006] Due to the by-product of chlorine gas in the high-temperature oxidation method, the post-treatment process is complex and there are safety hazards; the tail gas treatment of the high-temperature hydrolysis method is relatively easy, so the common method is still the high-temperature hydrolysis method. Related patents include ZL201711119459.3; US 3735000, US7686881B2, etc.

[0007] Nano-titanium dioxide can maintain excellent performance in high-temperature environments and is a widely used heat-resistant agent, which can be used to prepare heat-resistant materials. However, the improvement effect of the nano-titanium dioxide prepared by the existing publicly disclosed methods on the thermal stability of some polymer materials such as silicone rubber is still not ideal enough. Summary of the Invention

[0008] Based on this, the present invention provides a method for preparing an iron oxide-doped titanium oxide composite, which can prepare a composite of iron oxide-doped high-anatase crystalline titanium oxide for gas phase. When applied to polymer materials, the thermal stability of the polymer materials can be significantly improved.

[0009] The following technical solutions are included to achieve the above object.

[0010] In the first aspect of the present invention, a method for preparing an iron oxide-doped titanium oxide composite is provided. The preparation method includes the following steps:

[0011] Vaporized titanium tetrachloride, hydrogen and combustion-supporting gas are mixed in a reactor and then ignited, and then enter a reaction furnace for reaction to obtain titanium dioxide for gas phase method. The temperature in the reaction furnace is 280°C to 400°C.

[0012] The obtained titanium dioxide for gas phase method and an iron oxide precursor are introduced into an aggregator for mixing, and a gas-solid mixture is generated by reaction.

[0013] The powder in the gas-solid mixture is separated, and the powder is input into a deacidification device for deacidification treatment to obtain an iron oxide-doped titanium oxide composite. The temperature in the deacidification device is 400 to 500°C.

[0014] In some embodiments, the temperature in the reaction furnace is 280°C to 380°C; the preferred temperature is 300°C to 380°C, more preferably 300°C to 350°C, and still more preferably 310°C to 330°C.

[0015] In some embodiments, the temperature in the deacidification device is 400°C to 480°C.

[0016] In some embodiments, the deacidification device includes two stages of deacidification furnaces connected in sequence. The powder is subjected to staged heating and deacidification in the deacidification furnace, and the temperature of each stage from the powder inlet to the powder outlet direction in the deacidification furnace increases in sequence.

[0017] Preferably; the deacidification furnace performs three-stage heating and deacidification on the powder in sequence. The temperature of the first-stage heating is 400°C to 410°C, the temperature of the second-stage heating is 445°C to 455°C, and the temperature of the third-stage heating is 475°C to 485°C; preferably, the temperature of the first-stage heating is 400°C to 405°C, the temperature of the second-stage heating is 448°C to 452°C, and the temperature of the third-stage heating is 478°C to 482°C. The deacidification time is 20 min to 25 min.

[0018] In some of these 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 the combustion-supporting gas input into the reactor is 30 kg / h to 50 kg / h.

[0019] In some of these embodiments, the temperature inside the aggregator is 250 °C to 400 °C; the preferred temperature is 280 °C to 380 °C; more preferably it is 300 °C to 380 °C, and even more preferably the temperature is 360 °C to 380 °C.

[0020] In some of these embodiments, the aggregator includes a pipeline, a driving device, and spiral ribbon stirring blades; a first feed port and a plurality of second feed ports are provided on the pipeline, the gas-phase titanium dioxide enters the pipeline through the first feed port, the iron oxide precursor enters the pipeline through the second feed port, the spiral ribbon stirring blades are arranged inside the pipeline, and the output end of the driving device is connected to the spiral ribbon stirring blades and drives the spiral ribbon stirring blades to rotate.

[0021] In some of these embodiments, the iron oxide precursor is iron chloride; preferably, the iron chloride is an aqueous iron chloride solution or anhydrous iron chloride; more preferably, the iron chloride is an aqueous iron chloride solution. Calculated by the mass of iron chloride, after atomization, the aqueous iron chloride solution 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, and more preferably 110 g / h to 130 g / h; and / or,

[0022] The combustion-supporting gas is air or oxygen.

[0023] The second aspect of the present invention provides an iron oxide-doped titanium oxide composite prepared by the preparation method of the iron oxide-doped titanium oxide composite as described above.

[0024] The third aspect of the present invention provides an iron oxide-doped titanium oxide composite, where the iron oxide-doped titanium oxide composite is iron oxide-doped titanium dioxide; the crystal form of the titanium dioxide is a mixed crystal form of anatase type and rutile type, and the proportion of anatase type titanium dioxide in the titanium dioxide is more than 75%;

[0025] Among them, the pH value of the suspension prepared by formulating the iron oxide-doped titanium oxide composite into a suspension with a mass concentration of 4% is 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%.

[0026] In some embodiments, the specific surface area of the iron oxide-doped titanium oxide composite is 35 m 2 / g to 50 m 2 / g, preferably 40 m 2 / g to 45 m 2 / g, more preferably 40 m 2 / g to 43 m 2 / g.

[0027] The fourth aspect of the present invention provides an application of the iron oxide-doped titanium oxide composite as described above as a heat-resistant agent in the preparation of heat-resistant materials.

[0028] The fifth aspect of the present invention provides a silicone rubber which, by weight, consists of the following components:

[0029]

[0030] Among them, the iron oxide-doped titanium oxide composite is the iron oxide-doped titanium oxide composite as described above.

[0031] In some embodiments, the silicone rubber consists of the following components:

[0032]

[0033] 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane 1 to 2 parts

[0034] Hydroxy silicone oil 5 to 8 parts.

[0035] The sixth aspect of the present invention provides a preparation method of the silicone rubber as described above, and the preparation method includes the following steps:

[0036] Mix methyl vinyl silicone rubber, fumed silica, iron oxide-doped titanium oxide composite, bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) and hydroxy silicone oil evenly in an open mill, and then carry out primary vulcanization at 175°C to 185°C for 8 min to 12 min in a flat vulcanizer. After standing at room temperature for 24 h, carry out secondary vulcanization at 195°C to 205°C for 1.5 h to 2.5 h.

[0037] In the present invention, by controlling the temperature in the reaction furnace to be 280°C to 400°C, nano-scale gas-phase titanium dioxide particles with an anatase-rutile mixed crystal form are first obtained, and then the gas-phase titanium dioxide particles are reacted with iron oxide. The reaction product is subjected to deacidification treatment at a specific deacidification temperature (400 - 500°C) to finally obtain an iron oxide-doped titanium dioxide composite. A synergistic effect can be generated between the titanium oxide and iron oxide in the iron oxide-doped titanium dioxide composite, which can effectively improve the thermal stability of the polymer material. Description of the Drawings

[0038] Figure 1 It is the overall structure diagram of the device used in the preparation method of the iron oxide-doped titanium oxide composite;

[0039] Figure 2 is Figure 1 the structural schematic diagram of the deacidification furnace of

[0040] Figure 3 the XRD test result of the sample.

[0041] Explanation of the reference numerals in the drawings:

[0042] 1. Reactor; 2. Connector; 21. Cooling gas inlet; 3. Reaction furnace; 4. Aggregator; 41. Pipeline; 42. Driving device; 43. Helical ribbon stirring blade; 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 manners

[0043] For the convenience of understanding the present invention, the present invention will be described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0044] The experimental methods without specific conditions noted in the following embodiments are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. All kinds of commonly used chemical reagents used in the embodiments are commercially available products.

[0045] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0046] An embodiment of the present invention provides a preparation method of an iron oxide-doped titanium oxide composite, and the preparation method includes the following steps:

[0047] Vaporized titanium tetrachloride, hydrogen and combustion-supporting gas are mixed in a reactor and then ignited, and enter a reaction furnace for reaction to obtain titanium dioxide by the gas-phase method, and the temperature in the reaction furnace is 280°C to 400°C;

[0048] The obtained titanium dioxide by the gas-phase method and the iron oxide precursor are introduced into an aggregator for mixing, and a gas-solid mixture is generated by reaction;

[0049] Separate the powder in the gas-solid mixture, input the powder into a deacidification device for deacidification treatment to obtain an iron oxide-doped titanium oxide composite, and the temperature in the deacidification device is 400-500 °C.

[0050] The inventors found in long-term research that among the crystal structures of titanium dioxide, the most stable structure is the rutile type. However, in some functions, such as a heat-resistant agent for polymer materials, it is the titanium dioxide with a mixed crystal structure of anatase type and rutile type that has better performance, especially when doped with some other metal oxides, the performance is even better. However, different ratios of the anatase type and rutile type mixed crystal structures, as well as different metal oxides doped, will significantly affect the thermal stability of polymer materials, making it difficult to break through the improvement effect of the metal oxide-doped titanium dioxide composite prepared by the existing preparation methods on the thermal stability of polymer materials. Therefore, in the present invention, by controlling the temperature in the reaction furnace to be 280 °C to 400 °C, first prepare nanoscale gas-phase titanium dioxide particles with a mixed crystal structure of anatase type - rutile type in which the proportion of anatase type titanium dioxide is controlled above 80%, then react the gas-phase titanium dioxide particles with iron oxide, and subject the reaction product to deacidification treatment at a specific deacidification temperature (400-500 °C) to finally obtain an iron oxide-doped titanium dioxide composite. A synergistic effect can be generated between the titanium oxide and iron oxide in the iron oxide-doped titanium dioxide composite, which can effectively improve the thermal stability of polymer materials.

[0051] In some embodiments, the device used in the preparation method of the above iron oxide-doped titanium oxide composite of the present invention is as follows Figure 1 and Figure 2 As shown, the formation reaction of the gas-phase titanium dioxide is carried out in the reaction furnace 3, where a reactor 1 communicating with the reaction furnace 3 is provided above the reaction furnace 3, and the vaporized raw material TiCl 4It enters the reactor 1 together with dried air and hydrogen, is ejected from the nozzle of the reactor 1 and ignited for reaction. The reaction flame enters the reaction furnace 3, and a high-temperature hydrolysis reaction is carried out under specific temperature control to generate titanium dioxide particles with a specific particle size and a specific crystal form. Among them, by controlling the temperature in the reaction furnace 3 to be 280°C to 400°C, a gas-phase titanium dioxide gas-solid mixture with an anatase crystal form ratio higher than 80% is obtained. Further preferably, a connector 2 is provided between the reactor 1 and the reaction furnace 3. Cooling gas inlets 21 are provided on both opposite sides of the connector 2. The cooling gas inlets 21 are inclined on the connector 2. The cooling gas such as hydrogen, oxygen or air entering from the cooling gas inlets 21 on both opposite sides of the connector 2 forms a spiral downward air flow in the reaction furnace 3, which can quickly reduce the temperature of the reaction product to a specific temperature and at the same time reduce the concentration of the reaction product. It avoids particle collision and condensation into large particles, as well as crystal form transformation at high temperatures, thereby realizing the control of the particle size and crystal form structure.

[0052] The product obtained by the reaction in the reaction furnace 3 is TiO 2 and HCl and an excess air mixture. At this time, the generated titanium dioxide particles are very small (<100 nm), and at the same time the particle concentration is also very low, making it difficult to collect. Therefore, it needs to pass through the aggregator 4 to make the particles collide with each other to form aggregates (particle size 0.2 microns - 5 microns) for easy collection. Specifically, in some embodiments, the aggregator 4 includes a pipeline 41, a driving device 42 and a spiral ribbon stirring blade 43; a first feed port 44 and a plurality of second feed ports 45 are provided on the pipeline 41. The gas-phase titanium dioxide enters the pipeline 41 through the first feed port 44, and the iron oxide precursor enters the pipeline 41 through the second feed ports 45. The spiral ribbon stirring blade 43 is arranged in the pipeline 41, and the output end of the driving device 42 is connected to the spiral ribbon stirring blade 43 and drives the spiral ribbon stirring blade 43 to rotate. Specifically, the plurality of second feed ports 45 are dispersedly arranged on the pipeline 41 along the length extension direction of the pipeline 41. The iron oxide precursor can enter the pipeline 41 in an atomized state or a vaporized state through the second feed ports 45, and iron oxide particles are generated by reaction in the pipeline 41. The iron oxide particles collide with the titanium dioxide particles and adhere to the surface and inside of the titanium dioxide aggregates. Inside the aggregator 4, a spiral ribbon stirring blade 43 is provided, and the driving device 42 such as a rotating motor drives it to rotate, pushing the powder forward, which is beneficial to the mixing of the powder. At the same time, during the rotation process, the inner wall of the pipeline 41 is also scraped to prevent particles from depositing on the pipe wall.

[0053] Furthermore, a cooling jacket 46 is provided on the outer peripheral wall of the pipeline 41. Under the action of the cooling jacket 46, the temperature inside the pipeline 41 is controlled to be 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.

[0054] The solid-gas mixture material coming out of the aggregator 4 needs to be further separated to obtain solid powder and then undergo deacidification treatment. In this embodiment, the 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, the bottom of the cyclone separator 5 is connected to the buffer tank 6, an exhaust port is provided at the top of the buffer tank 6 and 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. It can be understood that the solid-gas mixture enters the cyclone separator 5 for solid-gas separation. Under the action of centrifugal force, the gas separated inside the cyclone separator 5 enters the bag filter 7 from the top, and the powder comes out from the bottom and enters the buffer tank 6. An exhaust port is provided at the top of the buffer tank 6 and is connected to the bag filter 7. The powder entrained in the gas coming out of the exhaust port is collected by the bag filter 7. The powder collected in the bag filter 7 comes out from the bottom and then enters the buffer tank 6. The powder in the buffer tank 6 comes out and enters the pulverizing device 8. Under the pulverization of the pulverizing device 8, it is further homogenized, and at the same time, large particles are also pulverized. The said pulverizing device 8 can be a pneumatic pulverizing device or a mechanical pulverizing device, preferably a pneumatic pulverizing device. The powder can be further pulverized and homogenized, and the iron oxide particles can be further evenly dispersed in the titanium dioxide. The pulverized powder enters a deacidification device such as a fluidized bed deacidification furnace for deacidification treatment.

[0055] In some embodiments, the temperature inside the deacidification device is 400°C to 480°C.

[0056] In some embodiments, the deacidification device includes two sequentially connected deacidification furnaces 9, that is, 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 staged heating and deacidification in the deacidification furnace 9, and the temperatures of each stage in the deacidification furnace 9 increase sequentially from the powder inlet to the powder outlet direction; preferably, the deacidification furnace 9 performs three-stage heating and deacidification on the powder, the temperature of the first-stage heating is 400°C to 410°C, the temperature of the second-stage heating is 445°C to 455°C, and the temperature of the third-stage heating is 470°C to 480°C; the deacidification time is 20 min to 25 min. Specifically, the deacidification furnace 9 adopts a two-stage series structure, and the powder enters from the upper end of the deacidification furnace 9 and flows out from the lower end. It can be understood that the first stage, the second stage and the third stage in the deacidification furnace 9 respectively correspond to the top section, the middle section and the bottom section in the deacidification furnace 9, and each section is in a connected state, so that the deacidification temperature increases sequentially when the powder flows from top to bottom, which can further improve the deacidification effect. After deacidification by the deacidification furnace 9, most of the HCl gas adsorbed on the surface of the powder can be removed. A heating device 91 is arranged in the deacidification furnace 9, such as heating sheets are installed on the periphery of the deacidification furnace 9, to control the temperature range of different sections in the deacidification furnace 9. At the same time, a plurality of gas inlets are arranged on the furnace wall of the deacidification furnace 9 to introduce deacidification auxiliary gas to assist in deacidification. An exhaust port is arranged at the top of the deacidification furnace 9, which is connected to a bag filter 7 to collect the powder entrained by the airflow, and the collected powder is returned to the first-stage deacidification furnace 9 for recovery. At the bottom of the deacidification furnace 9 are large-particle powders that fall by air flotation, which can be returned to the pulverizing device 8 for recovery.

[0057] In some embodiments, a plurality of annular gas outlet pipes 92 are arranged inside the deacidification furnace 9, a plurality of micropores are opened on the annular gas outlet pipes 92, the gas inlet of the deacidification furnace 9 is communicated with 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. In addition, the gas inlet of the deacidification furnace 9 is connected to a pipeline heater through an input pipe, and the pipeline heater heats the gas and then inputs it into the deacidification furnace 9 through the input pipe and the annular gas outlet pipes 92. Under the combined action of the heating device 91 of the deacidification furnace 9, the temperature in the deacidification furnace 9 is ensured to be 400 - 500°C, preferably 400 - 480°C. At this temperature, on the one hand, the HCl gas adsorbed on the surface of the powder is effectively desorbed, and on the other hand, the unreacted iron oxide precursor reacts completely. At the same time, at this temperature, part of the anatase titanium oxide is converted into rutile titanium oxide, so that the iron oxide particles are embedded inside the iron oxide crystal grains. An iron oxide-doped titanium oxide composite powder with a stronger synergistic effect in improving the heat resistance of polymer materials is obtained.

[0058] The iron oxide-doped titanium oxide composite powder prepared by this method can significantly improve the thermal stability of silicone rubber when a small amount is added to the silicone rubber, and has good market prospects in the aspect of heat stabilizers for polymer materials.

[0059] Due to its relatively small particle size and high specific surface area, gas-phase titanium dioxide is relatively easy to adsorb HCl gas during production. In the deacidification process, high temperature is required for auxiliary desorption, and during this process, anatase titanium dioxide is often easily converted into rutile titanium dioxide. Therefore, in the preparation of titanium dioxide products with a high anatase ratio, temperature control is extremely important. In the prior art, the deacidification temperature needs to be controlled below 400 °C (because nano-titanium dioxide starts to undergo crystal form transformation at this temperature). In this embodiment, the inventors found that during the deacidification process of the composite powder formed by introducing iron oxide particles after the formation of titanium dioxide particles, by controlling the temperature between 400 and 500 °C, a better synergistic effect can be obtained, and the thermal stability of the polymer material can be better improved. The reason is that the introduction of iron oxide can increase the crystal form transformation temperature of titanium dioxide, so the deacidification temperature can be increased, and the deacidification efficiency can be improved without excessive crystal form transformation. In addition, after the formation of titanium dioxide particles, an iron oxide precursor is introduced, and then at this specific deacidification temperature, a small part of anatase titanium dioxide also undergoes crystal form transformation, enabling iron oxide to enter the titanium dioxide lattice, obtaining an iron oxide-doped titanium dioxide composite powder. This iron oxide-doped titanium dioxide composite powder is significantly different from the titanium oxide / iron oxide hybrid material obtained by mixing an iron oxide precursor and a titanium dioxide precursor and carrying out a combustion reaction together in the prior art, as well as the physical mixture of titanium oxide / iron oxide. The iron oxide-doped titanium dioxide composite powder obtained by the process of this embodiment can obtain a good synergistic effect at a low content of iron oxide.

[0060] 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 using ferric chloride, it is heated to 300 - 350 °C through a raw material vaporizer to sublimate ferric chloride into the aggregator. Preferably, it is an aqueous solution of ferric chloride, which is atomized into the aggregator by hot nitrogen. The ferric chloride is an aqueous solution of ferric chloride, and calculated by 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, preferably 100 g / h to 130 g / h.

[0061] 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 the combustion-supporting gas input into the reactor is 30 kg / h to 50 kg / h.

[0062] In some embodiments, the temperature in the reaction furnace 3 is 280 °C to 380 °C; the preferred temperature is 300 °C to 380 °C, further preferably 300 °C to 350 °C, and more preferably 310 °C to 330 °C.

[0063] An embodiment of the present invention also provides an iron oxide-doped titanium oxide composite, and the iron oxide-doped titanium oxide composite is iron oxide-doped titanium dioxide; the crystal form of the titanium dioxide is a mixed crystal form of anatase type and rutile type, and the proportion of the anatase type titanium dioxide is more than 75%, preferably more than 78%;

[0064] Among them, the pH value of the suspension prepared by formulating the iron oxide-doped titanium oxide composite with a mass concentration of 4% is 3.2 to 4.5, preferably the pH value is 3.3 to 4, and more preferably the pH value is 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%.

[0065] The following further describes the present invention in detail with specific embodiments.

[0066] Example 1

[0067] This example provides a preparation method of an iron oxide-doped titanium oxide composite, and the device used is as shown in Figure 1 and Figure 2 shown. The specific steps of this preparation method are as follows:

[0068] The vaporized titanium tetrachloride enters the reactor at a flow rate of 15 kg / h; the reaction hydrogen is 0.4 kg / h; the reaction air is 45 kg / h. After mixing evenly, the reaction is ignited, and the reaction flame enters the reaction furnace. The temperature in the reaction furnace is adjusted to 320 °C by introducing cooling air to carry out the reaction to obtain gas-phase titanium dioxide;

[0069] An iron oxide precursor FeCl 3 aqueous solution is introduced into the aggregator, and is atomized into the aggregator at a flow rate of 120 g / h according to the mass of FeCl 3 to control the temperature of the aggregator at 380 °C.

[0070] The powder after airflow pulverization enters the deacidification furnace from the top of the deacidification furnace and undergoes three-stage heating deacidification treatment in sequence, and flows out from the bottom of the deacidification furnace after the deacidification is completed. The three-stage temperatures of the deacidification furnace from bottom to top are 480 °C, 450 °C and 400 °C respectively. The residence time of the powder in the two-stage deacidification furnace is 25 min each. Finally, the deacidified Sample 1 is obtained.

[0071] Example 2

[0072] This example provides a preparation method of an iron oxide-doped titanium oxide composite. This preparation method is the same as that of Example 1, and the difference is:

[0073] The reaction temperature in the reactor is 280 °C.

[0074] An iron oxide precursor FeCl 3 aqueous solution is introduced into the aggregator and atomized into the aggregator at a total mass of 200 g / h according to FeCl 3

[0075] The powder after jet milling enters the deacidification furnace for deacidification treatment. The temperatures of the three sections from the bottom to the top in the deacidification furnace are 420 °C, 410 °C and 400 °C respectively, and the residence times of the powder in the two-stage deacidification furnace are 25 min each. Finally, the deacidified Sample 2 is obtained.

[0076] Comparative Example 1

[0077] This comparative example provides a method for preparing gas-phase titanium dioxide. This preparation method is the same as that of Example 1, except that:

[0078] No iron oxide precursor is introduced into the aggregator, and the temperature in the aggregator is controlled at 380 °C to obtain a gas-solid mixed powder.

[0079] The powder after jet milling enters the deacidification furnace for deacidification treatment. The temperatures of the three sections from the bottom to the top in the deacidification furnace are 380 °C, 350 °C and 320 °C respectively, and the residence times of the powder in the two-stage deacidification furnace are 25 min each. Finally, the deacidified Sample 3 is obtained.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing gas-phase titanium dioxide. This preparation method is the same as that of Example 1, except that:

[0082] No iron oxide precursor is introduced into the aggregator, and the temperature in the aggregator is controlled at 380 °C to obtain a gas-solid mixed powder.

[0083] The temperatures of the three sections from the bottom to the top in the deacidification furnace are 480 °C, 450 °C and 400 °C respectively, and the residence times of the powder in the two-stage deacidification furnace are 25 min each. Finally, the deacidified Sample 4 is obtained.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. This preparation method is the same as that of Example 1, except that:

[0086] Vaporized titanium tetrachloride enters the reactor at a flow rate of 15 kg / h; reaction hydrogen 0.4 kg / h; reaction air 45 kg / h. After mixing evenly, it is ignited and reacted. The reaction flame enters the reaction furnace, and at the same time, an iron oxide precursor FeCl 3 aqueous solution is introduced into the reaction furnace according to FeCl​3 A total of 120 g / h of the mass is atomized into the reaction furnace, and cooling air is introduced to adjust the temperature in the reaction furnace to 320 °C for the reaction.

[0087] Finally, the deacidified Sample No. 5 is obtained.

[0088] Comparative Example 4

[0089] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. The preparation method is the same as that of Example 1, except that:

[0090] The powder after air flow pulverization enters the deacidification furnace for deacidification treatment. The temperatures of the three sections of the deacidification furnace from bottom to top are 380 °C, 350 °C and 320 °C respectively, and the residence times of the powder in the two-stage deacidification furnace are 25 min respectively. Finally, the deacidified Sample No. 6 is obtained.

[0091] Comparative Example 5

[0092] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. The preparation method is the same as that of Example 1, except that:

[0093] The powder after air flow pulverization enters the deacidification furnace for deacidification treatment. The temperatures of the three sections of the deacidification furnace from bottom to top are 580 °C, 550 °C and 550 °C respectively, and the residence times of the powder in the two-stage deacidification furnace are 25 min respectively. Finally, the deacidified Sample No. 7 is obtained.

[0094] Comparative Example 6

[0095] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. The preparation method is the same as that of Example 1, except that:

[0096] An iron oxide precursor FeCl 3 aqueous solution is introduced into the aggregator, and a total of 300 g / h of FeCl 3 by mass is atomized into the aggregator. Finally, the deacidified Sample No. 8 is obtained.

[0097] Comparative Example 7

[0098] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. The preparation method is the same as that of Example 1, except that:

[0099] The temperature in the reaction furnace is adjusted to 250 °C. Finally, the deacidified Sample No. 9 is obtained.

[0100] Comparative Example 8

[0101] This comparative example provides a method for preparing an iron oxide-doped titanium oxide composite. The preparation method is the same as that of Example 1, except that:

[0102] Adjust the temperature of the aggregator to 450 °C. Finally, obtain the deacidified Sample 10#.

[0103] Test the specific surface area of the samples prepared in the examples and comparative examples by a specific surface area analyzer.

[0104] Test the crystal form and its proportion of the samples by XRD.

[0105] Characterize the deacidification effect by testing the pH value of a 4% aqueous suspension.

[0106] Test the Fe content in the samples by ICP-OES.

[0107] The test results are shown in Table 1.

[0108] Table 1 shows the test results of the samples. Figure 3 It is the XRD test results of Samples 1-3#.

[0109] Table 1 Test Results of Basic Indexes of Samples

[0110]

[0111] The reaction temperatures and deacidification temperatures of Example 1 and Example 2 are different, and the dosages of iron oxide precursors are also different. 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-type crystals in Sample 1# is lower.

[0112] The deacidification temperatures of Comparative Example 1 and Comparative Example 2 are different, and the deacidification temperature of Comparative Example 2 is higher. The proportion of anatase-type crystals in Sample 4# is lower, but the pH value of the product is higher. It shows that crystal form transformation occurs during the deacidification process.

[0113] The difference between Comparative Example 3 and Example 1 lies in the different positions where the iron oxide precursor is introduced. In Comparative Example 3, the iron oxide and titanium oxide precursors enter the reactor simultaneously, and a hybrid material of titanium oxide and iron oxide is formed. The iron oxide does not enter the titanium oxide lattice.

[0114] The difference between Comparative Example 4 and Comparative Example 1 is that an iron oxide precursor is introduced. Compared with the examples, the deacidification temperature is lower. By comparing Example 1, 2 and Comparative Example 1, 2, 4, it can be found that after adding the iron oxide precursor, the deacidification of the gas-phase titanium dioxide product will be more difficult. The deacidification temperature of Comparative Example 4 is insufficient at this time, resulting in a very low pH value of Sample 6#.

[0115] Compared with Example 1, Comparative Example 5 increases the deacidification temperature. The pH value of Sample 7# has increased, but the proportion of anatase-type crystals has decreased.

[0116] Compared with Example 1, the feed amount of the iron oxide precursor was increased in Comparative Example 6. Therefore, the iron oxide content of the 8# sample increased, but its pH value decreased, and the product appearance also became darker.

[0117] Compared with Example 1, the temperature in the reaction furnace was decreased in Comparative Example 7, which would lead to the disadvantage that the precursor was not conducive to being converted into iron oxide and entering the titanium oxide lattice, resulting in a low iron content in the product.

[0118] Compared with Example 1, the temperature of the aggregator was increased in Comparative Example 8, which was also not conducive to the conversion of the precursor into iron oxide and entering the titanium oxide lattice. As a result, the iron content in the product was low, and the proportion of anatase-type crystals decreased.

[0119] To verify the influence of the samples obtained in the above examples and comparative examples on the heat resistance of silicone rubber, the samples were added to silicone rubber, and the specific formula was as follows:

[0120]

[0121] After the above materials were mixed evenly in an open mill, they were subjected to primary vulcanization at 180 °C × 10 min in a flat vulcanizer. After standing at room temperature for 24 h, they were subjected to secondary vulcanization at 200 °C × 2 h. The mechanical properties were tested after standing at room temperature for 24 h. At the same time, 10 samples were respectively subjected to heat stability tests at a constant temperature of 300 °C in a blast drying oven for 24 h - 120 h. Every once in a while, one sample was taken out, and the performance was tested after standing at room temperature for 24 h. The films obtained by adding the 1-10# samples corresponded to the 1-10# samples of the above examples and comparative examples respectively, and the test results are shown in Table 2-11.

[0122] Table 2 Application performance of the 1# sample in silicone rubber

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[0124]

[0125] Table 3 Application performance of the 2# sample in silicone rubber

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[0127] Table 4 Application performance of the 3# sample in silicone rubber

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[0129] Table 5 Application performance of the 4# sample in silicone rubber

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[0131] Table 6 Application performance of the 5# sample in silicone rubber

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[0133] Table 7 Application Performance of Sample No. 6 in Silicone Rubber

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[0135] Table 8 Application Performance of Sample No. 7 in Silicone Rubber

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[0137] Table 9 Application Performance of Sample No. 8 in Silicone Rubber

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[0139] Remark: The appearance of the film is slightly red

[0140] Table 10 Application Performance of Sample No. 9 in Silicone Rubber

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[0142]

[0143] Table 11 Application Performance of Sample No. 10 in Silicone Rubber

[0144]

[0145] From the comparison of the performance test results, as can be seen from Table 4 and Table 5, fumed titanium dioxide is helpful for the thermal stability of silicone rubber. The fumed titanium dioxide obtained in Comparative Example 1 has better thermal stability for silicone rubber than that in Comparative Example 2, indicating that the thermal stability of silicone rubber has a great relationship with the anatase crystal ratio of fumed titanium dioxide. When the anatase crystal ratio is <80%, there is no obvious effect on improving the heat resistance of silicone rubber.

[0146] As can be seen from Table 1 and Table 2, the iron oxide-doped titanium oxide composites obtained in Example 1 and Example 2 have a significant effect on improving the thermal stability of silicone rubber. Among them, in Example 1, the reaction temperature and deacidification temperature are increased compared with Example 2, which can cause partial crystal form transformation of anatase titanium dioxide, so that a better synergistic effect is generated between the two in the prepared iron oxide-doped titanium oxide composite, and the effect of improving the thermal stability of silicone rubber is significant. From the data results, it can be seen that after the silicone rubber is aged at 300 °C, its hardening degree is significantly slowed down, and the retention rates of tensile strength and elasticity (elongation at break) are significantly increased.

[0147] Comparing Comparative Example 3 with Example 1, as can be seen from Table 6 and Table 1, introducing iron oxide precursors at different positions results in different structures of the products. For the titanium oxide and iron oxide hybrid material obtained in Comparative Example 3, the proportion of iron oxide embedded in the titanium oxide lattice may be relatively low, and the synergistic effect formed by the two decreases.

[0148] Comparing Comparative Example 4 with Example 1, as can be seen from Table 7 and Table 1, a lower deacidification temperature will result in a lower pH value of the product and also lead to a decrease in its effect of improving the heat resistance of silicone rubber.

[0149] Comparing Comparative Example 5 with Example 1, as can be seen from Table 8 and Table 1, increasing the deacidification temperature will cause the crystal form of titanium dioxide to transform, and the proportion of anatase crystal form will decrease, resulting in a decrease in its effect of improving the heat resistance of silicone rubber.

[0150] Comparing Comparative Example 6 with Example 1, as can be seen from Table 9 and Table 1, increasing the feeding amount of iron oxide precursors increases the difficulty of deacidification, and the pH value of the product is lower. In addition, when the iron oxide content is too high, the appearance of the product becomes darker. A too low pH value is not conducive to improving the heat resistance of silicone rubber.

[0151] The differences between Comparative Example 7 and Comparative Example 8 and Example 1 lie in the different reaction temperatures. As can be seen from Table 10, Table 11 and Table 1, too high or too low a temperature is not conducive to iron oxide entering the titanium oxide lattice, resulting in a low iron content and affecting the performance.

[0152] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as falling within the scope described in this specification.

[0153] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for preparing an iron oxide-doped titanium oxide composite, characterized in that: The preparation method comprises the following steps: The vaporized titanium tetrachloride, hydrogen and combustion-supporting gas are mixed in a reactor and then ignited, and then enter a reaction furnace for reaction to obtain vapor-phase titanium dioxide, wherein the temperature in the reaction furnace is 280° C. to 400° C.; The obtained vapor-phase titanium dioxide and iron oxide precursor are introduced into a concentrator for mixing to react and generate a gas-solid mixture; The powder in the gas-solid mixture is separated and the powder is input into a deacidification device for deacidification to obtain an iron oxide-doped titanium oxide composite. The temperature in the deacidification device is 400-500°C.

2. The preparation method according to claim 1, characterized in that The temperature in the reaction furnace is 280°C to 380°C; preferably, the temperature is 310°C to 330°C.

3. The preparation method according to claim 1, characterized in that: The temperature in the deacidification device is 400°C to 480°C.

4. The preparation method according to claim 3, characterized in that: The deacidification device comprises two stages of deacidification furnaces connected in sequence; The powder is heated and deacidified in sections in the deacidification furnace, and the temperature of each section in the deacidification furnace increases successively from the powder inlet to the powder outlet; Preferably, the deacidification furnace performs three-stage heating deacidification on the powder in sequence, 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℃; the deacidification time is 20min~25min.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The flow rate of the titanium tetrachloride input into the reactor is 13kg / h to 17kg / h, the flow rate of the hydrogen input into the reactor is 0.1kg / h to 0.8kg / h, and the flow rate of the combustion-supporting gas input into the reactor is 30kg / h to 50kg / h.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The temperature in the concentrator is 250°C to 400°C; preferably 280°C to 380°C; more preferably 360°C to 380°C; and / or, The aggregator includes a pipeline, a driving device and a spiral ribbon stirring blade; a first feed port and a plurality of second feed ports are provided on the pipeline, the vapor-phase titanium dioxide enters the pipeline through the first feed port, the iron oxide precursor enters the pipeline through the second feed port, the spiral ribbon stirring blade is arranged in the pipeline, and the output end of the driving device is connected to the spiral ribbon stirring blade and drives the spiral ribbon stirring blade to rotate.

7. The preparation method according to any one of claims 1 to 4, characterized in that: 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 is atomized and passed into the concentrator at a flow rate of 100 g / h to 200 g / h, based on the mass of ferric chloride; and / or, The combustion-supporting gas is air or oxygen.

8. The iron oxide-doped titanium oxide composite prepared by the method for preparing the iron oxide-doped titanium oxide composite according to any one of claims 1 to 7.

9. An iron oxide-doped titanium oxide composite, characterized in that: The iron oxide-doped titanium oxide composite is titanium dioxide doped with iron oxide; the crystal form of the titanium dioxide is a mixed crystal form of anatase and rutile, and the proportion of anatase titanium dioxide in the titanium dioxide is more than 75%; The pH value of the suspension of the iron oxide doped titanium oxide composite with a mass concentration of 4% is 3.2-4.5, preferably 3.3-4, and more preferably 3.3-3.5; the iron content of the iron oxide doped titanium oxide composite is 0.6%-1.3%, preferably 0.6%-1.1%, and more preferably 0.6%-0.7%.

10. The iron oxide-doped titanium oxide composite according to claim 9, characterized in that The specific surface area of ​​the iron oxide doped titanium oxide composite is 35 m 2 / g~50m 2 / g, preferably 40m 2 / g~45m 2 / g, more preferably 40m 2 / g~43m 2 / g.

11. Use of the iron oxide-doped titanium oxide composite according to any one of claims 8 to 10 as a heat-resistant agent in the preparation of heat-resistant materials.

12. A silicone rubber, characterized in that: The silicone rubber is made of the following components in parts by weight: Wherein, the iron oxide-doped titanium oxide composite is the iron oxide-doped titanium oxide composite as claimed in any one of claims 8 to 10.

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