CN118495942A - A process for preparing an integrally formed Ti4O7 ceramic electrode by reducing TiC - Google Patents

Abstract

The present invention provides a process for preparing an integrally formed Ti ₄ O ₇ ceramic electrode by TiC reduction, which comprises the following steps: weighing raw materials of titanium dioxide, titanium carbide and binder according to a mass ratio of titanium dioxide: titanium carbide: binder = (5-10): (1-1.5): 1, fully mixing and grinding, pressing into tablets, and then sintering in an inert atmosphere, and cooling to obtain a product. The method of the present invention can prepare an integrally formed Ti ₄ O ₇ ceramic electrode, which has a higher hardness than a ceramic electrode prepared by a traditional method using a carbon source as a reducing agent, and the Ti ₄ O ₇ prepared by the method of the present invention has high purity and high reaction activity. When a constant current power supply used in industry is turned on, the degradation rate of the high-concentration refractory organic pollutant active brilliant blue KN-R reaches 79.59%, and the method of the present invention is simple to operate, has high safety, has low equipment requirements, does not require a vacuum environment, can shorten the production cycle, reduce production costs, and can be prepared for large-scale production.

Description

A process for preparing an integrally formed Ti4O7 ceramic electrode by reducing TiC

Technical Field

The invention relates to the fields of conductive materials, _catalytic chemical materials and new energy, and to a process for preparing a _Ti4O7 ceramic electrode, and in particular to a process for preparing an integrally formed _{Ti4O7 ceramic} electrode by reducing TiC.

Background Art

With the development of society and technology, a large amount of wastewater is generated, which has a serious burden on the environment, especially the pollution of the water environment. Therefore, how to better solve the problem of water pollution has attracted much attention. Titanium dioxide is a good active electrode material with a high blackness. Magneli phase Ti ₄ O ₇ has good conductivity at room temperature. Its single crystal conductivity is 1500Scm ^-1 and its volume density is 3.15g/cm ³ ~ 9.18/cm ^3. Magneli phase Ti ₄ O ₇ has high chemical stability, good corrosion resistance and wear resistance, which is superior to general industrial electrode materials. On the other hand, Magneli phase Ti ₄ O ₇ is widely used in environmental protection industry and water treatment field because of its excellent electrochemical properties, high oxygen evolution potential and easy anodization.

The preparation of Magneli phase compounds is usually carried out at high temperature and is obtained by reduction with reducing agents such as Ti, _H2 , C, _NH3 , etc. In the existing technology for preparing Magneli phase compounds, the main technologies are carbon thermal reduction technology and _H2 thermal reduction technology. In the carbon thermal reduction technology, the main carbon reducing agents used are carbon black and organic carbon sources. Although they are cheap and have a low reaction temperature, their carbon sources cannot be fully mixed with titanium dioxide, and the hardness of the one-piece molded electrode prepared by this method is extremely poor. The degree of reduction of _H2 thermal reduction technology is difficult to control, and the safety factor is difficult to guarantee. The above technology is not easy to industrially mass produce, so there is a great need for a method that is easy to operate and can ensure production safety while controlling costs within a low range.

Summary of the invention

The invention provides a process for preparing an integrally formed _{Ti4O7 ceramic} electrode by reducing TiC, which has a simple production process, a short cycle and low cost.

To achieve the above object, the technical solution adopted by the present invention is as follows: A process for preparing an integrally formed Ti ₄ O ₇ ceramic electrode by reducing TiC, comprising the following steps:

Step 1: Weigh the raw materials titanium dioxide, titanium carbide, and binder in a mass ratio of titanium dioxide: titanium carbide: binder = (5-10): (1-1.5): 1, mix and grind them thoroughly, and press them into tablets to obtain a precursor substrate tablet;

Step 2: Place the precursor substrate sheet obtained in step 1 in a porcelain boat and place it in a tubular furnace, introduce an inert atmosphere into the furnace chamber, exhaust the air in the furnace, heat it to 1130-1160°C (preferably 1140-1150°C) at a heating rate of 5-20°C/min, calcine it _for 1-4h (preferably 1.5-3h), and then cool it to room temperature to obtain a _Ti4O7 ceramic electrode.

Preferably, in step 1, the binder comprises polypropylene powder and polyvinyl butyral mixed in a mass ratio of (0.5-1.5):(0.5-1.5) (preferably 1:1).

Preferably, in step 1, the polypropylene powder and polyvinyl butyral in the binder are mixed to obtain a powder with a particle size of 5-10 μm.

Preferably, in step 1, the titanium dioxide is anatase-type titanium dioxide.

Preferably, in step 1, the titanium dioxide has a particle size of 1 to 2 μm and a purity of 99.9%.

Preferably, in step 1, the titanium carbide has a particle size of 2 to 4 μm and a purity of 99%.

Preferably, in step 1, the tabletting step is: dry pressing, the pressure is 50-100 MPa (preferably 50-80 MPa), and the time is 60 to 180 s (preferably 60 to 100 s).

Preferably, the precursor substrate sheet includes disc-shaped, square, round square, rectangular, triangular and tubular structures.

Preferably, in step 2, the inert atmosphere is argon; the argon is high-purity argon with a purity of 99.999%.

Preferably, in step 2, the porcelain boat is located at the center of the furnace chamber to ensure that its height from the upper and lower sides of the furnace chamber is basically consistent.

The beneficial effects of the present invention are:

(1) Magneli phase Ti ₄ O ₇ is the phase with the best electrical conductivity and is an excellent conductive material. It also has many other excellent properties such as good electrochemical stability, strong corrosion resistance and wear resistance. The present invention adopts TiC reduction technology to obtain an integrally formed ceramic electrode of Ti ₄ O ₇ . The product obtained by the method of the present invention has higher reaction activity and higher catalytic efficiency than ordinary titanium dioxide electrode materials under the same conditions.

(2) The hardness of the product prepared by the method of the present invention is higher than that of the ceramic electrode prepared by the traditional method using a carbon source as a reducing agent.

(3) TiC is used as both a reaction raw material and a reducing agent. The C and CO generated during the reaction process play a reducing role and are finally discharged as gas without any residual carbon impurities. The product has high phase purity.

(4) This method uses physical grinding and then directly calcining in the temperature range of 1130-1160°C to obtain the product. It is simple to operate, highly safe, does not require a vacuum environment, has low requirements on equipment, has a wide source of reducing atmosphere, can shorten the production cycle, reduce production costs, and can be used for large-scale industrial production.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a physical picture of the precursor substrate sheet prepared in Example 1 of the present invention.

FIG. 2 is a physical picture of the Ti ₄ O ₇ ceramic electrode prepared in Example 1 of the present invention.

FIG3 is an XRD diagram of the Ti ₄ O ₇ ceramic electrode prepared in Example 1 of the present invention.

FIG. 4 is a SEM image of the Ti ₄ O ₇ ceramic electrode prepared in Example 1 of the present invention.

FIG. 5 is a diagram showing the effect of using Ti ₄ O ₇ ceramic electrode as anode material to degrade reactive brilliant blue KN-R.

DETAILED DESCRIPTION

The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

Unless otherwise specified, the raw materials used in the following examples are all commercially available products. The particle size of titanium carbide is 2-4 μm and the purity is 99%; the particle size of titanium dioxide is 1-2 μm and the purity is 99.9%; and the argon gas is high-purity argon gas with a purity of 99.999%.

A method for preparing an _{integrally formed Ti4O7 ceramic} electrode by reducing TiC, the method comprising the following steps:

Step 1: Use an agate mortar to fully mix and grind titanium dioxide powder, titanium carbide powder and binder in a mass ratio of (5-10):(1-1.5):1 until the mixture is uniform, then put it into a mold and press it with a pressure of 50-100 MPa to obtain a precursor substrate sheet.

The titanium dioxide powder is anatase type; the binder comprises polypropylene powder (PP) and polyvinyl butyral (PVB) in a ratio of 1:1, and the powder particle size is 5 to 10 μm after the binder is mixed.

The titanium dioxide powder, titanium carbide powder and binder are fully mixed and ground to obtain a powder particle size of 1 to 2 μm.

Step 2: Place the precursor substrate sheet obtained in step 1 in a suspended manner in a ceramic boat, place the ceramic boat in a tube furnace, and ensure that it is located in the center of the furnace chamber, and close the tube furnace. Pass high-purity argon gas, ventilate for 20 to 30 minutes to exhaust the air, heat to 1130 to 1160°C at a heating rate of 5 to 20°C/min, calcine for 1 to 4 hours, and cool to room temperature after the insulation to obtain a Ti ₄ O ₇ ceramic electrode.

The precursor substrate sheet includes structures such as disc, square, round square, rectangular, triangular and tubular.

Example 1

A method for preparing an _{integrally formed Ti4O7 ceramic} electrode by reducing TiC, the method comprising the following steps:

Step 1: Use an agate mortar to fully mix and grind titanium dioxide powder, titanium carbide powder and binder in a mass ratio of 7:1.2:1 until the mixture is uniform, then put it into a mold and press it at a pressure of 60MPa to obtain a precursor substrate sheet with a diameter of 1.4cm and a thickness of 2mm. The actual picture of the precursor substrate sheet is shown in Figure 1.

The titanium dioxide powder is anatase type and has a particle size of 2 μm.

The binder comprises polypropylene powder (PP) and polyvinyl butyral (PVB) in a ratio of 1:1, and the powder particle size of the binder is 10 μm. The molecular weight of the polypropylene powder is 42.08, and the molecular weight of the polyvinyl butyral is 40,000-70,000.

Step 2: Place the precursor substrate sheet obtained in step 1 in a suspended ceramic boat, place the ceramic boat in a tube furnace, and ensure that it is located in the center of the furnace chamber to ensure that its height from the upper and lower parts of the furnace chamber is basically the same, and close the tube furnace. Pass high-purity argon gas, ventilate for 20 minutes to exhaust the air, heat to 1145°C at a heating rate of 20°C/min, calcine for 2 hours, and cool to room temperature after the insulation to obtain a Ti ₄ O ₇ ceramic electrode. Figure 2 shows a physical picture of the Ti ₄ O ₇ ceramic electrode prepared in this embodiment. It can be seen that the sheet is intact after firing, and the hardness is higher than that of the ceramic electrode prepared in Comparative Example 1 using a traditional carbon source as a reducing agent.

The prepared Ti ₄ O ₇ ceramic electrode sample was subjected to XRD test. As shown in FIG3 , compared with the PDF50-0787 standard card of Ti ₄ O ₇ , it can be seen that the sample is pure phase Ti ₄ O ₇ without any impurities.

The prepared Ti ₄ O ₇ ceramic electrode sample was ground into powder and observed under a scanning electron microscope, as shown in Figure 4. It can be seen from the figure that the surface porosity of the Ti ₄ O ₇ ceramic electrode is relatively high, and its specific surface area is larger than that of materials with no pores or even few pores of the same volume, so its effective contact area with wastewater is larger, and there are more reaction sites under the same volume, that is, the degradation efficiency is higher.

In this embodiment, the precursor substrate sheet includes disc-shaped, square, round square, rectangular, triangular and tubular structures.

Comparative Example 1

A method for preparing a titanium dioxide anode material, the method comprising the following steps:

Step 1: Use an agate mortar to fully mix and grind the titanium dioxide powder and the binder in a mass ratio of 7:1 until the mixture is uniform, then put it into a mold and press it at a pressure of 60 MPa to obtain a substrate sheet with a diameter of 1.4 cm and a thickness of 2 mm. The titanium dioxide powder is anatase type with a particle size of 2 μm.

The binder comprises polypropylene powder (PP) and polyvinyl butyral (PVB) in a ratio of 1:1, and the powder particle size of the binder is 10 μm. The molecular weight of the polypropylene powder is 42.08, and the molecular weight of the polyvinyl butyral is 40,000-70,000.

Step 2: Place the substrate sheet obtained in step 1 in a ceramic boat, place the ceramic boat in a tube furnace, and ensure that it is located in the center of the furnace chamber to ensure that its height from the upper and lower parts of the furnace chamber is basically the same, and close the tube furnace. Pass high-purity argon gas, ventilate for 20 minutes to exhaust the air, heat to 1145°C at a heating rate of 20°C/min, calcine for 2 hours, and cool to room temperature after the insulation to obtain the titanium dioxide anode material.

Example 2

Experiment on degradation of reactive brilliant blue KN-R using the Ti ₄ O ₇ ceramic electrode prepared in Example 1 as anode material:

The experimental device, i.e. the photoelectrocatalytic activity test device, consists of three parts: a magnetic stirrer, a photoelectrocatalytic reactor and a DC regulated power supply. The function of the magnetic stirrer is to keep the dye concentration in a relatively uniform state at all times. The working state of the DC regulated power supply is 120V, 0.09A.

Prepare 200 mL of 100 mg/L reactive brilliant blue KN-R solution, add 2.84 g of anhydrous sodium sulfate (Na ₂ SO ₄ ) as a supporting electrolyte, and pour the prepared reactive brilliant blue KN-R solution into an electrocatalytic reactor as a simulated dye. Use the Ti ₄ O ₇ ceramic electrode prepared in Example 1 as a reaction anode and a stainless steel sheet as a reaction cathode, insert them into the reactor, place them in parallel, and then turn on the agitator. After the solution is completely mixed, use a 5 mL pipette to take 3 mL of the reactor liquid as sample #1. Turn on the power to start the electrocatalytic reaction, which lasts for 120 minutes. During the entire electrocatalytic reaction, use a 5 mL pipette to take 3 mL of the reactor liquid every 20 minutes, and sort the samples in order.

After the experiment, the absorbance of all samples at 596 nm was measured by UV759 ultraviolet spectrophotometer (Shanghai Yidian Analytical Instrument Co., Ltd.), and the degradation rate of reactive brilliant blue KN-R was calculated according to formula 1. The experimental results are shown in Figure 5. It can be seen that the degradation rate of reactive brilliant blue KN-R, a high-concentration difficult-to-degrade organic pollutant, by the one-piece _Ti4O7 ceramic electrode prepared _by TiC reduction can reach 79.59%.

Where: D-degradation rate, %

A ₀ - initial absorbance of reactive brilliant blue KN-R solution;

A _t - the absorbance of reactive brilliant blue KN-R at time t of degradation.

Comparative Example 2

Experiment on degradation of reactive brilliant blue KN-R using the titanium dioxide electrode prepared in Comparative Example 1 as anode material:

The experimental device, i.e. the photoelectrocatalytic activity test device, consists of three parts: a magnetic stirrer, a photoelectrocatalytic reactor and a DC regulated power supply. The function of the magnetic stirrer is to keep the dye concentration in a relatively uniform state at all times. The working state of the DC regulated power supply is 120V, 0.09A.

Prepare 200 mL of 100 mg/L reactive brilliant blue KN-R solution, add 2.84 g of anhydrous sodium sulfate (Na ₂ SO ₄ ) as a supporting electrolyte, and pour the prepared reactive brilliant blue KN-R solution into the electrocatalytic reactor as a simulated dye. Use the titanium dioxide electrode prepared in Comparative Example 1 as the reaction anode and the stainless steel sheet as the reaction cathode, insert them into the reactor, place them in parallel, and then turn on the agitator. After the solution is completely mixed, use a 5 mL pipette to take 3 mL of the reactor liquid as sample #1. Turn on the power to start the electrocatalytic reaction, which lasts for 120 minutes. During the entire electrocatalytic reaction, use a 5 mL pipette to take 3 mL of the reactor liquid every 20 minutes, and sort the samples in order.

After the experiment, the absorbance of all samples at 596 nm was measured using a UV759 ultraviolet spectrophotometer (Shanghai Yidian Analytical Instrument Co., Ltd.), and the degradation rate of Reactive Brilliant Blue KN-R was calculated to be 25% according to Formula 1 in Example 2.

By comparing Example 2 with Comparative Document 2, when a constant current power supply used in industry is turned on, the degradation rate of the titanium dioxide anode material for the high-concentration difficult-to-degrade organic pollutant reactive brilliant blue KN-R is only 25%, while the one- _{piece Ti4O7} ceramic electrode prepared by TiC reduction can reach 79.59%, and the catalytic efficiency is three times that of ordinary titanium dioxide electrodes.

Comparative Example 3

A method for preparing an integrated ceramic electrode using conventional carbon source nano carbon black as a reducing agent, the method comprising the following steps:

Step 1: Use an agate mortar to fully mix and grind titanium dioxide powder, nano carbon black and binder in a mass ratio of 7:1.2:1 until they are evenly mixed, then put them into a mold and press them at a pressure of 60 MPa to obtain a precursor substrate sheet with a diameter of 1.4 cm and a thickness of 2 mm.

The titanium dioxide powder is anatase type and has a particle size of 2 μm.

The binder comprises polypropylene powder (PP) and polyvinyl butyral (PVB) in a ratio of 1:1, and the powder particle size of the binder is 10 μm. The molecular weight of the polypropylene powder is 42.08, and the molecular weight of the polyvinyl butyral is 40,000-70,000.

Step 2: Place the precursor substrate sheet obtained in step 1 in a suspended manner in a ceramic boat, place the ceramic boat in a tube furnace, and ensure that it is located in the center of the furnace chamber, and close the tube furnace. Pass high-purity argon gas, ventilate for 20 minutes to exhaust the air, heat to 1145°C at a heating rate of 20°C/min, calcine for 2 hours, and cool to room temperature after the insulation to obtain Ti ₄ O ₇ powder.

When using traditional carbon source nano-carbon black as a reducing agent to prepare one-piece ceramic electrodes, the resulting product has a loose structure, extremely poor hardness, and is extremely fragile. An one-piece electrode cannot be obtained by firing, and it is in powder form after firing. Therefore, traditional carbon sources are not suitable for the preparation of one-piece ceramic electrodes.

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (10)

1. A process for preparing an integrally formed Ti ₄ O ₇ ceramic sheet electrode by reducing TiC, characterized in that it comprises the following steps: Step 1: Weigh the raw materials titanium dioxide, titanium carbide, and binder in a mass ratio of titanium dioxide: titanium carbide: binder = (5-10): (1-1.5): 1, mix and grind them thoroughly, and press them into tablets to obtain a precursor substrate tablet; Step 2: Place the precursor substrate sheet prepared in step 1 in a porcelain boat and place it in a tubular furnace, introduce an inert atmosphere into the furnace chamber, exhaust the air in the furnace, heat it to 1130-1160°C at a heating rate of 5-20°C/min, calcine it for 1-4h, and then cool it to room temperature to obtain _{a Ti4O7} ceramic electrode. 2. The process for preparing an integrally formed Ti ₄ O ₇ ceramic electrode by reducing TiC according to claim 1, characterized in that in step 1, the binder comprises polypropylene powder and polyvinyl butyral mixed in a mass ratio of (0.5-1.5):(0.5-1.5). 3. The process for preparing an integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1 or 2, characterized in that in step 1, the particle size of the binder is _5-10 μm. 4. The process for preparing an _integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1, characterized in that in step 1, the titanium dioxide is anatase-type titanium dioxide. 5. The process for preparing an integrally formed _{Ti4O7 ceramic} electrode by reducing TiC according to claim 4, characterized in that in step 1, the particle size of the titanium dioxide is 1-2 μm and the purity is 99.9%. 6. The process for preparing an _integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1, characterized in that in step 1, the particle size of the titanium carbide is 2-4 μm and the purity is 99%. 7. The process for preparing an _integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1, characterized in that in step 1, the tabletting step is: dry pressing, with a pressure of 50-100 MPa and a time of 60 to 180 seconds. 8. The process for preparing an _integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1, characterized in that the precursor substrate sheet comprises a disc-shaped, square, round square, rectangular, triangular or tubular structure. 9. The process for preparing an _integrally formed _Ti4O7 ceramic electrode by reducing TiC according to claim 1, characterized in that in step 2, the inert atmosphere is argon; the argon is high-purity argon with a purity of 99.999%. 10. The process for preparing an _{integrally formed Ti4O7 ceramic} electrode by reducing TiC according to claim 1, wherein the ceramic boat in step 2 is located at the center of the furnace chamber.