Kaolin and talcum powder composite modified material and preparation process thereof

Abstract

The invention belongs to the technical field of inorganic non-metallic material modification, and discloses a kaolin and talcum powder composite modified material which comprises the following components in percentage by mass: 40%-50% of calcined kaolin, 20%-30% of fine talcum powder, 8%-12% of cobalt nitrate (Co (NO). 6HO), 6%-10% of nickel salt, 5%-8% of urea, 2.0%-3.0% of a silane coupling agent KH-570, 1.5%-2.0% of a titanate coupling agent TMC-130 and a proper amount of deionized water. According to the preparation method, a micropore-mesopore-macropore multilevel structure is constructed through cooperation of urea pyrolysis and mineral interlayer exfoliation, and electron transfer optimization of CoO-NiO heterojunction is combined, so that the CO oxidation initiation temperature is reduced to 220 DEG C or below, the catalytic efficiency is improved by 1.5 times compared with that of a single metal system, and excellent carbon deposition resistance is achieved. Through compounding of calcined kaolin and fine talcum powder and directional modification of double coupling agents, the material is endowed with high breaking strength and low thermal expansion coefficient, can resist the temperature of 1750 DEG C and can resist severe thermal shock for more than 20 times, the industrial production compatibility is outstanding, and double breakthrough of performance and economic benefits is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of modification of inorganic non-metallic materials, and particularly relates to a kaolin and talc composite modified material and a preparation process thereof. Background Art

[0002] Traditional kaolin-based composite materials are an important engineering material. However, they currently face multiple technical bottlenecks. Kaolin-based composite materials are materials mainly composed of kaolin and compounded with other materials. Kaolin is a non-metallic mineral mainly composed of kaolinite, with a layered silicate structure, and is widely used in various fields due to its excellent physical and chemical properties. However, traditional kaolin-based composite materials show deficiencies in mechanical properties. The flexural strength of a single mineral matrix is usually less than or equal to 15 MPa (according to ASTM C1161 standard), which makes it difficult for them to meet the requirements of high-load applications. In addition, the functions of these materials are relatively single, and the specific surface area of the unmodified layered structure often does not exceed 50 m² / g, which limits the possibility of them having both catalytic and strengthening functions at the same time. Meanwhile, the interfacial compatibility problem is also one of the key factors restricting the performance improvement of kaolin-based composite materials. Due to only using a single coupling agent for treatment, the shear strength of the organic-inorganic interface usually does not exceed 10 MPa (according to ASTM D3164 standard), further affecting the overall performance of the composite material. Therefore, it is necessary to improve them. Summary of the Invention

[0003] The purpose of the present invention is to provide a kaolin and talc composite modified material and a preparation process thereof to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A kaolin and talc composite modified material, including the following components by mass percentage: calcined kaolin 40%-50%, fine talc powder 20%-30%, cobalt nitrate (Co(NO3)2·6H2O) 8%-12%, nickel salt 6%-10%, urea 5%-8%, silane coupling agent KH-570 2.0%-3.0%, titanate coupling agent TMC-130 1.5%-2.0%, and appropriate amount of deionized water.

[0005] Preferably, the calcined kaolin is a product calcined at 600°C - 800°C, with a whiteness ≥ 94%, a specific surface area ≥ 80 m² / g, and is ball-milled to D50 ≤ 3 μm; The fine talc powder is pretreated by microwave with 0.1 mol / L - 0.5 mol / L hydrochloric acid, and the activation index ≥ 20%.

[0006] Preferably, the molar ratio of the nickel salt to cobalt nitrate is 1:1.2 - 1.5. After calcination, a CoO-NiO heterojunction is formed, and the interfacial spacing of the heterojunction is 0.23 - 0.25 nm; The mass ratio of the silane coupling agent to the titanate coupling agent is 1.2:1 - 1.5:1.

[0007] Preferably, the composite modified material has a three-level pore structure, including: Micropores: pore diameter < 2 nm, accounting for 10% - 15%; Mesopores: pore diameter 2 - 50 nm, accounting for 50% - 70%; Macropores: pore diameter > 50 nm, accounting for 20% - 30%; The total specific surface area ≥ 95 m² / g, and the pore volume ≥ 0.35 cm³ / g.

[0008] Preferably, it includes the following steps: (1) Raw material pretreatment: Ball-mill the calcined kaolin and zirconia balls at a ball-to-material ratio of 4:1 - 6:1 for 1.5 - 2.5 h at a rotation speed of 250 - 350 rpm to obtain kaolin powder with D50 ≤ 3 μm; Pre-mix the fine talc powder with 40 - 50% of the total amount of KH-570 at 50 - 70 °C, with a stirring speed of 800 - 1200 rpm for 30 - 60 min; (2) Slurry blending: Dissolve cobalt nitrate, nickel salt, and urea in deionized water, and add the pretreated kaolin and talc powder; After ultrasonic dispersion, add the remaining KH-570 and 60% of the total amount of TMC-130, and stir at 60 - 80 °C for 1 - 2 h; (3) Spray drying: The inlet air temperature is 160 - 200 °C, the outlet air temperature is 80 - 100 °C, and the atomization pressure is 0.2 - 0.5 MPa to obtain precursor particles with a particle size of 50 - 100 μm; (4) Stepwise calcination: The first stage: Keep the temperature at 250 - 350 °C for 1 - 3 h, and the heating rate ≤ 5 °C / min; The second stage: Keep the temperature at 500 - 700 °C for 2 - 4 h, and naturally cool to 300 °C; The third stage: Keep the temperature at 850 - 950 °C for 0.5 - 1.5 h, and the nitrogen flow rate is 1 - 3 L / min; (5) Post-treatment: The calcined product is airflow-crushed to D90 ≤ 20 μm; Screen through 325 meshes to obtain the final product.

[0009] Preferably, in the slurry blending in step (2), the viscosity of the slurry is controlled at 200-500 mPa·s; After the third stage of the step (4) stepwise calcination, the material crystal phase includes mullite and periclase.

[0010] Preferably, for the high-temperature catalytic carrier: after loading 0.5-2% Pt or Pd, the CO oxidation light-off temperature T50 ≤ 180 °C; Engineering plastic reinforcing phase: adding 20-30% to polypropylene, the flexural modulus ≥ 6 GPa, and the heat distortion temperature ≥ 150 °C; Refractory coating: coated on the metal matrix, the temperature resistance ≥ 1750 °C, and the thermal shock cycle ≥ 20 times without cracking.

[0011] Preferably, in the application of the high-temperature catalytic carrier, the specific surface area of the material ≥ 95 m² / g, and the noble metal dispersion ≥ 80%; In the application of the refractory coating, the coating thickness is 100-300 μm, and the thermal conductivity ≤ 1.5 W / (m·K).

[0012] Preferably, it includes: pore size distribution test: using an ASAP2460 type specific surface area analyzer, calculating the specific surface area by the BET method and calculating the mesopore distribution by the BJH method; Catalytic activity test: introducing a 1% CO / air mixture into a fixed-bed reactor, heating to 500 °C at a rate of 5 °C / min, and recording the T50 temperature; Interface binding energy test: single fiber pull-out method, fiber diameter 7 μm, loading rate 0.5 mm / min.

[0013] Preferably, in the catalytic activity test, the CO conversion rate is monitored in real time by on-line gas chromatography; The interface binding energy is calculated using the formula:

[0014] where, is the maximum pull-out force, d is the fiber diameter, and L is the embedded length.

[0015] The beneficial effects of the present invention are as follows: 1. Through the synergistic effect of pore formation by urea pyrolysis gas (NH3 / CO2) and the interlayer exfoliation of kaolin / talc powder, a hierarchical pore structure of micropores-mesopores-macropores is constructed (mesopores account for ≥60%, specific surface area ≥95 m² / g), significantly improving the density of active sites and the mass transfer efficiency of reactants. The formation of the CoO-NiO heterojunction (interface spacing 0.23 - 0.25 nm) optimizes the electron migration path, reducing the light-off temperature (T50) of CO oxidation to below 220 °C, a decrease of more than 50 °C compared to the single-metal system. Meanwhile, the mesoporous structure (pore diameter 50 - 200 nm) effectively alleviates the carbon deposition problem, and the activity retention rate is ≥95% after continuous operation for 100 h. This characteristic gives it significant advantages in the fields of automotive exhaust purification (DOC carrier) and VOCs catalytic combustion, and the noble metal loading can be reduced by more than 30%.

[0016] 2. By compounding calcined kaolin (flexural strength ≥18 MPa) and fine talc powder (particle size D50 ≤5 μm), and combining the directional modification with a double coupling agent (interface binding energy ≥1.5 J / m²), the flexural strength of the material is increased to 25 - 28 MPa, a more than 66% increase compared to traditional mineral composites (≤15 MPa). The stepwise calcination process (nitrogen protection at 900 °C) promotes the transformation of kaolin into mullite phase (3Al2O3·2SiO2), and talc powder generates periclase (MgO). The thermal expansion coefficient of the material is as low as 3.2×10⁻ 6 / °C (RT - 800 °C), and the refractoriness is ≥1750 °C. As a refractory coating, it can withstand more than 20 thermal shock cycles of 1000 °C ↔ 25 °C without cracking of the coating, and the thermal conductivity ≤1.5 W / (m·K), which is suitable for the protection of high-temperature components in aerospace.

[0017] 3. The process innovation of the present invention enables large-scale production: spray drying (particle sphericity ≥90%) and air jet milling (D90 ≤20 μm) ensure the uniformity of the material; the staged addition of coupling agents (pre-modified talc powder with KH-570, post-treatment of kaolin with TMC-130) improves the organic-inorganic interface compatibility by 35%, meeting the processing requirements such as injection molding and spraying. In the field of engineering plastics, adding 30% of the composite material can increase the flexural modulus of PP from 2.1 GPa to 6.5 GPa, and the heat distortion temperature from 62 °C to above 150 °C. Meanwhile, plasma post-treatment (power 50 - 100 W) further reduces the surface energy to 25 mN / m, enhancing the bonding force with matrices such as epoxy resin. This material has been successfully applied to industrial scenarios such as automotive catalysis, electronic packaging, and refractory kiln furniture, and the comprehensive cost is reduced by 20 - 40% compared to traditional solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the process flow chart of the preparation of the composite modified material of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0020] As Figure 1 shown, the embodiment of the present invention provides a composite modified material of kaolin and talc powder, which comprises the following components by mass percentage: calcined kaolin 40%-50%, fine talc powder (D50≤5μm) 20%-30%, cobalt nitrate (Co(NO3)2·6H2O) 8%-12%, nickel salt (Ni(NO3)2·6H2O or NiCl2·6H2O) 6%-10%, urea 5%-8%, silane coupling agent KH-570 2.0%-3.0%, titanate coupling agent TMC-130 1.5%-2.0%, and appropriate amount of deionized water.

[0021] Among them, the calcined kaolin is a product calcined at 600°C - 800°C, with a whiteness ≥ 94%, a specific surface area ≥ 80 m² / g, and is ball-milled to D50≤3μm; The fine talc powder is pretreated by microwave with 0.1mol / L - 0.5mol / L hydrochloric acid (power 300 - 500W, time 10 - 20min), and the activation index ≥ 20%.

[0022] Among them, the molar ratio of nickel salt to cobalt nitrate is 1:1.2 - 1.5, and a CoO-NiO heterojunction is formed after calcination, and the interfacial spacing of the heterojunction is 0.23 - 0.25nm; The mass ratio of silane coupling agent to titanate coupling agent is 1.2:1 - 1.5:1.

[0023] Among them, the composite modified material has a three-level pore structure, including: Micropores: pore diameter <2nm, accounting for 10%-15%; Mesopores: pore diameter 2 - 50nm, accounting for 50%-70%; Macropores: pore diameter >50nm, accounting for 20%-30%; The total specific surface area ≥ 95 m² / g, and the pore volume ≥ 0.35 cm³ / g.

[0024] Among them, it includes the following steps: (1) Pretreatment of raw materials: Ball-mill the calcined kaolin and zirconia balls at a ball-to-material ratio of 4:1 - 6:1 for 1.5 - 2.5h, with a rotation speed of 250 - 350rpm, to obtain kaolin powder with D50≤3μm; Pre-mix fine talcum powder with 40 - 50% of the total amount of KH-570 at 50 - 70°C, with a stirring speed of 800 - 1200 rpm for 30 - 60 min; (2) Slurry blending: Dissolve cobalt nitrate, nickel salt, and urea in deionized water (solid-liquid ratio 1:2 - 1:4), and add the pretreated kaolin and talcum powder; After ultrasonic dispersion (frequency 30 - 50 kHz, time 20 - 40 min), add the remaining KH-570 and 60% of the total amount of TMC-130, and stir at 60 - 80°C for 1 - 2 h; (3) Spray drying: Inlet air temperature 160 - 200°C, outlet air temperature 80 - 100°C, atomization pressure 0.2 - 0.5 MPa, to obtain precursor particles with a particle size of 50 - 100 μm; (4) Stepwise calcination: First stage: Keep the temperature at 250 - 350°C for 1 - 3 h, with a heating rate ≤ 5°C / min; Second stage: Keep the temperature at 500 - 700°C for 2 - 4 h, and naturally cool down to 300°C; Third stage: Keep the temperature at 850 - 950°C for 0.5 - 1.5 h, with a nitrogen flow rate of 1 - 3 L / min; (5) Post-treatment: The calcined product is air-flow pulverized (pressure 0.6 - 1.0 MPa) to D90 ≤ 20 μm; Screen through 325 mesh to obtain the final product.

[0025] Among them, in step (2) slurry blending, the slurry viscosity is controlled at 200 - 500 mPa·s (Brookfield viscometer, rotor LV3, rotation speed 60 rpm); After the third stage of step (4) stepwise calcination, the material crystal phase includes mullite (3Al2O3·2SiO2, PDF#15 - 0776) and periclase (MgO, PDF#45 - 0946).

[0026] Among them, for the high-temperature catalytic carrier: after loading 0.5 - 2% Pt or Pd, the CO oxidation light-off temperature T50 ≤ 180°C; For the engineering plastic reinforcing phase: add 20 - 30% to polypropylene (PP), with a flexural modulus ≥ 6 GPa and a heat distortion temperature (under a load of 1.82 MPa) ≥ 150°C; For the refractory coating: coated on the metal substrate, with a heat resistance ≥ 1750°C and a thermal shock cycle (1000°C ↔ 25°C) ≥ 20 times without cracking.

[0027] Among them, in the application of high-temperature catalytic carriers, the specific surface area of the material is ≥95 m² / g, and the noble metal dispersion is ≥80% (measured by the CO chemisorption method); In the application of refractory coatings, the coating thickness is 100 - 300 μm, and the thermal conductivity is ≤1.5 W / (m·K) (measured by the laser flash method).

[0028] Among them, it includes: pore size distribution test: using an ASAP2460 specific surface area analyzer, calculating the specific surface area by the BET method and the mesopore distribution by the BJH method; Catalytic activity test: introducing a 1% CO / air mixture (space velocity 10000 h⁻¹) into a fixed-bed reactor, heating to 500 °C at a rate of 5 °C / min, and recording the T50 temperature; Interface binding energy test: single fiber pull-out method (ASTM D2344), fiber diameter 7 μm, loading rate 0.5 mm / min.

[0029] Among them, in the catalytic activity test, the CO conversion rate is monitored in real time by an on-line gas chromatograph (GC-7890B, TCD detector); The interface binding energy is calculated using the formula:

[0030] Among them, is the maximum pull-out force, d is the fiber diameter, and L is the embedded length.

[0031] Examples Raw material ratio: Calcined kaolin (calcined at 700 °C) 45 kg Talc powder (D50 = 4 μm, microwave-treated with 0.3 mol / L HCl) 25 kg Co(NO3)2·6H2O 10 kg Ni(NO3)2·6H2O 8 kg Urea 7 kg KH-570 2.5 kg TMC-130 1.8 kg Preparation process: Kaolin ball milling: zirconia ball milling tank, ball-to-material ratio 5:1, rotation speed 300 rpm, time 2 h, obtaining a powder with D50 = 2.3 μm; Talc powder pretreatment: 1.0 kg of KH-570 is stirred with talc powder at 60 °C for 40 min (1200 rpm); Slurry blending: cobalt nitrate, nickel salt, and urea are dissolved in 150 kg of deionized water, adding mineral powder, and ultrasonic dispersion (40 kHz, 30 min); Secondary coupling: Add the remaining 1.5 kg of KH-570 and 1.08 kg of TMC-130, stir at 70 °C for 1.5 h; Spray drying: Inlet air temperature is 180 °C, outlet air temperature is 95 °C, atomization pressure is 0.3 MPa, to obtain particles with a particle size of 60 - 80 μm; Stepwise calcination: 300 °C / 2 h (5 °C / min) → 600 °C / 3 h (N2 1 L / min) → 900 °C / 1 h; Post-treatment: Jet milling (0.8 MPa) to D90 = 14 μm, sieving with a 325-mesh sieve.

[0032] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0033] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A kaolin and talc composite modified material, characterized in that: It comprises the following components by mass percentage: calcined kaolin 40%-50%, fine talc powder 20%-30%, cobalt nitrate (Co(NO3)2·6H2O) 8%-12%, nickel salt 6%-10%, urea 5%-8%, silane coupling agent KH-570 2.0%-3.0%, titanate coupling agent TMC-130 1.5%-2.0%, and appropriate amount of deionized water.

2. The composite modified material of kaolin and talcum powder according to claim 1, characterized in that: The calcined kaolin is a product calcined at 600°C - 800°C, with whiteness ≥94%, specific surface area ≥80 m² / g, and is ball-milled to D50 ≤3 μm; The fine talc powder is pretreated by microwave with 0.1 mol / L - 0.5 mol / L hydrochloric acid, and the activation index ≥20%; 3. A kaolin and talc powder composite modified material according to claim 1, characterized in that: The molar ratio of the nickel salt to cobalt nitrate is 1:1.2 - 1.5, and a CoO-NiO heterojunction is formed after calcination, with the interfacial spacing of the heterojunction being 0.23 - 0.25 nm; The mass ratio of the silane coupling agent to the titanate coupling agent is 1.2:1 - 1.5:

1.

4. A kaolin and talc composite modified material according to claim 1, characterized in that: The composite modified material has a three-level pore structure, including: Micropores: pore diameter <2 nm, accounting for 10% - 15%; Mesopores: pore diameter 2 - 50 nm, accounting for 50% - 70%; Macropores: pore diameter >50 nm, accounting for 20% - 30%; Total specific surface area ≥95 m² / g, pore volume ≥0.35 cm³ / g.

5. The preparation process of a kaolin and talc composite modified material according to any one of claims 1-4, characterized in that: It includes the following steps: (1) Raw material pretreatment: Ball-mill the calcined kaolin and zirconia balls at a ball-to-material ratio of 4:1 - 6:1 for 1.5 - 2.5 h at a rotation speed of 250 - 350 rpm to obtain kaolin powder with D50 ≤3 μm; Premix the fine talc powder with 40 - 50% of the total amount of KH-570 at 50 - 70°C, with a stirring speed of 800 - 1200 rpm for 30 - 60 min; (2) Slurry blending: Dissolve cobalt nitrate, nickel salt, and urea in deionized water, and add the pretreated kaolin and talc powder; After ultrasonic dispersion, add the remaining KH-570 and 60% of the total amount of TMC-130, and stir at 60 - 80°C for 1 - 2 h; (3) Spray drying: inlet air temperature 160 - 200°C, outlet air temperature 80 - 100°C, atomization pressure 0.2 - 0.5 MPa, to obtain precursor particles with a particle size of 50 - 100 μm; (4) Stepwise calcination: The first stage: keep at 250 - 350°C for 1 - 3 h, with a heating rate ≤5°C / min; The second stage: keep at 500 - 700°C for 2 - 4 h, and naturally cool to 300°C; The third stage: keep at 850 - 950°C for 0.5 - 1.5 h, with a nitrogen flow rate of 1 - 3 L / min; (5) Post-treatment: The calcined product is airflow-crushed to D90 ≤20 μm; Screen through 325 mesh to obtain the final product.

6. The preparation process of a kaolin and talc composite modified material according to claim 5, characterized in that: In the step (2) of slurry blending, the slurry viscosity is controlled at 200 - 500 mPa·s; After the third stage of the step (4) of stepwise calcination, the material crystal phase contains mullite and periclase.

7. Use of a kaolin and talc composite modified material according to any one of claims 1-4, characterized in that: High-temperature catalytic carrier: after loading 0.5 - 2% Pt or Pd, the CO oxidation light-off temperature T50 ≤180°C; Engineering plastic reinforcing phase: Add 20 - 30% to polypropylene, flexural modulus ≥ 6 GPa, heat distortion temperature ≥ 150 °C; Refractory coating: Coated on the metal matrix, temperature resistance ≥ 1750 °C, thermal shock cycle ≥ 20 times without cracking.

8. The application of a composite modified material of kaolin and talc powder according to claim 7, characterized in that: In the application of the high-temperature catalytic carrier, the specific surface area of the material ≥ 95 m² / g, noble metal dispersion ≥ 80%; In the application of the refractory coating, the coating thickness is 100 - 300 μm, and the thermal conductivity ≤ 1.5 W / (m·K).

9. The performance detection method of a kaolin and talcum powder composite modified material according to claim 1, wherein: It includes: Pore size distribution test: Using ASAP2460 specific surface area analyzer, calculating specific surface area by BET method and mesopore distribution by BJH method; Catalytic activity test: Pass 1% CO / air mixture into the fixed-bed reactor, heat up to 500 °C at a rate of 5 °C / min, and record the T50 temperature; Interface binding energy test: Single fiber pull-out method, fiber diameter 7 μm, loading rate 0.5 mm / min.

10. The performance detection method of a kaolin and talcum powder composite modified material according to claim 9, characterized in that: In the said catalytic activity test, the CO conversion rate is monitored in real time by on-line gas chromatography; The interface binding energy is calculated using the formula: Among them, is the maximum pull-out force, d is the fiber diameter, and L is the embedment length.

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