Heat storage ceramic with high resistance to silicon blockage and preparation process of heat storage ceramic

Abstract

The invention relates to heat storage ceramic with high silicon blockage resistance and a preparation process of the heat storage ceramic. The heat storage ceramic comprises a ceramic matrix and lanthanum-praseodymium-titanium modified liquid for dipping the ceramic matrix, the preparation raw materials of the ceramic matrix comprise the following components in parts by weight: 35-45 parts of kaolin, 20-30 parts of alumina powder, 10-14 parts of silicon carbide powder and 5-8 parts of a fluxing agent; the lanthanum-praseodymium-titanium modified liquid is prepared from the following raw materials: lanthanum nitrate, praseodymium nitrate, nano titanium dioxide sol and water. The heat storage ceramic is low in initial adhesion silicon content, easy to clean and gt in crusting stripping rate; and the silicon plugging resistance is good.

Description

Technical Field

[0001] This application relates to the field of industrial waste gas treatment technology, and in particular to a high silicon blockage-resistant heat storage ceramic and its preparation process. Background Technology

[0002] Regenerative Thermal Oxidizers (RTOs), as a high-purity and high-thermal-efficiency technology for treating organic waste gas, rely on high-temperature oxidation and decomposition of VOCs at 760℃~870℃, and recover heat through silicon-alumina-based regenerative ceramics, achieving a thermal efficiency of ≥90%, and are widely used in various industries. However, when treating silicon-containing organic compounds, the silicon element is converted into SiO2 after high-temperature oxidation. SiO2 combines with aluminosilicates on the surface of the silicon-alumina-based regenerative ceramic in a chemical bond-like form, crystallizing and growing on the ceramic surface and occupying the pores, causing ceramic blockage. In the early stages of blockage, the RTO system pressure increases and the main fan power consumption increases. (Based on a 50,000m³...) 3 According to the design load calculation, the power consumption increases by 16.3 kWh for every 1000 Pa increase in pressure; as the blockage worsens, it will lead to a reduction in the workshop's exhaust volume, and may even trigger an emergency shutdown of the RTO, affecting production.

[0003] Existing conventional thermal storage ceramics lack the ability to resist SiO2 crystallization and adhesion, thus failing to meet the practical requirements for treating silicon-containing organic waste gases. Therefore, the development of thermal storage ceramics with resistance to SiO2 crystallization and adhesion is an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a high-resistance silicon blockage thermal storage ceramic and its preparation process. When RTO treats silicon-containing organic waste gas, it has the ability to resist SiO2 crystal adhesion, which solves the problem of blockage caused by silicon accumulation in the pores of the thermal storage body.

[0005] In a first aspect of this application, this application provides a high-silicon-blocking-resistant thermal storage ceramic, comprising a ceramic matrix and a lanthanum-praseodymium-titanium modified liquid impregnating the ceramic matrix; the raw materials for preparing the ceramic matrix include the following components in parts by weight: 35-45 parts by weight of kaolin, 20-30 parts by weight of alumina powder, 10-14 parts by weight of silicon carbide powder, and 5-8 parts by weight of flux; the raw materials for preparing the lanthanum-praseodymium-titanium modified liquid include lanthanum nitrate, praseodymium nitrate, nano-titanium dioxide sol, and water.

[0006] By adopting the above technical solution, this application provides a high-resistance silicon-blocking thermal storage ceramic. This thermal storage ceramic has a low initial silicon content, is easy to clean, has a shell peeling rate >85.0%, and exhibits good anti-silicon-blocking performance. This may be because, on the one hand, the nano-titanium dioxide sol can promote the densification of the ceramic channel surface during high-temperature sintering, reduce surface energy and roughness, and reduce the physical anchoring points of SiO2 crystallization; on the other hand, rare earth elements and titanium ions react on the ceramic surface at high temperature to generate a dense composite oxide protective layer with a special lattice structure. This protective layer effectively shields the active silicate bonds inside the matrix, preventing the formation of strong chemical bonds between SiO2 generated in the exhaust gas and the ceramic matrix. Therefore, the attached silicon shell maintains only weak physical adsorption to the ceramic surface, and under sudden temperature changes or mechanical purging, it is very easy to peel off in large areas using the difference in thermal stress, thus endowing the ceramic with excellent high anti-silicon-blocking and easy-to-clean properties.

[0007] Optionally, in the lanthanum-praseodymium-titanium modified liquid, lanthanum nitrate is lanthanum nitrate hexahydrate and praseodymium nitrate is praseodymium nitrate hexahydrate.

[0008] Optionally, in the lanthanum-praseodymium-titanium modified solution, the mass ratio of lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate and nano titanium dioxide sol is (18-22):(9-11):(12-18).

[0009] By adopting the above technical solution and adjusting the amounts of lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, and nano-titanium dioxide sol according to the above weight ratio, when the mass ratio of lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, and nano-titanium dioxide sol is (18-22):(9-11):(12-18), the prepared heat storage ceramic can be guaranteed to have good anti-silicon blockage performance.

[0010] Optionally, in the lanthanum-praseodymium-titanium modified solution, the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is (7-15):5.

[0011] By adopting the above technical solution and adjusting the amounts of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate according to the above weight ratio, when the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is (7-15):5, it can be ensured that the obtained heat storage ceramic has a low initial attached silicon content, is easy to clean, has a high shell peeling rate, and good anti-silicon blockage performance.

[0012] Optionally, the preparation method of the lanthanum-praseodymium-titanium modified liquid includes the following steps: a1. Weigh water and ethanol, mix them evenly, add lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, and citric acid, stir, and obtain a lanthanum-praseodymium complex solution; a2. Under stirring conditions, the nano-titanium dioxide sol is added to the lanthanum-praseodymium complex solution obtained in step a1, and then sonicated and aged to obtain a lanthanum-praseodymium-titanium modified solution.

[0013] Optionally, the flux comprises 3.83-4.83 parts by weight of feldspar powder and 1.67-2.67 parts by weight of zinc borate.

[0014] In a second aspect of this application, a preparation process for the high silicon blockage-resistant thermal storage ceramic described in the first aspect of this application is provided, comprising the following steps: S1. Dry grind kaolin, alumina powder, and silicon carbide powder, and sieve them to obtain ultrafine powder. S2. Mix the ultrafine powder obtained in step S1 with a flux, knead, and granulate to obtain spherical particles. S3. Add the spherical particles obtained in step S2 into the mold, shape, and press to obtain a sheet-like airflow channel ceramic green body. S4. The sheet-like airflow channel ceramic green body obtained in step S3 is dried, impregnated in lanthanum-praseodymium-titanium modified liquid, dried, sintered, and cooled to obtain a high silicon blockage-resistant heat storage ceramic.

[0015] Optionally, in step S3, the molding process is isostatic pressing at 170-190MPa with a holding time of 5-7 minutes.

[0016] Optionally, in step S4, the immersion time in the lanthanum-praseodymium-titanium modified solution is 20-40 minutes.

[0017] Optionally, in step S4, the sintering conditions are to hold at 550-650℃ for 2-3 hours and at 1200-1300℃ for 4-6 hours.

[0018] In a third aspect of this application, this application provides an application of the high silicon blockage-resistant thermal storage ceramic described in the first aspect of this application in the RTO treatment of silicon-containing organic waste gas.

[0019] In summary, the present invention has at least one of the following beneficial technical effects: 1. This application provides a high-resistance silicon-blocking thermal storage ceramic. This ceramic has a low initial silicon content, is easy to clean, has a shell peeling rate >85.0%, and exhibits excellent resistance to silicon blockage. On one hand, the nano-titanium dioxide sol promotes the densification of the ceramic channel surface during high-temperature sintering, reducing surface energy and roughness, and decreasing the physical anchoring points for SiO2 crystallization. On the other hand, rare earth elements and titanium ions react at high temperatures on the ceramic surface to generate a dense composite oxide protective layer with a special lattice structure. This protective layer effectively shields the active silicate bonds within the matrix, preventing the formation of strong chemical bonds between SiO2 generated in the exhaust gas and the ceramic matrix. Therefore, the attached silicon shell maintains only weak physical adsorption to the ceramic surface, and under sudden temperature changes or mechanical purging, it is easily peeled off in large areas using thermal stress differences, thus endowing the ceramic with excellent high resistance to silicon blockage and easy cleaning performance.

[0020] 2. This application provides a high-silicon-resistant heat storage ceramic for use in RTO treatment of silicon-containing organic waste gas. The high-silicon-resistant heat storage ceramic has the ability to resist SiO2 crystal adhesion, and can solve the problem of blockage caused by silicon accumulation in the heat storage body pores when treating silicon-containing organic waste gas in RTO. Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] Nano titanium dioxide sol was purchased from Xianfeng Nano (XFI22), kaolin was purchased from Chengdu Kangbas Biotechnology Co., Ltd., alumina powder was purchased from Beijing Guoyan Kegong Experimental Equipment Co., Ltd. (ZMZSX0266), silicon carbide powder was purchased from Beijing Guoyan Kegong Experimental Equipment Co., Ltd. (ZMZSX0477), and feldspar powder was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd. (PA94080).

[0023] Preparation Example 1 Preparation of Lanthanum-Praseodymium-Titanium Modified Liquid a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 40g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O) and 20g of praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a lanthanum-praseodymium complex solution; a2. Under the condition of 600 r / min, 30 g of nano titanium dioxide sol was added to the lanthanum-praseodymium complex solution obtained in step a1, and ultrasonically dispersed at 250 W power for 30 min. Then, it was allowed to stand and age in a sealed container for 2 h to obtain lanthanum-praseodymium-titanium modified solution.

[0024] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that, in step a1, the total mass of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate remains unchanged at 60g, and the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is adjusted to 3:1.

[0025] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that, in step a1, the total mass of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate remains unchanged at 60g, and the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is adjusted to 7:5.

[0026] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that the total mass of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate in step a1 and the nano-titanium dioxide sol in step a2 remains unchanged at 90g, and the mass ratio of lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate and nano-titanium dioxide sol is adjusted to 44:22:24.

[0027] Specifically, step a1 is different, and is as follows: a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 44g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O) and 22g of praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a lanthanum-praseodymium complex solution.

[0028] Step a2 is different, specifically: a2, under the condition of 600 r / min, 24 g of nano titanium dioxide sol is added to the lanthanum-praseodymium complex solution obtained in step a1, and ultrasonically dispersed at 250 W power for 30 min, and then allowed to stand and age in a sealed container for 2 h to obtain lanthanum-praseodymium-titanium modified solution.

[0029] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that the total mass of nitric acid hexahydrate and praseodymium nitrate hexahydrate in step a1 and the nano-titanium dioxide sol in step a2 remains unchanged at 90g, and the mass ratio of nitric acid hexahydrate, praseodymium nitrate hexahydrate and nano-titanium dioxide sol is adjusted to 36:18:36.

[0030] Specifically, step a1 is different, and is as follows: a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 36g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O) and 18g of praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a lanthanum-praseodymium complex solution.

[0031] Step a2 is different, specifically: a2, under the condition of 600 r / min, 36g of nano titanium dioxide sol is added to the lanthanum-praseodymium complex solution obtained in step a1, and ultrasonically dispersed at 250W power for 30min, and then allowed to stand and age in a sealed container for 2h to obtain lanthanum-praseodymium-titanium modified solution.

[0032] Comparative Preparation Example 1 The difference between Preparation Example 1 and Preparation Example 2 is that, in step a1, lanthanum nitrate hexahydrate is replaced by praseodymium nitrate hexahydrate by mass.

[0033] Specifically, step a1 is different, specifically: a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 60g of praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a praseodymium complex solution; Accordingly, step a2 is as follows: a2, under the condition of 600 r / min, 30 g of nano titanium dioxide sol is added to the praseodymium complex solution obtained in step a1, and ultrasonically dispersed at 250 W power for 30 min, and then aged in a sealed container for 2 h to obtain praseodymium-titanium modified solution.

[0034] Comparative Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that, in step a2, praseodymium nitrate hexahydrate is replaced by lanthanum nitrate hexahydrate by mass.

[0035] Specifically, step a1 is different, specifically: a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 60g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a lanthanum complex solution. Accordingly, step a2 is as follows: a2. Under the condition of 600 r / min, 30 g of nano titanium dioxide sol is added to the lanthanum complex solution obtained in step a1, and ultrasonically dispersed at 250 W power for 30 min. Then, it is allowed to stand and age in a sealed container for 2 h to obtain lanthanum-titanium modified solution.

[0036] Comparative preparation example 3 The difference between Preparation Example 3 and Preparation Example 1 is that, in step a1, the mass of praseodymium hexahydrate is replaced with cerium nitrate hexahydrate.

[0037] Specifically, step a1 is different, and is as follows: a1. Weigh 200g of deionized water and 100g of anhydrous ethanol, mix them evenly, add 40g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O) and 20g of cerium nitrate hexahydrate (Ce(NO3)3·6H2O), then add 5g of citric acid, and stir magnetically at 400r / min for 20min at room temperature to obtain a lanthanum-cerium complex solution.

[0038] Accordingly, step a2 is as follows: a2. Under the condition of 600 r / min, 30 g of nano titanium dioxide sol is added to the lanthanum-cerium complex solution obtained in step a1, and ultrasonically dispersed at 250 W power for 30 min. Then, it is allowed to stand and age in a sealed container for 2 h to obtain lanthanum-cerium-titanium modified solution.

[0039] Comparative preparation example 4 The difference between Preparation Example 4 and Preparation Example 1 is that nano-titanium dioxide sol is not added in step a2.

[0040] Specifically, step a2 is different, namely: the lanthanum-praseodymium complex solution obtained in step a1 is ultrasonically dispersed at 250W power for 30 minutes, and then aged in a sealed container for 2 hours to obtain the lanthanum-praseodymium modified solution.

[0041] Example 1

[0042] Example 1 provides a high silicon blockage-resistant thermal storage ceramic, comprising a ceramic matrix and a lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1; wherein, the raw materials for preparing the ceramic matrix include the following components in parts by weight: 40 parts by weight of kaolin, 25 parts by weight of alumina powder, 12 parts by weight of silicon carbide powder, and 6.5 parts by weight of flux; wherein, the flux is composed of 4.33 parts by weight of feldspar powder and 2.17 parts by weight of zinc borate.

[0043] Preparation process S1. Dry grind kaolin, alumina powder and silicon carbide powder for 2.5 hours respectively, and pass them through a 250-mesh sieve to obtain ultrafine powder. S2. Add the ultrafine powder obtained in step S1 and the flux to a kneader, mix at 150 r / min for 6 min, knead at 450 r / min for 25 min at a constant temperature of 45℃ to obtain plastic clay; granulate the plastic clay by a rotary granulator at 350 r / min to obtain spherical particles with a particle size of 0.8 mm. S3. Add the spherical particles obtained in step S2 into the mold, and press them at 180MPa for 6 minutes to obtain a sheet-like airflow channel ceramic green body with an average pore diameter of 10mm and a parallel array distribution. S4. Place the sheet-like airflow channel ceramic green body obtained in step S3 into a drying oven and dry it at a low temperature of 70°C for 5 hours. Then, raise the temperature to 110°C and continue drying for 9 hours to obtain a dried ceramic green body. Next, completely immerse the dried ceramic green body in the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Preparation Example 1 for 30 minutes. After taking it out, use compressed air to blow away the excess residual liquid in the channels. Dry it again at 110°C for 3 hours and then put it into a sintering furnace. In an air atmosphere, raise the temperature to 600°C at 6°C / min and hold for 2.5 hours. Then raise the temperature to 1250°C at 4°C / min and hold for 5 hours. Let it cool naturally to room temperature with the furnace to obtain a high silicon blockage-resistant heat storage ceramic.

[0044] Example 2

[0045] Example 2 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 2.

[0046] Other preparation processes are the same as in Example 1.

[0047] Example 3

[0048] Example 3 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 3.

[0049] Other preparation processes are the same as in Example 1.

[0050] Example 4

[0051] Example 4 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 4.

[0052] Other preparation processes are the same as in Example 1.

[0053] Example 5

[0054] Example 5 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 5.

[0055] Other preparation processes are the same as in Example 1.

[0056] Comparative Example 1 Comparative Example 1 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Preparation Example 1 is replaced with the praseodymium-titanium modified liquid prepared by the preparation method of Comparative Example 1.

[0057] Other preparation processes are the same as in Example 1.

[0058] Comparative Example 2 Comparative Example 2 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-titanium modified liquid prepared by the preparation method of Comparative Example 2.

[0059] Other preparation processes are the same as in Example 1.

[0060] Comparative Example 3 Comparative Example 3 provides a high silicon blockage-resistant thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-cerium-titanium modified liquid prepared by the preparation method of Comparative Example 3.

[0061] Other preparation processes are the same as in Example 1.

[0062] Comparative Example 4 Comparative Example 4 provides a high-silicon-blockage thermal storage ceramic. The difference from Example 1 is that in step S4, the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is replaced with the lanthanum-praseodymium modified liquid prepared by the preparation method of Comparative Example 4.

[0063] Other preparation processes are the same as in Example 1.

[0064] Comparative Example 5 Comparative Example 5 provides a high silicon blockage-resistant thermal storage ceramic, which differs from Example 1 in that the step of impregnating the dried ceramic green body in the lanthanum-praseodymium-titanium modified liquid prepared by the preparation method of Example 1 is omitted in step S4.

[0065] Specifically, step S4 is different, specifically: S4, the sheet-like airflow channel ceramic green body obtained in step S3 is placed in a drying oven and dried at a low temperature of 70℃ for 5 hours, then heated to 110℃ and dried for another 9 hours to obtain a dried ceramic green body; it is placed in a sintering furnace and heated to 600℃ at 6℃ / min in an air atmosphere and held for 2.5 hours; then heated to 1250℃ at 4℃ / min and held for 5 hours, and then naturally cooled to room temperature with the furnace to obtain a high silicon blockage-resistant heat storage ceramic.

[0066] Other preparation processes are the same as in Example 1.

[0067] Performance testing Test Example: Simulated Silicon Junction Shell Peeling Efficiency Test The high silicon-resistant heat storage ceramics prepared in Examples 1-5 and Comparative Examples 1-5 were cut into standard test blocks of 20mm×20mm×5mm. After ultrasonic cleaning and drying, the mass of the standard test blocks was weighed and recorded as m0 for later use.

[0068] A molten silica powder suspension with a solid content of 60 wt% was prepared and uniformly sprayed onto the surface of the internal channels of the test block using a high-pressure spray gun. The test block was placed in a high-temperature muffle furnace and kept at 1050℃ for 2 hours to allow the silica powder to form a dense sintered glaze layer on the ceramic surface. After cooling, the mass of the test block was weighed and recorded as m1. The initial attached silica shell mass W0 = m1 - m0 was calculated.

[0069] The silicon-coated test blocks were placed in a tubular resistance furnace, heated to 800℃, and held for 30 minutes. A pulse nozzle probe was inserted into the furnace chamber, aligned with the axial direction of the test block's channels, and an online cleaning cycle was performed: first, atomized water (pressure 0.4 MPa, flow rate 0.3 L / min) was sprayed for 1.5 seconds, followed immediately by dry compressed air (pressure 0.7 MPa) for 4.0 seconds; this process was defined as one pulse cycle, and each test block underwent 5 consecutive pulse cycles. After cleaning, the test blocks were removed and allowed to cool naturally to room temperature. After drying, the mass of the test blocks was measured and recorded as m2. The residual mass of the silicon crust, W1 = m2 - m0, was calculated. The crust peeling rate η was calculated using the formula η = (W0 - W1) / W0 × 100%. Three parallel samples were tested for each group of samples, and the average value was taken as the final result. The test results are shown in Table 1.

[0070] Table 1. Test results of simulated silicon junction shell peeling efficiency

[0071] Conclusion Analysis and Summary Based on Examples 1-3 and Table 1, it can be seen that adjusting the amount of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate in the lanthanum-praseodymium-titanium modified solution can affect the shell peeling rate. In Example 1, when the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is 2:1, the resulting heat storage ceramic has the best shell peeling rate, which is better than that of Examples 2 and 3.

[0072] Based on Examples 1, 4-5 and Table 1, it can be seen that by keeping the mass of lanthanum nitrate hexahydrate and praseodymium nitrate hexahydrate constant, adjusting the amount of silicon nitric acid hexahydrate, praseodymium nitrate hexahydrate and nano-titanium dioxide sol can affect the shell peeling rate. In Example 1, when the mass ratio of nitric acid hexahydrate, praseodymium nitrate hexahydrate and nano-titanium dioxide sol is 4:2:3, the resulting heat storage ceramic has the best shell peeling rate, which is better than that of Examples 4 and 5.

[0073] Based on Examples 1, Comparative Examples 1-2, and Table 1, it can be seen that in Comparative Example 1, replacing lanthanum nitrate hexahydrate with praseodymium nitrate hexahydrate by mass, and in Comparative Example 2, replacing praseodymium nitrate hexahydrate with lanthanum nitrate hexahydrate by mass, significantly reduced the shell peeling rate of the prepared thermal regenerator ceramics. This may be because lanthanum and praseodymium have different ionic radii and 4f electron configurations. When they are combined in a specific ratio, they can produce a synergistic doping effect in the titanate lattice, forming optimal lattice distortion and surface oxygen vacancy distribution. Using lanthanum or praseodymium alone leads to excessive or insufficient lattice distortion, failing to achieve the optimal surface chemical inertness state. This increases the probability of SiO2 particles bonding with the surface at high temperatures, reducing the shell peeling rate.

[0074] Based on Example 1, Comparative Example 3, and Table 1, it can be seen that in Comparative Example 3, replacing lanthanum nitrate hexahydrate by mass with cerium nitrate hexahydrate significantly reduced the shell peeling rate of the prepared heat storage ceramics. This may be because, on the one hand, praseodymium, mainly in the +3 valence and supplemented by the +4 valence, can provide appropriate charge compensation and lattice disturbance in the titanate lattice, promoting the formation of La-Pr-Ti-O solid solution; while cerium, under a high-temperature oxidizing atmosphere, […]. 4+ CeO2 is dominant and tends to segregate to form an independent CeO2 phase, disrupting the structural continuity of the La-Pr-Ti-O surface composite oxide protective layer. On the other hand, CeO2 has a certain chemical affinity with SiO2, providing additional nucleation sites for silicon deposition. Consequently, Ce substitution for Pr leads to a significant decrease in the shell peeling rate.

[0075] Based on Example 1, Comparative Example 4, and Table 1, it can be seen that in Comparative Example 4, without the addition of nano-titanium dioxide sol to the modified solution, the anti-silicon blockage effect of the prepared ceramic was significantly reduced, and the shell peeling rate was significantly decreased. This may be because, without the addition of nano-titanium dioxide sol, rare earth oxides are directly exposed on the ceramic surface. Rare earth oxides are alkaline and readily react with SiO2 to form rare earth silicate salts, which enhance the bonding force between SiO2 and the ceramic surface, making the shell difficult to peel off. After adding TiO2 sol, a TiO2-rare earth composite protective layer is formed, reducing the direct contact between rare earth oxides and SiO2, lowering surface reactivity, and thus improving the anti-silicon blockage performance and shell peeling rate.

[0076] Based on Example 1, Comparative Example 5, and Table 1, it can be seen that in Comparative Example 5, omitting the step S4 of impregnating the dried ceramic green body in the lanthanum-praseodymium-titanium modified solution obtained by the preparation method of Preparation Example 1 significantly reduced the shell peeling rate of the prepared thermal regenerator ceramic. This may be because the unmodified ceramic surface directly exposes the aluminosilicate matrix, and the Si-O-Al bonds on the surface chemically bond with SiO2, forming a dense sintered layer. Consequently, the anti-silicon blockage performance is significantly worse, and the shell peeling rate is significantly reduced.

[0077] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the products, methods and principles of this application should be covered within the scope of protection of this application.

Claims

1. A high-resistance silicon blockage thermal storage ceramic, characterized in that, Including lanthanum-praseodymium-titanium modified liquids for ceramic matrices and impregnated ceramic matrices; The raw materials for preparing the ceramic matrix include the following components in parts by weight: 35-45 parts by weight of kaolin, 20-30 parts by weight of alumina powder, 10-14 parts by weight of silicon carbide powder, and 5-8 parts by weight of flux. The raw materials for preparing the lanthanum-praseodymium-titanium modified liquid include lanthanum nitrate, praseodymium nitrate, nano-titanium dioxide sol, and water.

2. The high silicon blockage resistance thermal storage ceramic according to claim 1, characterized in that, In the lanthanum-praseodymium-titanium modified solution, lanthanum nitrate is lanthanum nitrate hexahydrate, and praseodymium nitrate is praseodymium nitrate hexahydrate.

3. The high-silicon-blockage-resistant thermal storage ceramic according to claim 2, characterized in that, In the lanthanum-praseodymium-titanium modified solution, the mass ratio of lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate and nano titanium dioxide sol is (18-22):(9-11):(12-18).

4. The high-silicon-blockage-resistant thermal storage ceramic according to claim 2, characterized in that, In the lanthanum-praseodymium-titanium modified solution, the mass ratio of lanthanum nitrate hexahydrate to praseodymium nitrate hexahydrate is (7-15):

5.

5. The high silicon blockage-resistant thermal storage ceramic according to claim 2, characterized in that, The preparation method of the lanthanum-praseodymium-titanium modified liquid includes the following steps: a1. Weigh water and ethanol, mix them evenly, add lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, and citric acid, stir, and obtain a lanthanum-praseodymium complex solution; a2. Under stirring conditions, the nano-titanium dioxide sol is added to the lanthanum-praseodymium complex solution obtained in step a1, and then sonicated and aged to obtain a lanthanum-praseodymium-titanium modified solution.

6. The high-silicon-blockage-resistant thermal storage ceramic according to claim 1, characterized in that, The flux comprises 3.83-4.83 parts by weight of feldspar powder and 1.67-2.67 parts by weight of zinc borate.

7. A preparation process for the high silicon blockage-resistant thermal storage ceramic according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Dry grind kaolin, alumina powder, and silicon carbide powder, and sieve them to obtain ultrafine powder. S2. Mix the ultrafine powder obtained in step S1 with a flux, knead, and granulate to obtain spherical particles. S3. Add the spherical particles obtained in step S2 into the mold, shape, and press to obtain a sheet-like airflow channel ceramic green body. S4. The sheet-like airflow channel ceramic green body obtained in step S3 is dried, impregnated in lanthanum-praseodymium-titanium modified liquid, dried, sintered, and cooled to obtain a high silicon blockage-resistant heat storage ceramic.

8. The preparation process of the high silicon blockage-resistant thermal storage ceramic according to claim 7, characterized in that, In step S3, the molding process involves isostatic pressing at 170-190 MPa for a holding time of 5-7 minutes.

9. The preparation process of the high silicon blockage-resistant thermal storage ceramic according to claim 7, characterized in that, In step S4, the sintering conditions are to hold at 550-650℃ for 2-3 hours and at 1200-1300℃ for 4-6 hours.

10. The application of the high silicon blockage-resistant thermal storage ceramic according to any one of claims 1-6 in the RTO treatment of silicon-containing organic waste gas.

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