A heat accumulating material, its preparation method and use

Abstract

The present application belongs to the technical field of low-carbon dehydrogenation additives, and particularly relates to a heat storage material and a preparation method and application thereof. The heat storage material comprises, in percentage by mass, 70-92% of a heat storage main component, 5-25% of alpha-Al2O3, 1-8% of Sb2O3 and 0.5-5% of SiO2; and the heat storage main component comprises at least three of MgO, CaO, NiO, ZrO2 and CeO2. The present application prepares the heat storage material with high side pressure strength and excellent thermal shock stability through the synergistic effect of the MgO-CaO-NiO-ZrO2 / CeO2 multi-component heat storage system, the electronic modification of Sb2O3 and the structural strengthening of SiO2. The material can effectively reduce the bed temperature drop, improve the propylene selectivity and exhibit good long-term operation stability.

Description

Technical Field

[0001] This invention belongs to the field of low-carbon dehydrogenation additives technology, specifically relating to a heat storage material, its preparation method, and its application. Background Technology

[0002] Thermal storage materials are common components in thermal storage equipment, typically including metal thermal storage materials, ceramic thermal storage materials, and phase change thermal storage materials. Alkane dehydrogenation is generally an endothermic reaction, and the entire process can be operated as an adiabatic cyclic process. On the one hand, in the propane dehydrogenation process, the catalyst bed often suffers from uneven axial and radial temperature distribution, leading to localized decreases in reaction efficiency and easy catalyst deactivation. On the other hand, the objectively existing uneven pressure drop in the bed causes inconsistent temperature drops at different locations during the reaction due to flow deviation, resulting in uneven reaction and severely affecting catalyst lifespan and propylene yield.

[0003] In traditional processes, in order to maintain the reaction temperature, a large amount of inert alumina and other heat storage materials are often added to the catalyst bed, resulting in the actual catalyst filling volume only accounting for 50%-70% of the bed, low reactor space utilization, large equipment size, and high energy consumption.

[0004] Chinese invention patent application CN117925196A discloses a heat balance material for the dehydrogenation process of low-carbon alkanes, its preparation method, and its application, relating to the field of low-carbon alkane dehydrogenation technology. The heat balance material contains a carrier, a main active component, and a co-active component; the main active component includes Cu, and the co-active component includes Ca and at least one element from Group IVA. By adding an element from Group IVA to the co-active component, the distribution of the main active component in the heat balance material can be made more uniform. The preparation method, involving kneading, a first high-temperature calcination, impregnation, and a second high-temperature calcination, reduces sintering caused by repeated high-temperature calcination of the main active component. However, its preparation requires multiple impregnation and calcination processes, making the process complex and the active component prone to sintering.

[0005] Chinese invention patent application CN112812751A discloses a heat storage material and its preparation method for a propane catalytic dehydrogenation process to propylene. The heat storage material is a supported composite metal oxide xMaOb / carrier, where M = one or more of Ba, Mg, Mn, Zr, Ca, Ce, Bi, Cu, Co, Mo, Fe, Ni, Na, Nb, and Sb, a = 1-3, b = 1-3, and x is the loading of the composite metal oxide, with a value of 10-30 wt%. Although this heat storage material can release heat during the regeneration stage, it does not involve material morphology control. Traditional powder or granular materials are prone to increased pressure drop and wear, and the bed temperature uniformity is insufficient.

[0006] Chinese invention patent application CN107074683A discloses a CuO heat-releasing material that releases heat by reacting CO with CuO to form Cu and CO2. However, this method introduces components such as CO and CO2 along with heat, causing a decrease in the partial pressure of the reaction gases and affecting the reaction conversion rate.

[0007] Therefore, developing a heat storage material with higher heat storage density, better thermal stability, and simpler preparation is of great significance for promoting the advancement of propane dehydrogenation process. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a heat storage material for propane dehydrogenation processes, its preparation method, and its application.

[0009] To achieve the above-mentioned objectives of this invention, the specific technical solution adopted by this invention is as follows:

[0010] A heat storage material, by mass percentage, comprises: 70%-92% heat storage main component, 5%-25% α-Al2O3, 1%-8% Sb2O3 and 0.5%-5% SiO2; wherein the heat storage main component comprises at least three of MgO, CaO, NiO, ZrO2 and CeO2.

[0011] Preferably, the mass ratio of MgO, CaO and NiO in the main thermal storage components is (4-6):(1.5-3):1.

[0012] More preferably, the main thermal storage component is composed of MgO, CaO, NiO and ZrO2, and the mass ratio of MgO, CaO, NiO and ZrO2 is (4-6):(1.5-3):1:(1-2).

[0013] More preferably, the main thermal storage component is composed of MgO, CaO, NiO and CeO2, and the mass ratio of MgO, CaO, NiO and CeO2 is (3.5-6):(1.5-3.5):1:(1-3.5).

[0014] Preferably, the properties of the heat storage material include: a cylindrical strip with a diameter of 2-4 mm and a length of 5-12 mm, and a lateral compressive strength ≥400 N / cm.

[0015] The main thermal storage component adopts a multi-component system of MgO-CaO-NiO-ZrO2 / CeO2. Among them, MgO and CaO have high latent heat of phase change and suitable phase change temperature, NiO can optimize the lattice arrangement and enhance thermal conductivity, and ZrO2 and CeO2 have excellent high-temperature stability and can suppress phase change decay during thermal cycling. By limiting the mass ratio of MgO, CaO and NiO, the synergistic thermal storage effect of the multi-component system is achieved, maximizing the thermal storage capacity.

[0016] α-Al2O3 can serve as a framework structure in heat storage materials, improving the overall compressive strength and wear resistance of the material and extending its service life.

[0017] As an electronic dopant, Sb2O3 can be embedded into the lattice of the main component, optimizing its electronic structure and enhancing its high-temperature stability. At the same time, the glass phase it forms at high temperatures can encapsulate the active components, inhibiting carbon deposition and particle sintering.

[0018] As a structural aid, SiO2 can form a stable composite structure with α-Al2O3 and the main heat storage components. As a sintering aid, it can lower the sintering temperature, promote grain boundary migration, and improve the density and strength of the material.

[0019] This invention also relates to a method for preparing the above-mentioned heat storage material, comprising the following steps:

[0020] (1) Take the precursor of the main heat storage component, α-Al2O3, Sb2O3 and SiO2, mix them, add binder and water, and knead into a uniform plastic body;

[0021] (2) The plastic body is extruded into strips, dried, and granulated to obtain strip material;

[0022] (3) The strip is roasted to obtain the heat storage material.

[0023] Preferably, the binder in step (1) is selected from at least one of polyvinyl alcohol, aluminum sol, and methylcellulose, and the amount of binder added is 2%-8% of the total mass of the raw material powder, and the amount of water added is 20%-35% of the total mass of the raw material powder.

[0024] Preferably, the precursor of the main heat storage component in step (1) is selected from at least three of Mg(OH)2, CaCO3, Ni(NO3)2·6H2O, Zr(OH)4 and Ce(NO3)3·6H2O; the drying temperature in step (2) is 100-180℃ and the drying time is 2-10h.

[0025] Preferably, the calcination conditions in step (3) are: heating to 1300-1500℃ at a rate of 1-3℃ / min and holding at this temperature for 2-4 hours.

[0026] This invention also relates to the application of the above-mentioned heat storage material in the dehydrogenation of alkane to olefins reaction.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) This invention utilizes the synergistic effect of a MgO-CaO-NiO-ZrO2 / CeO2 multi-element thermal storage system, combined with Sb2O3 electronic modification and SiO2 structural reinforcement, to prepare a thermal storage material with high lateral pressure strength (≥480 N / cm) and excellent thermal shock stability (no cracks after 50 cycles). In the propane dehydrogenation reaction, this material can effectively reduce the bed temperature drop (≤30℃), improve propylene selectivity (≥93.9%), and exhibit good long-term operational stability (propylene selectivity retention rate >98.5% after 500h).

[0029] (2) The preparation method of the present invention is simple, adopting a one-step mixing-extrusion-calcination method, avoiding multiple impregnation and calcination; no precious metals or complex post-processing are required, which reduces production costs. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are not intended to limit the present invention, but only to illustrate the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0031] Polyvinyl alcohol (PVA-1788) was purchased from Sinopharm Chemical Reagent Co., Ltd.; α-Al₂O₃ powder (purity >99%) was purchased from China Aluminum Shandong Co., Ltd.; Sb₂O₃ powder (purity >99.5%) was purchased from Hunan Chenzhou Mining Co., Ltd.; and SiO₂ powder (white carbon black, purity >99.8%) was purchased from Hubei Huifu Nanomaterials Co., Ltd.

[0032] Example 1

[0033] A heat storage material, by mass percentage, comprises: MgO 38%, CaO 15%, NiO 7%, ZrO2 12%, α-Al2O3 18%, Sb2O3 35%, and SiO2 5%.

[0034] The preparation method of the above-mentioned heat storage material is as follows:

[0035] (1) Weigh 58.4g of Mg(OH)2, 32.6g of CaCO3, 28.6g of Ni(NO3)2·6H2O, 18.5g of Zr(OH)4, 18g of α-Al2O3 powder, 5g of Sb2O3 powder and 5g of SiO2 powder, mix them evenly, add 5% of the total mass of the raw material powder in polyvinyl alcohol solution (concentration 10wt.%) and 30% of the total mass of the raw material powder in deionized water, mix and knead in a kneader for 30min to obtain a uniform plastic body.

[0036] (2) The plastic body is fed into the extruder and extruded into a continuous strip material with a diameter of 5 mm. It is dried at 150°C for 6 hours and then granulated to obtain a strip material with a length of 8 mm.

[0037] (3) Place the strip material in a high-temperature furnace, heat it to 1450℃ at 3℃ / min, keep it at that temperature for 4 hours, and then cool it with the furnace to obtain the desired product.

[0038] Example 2

[0039] A heat storage material, by mass percentage, comprises: MgO 35%, CaO 18%, NiO 6%, CeO2 20%, α-Al2O3 15%, Sb2O3 3% and SiO2 3%.

[0040] The preparation method of the above-mentioned heat storage material is as follows:

[0041] (1) Weigh 54.1g of Mg(OH)2, 39.1g of CaCO3, 24.5g of Ni(NO3)2·6H2O, 68.3g of Ce(NO3)3·6H2O, 15g of α-Al2O3 powder, 3g of Sb2O3 powder and 3g of SiO2 powder, mix them evenly, add 5% of the total mass of the raw material powder in polyvinyl alcohol solution (concentration 10wt.%) and 25% of the total mass of the raw material powder in deionized water, mix and knead in a kneader for 40min to form a uniform plastic body.

[0042] (2) The plastic body is fed into the extruder and extruded into a continuous strip material with a diameter of 3 mm. It is dried at 130°C for 8 hours and then pelletized to obtain a strip material with a length of 6 mm.

[0043] (3) Place the strip material in a high-temperature furnace and heat it to 1400°C at a rate of 2°C / min. Hold it at that temperature for 4 hours and then cool it with the furnace to obtain the heat storage material.

[0044] Example 3

[0045] A heat storage material, by mass percentage, comprises: MgO 40%, CaO 16%, NiO 8%, ZrO 25%, CeO 210%, α-Al2O3 15%, Sb2O3 4%, and SiO 22%.

[0046] The preparation method of the above-mentioned heat storage material is as follows:

[0047] (1) Weigh 61.5g of Mg(OH)2, 34.8g of CaCO3, 32.7g of Ni(NO3)2·6H2O, 7.7g of Zr(OH)4, 34.2g of Ce(NO3)3·6H2O, 15g of α-Al2O3 powder, 4g of Sb2O3 powder and 2g of SiO2 powder. After mixing evenly, add 6% of the total mass of the raw material powder in a polyvinyl alcohol solution (concentration 10wt.%) and 28% of the total mass of the raw material powder in deionized water. Mix and knead in a kneader for 35min to obtain a uniform plastic body.

[0048] (2) The plastic body is fed into the extruder and extruded into a continuous strip material with a diameter of 4 mm. It is dried at 160°C for 5 h and then granulated to obtain a strip material with a length of 10 mm.

[0049] (3) Place the strip material in a high-temperature furnace and heat it to 1350°C at a rate of 2.5°C / min. Hold it at that temperature for 4 hours and then cool it with the furnace to obtain the heat storage material.

[0050] Comparative Example 1

[0051] The only difference between this comparative example and Example 1 is that it does not contain Sb2O3. Its specific composition is: MgO 38%, CaO 15%, NiO 7%, ZrO2 12%, α-Al2O3 23%, and SiO 25%.

[0052] Preparation method: In step (1), Sb2O3 powder is removed, and α-Al2O3 powder is adjusted to 23g. The remaining steps are exactly the same as in Example 1.

[0053] Comparative Example 2

[0054] The only difference between this comparative example and Example 1 is that it does not contain SiO2. The specific composition is: MgO 38%, CaO 15%, NiO 7%, ZrO2 12%, α-Al2O3 18%, and Sb2O3 10%.

[0055] Preparation method: In step (1), remove SiO2 powder and adjust Sb2O3 powder to 10g. The remaining steps are exactly the same as in Example 1.

[0056] Comparative Example 3

[0057] The only difference between this comparative example and Example 1 is the proportion of Sb2O3 and SiO2. The specific composition is: MgO 38%, CaO 15%, NiO 7%, ZrO2 12%, α-Al2O3 18%, Sb2O3 0.3% and SiO2 9.7%.

[0058] Preparation method: Weigh 58.4g of Mg(OH)2, 32.6g of CaCO3, 28.6g of Ni(NO3)2·6H2O, 18.5g of Zr(OH)4, 18g of α-Al2O3 powder, 0.3g of Sb2O3 powder, and 9.7g of SiO2 powder. Mix them evenly and then add 5% of the total mass of the raw material powder in a polyvinyl alcohol solution (concentration 10wt.%) and 30% of the total mass of the raw material powder in deionized water. Mix and knead in a kneader for 30 minutes to obtain a uniform plastic body; the remaining steps are exactly the same as in Example 1.

[0059] Comparative Example 4

[0060] The only difference between this comparative example and Example 1 is that the main components of the thermal storage are only MgO and CaO, without NiO and ZrO2. The specific composition is: MgO 50%, CaO 22%, α-Al2O3 18%, Sb2O3 5%, and SiO2 5%.

[0061] Preparation method: In step (1), Ni(NO3)2·6H2O and Zr(OH)4 are removed, Mg(OH)2 is adjusted to 77.0g, and CaCO3 is adjusted to 47.8g. The remaining steps are exactly the same as in Example 1.

[0062] Comparative Example 5

[0063] The only difference between this comparative example and Example 1 is that the mass ratio of MgO, CaO, and NiO is 1.43:2.14:1. The specific composition is: MgO 20%, CaO 30%, NiO 14%, ZrO2 12%, α-Al2O3 18%, Sb2O3 3%, and SiO2 3%.

[0064] Preparation method: Weigh 30.8g of Mg(OH)2, 65.2g of CaCO3, 57.3g of Ni(NO3)2·6H2O, 18.5g of Zr(OH)4, 18g of α-Al2O3 powder, 3g of Sb2O3 powder and 3g of SiO2 powder, mix them evenly, and then add 5% of the total mass of the raw material powder in polyvinyl alcohol solution (concentration 10wt.%) and 30% of the total mass of the raw material powder in deionized water. Mix and knead in a kneader for 30 minutes to obtain a uniform plastic body; the remaining steps are exactly the same as in Example 1.

[0065] Comparative Example 6

[0066] The only difference between this comparative example and Example 1 is that the α-Al2O3 content is 3%. The specific composition is: MgO 45%, CaO 17%, NiO 8%, ZrO2 14%, α-Al2O3 3%, Sb2O3 5%, and SiO2 8%.

[0067] Preparation method: Weigh 69.7g of Mg(OH)2, 37.0g of CaCO3, 32.7g of Ni(NO3)2·6H2O, 21.6g of Zr(OH)4, 3g of α-Al2O3 powder, 5g of Sb2O3 powder and 8g of SiO2 powder, mix them evenly, and then add 5% of the total mass of the raw material powder in polyvinyl alcohol solution (concentration 10wt.%) and 30% of the total mass of the raw material powder in deionized water. Mix and knead in a kneader for 30 minutes to obtain a uniform plastic body; the remaining steps are exactly the same as in Example 1.

[0068] Comparative Example 7

[0069] The only difference between this comparative example and Example 1 is that the calcination temperature in step (3) is 900°C, while the other components and preparation methods are the same as in Example 1.

[0070] Comparative Example 8

[0071] The only difference between this comparative example and Example 1 is that the calcination temperature in step (3) is 1600℃, while the other components and preparation methods are the same as in Example 1.

[0072] Effect test

[0073] Test Example 1: Physical Properties and Thermal Stability Test

[0074] 1. Lateral compressive strength: A universal testing machine (model: Instron 5967) was used with an indenter speed of 1 mm / min. The sample was placed horizontally between two parallel indenters (the contact length was 1 / 2 of the sample length). Ten complete cylindrical strips (without cracks or notches) were tested. The maximum pressure at fracture was recorded, and the lateral compressive strength was calculated (lateral compressive strength = maximum pressure / contact length). The maximum and minimum values ​​were removed, and the average value was taken.

[0075] 2. Thermal shock test: Place the sample in a muffle furnace at 600℃ for 30 min (heating rate 5℃ / min), then quickly and completely immerse it in 25℃ deionized water with tweezers. After soaking for 5 min, remove the sample and dry it at 120℃ for 2 h. Repeat the above operation 50 times. After each cycle, observe the sample with a stereomicroscope (magnification 20x). Cracks with a width ≥0.01 mm are considered valid cracks.

[0076] The test results are shown in Table 1.

[0077] Table 1 Performance Test Results

[0078]

[0079] Test Example 2: Performance Test of Alkane Dehydrogenation Reaction

[0080] The process used is a fixed-bed process, and the reactor is a constant-temperature reactor. The regenerative material and chromium-based dehydrogenation catalyst are loaded at a mass ratio of 1:1. The temperature is 600℃, the pressure is 0.1MPa, and the propane weight hourly space velocity is 2h⁻¹. -1 Samples were taken for analysis after 10 hours of reaction. Gas chromatography was used to detect the components of the reaction products, and the propane conversion, propylene selectivity, and byproduct (methane) selectivity were calculated. Bed temperature changes were monitored using thermocouples.

[0081] The test results are shown in Table 2.

[0082] Table 2 Results of Alkane Dehydrogenation Reaction Performance Tests

[0083]

[0084] Test Example 3: Long-term stability test

[0085] To verify the long-term stability of the additive of this invention, a 500-hour continuous reaction experiment was conducted. Samples were taken and analyzed every 100 hours to record the retention of propylene selectivity. Strength decay rate = (initial lateral pressure strength - lateral pressure strength after 500 hours) / initial lateral pressure strength × 100%. The test results are shown in Table 3.

[0086] Table 3 Long-term stability test results

[0087]

[0088] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A heat storage material, characterized in that, The thermal storage material comprises, by mass percentage: 70%-92% thermal storage main component, 5%-25% α-Al2O3, 1%-8% Sb2O3 and 0.5%-5% SiO2; the thermal storage main component comprises at least three of MgO, CaO, NiO, ZrO2 and CeO2, and includes at least MgO, CaO and NiO; The mass ratio of MgO, CaO and NiO in the main thermal storage components is (4-6):(1.5-3):1; The method for preparing the heat storage material includes the following steps: (1) Take the precursor of the main heat storage component, α-Al2O3, Sb2O3 and SiO2, mix them, add binder and water, and knead into a uniform plastic body; (2) The plastic body is extruded into strips, dried, and granulated to obtain strip material; (3) The strip is roasted to obtain the heat storage material; The calcination conditions described in step (3) are: heating to 1300-1500℃ at a rate of 1-3℃ / min and holding at this temperature for 2-4 hours.

2. The heat storage material according to claim 1, characterized in that, The main thermal storage component consists of MgO, CaO, NiO and ZrO2, with a mass ratio of (4-6):(1.5-3):1:(1-2).

3. The heat storage material according to claim 1, characterized in that, The main thermal storage component consists of MgO, CaO, NiO and CeO2, with a mass ratio of (3.5-6):(1.5-3.5):1:(1-3.5).

4. The heat storage material according to any one of claims 1-3, characterized in that, The properties of the heat storage material include: a cylindrical strip with a diameter of 2-4 mm and a length of 5-12 mm, and a lateral compressive strength ≥400 N / cm.

5. A method for preparing the heat storage material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Take the precursor of the main heat storage component, α-Al2O3, Sb2O3 and SiO2, mix them, add binder and water, and knead into a uniform plastic body; (2) The plastic body is extruded into strips, dried, and granulated to obtain strip material; (3) The strip is roasted to obtain the heat storage material; The calcination conditions described in step (3) are: heating to 1300-1500℃ at a rate of 1-3℃ / min and holding at this temperature for 2-4 hours.

6. The preparation method according to claim 5, characterized in that, The binder mentioned in step (1) is selected from at least one of polyvinyl alcohol, aluminum sol, and methylcellulose. The amount of binder added is 2%-8% of the total mass of the raw material powder, and the amount of water added is 20%-35% of the total mass of the raw material powder.

7. The preparation method according to claim 5, characterized in that, The precursor of the main heat storage component in step (1) is selected from at least three of Mg(OH)2, CaCO3, Ni(NO3)2·6H2O, Zr(OH)4 and Ce(NO3)3·6H2O; the drying temperature in step (2) is 100-180℃ and the drying time is 2-10h.

8. The application of the heat storage material according to any one of claims 1-4 in the dehydrogenation of alkane to olefins reaction.

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