A chemical heat storage and release material with high light absorption and cyclic stability, and its preparation method and application

Abstract

The present invention discloses a chemical heat storage material with high light absorption and cycle stability, and its preparation method and application. The chemical heat storage material includes a main heat storage precursor material, a secondary heat storage precursor material, an optical modification material and an anti-sintering modifier; wherein the main heat storage precursor material is a calcium-based compound whose product is only calcium oxide after high-temperature calcination; the secondary heat storage precursor material is a cobalt-based compound whose product is cobalt oxide after high-temperature calcination; the optical modification material is a substance with enhanced solar radiation absorption ratio; the anti-sintering modifier is a substance that can hinder the agglomeration, adhesion and agglomeration of heat storage material particles. The heat storage material of the present invention can improve the overall absorption ratio of solar radiation, simplify the high-temperature concentrated heat collection and heat storage system, and can additionally improve the absorption ratio of specific bands, while having better heat storage reaction cycle stability and higher energy storage density.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermochemical energy storage, and specifically relates to a chemical heat storage and release material with high light absorption and cyclic stability, and a preparation method and application thereof. Background Art

[0002] Energy power is the foundation of social progress and development. At present, the consumption of a large amount of fossil energy in the world has caused environmental degradation and energy crisis. In order to accelerate the transformation of the global energy structure to a low-carbon one, an energy revolution is imperative. The high-temperature heat generated by solar energy after concentration is an ideal renewable energy source. Efficient energy storage technology can solve the inherent problem of the imbalance between the supply and demand of energy in time and space, which is of great significance to promoting the green transformation of the energy structure.

[0003] Among efficient energy storage technologies, thermochemical heat storage has a higher energy storage density and a higher operating temperature, and can achieve almost lossless heat storage. It is suitable for seasonal long-term heat storage and long-distance transportation, and can maximize the efficiency of solar energy storage. It has received much attention in solar energy utilization systems.

[0004] Among high-temperature thermochemical heat storage and release materials, calcium-based carbonates and cobalt-based metal oxides not only have high energy storage density (873-3184 kJ / kg), but also have high reaction temperatures. The energy storage density and operating temperature of the two are compatible with the requirements of solar concentrating high-temperature heat storage systems. However, calcium-based carbonate heat storage materials will undergo severe sintering after multiple cycles, resulting in particle agglomeration and pore clogging, which in turn inhibits the diffusion of the reaction gas on the solid surface, resulting in low conversion rate of heat storage and release reactions and poor cycle stability. In addition, the absorption ratio of calcium-based carbonate to solar radiation energy is less than 10%, which hinders the direct absorption of solar heat and increases the heat transfer resistance; while cobalt-based metal oxides are relatively expensive and toxic; and the current material anti-sintering stabilizers and high light absorption modifiers do not directly participate in the heat storage process, resulting in further loss of mass energy storage density. The above problems seriously restrict the practical application of calcium-based carbonates and cobalt-based metal oxides in thermochemical heat storage. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] One of the objects of the present invention is to provide a chemical heat storage and release material with high light absorption and cyclic stability. The heat storage material can improve the overall absorption ratio of solar radiation and additionally improve the absorption ratio of specific bands so as to maximize the utilization efficiency of solar energy in combination with photovoltaic power generation. At the same time, compared with traditional calcium-based heat storage materials, the material has better heat storage and release reaction cyclic stability.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a chemical heat storage material with high light absorption and cycle stability, comprising a primary heat storage precursor material, a secondary heat storage precursor material, an optical modification material and an anti-sintering modifier;

[0009] Wherein, the main heat storage precursor material is a calcium-based compound whose product after high-temperature calcination is only calcium oxide;

[0010] The secondary heat storage precursor material is a cobalt-based compound whose product is cobalt oxide after high-temperature calcination;

[0011] The optical modification material is a substance having an enhanced solar radiation absorption ratio; the optical modification material or its precursor material is one or more of cobalt-based metal oxides, manganese-based metal oxides, cobalt-based metal nitrates, manganese-based metal nitrates and their respective hydrates;

[0012] The anti-sintering modifier is a substance that can hinder the agglomeration, adhesion and agglomeration of heat storage and release material particles; the anti-sintering modifier or its precursor material is one or more of manganese-based metal oxides, magnesium-based metal oxides, manganese-based metal nitrates, magnesium-based metal nitrates and their respective hydrates.

[0013] As a preferred solution of the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the calcium-based compound includes one or more of calcium hydroxide, nano calcium carbonate, micro calcium carbonate, calcium nitrate and hydrates thereof.

[0014] As a preferred solution of the chemical heat storage and release material with high light absorption and cycle stability of the present invention, the cobalt-based compound includes one or more of cobalt tetroxide, cobalt oxide, cobalt nitrate and hydrates thereof.

[0015] As a preferred embodiment of the chemical heat storage and release material with high light absorption and cycle stability of the present invention, the main heat storage and release precursor material, the secondary heat storage and release precursor material, the optical modified material, and the anti-sintering modified material are in a ratio of 1:0 to 0.3:0 to 0.1:0 to 0.1 according to the molar ratio of the metal atoms contained in each of them.

[0016] Another object of the present invention is to provide a method for preparing a chemical heat storage and release material having high light absorption and cycle stability as described in any one of the above items, comprising:

[0017] The main heat storage and release precursor material, the secondary heat storage and release precursor material, the organic acid, the optical modifier precursor material, and the anti-sintering modifier precursor material are mixed respectively;

[0018] The mixture is dispersed, stirred, dried, and calcined to obtain a heat storage material.

[0019] As a preferred embodiment of the method for preparing the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the organic acid is one or more of citric acid and its hydrates;

[0020] The molar ratio of the total amount of metal atoms contained in the heat storage and release material to the organic acid is 1:0.5-1.5.

[0021] As a preferred embodiment of the method for preparing a chemical heat storage material with high light absorption and cyclic stability of the present invention, the separate mixing includes dissolving the precursor of the main heat storage material, the precursor of the secondary heat storage material and the organic acid in deionized water, and stirring them evenly to obtain solution A; dissolving the precursor of the optical modification material, the precursor of the anti-sintering modification material and the organic acid in deionized water, and stirring them evenly to obtain solution B.

[0022] As a preferred embodiment of the method for preparing the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the dispersion includes but is not limited to using an ultrasonic dispersing cleaner to ultrasonically treat the above-mentioned solution A and solution B separately, and then mixing the dispersed solution A and solution B, and dispersing them using ultrasonic treatment.

[0023] As a preferred solution of the method for preparing the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the stirring includes but is not limited to being achieved under heating conditions using a magnetic stirrer.

[0024] As a preferred solution of the method for preparing the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the drying includes but is not limited to being achieved under heating conditions in a vacuum drying oven in a vacuum negative pressure atmosphere.

[0025] As a preferred solution of the method for preparing the chemical heat storage and release material with high light absorption and cyclic stability of the present invention, the calcination treatment is performed at a temperature of 750 to 900° C. and a calcination time of 0.5 to 2 hours.

[0026] Another object of the present invention is to provide an application of a chemical heat storage and release material having high light absorption and cyclic stability as described in any one of the above, wherein metal oxides and carbonates store and release heat simultaneously, thereby reducing the inert mass in the thermochemical heat storage and release material and maximizing the efficiency of solar energy utilization;

[0027] Specifically, the chemical heat storage and release material is subjected to a mixed heat storage and release chemical reaction in a mixed gas environment;

[0028] Wherein, the mixed gas is one or more of nitrogen, oxygen and carbon dioxide.

[0029] As a preferred solution for the application of the present invention, in the heat storage reaction, the mixed gas is only nitrogen; in the heat release reaction, the mixed gas is a mixed gas of oxygen and carbon dioxide.

[0030] As a preferred embodiment of the present invention, in the mixed gas of the exothermic reaction, the volume ratio of carbon dioxide to oxygen at normal temperature and pressure is 1:0-1.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The heat storage and release material of the present invention can improve the overall absorption ratio of solar radiation, simplify the high-temperature concentrated heat collection and heat storage system, and can additionally improve the absorption ratio of specific bands, so as to maximize the utilization efficiency of solar energy in combination with photovoltaic power generation; at the same time, compared with traditional calcium-based heat storage materials, the material of the present invention has better heat storage and release reaction cycle stability and higher energy storage density. The implementation and application of the thermochemical heat storage and release of the present invention realizes the simultaneous heat storage and release of metal oxides and carbonates, which can reduce the inert mass in the thermochemical heat storage and release material and maximize the utilization efficiency of solar energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0034] Figure 1 A comparison diagram of the optical properties of the chemical heat storage and release material of Example 2 of the present invention and a control material;

[0035] Figure 2 A comparison chart of the effective conversion rate and energy storage density of the chemical heat storage and release material of Example 2 of the present invention and the control material;

[0036] Figure 3 This is a comparison chart of solar radiation absorption ratio of heat storage and release materials under different raw material ratios;

[0037] Figure 4 This is a comparison chart of the effective conversion rate of heat storage and release materials under different raw material ratios;

[0038] Figure 5 This is a comparison chart of the effective conversion rate of heat storage and release materials under the action of different precursors;

[0039] Figure 6 It is a comparison chart of the effective conversion rate of heat storage and release materials at different calcination temperatures;

[0040] Figure 7 This is the X-ray diffraction pattern of the chemical heat storage and release material of Example 2 of the present invention. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0044] The reaction conversion rate calculation formula of the present invention is:

[0045]

[0046] The energy storage density calculation formula of the present invention is:

[0047]

[0048] Among them, m gas Indicates the mass change of gas in the heat storage and release cycle reaction, m re is the mass of the material when it decomposes to the lowest point under high temperature calcination, both of which are obtained from the thermogravimetric curve. CaO ,M CoO , is the molar mass of the corresponding substance. (CaO+CoO) / All Indicates the mass ratio of CaO and CoO in the material, R CaO / All and R CoO / All Respectively represent the mass proportion of CaO and CoO in the material. ΔH CaO The theoretical maximum energy density of calcium oxide material is 3184 kJ / kg, ΔH CoOThe theoretical maximum energy density of cobalt oxide material is 873 kJ / kg.

[0049] The solar radiation spectrum absorption ratio and the solar radiation absorption ratio calculation formula of the present invention are:

[0050] A(λ)=1-R(λ)

[0051]

[0052] Wherein, R(λ) is the reflectance spectrum of the material, and I(λ) is the standard solar spectrum AM1.5D (ASTM G173).

[0053] In the embodiment of the present invention, a synchronous thermal analyzer (STA8000, PerkinElmer) was used to carry out heat storage / heat release cycle tests on the corresponding materials. The heat storage conditions are: in a nitrogen atmosphere, stay at 850°C for 5 minutes, then cool down to 750°C to complete the heat storage process; the heat release conditions are: in a mixed atmosphere of carbon dioxide and oxygen, stay at 750°C for 10 minutes, then heat up to 850°C to complete the heat release process; the number of cycles is 10 to 12 times.

[0054] In the embodiment of the present invention, an ultraviolet-visible-near infrared spectrophotometer (UVI, lamda 950) is used to test the light absorption performance of the corresponding materials. The wavelength λ of the incident light ranges from 300 to 2500 nm, and the scanning mode is reflectivity R%.

[0055] In the embodiment of the present invention, a desktop XRD (Aeris) device is used to carry out X-ray diffraction on the corresponding material at room temperature to obtain an X-ray diffraction spectrum and analyze the phase composition.

[0056] In the embodiment of the present invention, a scanning electron microscope (SEM) test is performed using a Sirion 200 device to observe the microscopic morphology of the material.

[0057] Calcium carbonate used in the examples of the present invention was purchased from Shanghai Bioengineering Co., Ltd.; calcium nitrate, magnesium nitrate or its hydrate was purchased from Sinopharm Chemical Reagent Co., Ltd.; cobalt tetraoxide and cobalt (II) nitrate hydrate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; anhydrous citric acid, manganese (II) nitrate or its hydrate was purchased from Shanghai McLean Biochemical Technology Co., Ltd. All raw materials used were analytically pure unless otherwise specified.

[0058] Example 1

[0059] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.194 g of cobalt nitrate hexahydrate, and 1.408 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution A.

[0060] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution B.

[0061] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0062] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0063] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0064] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 1.

[0065] It was determined that the energy storage density corresponding to the last cycle of the chemical heat storage material of Example 1 was 1486 kJ / kg, which is 1.54 times that of ordinary calcium carbonate. The conversion rate dropped from 64.57% to 59.04% after twelve heat storage cycles, and the average decay was only 0.46% each time, which is 8% of ordinary calcium carbonate, and has good cycle stability. The solar radiation absorption ratio is 67.33%, which is 7.07 times that of ordinary calcium carbonate.

[0066] Example 2

[0067] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.388 g of cobalt nitrate hexahydrate, and 1.536 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution A.

[0068] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution B.

[0069] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0070] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0071] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0072] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 2.

[0073] It was determined that the energy storage density of the chemical heat storage material of Example 2 in the last cycle was 1468 kJ / kg, which is 1.53 times that of ordinary calcium carbonate. The conversion rate increased from 59.41% to 62.06% after twelve heat storage cycles, with an average increase of 0.22% each time, showing excellent cycle stability. The solar radiation absorption ratio was 75.79%, which is 7.96 times that of ordinary calcium carbonate.

[0074] Example 3

[0075] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.582 g of cobalt nitrate hexahydrate, and 1.664 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution A.

[0076] (2) Weigh 0.191 g of manganese nitrate hexahydrate, 0.128 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution B.

[0077] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0078] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0079] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0080] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 3.

[0081] It was determined that the energy storage density of the chemical heat storage material of Example 3 in the last cycle was 806 kJ / kg, which is lower than that of ordinary calcium carbonate. The conversion rate increased from 36.24% to 36.38% after twelve heat storage cycles, with an average increase of 0.01% each time, which has good cycle stability, but the overall conversion rate is low. The solar radiation absorption ratio is 80.87%, which is 8.49 times that of ordinary calcium carbonate.

[0082] By comparing Examples 1 to 3 with ordinary calcium carbonate materials, it is found that the optical properties and cycle stability of the materials in the three ratios of Examples 1 to 3 are greatly improved compared with ordinary calcium carbonate, and considering the energy storage density comprehensively, the materials in Examples 1 and 2 are better than the material in Example 3.

[0083] Example 4

[0084] (1) Weigh 1.573 g of calcium nitrate tetrahydrate and 1.28 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution A.

[0085] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.128 g of magnesium nitrate hexahydrate, and 0.192 g of anhydrous citric acid, dissolve them in deionized water, and stir with a glass rod to prepare solution B.

[0086] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0087] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0088] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0089] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 4.

[0090] It was determined that the energy storage density of the chemical heat storage material of Example 4 in the last cycle was 2191 kJ / kg, which is 2.28 times that of ordinary calcium carbonate. The conversion rate dropped from 82.42% to 78.56% after twelve heat storage cycles, and the average decay was only 0.32% each time, which is 5.5% of ordinary calcium carbonate, and has good cycle stability. The solar radiation absorption ratio is 49.63%, which is 5.21 times that of ordinary calcium carbonate.

[0091] Figure 3 The optical properties of ordinary calcium carbonate and the materials in Examples 1 to 4, that is, chemical heat storage materials under different raw material ratios, are compared. It can be seen from the figure that the absorption ratio of solar radiation of the material in the present invention can be increased to more than eight times that of traditional calcium-based heat storage materials. At the same time, the optical properties of the material in Example 4 are compared with the materials in Examples 1 to 3, and it can be seen that the addition of cobalt can greatly improve the optical properties, confirming the optical modification effect of cobalt.

[0092] Figure 4By comparing the cycle stability of common calcium carbonate and the materials of Examples 1 to 3, it can be found that the optical properties and cycle stability of the materials in Examples 1 to 3 are better than those of common calcium carbonate materials.

[0093] The optical properties of the material in Example 2 are better than those in Examples 1 and 4, the energy storage density is higher than that in Example 3, and the cycle stability is better than that in Examples 1, 3, and 4. Taking into account the optical properties, cycle stability, and energy storage density, the effects of different types of calcium-based material precursors, cobalt-based material precursors, and calcination temperatures during preparation on the cycle stability and energy storage density of the heat storage material are further described below on the basis of Example 2.

[0094] Example 5

[0095] (1) Weigh 0.667 g of nano-calcium carbonate, 0.388 g of cobalt nitrate hexahydrate, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water and 10 mL of anhydrous ethanol, and stir with a glass rod to prepare solution A.

[0096] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0097] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0098] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0099] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0100] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 5.

[0101] It was determined that the energy storage density of the chemical heat storage material of Example 5 in the last cycle was 1126 kJ / kg, which is 1.18 times that of ordinary calcium carbonate. The conversion rate dropped from 49.57% to 44.76% after ten heat storage cycles, with an average decay of 0.48% each time, which is 8.3% of ordinary calcium carbonate.

[0102] Example 6

[0103] (1) Weigh 0.667 g of micronized calcium carbonate, 0.388 g of cobalt nitrate hexahydrate, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water and 10 mL of anhydrous ethanol, and stir with a glass rod to prepare solution A.

[0104] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0105] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0106] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0107] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0108] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 6.

[0109] It was determined that the energy storage density of the chemical heat storage material of Example 6 in the last cycle was 1113 kJ / kg, which is 1.17 times that of ordinary calcium carbonate. The conversion rate dropped from 49.09% to 44.21% after ten heat storage cycles, with an average decay of 0.49% each time, which is 8.5% of ordinary calcium carbonate.

[0110] Example 7

[0111] (1) Weigh 0.493 g of calcium hydroxide, 0.388 g of cobalt nitrate hexahydrate, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water and 10 mL of anhydrous ethanol, and stir with a glass rod to prepare solution A.

[0112] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0113] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0114] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0115] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0116] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 7.

[0117] It was determined that the energy storage density of the chemical heat storage material of Example 7 in the last cycle was 1118 kJ / kg, which is 1.17 times that of ordinary calcium carbonate. The conversion rate dropped from 48.53% to 44.41% after ten heat storage cycles, with an average decay of 0.41% each time, which is 7.1% of ordinary calcium carbonate.

[0118] Example 8

[0119] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.321 g of cobalt trioxide, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water and 10 mL of anhydrous ethanol, and stir with a glass rod to prepare solution A.

[0120] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0121] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0122] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0123] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0124] (6) The dried material was transferred to a muffle furnace, heated to 850° C. in an air atmosphere, calcined at 850° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 8.

[0125] It was determined that the energy storage density of the chemical heat storage material of Example 8 in the last cycle was 953 kJ / kg, which is the same as that of ordinary calcium carbonate. The conversion rate dropped from 41.92% to 37.86% after ten heat storage cycles, with an average decay of 0.41% each time, which is 7.1% of ordinary calcium carbonate.

[0126] Figure 5The cycle performance of materials under different precursors was compared. It can be seen from the figure that the cycle stability of the materials in Examples 2 and 5 to 8 is better than that of ordinary calcium carbonate materials, among which the precursor combination in Example 2 is the best.

[0127] Example 9

[0128] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.388 g of cobalt trioxide, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution A.

[0129] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0130] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0131] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0132] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0133] (6) The dried material was transferred to a muffle furnace, heated to 750° C. in an air atmosphere, calcined at 750° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 9.

[0134] It was determined that the energy storage density of the chemical heat storage material of Example 9 in the last cycle was 1279 kJ / kg, which is 1.34 times that of ordinary calcium carbonate. The conversion rate dropped from 53.33% to 50.80% after twelve heat storage cycles, and the average attenuation was only 0.21% each time, which is 3.7% of ordinary calcium carbonate.

[0135] Example 10

[0136] (1) Weigh 1.573 g of calcium nitrate tetrahydrate, 0.388 g of cobalt trioxide, and 1.536 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution A.

[0137] (2) Weigh 0.143 g of manganese nitrate hexahydrate, 0.171 g of magnesium nitrate hexahydrate, and 0.224 g of anhydrous citric acid, dissolve them in 5 mL of deionized water, and stir with a glass rod to prepare solution B.

[0138] (3) Place solution A and solution B in an ultrasonic dispersion cleaner and perform ultrasonic treatment for 20 min each. Mix the two ultrasonically dispersed solutions, stir with a glass rod, and perform ultrasonic treatment for another 20 min.

[0139] (4) The mixed solution was placed on a magnetic stirrer and heated and stirred for 3 hours.

[0140] (5) The gel was placed in a vacuum drying oven at 120°C and dried after evacuation.

[0141] (6) The dried material was transferred to a muffle furnace, heated to 900° C. in an air atmosphere, calcined at 900° C. for 1 hour, and then naturally cooled to room temperature to obtain the chemical heat storage and release material of Example 10.

[0142] It was determined that the energy storage density of the chemical heat storage material of Example 10 in the last cycle was 1268 kJ / kg, which is 1.33 times that of ordinary calcium carbonate. The conversion rate dropped from 53.33% to 50.37% after twelve heat storage cycles, with an average increase of 0.05% each time, showing excellent cycle stability.

[0143] Examples 2, 9, and 10 illustrate the effects of different calcination temperatures on the material cycle performance. Figure 6 It can be seen that at calcination temperatures of 750°C, 850°C and 900°C, the preparation method of the present invention can prepare thermochemical heat storage and release materials with good cycle performance, among which the calcination temperature of 850°C is the best, followed by 750°C and 900°C.

[0144] Taking into account the optical properties, cycle performance and heat storage density, the chemical heat storage and release material in Example 2 is the optimal chemical heat storage and release material.

[0145] like Figure 1 As shown, the chemical heat storage and release material in Example 2 has good optical absorption performance compared with commercial calcium carbonate, and improves the spectral absorption ratio of the material to solar radiation in the entire band of 300-2500nm, and the absorption ratio of solar radiation is increased to 7.96 times that of traditional calcium-based heat storage materials.

[0146] like Figure 2 As shown, the chemical heat storage and release material in Example 2 has good storage / release reaction cycle stability compared with commercial calcium carbonate, and the 12th cycle conversion rate of commercial calcium carbonate is increased from less than 30.21% to 62.06%; the material has a high energy storage density, which increases the 12th cycle energy storage density of traditional calcium-based heat storage materials from 961.79 kJ / kg to 1467.54 kJ / kg.

[0147] The raw material ratio, precursor type, preparation conditions, and corresponding heat storage density, conversion rate change, and optical properties of the chemical heat storage and release materials described in Examples 1 to 10 are shown in Table 1. The solar radiation spectrum absorption ratio curve and absorption ratio bar graph of the representative materials are shown in Table 1. Figure 3 The change of conversion rate with the number of cycles is shown in Figure 4 , Figure 5 , Figure 6 As shown. To show the influence of the ratio, type and calcination temperature of different main heat storage and release materials, secondary heat storage and release materials, optical modification materials and anti-sintering materials on the chemical heat storage and release performance and optical properties.

[0148] Table 1

[0149]

[0150]

[0151] The phase analysis of the material after high temperature calcination is as follows: Figure 7 As shown. The XRD pattern shows obvious CaO and Ca3Co 2-x Mn x O6 peak, indicating the formation of a continuous and uniform solid solution. Phase analysis shows that the addition of cobalt causes the appearance of Ca3Co 2-x Mn x O6 is a complex solid solution. This complex solid solution can change the electronic structure of the original crystal, making it easier for electrons near the Fermi surface to transition, and improving the light absorption performance. At the same time, this structure is evenly dispersed and supported between the particles, hindering the sintering and fusion between the heat storage particles, ensuring the mass transfer channel of the gas, and improving the cycle stability to a certain extent; under the combined effect of the above factors, the optimal chemical heat storage and release material Example 2 of the present invention exhibits excellent chemical heat storage and release performance.

[0152] Compared with traditional calcium carbonate / calcium oxide heat storage and release materials, the material in the present invention has a high absorption ratio of solar radiation. The present invention can increase the solar radiation absorption ratio of the heat storage material to more than eight times that of traditional calcium-based heat storage materials. The reason why the present invention has such a beneficial effect is that the special preparation process in the present invention introduces metal atoms such as cobalt atoms and manganese atoms into the original calcium-based heat storage material. The doping effect causes the material to absorb solar radiation more easily to undergo transitions, effectively improving the absorption ratio of the material in the full band of solar radiation from 300 to 2500nm. And especially improves the absorption ratio of the <500nm band and the infrared band >1350nm. This photothermal property enables the thermochemical heat storage and release material in the present invention to be combined with photovoltaic power generation through a spectral divider, thereby improving the efficiency of the photovoltaic-photothermal-thermochemical complementary solar energy utilization system.

[0153] The material of the present invention has good storage / release reaction cycle stability and high energy storage density. The present invention can increase the 12-cycle conversion rate of traditional calcium-based heat storage materials from 30.21% to more than 60%, and the corresponding energy storage density is increased from 962kJ / kg to more than 1450kJ / kg. The reason why the present invention has such a beneficial effect is that manganese metal elements form a sufficient amount of stable substance Ca3Co with calcium and cobalt metal elements. 2-x Mn x O6, this structure is evenly dispersed and supported between particles, which hinders the sintering and fusion between heat storage particles and ensures the mass transfer channel of gas; at the same time, the incorporation of magnesium metal elements causes the internal expansion of the heat storage material to appear more porous structures, and the porous configuration is conducive to gas diffusion and increases the contact area between gas and solid, so that more solid materials can participate in the gas-solid reaction; under the joint action of the above factors, the material in the present invention exhibits stable cycle performance.

[0154] In the heat storage / release application of the present invention, metal oxides and carbonates store heat simultaneously, further improving the energy storage density. The modifiers in the previous modified calcium carbonate heat storage materials do not directly participate in the thermochemical heat storage and release reaction, and the mass they occupy is invalid mass, which reduces the mass energy storage density of the heat storage material. The cobalt metal oxide in the present invention acts as both an optical property modifier and a secondary heat storage material, and performs heat storage and release reactions with the main heat storage material in a mixed atmosphere of carbon dioxide and oxygen.

[0155] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A chemical heat storage and release material with high light absorption and cyclic stability, characterized in that: Including, a primary heat storage and release precursor material, a secondary heat storage and release precursor material, an optical modification material and an anti-sintering modifier; Wherein, the main heat storage precursor material is a calcium-based compound whose product after high-temperature calcination is only calcium oxide; The secondary heat storage precursor material is a cobalt-based compound whose product is cobalt oxide after high-temperature calcination; The optical modification material is a substance having an enhanced solar radiation absorption ratio; the optical modification material or its precursor material is one or more of cobalt-based metal oxides, manganese-based metal oxides, cobalt-based metal nitrates, manganese-based metal nitrates and their respective hydrates; The anti-sintering modifier is a substance that can hinder the agglomeration, adhesion and agglomeration of heat storage and release material particles; the anti-sintering modifier or its precursor material is one or more of manganese-based metal oxides, magnesium-based metal oxides, manganese-based metal nitrates, magnesium-based metal nitrates and their respective hydrates.

2. The chemical heat storage and release material with high light absorption and cyclic stability as claimed in claim 1, characterized in that: The calcium-based compound includes one or more of calcium hydroxide, nano calcium carbonate, micro calcium carbonate, calcium nitrate and hydrates thereof.

3. The chemical heat storage and release material with high light absorption and cyclic stability as claimed in claim 1 or 2, characterized in that: The cobalt-based compound includes one or more of cobalt tetraoxide, cobalt oxide, cobalt nitrate and hydrates thereof.

4. The chemical heat storage and release material with high light absorption and cyclic stability as claimed in claim 3, characterized in that: The main exothermic storage precursor material, the secondary exothermic storage precursor material, the optical modification material, and the anti-sintering modifier are in a ratio of 1:0~0.3:0~0.1:0~0.1 according to the molar ratio of the metal atoms contained in each of them; the values ​​of the main exothermic storage precursor material, the secondary exothermic storage precursor material, the optical modification material, and the anti-sintering modifier are not 0.

5. The method for preparing a chemical heat storage and release material having both high light absorption and cyclic stability as claimed in any one of claims 1 to 4, characterized in that: include, The main heat storage and release precursor material, the secondary heat storage and release precursor material, the organic acid, the optical modifier precursor material, and the anti-sintering modifier precursor material are mixed respectively; The mixture is dispersed, stirred, dried, and calcined to obtain a heat storage material.

6. The method for preparing the chemical heat storage and release material with high light absorption and cyclic stability as claimed in claim 5, characterized in that: The organic acid is one or more of citric acid and its hydrates; The molar ratio of the total amount of metal atoms contained in the heat storage and release material to the organic acid is 1:0.5-1.

5.

7. The method for preparing the chemical heat storage and release material having both high light absorption and cyclic stability as claimed in claim 5 or 6, characterized in that: The calcination treatment is performed at a temperature of 750-900° C. and a calcination time of 0.5-2 hours.

8. The use of the chemical heat storage and release material with high light absorption and cyclic stability as claimed in any one of claims 1 to 4, characterized in that: The chemical heat storage and release material is subjected to a mixed heat storage and release chemical reaction in a mixed gas environment; Wherein, the mixed gas is one or more of nitrogen, oxygen and carbon dioxide.

9. The use according to claim 8, characterized in that: In the heat storage reaction, the mixed gas is only nitrogen; in the heat release reaction, the mixed gas is a mixed gas of oxygen and carbon dioxide.

10. The use according to claim 9, characterized in that: In the mixed gas of the exothermic reaction, the volume ratio of carbon dioxide to oxygen at normal temperature and pressure is 1:0~1.

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