Preparation method and application of zrtio4 single-atom catalyst with rich oxygen vacancies

Abstract

The application discloses a preparation method and application of a ZrTiO4 single-atom catalyst rich in oxygen vacancies, and belongs to the technical field of hydrogen storage materials and preparation thereof. (SA) The ZrTiO4 single-atom catalyst rich in oxygen vacancies is Y / ZrTiO4 catalyst, and a preparation method thereof takes the precursors of Zr and Ti as raw materials, constructs a ZrTiO4 carrier rich in oxygen vacancies through reduction treatment, and introduces monodispersed Y single atoms by using an in-situ anchoring strategy.The obtained catalyst has rich oxygen vacancies and stable Y-O coordination structures, constructs high-density active sites and effectively regulates the electronic structure of the active sites.The catalyst is compounded with sodium cyanide and aluminum to prepare a composite hydrogen storage system, can catalyze the synthesis of sodium aluminum hydride at low temperature, effectively stores hydrogen, and realizes low-temperature and high-efficiency hydrogen release of the hydrogen storage system.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage materials and their preparation technology, and in particular to a method for preparing and applying a ZrTiO4 supported single-atom catalyst rich in oxygen vacancies. Background Technology

[0002] Hydrogen energy is considered one of the most promising energy carriers due to its high energy density and clean, pollution-free nature. However, safe and efficient hydrogen storage technology remains a key issue restricting the large-scale application of hydrogen energy. Among solid-state hydrogen storage materials, sodium aluminum hydride (NaAlH4) has attracted widespread attention due to its high theoretical hydrogen storage capacity (approximately 7.4 wt%) and certain reversible hydrogen storage and release performance. However, NaAlH4 suffers from high thermodynamic stability, high hydrogen release temperature (typically above 150℃), and slow hydrogen absorption and release kinetics, which severely limit its practical application.

[0003] Currently, improving the reaction kinetics of the NaAlH4 system by introducing catalysts is considered one of the most effective methods. In particular, the composite system based on the in-situ reaction of sodium hydride (NaH) and metallic aluminum (Al) to synthesize NaAlH4 shows promising application prospects due to its low raw material cost and uniform component dispersion. However, this system still faces challenges such as difficulty in hydrogen molecule activation, limited solid-phase diffusion, and insufficient reaction interfaces, resulting in a slow NaAlH4 formation rate and low conversion efficiency, typically requiring higher temperatures and longer reaction times.

[0004] Existing catalysts mostly utilize transition metals and their compounds in nanoparticle form, but these suffer from low active site utilization and susceptibility to agglomeration and deactivation during cycling. Furthermore, the activity of nanoparticle catalysts is complex and difficult to control at the atomic scale. Single-atom catalysts, due to their maximized atomic utilization and unique electronic structure, exhibit superior performance in catalysis. However, single atoms are prone to migration and agglomeration, resulting in poor stability; therefore, it is necessary to construct support systems that can provide strong interactions.

[0005] Oxide supports, due to their structural stability and high tunability, have significant application value in single-atom catalysts. Among them, ZrTiO4, as a stable composite oxide, exhibits excellent thermal and chemical stability. By introducing oxygen vacancy defects into its structure, unsaturated coordination sites can be formed, which is beneficial for the anchoring and dispersion of single atoms, and can also regulate the electronic structure, thereby promoting catalytic reactions. In addition, the rare earth metal yttrium has a strong oxygen affinity. When introduced into oxide supports in single-atom form, it can form stable coordination structures with oxygen vacancies, thereby improving the stability of single atoms and promoting the adsorption and activation of hydrogen molecules.

[0006] Therefore, developing a method for controllably constructing oxygen-vacancy-rich ZrTiO4 supports and achieving stable anchoring and efficient catalysis of rare earth single atoms, and elucidating their mechanism of action in the NaAlH4 system, is of great scientific significance and application value for promoting the practical application of high-capacity solid-state hydrogen storage materials. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for preparing and applying a ZrTiO4-supported single-atom catalyst rich in oxygen vacancies. Using ZrTiO4 as a support, oxygen vacancy defects are introduced into its structure through reduction treatment, and yttrium is dispersed in single-atom form on the support surface or in the crystal lattice, forming a stable coordination structure. Oxygen vacancies not only serve as anchoring sites for single atoms, effectively inhibiting their migration and aggregation, but also regulate the electronic structure of the support, thereby enhancing catalytic activity. This effectively solves the problems of high reaction temperature, slow kinetics, low conversion efficiency, and insufficient catalyst stability in the NaAlH4 hydrogen absorption and desorption process.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a ZrTiO4 supported single-atom catalyst rich in oxygen vacancies, wherein the support is ZrTiO4 rich in oxygen vacancies, the active component is a single-atom metal Y, and the loading amount of the single-atom metal is 0.5~2 wt%.

[0009] This invention also provides a method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst, comprising the following steps: mixing a zirconium source, a titanium source, and a single-atom yttrium precursor in an organic solvent, adding a stabilizer and stirring continuously to form a homogeneous sol; drying and grinding the sol to obtain Y / ZrTiO4 precursor powder; calcining the Y / ZrTiO4 precursor powder to remove organic matter, and then calcining it under a reducing atmosphere to introduce oxygen vacancies and form ZrTiO4, denoted as Y. (SA) / ZrTiO4 catalyst.

[0010] Furthermore, the zirconium source is Zr(OC3H7)4, the titanium source is selected from Ti(OC4H9)4, the single-atom yttrium precursor is Y(NO3)3·6H2O, and the organic solvent is anhydrous ethanol.

[0011] Furthermore, the stabilizer is acetylacetone.

[0012] Furthermore, the calcination temperature is 300°C and the time is 2 hours.

[0013] Furthermore, the calcination temperature under a reducing atmosphere is 800°C, and the time is 4 hours.

[0014] Furthermore, the reducing atmosphere is an H2 / Ar atmosphere, with H2 accounting for 5% of the volume.

[0015] This invention also provides the application of a ZrTiO4 supported single-atom catalyst rich in oxygen vacancies in the catalytic NaAlH4 composite hydrogen storage system.

[0016] Further, the operation steps of the application are as follows: sodium hydride and aluminum are mixed in a molar ratio of 1:1 and ball-milled to form a sodium hydride / aluminum NaH / Al mixture; the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst is mixed with the sodium hydride / aluminum mixture to carry out a hydrogen absorption reaction to obtain an aluminum hydride sodium composite hydrogen storage system, wherein the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst accounts for 5~9 wt% of the aluminum hydride sodium composite hydrogen storage system.

[0017] Furthermore, the NaAlH4 composite hydrogen storage system is applied in solid-state hydrogen storage.

[0018] Compared with the prior art, the present invention has at least the following advantages and technical effects: In the Y(SA) / ZrTiO4 catalyst prepared by this invention, yttrium active atoms are uniformly and stably attached to the ZrTiO4 support surface in an atomically dispersed manner, achieving nearly 100% utilization of yttrium active atoms, maximizing the catalytic effect of active atoms, and avoiding waste of active metal resources. Simultaneously, oxygen vacancies on the support surface can act as atomic traps, forming strong covalent or ionic bonds with yttrium single atoms, producing a strong anchoring effect. This effectively inhibits the migration and aggregation of single atoms during the hydrogen absorption and desorption cycles of the hydrogen storage material, preventing the formation of metal clusters. This solves the problems of easy deactivation of active sites and easy structural collapse in traditional catalysts, significantly improving the structural stability and long-term service performance of the catalyst during recycling.

[0019] This catalyst, leveraging the synergistic electronic effect between oxygen vacancies and yttrium single-atom sites, endows the composite hydrogen storage system with excellent low-temperature synthesis and dehydrogenation performance, demonstrating significant catalytic advantages. Experimental data show that the addition of 7 wt% Y... (SA) The ZrTiO4 composite hydrogen storage system achieves a peak hydrogen release temperature as low as 132℃ in the first step, with a hydrogen release capacity of 5.05 wt% before 300℃. Compared to the pure ball-milled NaH / Al system without catalyst, the peak hydrogen release temperature is reduced by 93℃, and the hydrogen release capacity is significantly increased. Furthermore, compared to ordinary ZrTiO4 support-modified systems lacking single atoms and oxygen vacancies, this catalyst-modified system exhibits a lower hydrogen release temperature and a higher hydrogen release capacity, fully demonstrating that the synergistic effect of oxygen vacancies and single atoms is the core of optimizing low-temperature hydrogen release performance. This effectively reduces the energy consumption of hydrogen release from the storage material and is suitable for low-temperature hydrogen storage applications.

[0020] Y (SA)The ZrTiO4 catalyst can efficiently catalyze the hydrogen absorption and desorption reactions of NaAlH4, greatly improving the problem of slow reaction kinetics. Under isothermal conditions of 150℃, the composite hydrogen storage system doped with this catalyst can release 4.13 wt% hydrogen in just 40 minutes. In contrast, the comparative systems with no single-atom ZrTiO4 support, no oxygen vacancies, and single-atom ZrTiO4 support, respectively, only release 3.52 wt% and 3.13 wt% hydrogen under the same conditions, while the pure NaH / Al system without catalyst releases only 0.84 wt% hydrogen in 2 hours. This catalyst can quickly overcome the reaction energy barrier, accelerate the hydrogen desorption rate, shorten the hydrogen absorption and desorption reaction time of hydrogen storage materials, improve the working efficiency of hydrogen storage systems, and meet the requirements for rapid hydrogen release.

[0021] This invention optimizes and improves the preparation process by controlling the hydrogen atmosphere, ball-to-material ratio, ball milling speed, and intermittent ball milling mode, combined with a gentle hydrogen absorption post-treatment step, relying on Y... (SA) The catalytic action of ZrTiO4 catalyst enables the in-situ one-step synthesis of NaAlH4 composite hydrogen storage materials from NaH and Al powders under mild conditions ≤150℃. This synthesis method features a simple process flow, mild reaction conditions, no need for harsh high-temperature and high-pressure preparation environments, high synthesis conversion rate, effectively reducing the production cost and energy consumption of hydrogen storage materials, simplifying the production process, facilitating large-scale industrial production, and possessing good engineering application value. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The (1 wt% Y) prepared in Example 2 (SA) X-ray diffraction (XRD) pattern of ZrTiO4 catalyst, where ZrTiO4(O) L ) refers to ZrTiO4 that does not contain oxygen vacancies, ZrTiO4(O V ) refers to ZrTiO4 containing oxygen vacancies, and refers to Y / ZrTiO4(O V ZrTiO4 containing oxygen vacancies and supporting single-atom Y; Figure 2 The (1 wt% Y) prepared in Example 2 (SA) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) spectra and elemental distribution mapping of the ZrTiO4 catalyst; Figure 3 The (1 wt% Y) prepared in Example 2 (SA) Electron paramagnetic resonance (EPR) spectra of ZrTiO4 catalyst, wherein ZrTiO4(O L ) refers to ZrTiO4 that does not contain oxygen vacancies, ZrTiO4(O V ) refers to ZrTiO4 containing oxygen vacancies, and refers to Y / ZrTiO4(O V ZrTiO4 containing oxygen vacancies and supporting single-atom Y; Figure 4 The (1 wt% Y) prepared in Example 2 (SA) X-ray photoelectron spectroscopy (XPS) images of ZrTiO4 catalyst, where images a, b, c, and d are ZrTiO4(O) catalysts, respectively. L ZrTiO4(O) V ), Y / ZrTiO4(O V XPS plots of Zr 3d, Ti 2p, O 1s and Y 3d of the sample; Figure 5 7 wt% of Examples 4, 5, and 6 x wt%Y (SA) ) / ZrTiO4 ( x Temperature-programmed desorption (TPD) curves of the NaAlH4 composite system catalyzed by catalysts of =0.5, 1, 2); Figure 6 The products prepared in Examples 5, 7, and 8 contain x wt%(1 wt% Y (SA) ) / ZrTiO4 ( x Comparison of TPD hydrogen release curves of composite hydrogen storage systems (=5, 7, 9); Figure 7 The middle part consists of a ball-milled NaH / Al mixture (NaAlH4 ball-milled in Comparative Example 1), a NaH / Al mixture with 7 wt% oxygen vacancies (Comparative Example 3), and a NaH / Al mixture without oxygen vacancies (Comparative Example 2), as well as the mixture containing 7 wt% (1 wt% Y) prepared in Example 5. (SA) Comparison of TPD hydrogen release curves of the ZrTiO4 / ZrTiO4 composite hydrogen storage system; Figure 8 The NaH / Al mixtures prepared in Example 1 (ball-milled NaAlH4), NaH / Al mixtures with 7 wt% oxygen vacancies (Comparative Example 3) and those without oxygen vacancies (Comparative Example 2) containing 7 wt% (1 wt% Y) were compared with those prepared in Example 5. (SA) Isothermal hydrogen desorption curve of the ZrTiO4 composite hydrogen storage system at 150℃. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] This invention provides a ZrTiO4 supported single-atom catalyst rich in oxygen vacancies, wherein the support is ZrTiO4 rich in oxygen vacancies, the active component is a single-atom metal Y, and the loading amount of the single-atom metal is 0.5~2 wt%.

[0030] This invention provides a single-atom catalyst for catalyzing NaAlH4, wherein the support is ZrTiO4 rich in oxygen vacancies, and the single atom is metallic Y, with the loading of the single-atom metal being 0.5~2 wt%. ZrTiO4 is a composite oxide with excellent thermal and chemical stability, and its unique crystal structure can accommodate a large number of oxygen vacancy defects. This invention introduces a high concentration of oxygen vacancies into the ZrTiO4 lattice through controlled reduction treatment (high-temperature annealing in a hydrogen / argon mixed atmosphere). The presence of these oxygen vacancies has multiple synergistic effects: First, oxygen vacancies significantly alter the electronic structure of ZrTiO4, improving its conductivity and surface reactivity, while simultaneously enhancing the metal-support interaction (MSI) between the support and the loaded metal, forming an "electron-poor support-electron-rich single atom" interface, which is beneficial for the stable anchoring of the single-atom metal and prevents its migration and aggregation during the catalytic reaction; second, the oxygen vacancies themselves can participate in the reaction as additional active sites, forming a "defect-single atom" dual active center with the single atom, synergistically promoting the adsorption and activation of reactant molecules.

[0031] In the single-atom catalyst of this invention, metallic Y is stably supported on an oxygen-vacancy-rich ZrTiO4 support in an atomically dispersed form. The single-atom Y possesses a highly unsaturated coordination environment, exposing abundant active sites, enabling efficient adsorption and activation of hydrogen molecules to generate active hydrogen species. Simultaneously, the presence of oxygen vacancies further enhances the affinity of the ZrTiO4 surface for Al species, promoting Al adsorption and dispersion. The active hydrogen species react with activated Al and Na to gradually form [AlH4]⁻ anions, ultimately generating NaAlH4. The strong synergistic catalytic effect between the single atom and the oxygen vacancies on the support effectively lowers the reaction energy barriers for H2 dissociation and Al-H bond formation.

[0032] Traditional hydrogen desorption from NaAlH4 typically requires temperatures above 150°C. The oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst constructed in this invention significantly reduces the activation energy of the reaction due to the high intrinsic activity of the single-atom Y and the synergistic effect of the oxygen vacancies on the support, allowing NaAlH4 to desorb hydrogen at milder temperatures (e.g., 60-120°C). This catalyst combines high atom economy, excellent catalytic activity, and good stability, showing broad application prospects in the field of hydrogen storage materials.

[0033] This invention also provides a method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst, comprising the following steps: mixing a zirconium source, a titanium source, and a single-atom yttrium precursor in an organic solvent, adding a stabilizer and stirring continuously to form a homogeneous sol; drying and grinding the sol to obtain Y / ZrTiO4 precursor powder; calcining the Y / ZrTiO4 precursor powder to remove organic matter, and then calcining it under a reducing atmosphere to introduce oxygen vacancies and form ZrTiO4, denoted as Y. (SA) / ZrTiO4 catalyst.

[0034] In some embodiments of the present invention, the zirconium source is Zr(OC3H7)4, the titanium source is selected from Ti(OC4H9)4, the single-atom yttrium precursor is Y(NO3)3·6H2O, and the organic solvent is anhydrous ethanol.

[0035] In some embodiments of the present invention, the stabilizer is acetylacetone.

[0036] In some embodiments of the present invention, the calcination temperature is 300°C and the time is 2 hours.

[0037] In some embodiments of the present invention, the calcination temperature under a reducing atmosphere is 800°C and the time is 4 h.

[0038] In some embodiments of the present invention, the reducing atmosphere is an H2 / Ar atmosphere, wherein the volume ratio of H2 is 5%.

[0039] This invention also provides an application of a ZrTiO4 supported single-atom catalyst rich in oxygen vacancies in the catalytic NaAlH4 composite hydrogen storage system.

[0040] In some embodiments of the present invention, the operation steps of the application are as follows: sodium hydride and aluminum are mixed in a molar ratio of 1:1 and ball-milled to form a sodium hydride / aluminum NaH / Al mixture; the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst is mixed with the sodium hydride / aluminum mixture to carry out a hydrogen absorption reaction to obtain an aluminum-sodium hydride composite hydrogen storage system, wherein the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst accounts for 5-9 wt% of the aluminum-sodium hydride composite hydrogen storage system.

[0041] This invention also provides an application of the NaAlH4 composite hydrogen storage system in solid-state hydrogen storage.

[0042] Example 1 (0.5 wt% Y (SA) The preparation method of the ZrTiO4 catalyst includes the following steps: 60 ml of ethylene glycol was added to a beaker, followed by 4.7 ml of zirconium source (Zr(OC3H7)4) and 3.45 ml of titanium source (Ti(OC4H9)4), and stirred until homogeneous. Then, 2 ml of acetylacetone, a stabilizer, was added and stirred continuously to help control the hydrolysis rate. 43 mg of Y(NO3)3·6H2O was dissolved in 2 ml of anhydrous ethanol and then added dropwise to the above mixture. The mixture was stirred continuously at room temperature for 2 h to form a homogeneous sol solution. The resulting solution was dried in a forced-air drying oven at 150 °C for 24 h and then ground to obtain Y / ZrTiO4 precursor powder. The Y / ZrTiO4 precursor powder was calcined in a muffle furnace at 300 °C for 2 h to remove organic matter. Subsequently, it was calcined in a 5% H2 / Ar atmosphere at a temperature increase of 3 °C / min to 800 °C for 4 h to obtain (0.5 wt% Y) (SA) ) / ZrTiO4 catalyst.

[0043] Example 2 (1 wt% Y (SA) The preparation method of the ZrTiO4 catalyst includes the following steps: 60 ml of ethylene glycol was added to a beaker, followed by 4.7 ml of zirconium source (Zr(OC3H7)4) and 3.45 ml of titanium source (Ti(OC4H9)4). The mixture was stirred until homogeneous, and then 2 ml of acetylacetone, a stabilizer, was added and stirred continuously to help control the hydrolysis rate. 86 mg of Y(NO3)3·6H2O was dissolved in 4 ml of anhydrous ethanol and then added dropwise to the above mixture. The mixture was stirred continuously at room temperature for 2 h to form a homogeneous sol solution. The resulting solution was dried in a forced-air drying oven at 150 °C for 24 h and then ground to obtain Y / ZrTiO4 precursor powder. The Y / ZrTiO4 precursor powder was calcined in a muffle furnace at 300 °C for 2 h to remove organic matter. Subsequently, it was calcined in a 5% H2 / Ar atmosphere at a temperature increase of 3 °C / min to 800 °C for 4 h to obtain (1 wt% Y (SA) ) / ZrTiO4 catalyst.

[0044] The (1 wt% Y) prepared in Example 2 (SA) The ZrTiO4 catalyst underwent a series of characterizations: Figure 1 The XRD patterns show that the ZrTiO4 samples treated differently all maintained the pure phase structure; the introduction of oxygen vacancies and Y doping did not destroy the main crystal phase structure of ZrTiO4. Figure 2 The HAADF-STEM spectra and elemental distribution mapping diagrams show that the elements are uniformly distributed and that element Y is dispersed as single atoms on the ZrTiO4 support. Figure 3The EPR characterization showed a distinct symmetric signal at g=2.003, indicating the presence of a large number of unpaired electron-captured oxygen vacancies in the catalyst, confirming its oxygen-vacancy-rich characteristics. Figure 4 XPS analysis showed that Ti and Zr existed stably in the +4 valence in all samples; O 1s spectra confirmed (1 wt% Y) (SA) The successful introduction of oxygen vacancies into ZrTiO4 resulted in an oxygen vacancy peak area accounting for 39.7%. Furthermore, the Y element was used as the Y... 3+ The valence state was successfully doped without introducing any impurity phases.

[0045] Example 3 (2 wt% Y (SA) The preparation method of the ZrTiO4 catalyst includes the following steps: 60 ml of ethylene glycol was added to a beaker, followed by 4.7 ml of zirconium source (Zr(OC3H7)4) and 3.45 ml of titanium source (Ti(OC4H9)4), and stirred until homogeneous. Then, 2 ml of stabilizer acetylacetone was added and stirred continuously to help control the hydrolysis rate. 172 mg of Y(NO3)3·6H2O was dissolved in 6 ml of anhydrous ethanol and then added dropwise to the above mixture. The mixture was stirred continuously at room temperature for 2 h to form a homogeneous sol solution. The resulting solution was dried in a forced-air drying oven at 150 °C for 24 h and then ground to obtain Y / ZrTiO4 precursor powder. The Y / ZrTiO4 precursor powder was calcined in a muffle furnace at 300 °C for 2 h to remove organic matter. Subsequently, it was calcined in a 5% H2 / Ar atmosphere at a temperature increase of 3 °C / min to 800 °C for 4 h to obtain (2 wt% Y) (SA) ) / ZrTiO4 catalyst.

[0046] Example 4 (0.5 wt% Y (SA) The preparation method of the NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4 includes the following steps: In a glove box protected by an argon atmosphere, NaH and Al were mixed at a molar ratio of 1:1. The NaH / Al mixture was then combined with the (0.5 wt% Y) solution prepared in Example 1. (SA) ZrTiO4 is calculated according to the chemical composition x(NaH / Al) - y((0.5 wt% Y) (SA) Mixing () / ZrTiO4) by mass percentage () x = 93 wt%, y= 7 wt%), to obtain a mixture; the above mixture was placed in a ball mill jar, charged with hydrogen gas at 4 MPa, and then placed in a planetary ball mill with a ball-to-material ratio of 100:1, a rotation speed of 500 rpm, a program set to mill for 15 min with a 10 min pause in between, milling for 24 h, and then hydrogen absorption at 100 bar hydrogen pressure and 130 °C for 8 h to obtain (0.5 wt% Y) (SA) A NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4.

[0047] Example 5 (1 wt% Y (SA) The preparation method of the NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4 includes the following steps: In a glove box protected by an argon atmosphere, NaH and Al were mixed at a molar ratio of 1:1. The NaH / Al mixture was then combined with the (1 wt% Y) solution prepared in Example 2. (SA) According to the chemical composition of ZrTiO4 x (NaH / Al) - y ((1 wt% Y (SA) Mixing () / ZrTiO4) by mass percentage () x = 93 wt%, y = 7 wt%), to obtain a mixture; the above mixture was placed in a ball mill jar, charged with hydrogen gas at 4 MPa, and then placed in a planetary ball mill with a ball-to-material ratio of 100:1, a rotation speed of 500 rpm, and a program set to ball mill for 15 min with a 10 min pause in between, for 24 h of ball milling. Hydrogen was then absorbed for 8 h at a hydrogen pressure of 100 bar and a temperature of 130 °C to obtain (1 wt% Y) (SA) A NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4.

[0048] Example 6 (2 wt% Y (SA) The preparation method of the NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4 includes the following steps: In a glove box protected by an argon atmosphere, NaH and Al were mixed at a molar ratio of 1:1. The NaH / Al mixture was then combined with the (2 wt% Y) solution prepared in Example 3. (SA) According to the chemical composition of ZrTiO4 x (NaH / Al) - y ((2 wt% Y (SA) Mixing () / ZrTiO4) by mass percentage () x = 93 wt%, y= 7 wt%), to obtain a mixture; place the above mixture in a ball mill jar, fill with hydrogen gas at 4 MPa, and then put it into a planetary ball mill with a ball-to-material ratio of 100:1, a rotation speed of 500 rpm, and a program set to ball mill for 15 min with a 10 min pause in between, for 24 h of ball milling. Then, absorb hydrogen at 100 bar hydrogen pressure and 130 °C for 8 h to obtain (2 wt% Y) (SA) A NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4.

[0049] To evaluate the catalytic effects of the three catalysts in Examples 1, 2, and 3, the hydrogen desorption performance of the composite materials in Examples 4, 5, and 6 was tested. The ball milling hydrogen absorption conditions were consistent for all three systems, followed by heating to 300°C at a rate of 2°C / min to test the TPD. The TPD test results are as follows: Figure 5 As shown: NaAlH4- 7 wt% ((0.5 wt% Y) (SA) The peak hydrogen release temperature of () / ZrTiO4) in the first step is 136℃, and the hydrogen release capacity at 300℃ is 4.85 wt%; NaAlH4- 7 wt% ((1 wt% Y) (SA) The peak hydrogen release temperature of () / ZrTiO4) in the first step is 132℃, and the hydrogen release capacity at 300℃ is 5.05 wt%; NaAlH4-7 wt% ((2 wt% Y) (SA) The peak hydrogen release temperature of (ZrTiO4) in the first step is 150℃, and the hydrogen release capacity is 4.63 wt% at 300℃. In summary, the system in Example 5 has the best hydrogen storage performance.

[0050] Example 7 (1 wt% Y (SA) The preparation method of the NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4 includes the following steps: In a glove box protected by an argon atmosphere, NaH and Al were mixed at a molar ratio of 1:1. The NaH / Al mixture was then combined with the (1 wt% Y) solution prepared in Example 2. (SA) According to the chemical composition of ZrTiO4 x (NaH / Al) - y ((1 wt% Y (SA) Mixing () / ZrTiO4) by mass percentage () x = 95 wt%, y= 5 wt%), to obtain a mixture; place the above mixture in a ball mill jar, fill with hydrogen gas at 4 MPa, and then put it into a planetary ball mill with a ball-to-material ratio of 100:1, a rotation speed of 500 rpm, and a program set to mill for 15 minutes with a 10-minute pause in between, for 24 hours. Then, absorb hydrogen at 100 bar hydrogen pressure and 130°C for 8 hours to obtain (1 wt% Y) (SA) A NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4.

[0051] Example 8 (1 wt% Y (SA) The preparation method of the NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4 includes the following steps: In a glove box protected by an argon atmosphere, NaH and Al were mixed at a molar ratio of 1:1. The NaH / Al mixture was then combined with the (1 wt% Y) solution prepared in Example 2. (SA) According to the chemical composition of ZrTiO4 x (NaH / Al) - y ((1 wt% Y (SA) Mixing () / ZrTiO4) by mass percentage () x = 91 wt%, y = 9 wt%), to obtain a mixture; place the above mixture in a ball mill jar, fill with hydrogen gas at 4 MPa, and then put it into a planetary ball mill with a ball-to-material ratio of 100:1, a rotation speed of 500 rpm, and a program set to mill for 15 minutes with a 10-minute pause in between, for 24 hours. Then, absorb hydrogen at 100 bar hydrogen pressure and 130°C for 8 hours to obtain (1 wt% Y) (SA) A NaAlH4 composite hydrogen storage system catalyzed by ZrTiO4.

[0052] Comparative Example 1 The preparation method of the NaAlH4 composite hydrogen storage system includes the following steps: In an argon-atmosphere protected glove box, NaH and Al were mixed at a molar ratio of 1:1, placed in a ball mill jar, and charged with 4 MPa of hydrogen gas. Then, the mixture was placed in a planetary ball mill with a ball-to-material ratio of 100:1 and a rotation speed of 500 rpm. The program was set to mill for 15 minutes with a 10-minute pause in between, for a total of 24 hours. Hydrogen was absorbed at a hydrogen pressure of 100 bar and a temperature of 130°C for 8 hours to obtain a ball-milled NaH / Al mixture.

[0053] Comparative Example 2 The only difference from Example 5 is that the catalyst used is a ZrTiO4 catalyst without oxygen vacancies, prepared using the following method: 60 ml of ethylene glycol was added to a beaker, followed by the addition of 4.7 ml of zirconium source (Zr(OC3H7)4) and 3.45 ml of titanium source (Ti(OC4H9)4), and stirred until homogeneous. Then, 2 ml of stabilizer acetylacetone was added and stirred continuously to help control the hydrolysis rate. The resulting solution was dried in a forced-air drying oven at 150°C for 24 h and then ground to obtain ZrTiO4 precursor powder. The Y / ZrTiO4 precursor powder was calcined in a muffle furnace at 300°C for 2 h to remove organic matter, thus obtaining the ZrTiO4 catalyst without oxygen vacancies.

[0054] Comparative Example 3 The only difference from Example 5 is that the catalyst used is an oxygen-vacancy ZrTiO4 catalyst prepared by the following method: 60 ml of ethylene glycol is added to a beaker, and 4.7 ml of zirconium source (Zr(OC3H7)4) and 3.45 ml of titanium source (Ti(OC4H9)4) are added and stirred until homogeneous. Then, 2 ml of stabilizer acetylacetone is added and stirred continuously to help control the hydrolysis rate. The resulting solution is dried in a forced-air drying oven at 150°C for 24 h and then ground to obtain ZrTiO4 precursor powder. The ZrTiO4 precursor powder is calcined in a muffle furnace at 300°C for 2 h to remove organic matter. Subsequently, it is calcined in a 5% H2 / Ar atmosphere at a temperature of 3°C / min to 800°C for 4 h to obtain the oxygen-vacancy ZrTiO4 catalyst.

[0055] To evaluate (1 wt% Y) (SA) To optimize the doping ratio of the ZrTiO4 catalyst, three control experiments (Examples 5, 7, and 8) were conducted. All experiments involved heating from room temperature to 300°C at a rate of 2°C / min to test the TPD (Total Potential Displacement). The TPD test results are as follows: Figure 6 As shown, by Figure 6 It can be seen that: in containing x wt%(1 wt% Y (SA) / ZrTiO4( x In a system with (=5, 7, 9), NaAlH4- 7 wt% (1 wt% Y) (SA) The ZrTiO4 system exhibits the best performance, with the lowest hydrogen release temperature and the highest hydrogen release rate. Figure 7 The NaH / Al mixtures prepared in Example 1 (Ball-milled NaAlH4), the NaH / Al mixtures with 7 wt% oxygen-containing vacancies (Comparative Example 3), and the NaH / Al mixtures without oxygen vacancies (Comparative Example 2), as well as the mixture containing 7 wt% (1 wt% Y) prepared in Example 5, are examples of such mixtures. (SA)A comparison of the TPD hydrogen release curves of the composite hydrogen storage system of / ZrTiO4 shows that: the peak temperature of the first hydrogen release in the pure NaAlH4 system is 225℃, and the hydrogen release amount at 300℃ is 4.3wt%; the peak temperature of the first hydrogen release in the ZrTiO4 addition system with oxygen vacancies is 146℃, and the hydrogen release amount at 300℃ is 5.18wt%; the peak temperature of the first hydrogen release in the ZrTiO4 addition system without oxygen vacancies increases to 153℃, and the hydrogen release amount at 300℃ decreases to 4.82wt%; while the 7wt% (1wt% Y) of the present invention... (SA) Compared with the pure NaAlH4 system and the ZrTiO4 addition system with or without oxygen vacancies, the ZrTiO4 catalytic system combines low-temperature hydrogen release characteristics (peak temperature of the first hydrogen release step is 132℃) and high capacity advantages (hydrogen release of 5.05 wt% at 300℃), improving hydrogen storage performance by 17% compared with the pure NaAlH4 system, and has the best catalytic effect.

[0056] Figure 8 The examples in the middle are: a ball-milled NaH / Al mixture (ball-milled NaAlH4) as Comparative Example 1, a NaH / Al mixture with 7 wt% oxygen vacancies added (Comparative Example 3), and a NaH / Al mixture without oxygen vacancies in Comparative Example 2, as well as the mixture containing 7 wt% (1 wt% Y) prepared in Example 5. (SA) Isothermal hydrogen desorption curve of the composite hydrogen storage system of γ-O4 / ZrTiO4 at 150 °C. Containing 7 wt% (1 wt% Y) (SA) The composite hydrogen storage system of NaH / ZrTiO4 can release 4.13 wt% hydrogen in just 40 min, while the pure NaH / Al system releases only 0.84 wt% (Ball-milled NaAlH4) in 2 h at the same temperature.

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A ZrTiO4 supported single-atom catalyst rich in oxygen vacancies, characterized in that, Its carrier is ZrTiO4 rich in oxygen vacancies, and the active component is a single-atom metal Y, wherein the loading of the single-atom metal is 0.5~2 wt%.

2. A method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 1, characterized in that, The process includes the following steps: mixing a zirconium source, a titanium source, and a single-atom yttrium precursor in an organic solvent, adding a stabilizer and stirring continuously to form a homogeneous sol; drying the sol and grinding it to obtain Y / ZrTiO4 precursor powder; calcining the Y / ZrTiO4 precursor powder to remove organic matter, followed by calcination under a reducing atmosphere to introduce oxygen vacancies and form ZrTiO4, denoted as Y. (SA) / ZrTiO4 catalyst.

3. The method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 2, characterized in that, The zirconium source is Zr(OC3H7)4, the titanium source is selected from Ti(OC4H9)4, the single-atom yttrium precursor is Y(NO3)3·6H2O, and the organic solvent is anhydrous ethanol.

4. The method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 2, characterized in that, The stabilizer is acetylacetone.

5. The method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 2, characterized in that, The roasting temperature was 300℃ and the time was 2 hours.

6. The method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 2, characterized in that, The calcination temperature under a reducing atmosphere is 800℃, and the time is 4 hours.

7. The method for preparing the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst according to claim 2, characterized in that, The reducing atmosphere is an H2 / Ar atmosphere, with H2 accounting for 5% of the volume.

8. The application of the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst of claim 1 in the catalytic NaAlH4 composite hydrogen storage system.

9. The application according to claim 8, characterized in that, The operation steps are as follows: Sodium hydride and aluminum are mixed in a molar ratio of 1:1 and ball-milled to form a sodium hydride / aluminum mixture; the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst is mixed with the sodium hydride / aluminum mixture to carry out a hydrogen absorption reaction to obtain an aluminum hydride sodium composite hydrogen storage system, wherein the oxygen-vacancy-rich ZrTiO4 supported single-atom catalyst accounts for 5~9 wt% of the aluminum hydride sodium composite hydrogen storage system.

10. The application according to claim 8 or 9, characterized in that, The NaAlH4 composite hydrogen storage system is used in solid-state hydrogen storage.

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