Ni-MoOx / HTO nano-catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a Ni-MoOx / HTO nano-catalyst and a preparation method and application thereof. The method comprises the following steps: uniformly mixing Cs2CO3 and TiO2, grinding and calcining to obtain CsTO powder; then dispersing in water, adding a hydrochloric acid solution for reaction, filtering, washing and drying to obtain an HTO carrier; the preparation method comprises the following steps: dispersing an HTO carrier in water, then adding NiCl2. 6H2O and Na2MoO4. 2H2O, and carrying out ultrasonic treatment to obtain a suspension; and adding a reducing agent into the suspension to carry out reduction reaction until no bubble is generated, thereby obtaining the Ni-MoOx / HTO nano-catalyst. The catalyst shows excellent catalytic performance and excellent cycle stability in the reaction of hydrogen production through hydrolysis of ammonia borane, and the conversion frequency (TOF) of the catalytic reaction at 298 K under the condition of no additive reaches 143.9 min <-1 >.

Description

Technical Field

[0001] This application belongs to the technical field of catalysts, and specifically relates to a Ni-MoO x / HTO nanocatalyst and its preparation method and application. Background Art

[0002] As an energy carrier with great application prospects, hydrogen has been widely used in fuel cell systems. How to safely and effectively store and transport hydrogen is an important and challenging issue in the field of fuel cells. Ammonia borane (NH3BH3, AB) is regarded as a chemical hydrogen storage material with broad application prospects due to its high hydrogen content (19.6 wt%), long-term stability, and non-toxicity. Under the action of a suitable catalyst, ammonia borane can release high-purity H2 under mild conditions (NH3BH3 + 2H2O → NH4 + + BO2 - + 3H2).

[0003] Nickel-based catalysts have excellent catalytic activity and have been proven to be ideal transition metal catalysts for hydrogen production by ammonia borane hydrolysis. However, nickel-based catalysts are prone to significant reduction in catalytic activity due to particle aggregation during preparation and catalysis. Therefore, there is an urgent need to develop non-precious metal catalysts with high activity and high stability to rapidly catalyze hydrogen production by ammonia borane hydrolysis. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art and provide a Ni-MoO x / HTO nanocatalyst and its preparation method and application. Specifically, the following technical solutions are adopted: In the first aspect, the present invention provides a preparation method of a Ni-MoO x / HTO nanocatalyst, including the following steps: S1. Mix Cs2CO3 and TiO2, grind, and calcine to obtain CsTO powder; S2. Disperse the CsTO powder in water, then add a hydrochloric acid solution for reaction, filter, wash, and dry to obtain an HTO support; S3. Disperse the HTO support in water, then add NiCl2·6H2O and Na2MoO4·2H2O, and ultrasonicate to obtain a suspension; S4. Add a reducing agent to the suspension for a reduction reaction until no bubbles are generated to obtain the Ni-MoO x / HTO nanocatalyst.

[0005] The present invention uses layered HTO as a support and prepares Ni-MoO x / HTO catalyst. The HTO support regulates the electron density of the supported metal nanoparticles through metal-support electronic interaction (EMSI), optimizing the adsorption / desorption energy barrier of the active sites; the Mo species disperse the nanoparticles and reduce the crystallinity of the metal nanoparticles, achieving an increase in the electron density on the surface of metallic Ni, thereby improving the catalytic performance of the catalyst. In addition, the HTO support has excellent chemical and thermal stability and can maintain its structural integrity under harsh reaction conditions (such as strong acid / alkali environments, high temperature and high pressure), which will further ensure the stability of the catalytic cycle.

[0006] As a further preferred embodiment, the molar ratio of the Cs2CO3, the TiO2 and the hydrochloric acid solution is 1:5.3:37.3.

[0007] As a further preferred embodiment, the dosage ratio of the HTO support, the NiCl2·6H2O and the Na2MoO4·2H2O is 10 mg - 50 mg: 11.88 mg: 0.001 mmol - 0.005 mmol.

[0008] In the above preparation process, the dosage of Na2MoO4·2H2O will affect the catalytic performance of the finally prepared Ni-MoO x / HTO nanocatalyst. By changing the addition amount of the dopant sodium molybdate (Na2MoO4·2H2O), precise control of the doping amount of MoO x can be achieved. The Mo species can disperse the nanoparticles and reduce the crystallinity of the metal nanoparticles, achieving an increase in the electron density on the surface of metallic Ni, thereby improving the catalytic performance of the catalyst. When the dosage of Na2MoO4·2H2O is 0.004 mmol, that is, the doping amount of MoO x is 0.004 mmol, the Ni-MoO x / HTO nanocatalyst exhibits the best performance for hydrogen production by ammonia borane hydrolysis.

[0009] In addition, in the above preparation process, the doping amount of MoO x and the dosage of the HTO support will simultaneously affect the catalytic activity of the Ni-MoO x / HTO nanocatalyst. Under the condition of fixing the dosage of the HTO support (40 mg), when the addition amount of MoO x is 0.004 mmol, the catalyst exhibits the best catalytic activity; further fixing the doping amount of MoO x at 0.004 mmol, continuous regulation of the Ni nanoparticle loading amount is achieved by adjusting the dosage of the HTO support. When the mass of the added support is 40 mg (corresponding to a Ni loading of 6.8 wt%), the best catalytic performance is achieved.

[0010] As a further preferred embodiment, the specific process of the calcination is as follows: Mix Cs2CO3 and TiO2 evenly, and place the powder obtained after grinding in a muffle furnace and heat it at a heating rate of 5 °C·min -1 to 800 °C for isothermal calcination, cool, and obtain CsTO powder.

[0011] As a further preferred embodiment, the time of the isothermal calcination is 18 h - 24 h.

[0012] As a further preferred embodiment, the reducing agent includes sodium borohydride.

[0013] In a second aspect, the present invention provides a Ni-MoO x / HTO nanocatalyst, which is prepared by the above preparation method.

[0014] The Ni-MoO x / HTO nanocatalyst of the present invention has excellent catalytic activity and cyclic stability due to the synergistic effect between Ni species, MoO x and the HTO support, ultrafine Ni metal nanoparticles, and the excellent chemical and thermal stability of the HTO support, and is a catalyst with great development prospects.

[0015] As a further preferred embodiment, the loading amount of Ni in the Ni-MoO x / HTO nanocatalyst is 5.5 wt% - 22.7 wt%.

[0016] According to the data of the examples of the present invention, when the Ni loading amount is 6.8 wt%, the Ni-MoO x / HTO nanocatalyst reaches the maximum hydrogen production rate.

[0017] In a third aspect, the present invention provides the application of the above Ni-MoO x / HTO nanocatalyst in the catalytic hydrolysis of ammonia borane for hydrogen production.

[0018] As a further preferred embodiment, the temperature for the Ni-MoO x / HTO nanocatalyst to catalyze the hydrolysis of ammonia borane for hydrogen production is 288K - 303K.

[0019] The beneficial effects of the present invention are as follows: (1) The present invention uses layered HTO as a support and prepares Ni-MoO x / HTO catalyst. The HTO support adjusts the electron density of the supported metal nanoparticles through metal-support electronic interaction (EMSI) to optimize the adsorption / desorption energy barrier of the active sites; the Mo species disperse the nanoparticles and reduce the crystallinity of the metal nanoparticles, achieving an increase in the electron density on the surface of metallic Ni, thereby improving the catalytic performance of the catalyst. In addition, the HTO support has excellent chemical and thermal stability and can maintain structural integrity under harsh reaction conditions (such as strong acid / alkaline environments, high temperature and high pressure), which will further ensure the stability of the catalytic cycle.

[0020] (2) The Ni-MoO x / HTO catalyst prepared in the present invention exhibits excellent catalytic performance, 100% H2 selectivity and excellent stability. The TOF value of the Ni-MoO x / HTO for catalytic hydrolysis of ammonia borane to produce hydrogen can reach 143.9 min -1 .

[0021] (3) The catalyst provided by the present invention has the advantages of high efficiency, stability and low preparation cost, and is a catalyst with great development prospects. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 Shown is the transmission electron microscopy image of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention (shown as (a) therein), the particle size statistical chart of the Ni-MoO x nanoparticles (shown as (b) therein), the transmission electron microscopy image of the Ni / HTO nanocatalyst prepared in Comparative Example 2 (shown as (c) therein) and the Ni-MoO x nanoparticle size statistical chart (shown as (d) therein) and the transmission electron microscopy image of the Ni-MoO x nanocatalyst prepared in Comparative Example 3 (shown as (e) therein) and the Ni-MoO x nanoparticle size statistical chart (shown as (f) therein); Figure 2 Shown is the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the Ni / HTO nanocatalyst prepared in Comparative Example 2 and the Ni-MoO xNi 2p X-ray photoelectron spectroscopy (XPS) of the nanocatalyst; Figure 3 Shown is the Mo 3d X-ray photoelectron spectroscopy (XPS) of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention; Figure 4 Shown is the Ni-MoO prepared in Example 1 of the present invention x X-ray diffraction (XRD) patterns of the / HTO nanocatalyst, the Ni / HTO nanocatalyst prepared in Comparative Example 2, and the HTO support prepared in Comparative Example 4; Figure 5 Shown is the Ni-MoO prepared in Example 1 of the present invention x Fourier transform infrared spectroscopy (FT-IR) patterns of the / HTO nanocatalyst prepared in Example 1 of the present invention and the HTO support prepared in Comparative Example 4; Figure 6 Shown are the Ni-MoO prepared in Examples 1-5 of the present invention x / HTO nanocatalyst for the performance test of catalytic hydrolysis of ammonia borane to produce hydrogen at different dosages of Na2MoO4·2H2O (shown as (a)) and the corresponding TOF value graph (shown as (b)); Figure 7 Shown are the Ni-MoO prepared in Examples 1, 6-9 of the present invention x / HTO nanocatalyst for the performance test of catalytic hydrolysis of ammonia borane to produce hydrogen at different dosages of the HTO support (shown as (a)) and the corresponding TOF value graph (shown as (b)); Figure 8 Shown is the Ni-MoO prepared in Example 1 of the present invention x / HTO nanocatalyst and the Ni nanocatalyst, Ni / HTO nanocatalyst, Ni-MoO prepared in Comparative Examples 1-4 x Nanocatalyst and HTO support for the performance test of catalytic hydrolysis of ammonia borane to produce hydrogen at 298 K (shown as (a)) and the corresponding TOF value graph (shown as (b)); Figure 9 Shown is the Ni-MoO prepared in Example 1 of the present invention x / HTO nanocatalyst, the Ni-CrO prepared in Comparative Example 5 x / HTO nanocatalyst and the Ni-WO prepared in Comparative Example 6 x / HTO nanocatalyst for the performance test of catalytic hydrolysis of ammonia borane to produce hydrogen at 298 K (shown as (a)) and the corresponding TOF value graph (shown as (b)); Figure 10As shown, the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the Ni-MoO x / TiO2 (commercial) nanocatalyst prepared in Comparative Example 7, and the Ni-MoO x / CsTO nanocatalyst prepared in Comparative Example 8, the performance graph (as shown in (a) therein) of catalyzing the hydrolysis of ammonia borane to produce hydrogen at 298 K and the corresponding TOF value graph (as shown in (b) therein); Figure 11 As shown, the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the performance test graph (as shown in (a) therein) of catalyzing the hydrolysis of ammonia borane to produce hydrogen at different temperatures and the Arrhenius curve graph (as shown in (b) therein), the performance test graph (as shown in (c) therein) of the Ni / HTO nanocatalyst prepared in Comparative Example 2 for catalyzing the hydrolysis of ammonia borane to produce hydrogen at different temperatures and the Arrhenius curve graph (as shown in (d) therein), and the Ni-MoO x nanocatalyst prepared in Comparative Example 3, the performance test graph (as shown in (e) therein) of catalyzing the hydrolysis of ammonia borane to produce hydrogen at different temperatures and the Arrhenius curve graph (as shown in (f) therein); Figure 12 As shown, the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the cyclic stability test graph (as shown in (a) therein) of catalyzing the hydrolysis of ammonia borane to produce hydrogen at 298 K, the cyclic stability test graph (as shown in (b) therein) of the Ni / HTO nanocatalyst prepared in Comparative Example 2 for catalyzing the hydrolysis of ammonia borane to produce hydrogen at 298 K, and the Ni-MoO x nanocatalyst prepared in Comparative Example 3, the cyclic stability test graph (as shown in (c) therein) of catalyzing the hydrolysis of ammonia borane to produce hydrogen at 298 K. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0025] Example 1 A preparation method of a Ni-MoO x / HTO nanocatalyst specifically includes the following steps: (1) Preparation of HTO Mix Cs2CO3 (26.7 mmol) and TiO2 (141.5 mmol) in a molar ratio of 1:5.3 in an agate mortar, and grind them thoroughly for 10 - 15 min until evenly mixed. Subsequently, place the obtained white powder in a muffle furnace and heat it to 800 °C at a heating rate of 5 °C·min -1 . After calcining at this temperature for 20 h, and after the sample cools naturally, repeat the above calcination process once to finally obtain white Cs2Ti6O 13 (denoted as CsTO) powder. Then, disperse the obtained CsTO evenly in 917 mL of deionized water, and slowly add 83 mL of 12 M hydrochloric acid solution under continuous stirring, and react at room temperature for 24 h. After the reaction, collect the white precipitate by vacuum filtration and wash it repeatedly with deionized water until the filtrate is neutral to finally obtain 40 mg of the target product HTO.

[0026] (2) Preparation of Ni-MoO x / HTO nanocatalyst Ultrasonically disperse 40 mg of the HTO support prepared in step (1) in 5 mL of deionized water for 5 min, then add NiCl2·6H2O (11.88 mg, 0.05 mmol) and Na2MoO4·2H2O (1.0 mg, 0.004 mmol), and continue ultrasonic treatment for 30 min to fully disperse the metal precursors. Subsequently, add 30 mg of NaBH4 to the suspension for reduction. After no gas is generated, obtain a Ni-MoO x with a MoO doping amount of 0.004 mmol and a 40 mg HTO support (corresponding to a Ni loading of 6.8 wt%) x / HTO nanocatalyst.

[0027] Example 2 A preparation method of a Ni-MoO x / HTO nanocatalyst is similar to the method in Example 1. The only difference is that the amount of Na2MoO4·2H2O in step (2) of Example 1 is changed from 0.004 mmol to 0.001 mmol, and other steps are exactly the same, to obtain a Ni-MoO x with a MoO doping amount of 0.001 mmol and a 40 mg HTO support x / HTO nanocatalyst.

[0028] Example 3 A Ni-MoO xPreparation method of Ni-MoO₂ₓ / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the amount of Na₂MoO₄·2H₂O in step (2) of Example 1 is changed from 0.004 mmol to 0.002 mmol, and other steps are exactly the same, obtaining MoO₂ₓ x with a doping amount of 0.002 mmol and an HTO support of 40 mg of Ni-MoO₂ₓ x / HTO nanocatalyst.

[0029] Example 4 A preparation method of Ni-MoO₂ₓ x / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the amount of Na₂MoO₄·2H₂O in step (2) of Example 1 is changed from 0.004 mmol to 0.003 mmol, and other steps are exactly the same, obtaining MoO₂ₓ x with a doping amount of 0.003 mmol and an HTO support of 40 mg of Ni-MoO₂ₓ x / HTO nanocatalyst.

[0030] Example 5 A preparation method of Ni-MoO₂ₓ x / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the amount of Na₂MoO₄·2H₂O in step (2) of Example 1 is changed from 0.004 mmol to 0.005 mmol, and other steps are exactly the same, obtaining MoO₂ₓ x with a doping amount of 0.005 mmol and an HTO support of 40 mg of Ni-MoO₂ₓ x / HTO nanocatalyst.

[0031] Example 6 A preparation method of Ni-MoO₂ₓ x / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the amount of the HTO support in step (2) of Example 1 is changed from 40 mg to 50 mg, and other steps are exactly the same, obtaining MoO₂ₓ x with a doping amount of 0.004 mmol and an HTO support of 50 mg (corresponding to a Ni loading of 5.5 wt%) of Ni-MoO₂ₓ x / HTO nanocatalyst.

[0032] Example 7 A preparation method of Ni-MoO₂ₓ xPreparation method of Ni-MoO₂ / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the dosage of HTO support in step (2) of Example 1 is changed from 40 mg to 30 mg, and other steps are exactly the same, obtaining MoO₂ x Ni-MoO₂ / HTO nanocatalyst with a doping amount of 0.004 mmol and 30 mg of HTO support (corresponding Ni loading of 8.9 wt%). x / HTO nanocatalyst.

[0033] Example 8 A preparation method of Ni-MoO₂ x / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the dosage of HTO support in step (2) of Example 1 is changed from 40 mg to 20 mg, and other steps are exactly the same, obtaining MoO₂ x Ni-MoO₂ / HTO nanocatalyst with a doping amount of 0.004 mmol and 20 mg of HTO support (corresponding Ni loading of 12.8 wt%). x / HTO nanocatalyst.

[0034] Example 9 A preparation method of Ni-MoO₂ x / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that the dosage of HTO support in step (2) of Example 1 is changed from 40 mg to 10 mg, and other steps are exactly the same, obtaining MoO₂ x Ni-MoO₂ / HTO nanocatalyst with a doping amount of 0.004 mmol and 10 mg of HTO support (corresponding Ni loading of 22.7 wt%). x / HTO nanocatalyst.

[0035] Comparative Example 1 A preparation method of Ni nanocatalyst. The preparation method is similar to that in step (2) of Example 1, and the only difference is that no HTO support and Na₂MoO₄·2H₂O dopant are added in step (2), and other steps are exactly the same as those in step (2) of Example 1, obtaining Ni nanocatalyst.

[0036] Comparative Example 2 A preparation method of Ni / HTO nanocatalyst. The preparation method is similar to that in Example 1, and the only difference is that no Na₂MoO₄·2H₂O dopant is added in step (2), and other steps are exactly the same as those in Example 1, obtaining Ni / HTO nanocatalyst.

[0037] Comparative Example 3 A preparation method of Ni-MoO₂ xPreparation method of nano-catalyst, the preparation method is similar to the method in step (2) of Example 1, the only difference is that no HTO support is added in step (2), and other steps are exactly the same as those in step (2) of Example 1, to obtain Ni-MoO x nano-catalyst.

[0038] Comparative Example 4 A preparation method of HTO support, the preparation method is exactly the same as the method in step (1) of Example 1, to obtain 40 mg of the target product HTO.

[0039] Comparative Example 5 A preparation method of Ni-CrO x / HTO nano-catalyst, the preparation method is similar to the method of Example 1, the only difference is that Na2MoO4·2H2O in step (2) is changed to Cr(NO3)3·6H2O, and other steps are exactly the same as those of Example 1, to obtain Ni-CrO x / HTO nano-catalyst.

[0040] Comparative Example 6 A preparation method of Ni-WO x / HTO nano-catalyst, the preparation method is similar to the method of Example 1, the only difference is that Na2MoO4·2H2O in step (2) is changed to Na2WO4·2H2O, and other steps are exactly the same as those of Example 1, to obtain Ni-WO x / HTO nano-catalyst.

[0041] Comparative Example 7 A preparation method of Ni-MoO x / TiO2 (commercial) nano-catalyst, the preparation method is similar to the method of Example 1, the only difference is that the HTO support in step (2) is changed to TiO2 (commercial) support, and other steps are exactly the same as those of Example 1, to obtain Ni-MoO x / TiO2 (commercial) nano-catalyst.

[0042] Comparative Example 8 A preparation method of Ni-MoO x / CsTO nano-catalyst, the preparation method is similar to the method of Example 1, the only difference is that the HTO support in step (2) is changed to CsTO support, and other steps are exactly the same as those of Example 1, to obtain Ni-MoO x / CsTO nano-catalyst.

[0043] Relevant characterization data were obtained for some of the materials prepared in the above examples, as follows: Figure 1The Ni-MoO prepared in Example 1 of the present invention is shown as x the transmission electron microscopy image of the / HTO nanocatalyst (shown as (a) therein) and the particle size statistical graph of Ni-MoO x nanoparticles (shown as (b) therein), the transmission electron microscopy image of the Ni / HTO nanocatalyst prepared in Comparative Example 2 (shown as (c) therein) and Ni-MoO x the particle size statistical graph of nanoparticles (shown as (d) therein) and the transmission electron microscopy image of the Ni-MoO x nanocatalyst prepared in Comparative Example 3 (shown as (e) therein) and Ni-MoO x the particle size statistical graph of nanoparticles (shown as (f) therein); and it can be seen from Figure 1 that the average particle size of Ni-MoO x particles in the / HTO nanocatalyst is 2.7 nm, the non-supported Ni-MoO x nanoparticles exhibit a relatively large average particle size of 3.5 nm, while the Ni particle size of the single-metal Ni / HTO reaches 4.2 nm. This phenomenon confirms that the HTO support inhibits metal agglomeration through the spatial confinement effect, while the introduction of MoO x further refines the Ni grain size through the electron synergy effect. This synergy between the support and the active component provides a dual regulation mechanism for the formation of highly dispersed small-size metal nanoparticles. x

[0044] Figure 2 The Ni 2p X-ray photoelectron spectroscopy (XPS) of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the Ni / HTO nanocatalyst prepared in Comparative Example 2 and the Ni-MoO x nanocatalyst prepared in Comparative Example 3 is shown; and it can be seen from Figure 2 that compared with Comparative Example 2 and Comparative Example 3, the binding energy of Ni in the Ni-MoO x / HTO nanocatalyst prepared in Example 1 shows a negative shift of 0.3 eV - 0.4 eV, indicating that in the catalyst Ni-MoO 0 / HTO, metallic Ni obtains electrons from MoO x and the support HTO. The transfer of electrons among Ni, MoO x and HTO is beneficial to the hydrolysis of NH3BH3. x

[0045] Figure 3 The Mo 3d X-ray photoelectron spectroscopy (XPS) of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention is shown; and it can be seen from Figure 3It can be seen that the characteristic signals with binding energies of 227.2 eV and 230.9 eV are for Mo 3+ and the characteristic signals with binding energies of 229.0 eV and 232.3 eV are for Mo 4+ and the characteristic signals with binding energies of 234.3 eV and 235.7 eV are for Mo 6+ indicating that in the catalyst Ni-MoO x / HTO, MoO x acts as an electron modulation medium in a non-stoichiometric form.

[0046] Figure 4 Shown in the following are the X-ray diffraction (XRD) patterns of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, the Ni / HTO nanocatalyst prepared in Comparative Example 2, and the HTO support prepared in Comparative Example 4; and it can be seen from Figure 4 that in Ni-MoO x / HTO and Ni / HTO samples, the complete retention of the characteristic diffraction peaks of HTO indicates that the crystal framework of the support is not damaged during the loading process of metal nanoparticles.

[0047] Figure 5 Shown in the following are the Fourier transform infrared spectroscopy (FT-IR) patterns of the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention and the HTO support prepared in Comparative Example 4; and it can be seen from Figure 5 that there are no significant displacements in terms of characteristic vibration frequencies, peak shapes, and relative intensities between Ni-MoO x / HTO and the HTO matrix, indicating that the loading process of Ni-MoO x nanoparticles does not cause significant distortion of the support framework structure. This is consistent with the analysis results of the X-ray diffraction (XRD) pattern, jointly confirming the structural stability of the HTO support in the composite catalyst system.

[0048] Example 10 Using the Ni-MoO x / HTO nanocatalyst prepared in Examples 1-5 of the present invention to catalyze the hydrolysis of ammonia borane to produce hydrogen, the specific process is as follows: Placing the catalyst in a 50 mL flask containing 4.46 mL of deionized water, with the amount of the catalyst being the amount of the catalyst prepared in each example, adding 1 mmol of ammonia borane for reaction under normal pressure at 298 K. The hydrogen production performance diagram and the corresponding TOF values are as Figure 6 shown, and the preparation conditions of the catalysts in Examples 1-5 and the results of the catalytic reaction are shown in Table 1.

[0049] Table 1 Preparation of Ni-MoO x / HTO nanocatalyst catalytic performance of ammonia borane hydrolysis to produce hydrogen As shown in Table 1, the Ni-MoO prepared in Examples 1 to 5 x Under the condition of fixed HTO carrier dosage (40 mg), the reaction rate of catalytic ammonia borane hydrolysis to produce hydrogen showed a trend of first increasing and then decreasing with the increase of Na2MoO4·2H2O dosage. When the dosage was 0.004 mmol, the Ni-MoO4 prepared in Example 1 x / HTO nanocatalysts showed the best performance for hydrogen production by hydrolysis of ammonia borane. This indicates that changing the amount of dopant sodium molybdate (Na2MoO4·2H2O) can achieve the effect of MoO x Precise control of doping amount. Mo species can disperse nanoparticles and reduce the crystallinity of metal nanoparticles, thereby increasing the electron density on the surface of metal Ni and thus improving the catalytic activity, making the final Ni-MoO x / HTO nanocatalysts have different catalytic performances in the reactions.

[0050] Embodiment 11 Ni-MoO prepared by Example 1, Example 6-Example 9 of the present invention x / HTO nanocatalyst catalyzes the hydrolysis of ammonia borane to produce hydrogen, and the specific process is as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of catalyst was the amount of catalyst prepared in each example. 1 mmol of ammonia borane was added at 298 K and normal pressure to react. The hydrogen production performance diagram and the corresponding TOF value are shown in FIG. Figure 7 The conditions for preparing the catalysts of Example 1, Example 6-Example 9 and the results of the catalytic reactions are shown in Table 2.

[0051] Table 2 Preparation of Ni-MoO in Example 1, Example 6-Example 9 x / HTO nanocatalyst catalytic performance of ammonia borane hydrolysis to produce hydrogen As shown in Table 2, the Ni-MoO prepared in Examples 1, 6-9 x / HTO nanocatalyst fixed MoO x Under the condition of a doping amount of 0.004 mmol, the catalytic reaction rate of catalytic ammonia borane hydrolysis to produce hydrogen shows a trend of first increasing and then decreasing with the dosage of carrier HTO. When the dosage is 40 mg (corresponding to a Ni loading of 6.8 wt%), the catalyst reaches the maximum hydrogen production rate.

[0052] Example 12 Using the Ni-MoO prepared in Example 1 of the present invention x / HTO nanocatalyst and each nanocatalyst prepared in Comparative Example 1 - Comparative Example 4 were used to catalyze the hydrolysis of ammonia borane to produce hydrogen. The specific process is as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of the catalyst was the amount of the catalyst prepared in each example. At 298 K under atmospheric pressure, 1 mmol of ammonia borane was added for the reaction. The hydrogen production performance graph and the corresponding TOF values are as Figure 8 shown, and the conditions for preparing the catalyst and the results of the catalytic reaction are shown in Table 3.

[0053] Table 3 Hydrogen production performance of each nanocatalyst prepared in Example 1 and Comparative Example 1 - Comparative Example 4 for catalyzing the hydrolysis of ammonia borane As can be seen from Table 3, the Ni-MoO prepared in Example 1 x / HTO nanocatalyst has higher activity in catalyzing the hydrolysis of ammonia borane to produce hydrogen than the catalysts prepared in Comparative Example 1 - Comparative Example 4. This performance improvement is attributed to the synergistic effect of the HTO support and the MoO x additive: HTO inhibits metal agglomeration through two-dimensional confinement, and MoO x optimizes the electronic structure of Ni through electronic modulation, jointly promoting the efficient utilization of active sites; among them, no gas generation was detected for the HTO support prepared in Comparative Example 4, indicating that metallic Ni is the core active site for the hydrolysis reaction.

[0054] Example 13 Using the Ni-MoO prepared in Example 1 of the present invention x / HTO nanocatalyst and each nanocatalyst prepared in Comparative Example 5 and Comparative Example 6 were used to catalyze the hydrolysis of ammonia borane to produce hydrogen. The specific process is as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of the catalyst was the amount of the catalyst prepared in each example. At 298 K under atmospheric pressure, 1 mmol of ammonia borane was added for the reaction. The hydrogen production performance graph and the corresponding TOF values are as Figure 9 shown, and the conditions for preparing the catalyst and the results of the catalytic reaction are shown in Table 4.

[0055] Table 4 Hydrogen production performance of each nanocatalyst prepared in Example 1, Comparative Example 5 and Comparative Example 6 for catalyzing the hydrolysis of ammonia borane As can be seen from Table 4, the Ni-MoO prepared in Example 1 x / HTO nanocatalyst exhibits the highest catalytic activity, while CrO x and WO xThere is no obvious improvement in the activity of Ni / HTO. This result verifies that there is a good synergistic effect between Ni-MoO x NPs and HTO.

[0056] Example 14 Using the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, and each of the nanocatalysts prepared in Comparative Example 7 and Comparative Example 8 was used to catalyze the hydrolysis of ammonia borane to produce hydrogen. The specific process is as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of the catalyst was the amount of the catalyst prepared in each example. 1 mmol of ammonia borane was added for reaction at 298 K under atmospheric pressure. The hydrogen production performance diagram and the corresponding TOF value diagram are as Figure 10 shown. The conditions for preparing the catalyst and the results of the catalytic reaction are shown in Table 5.

[0057] Table 5 Hydrogen production performance of each nanocatalyst prepared in Example 1, Comparative Example 7 and Comparative Example 8 for the hydrolysis of ammonia borane As can be seen from Table 5, the catalytic activity of Ni-MoO x nanoparticles supported on commercial TiO2 and CsTO is much lower than that of Ni-MoO x / HTO. This result further verifies that there is a good synergistic effect between Ni-MoO x NPs and HTO.

[0058] Example 15 Using the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, and each of the nanocatalysts prepared in Comparative Example 2 and Comparative Example 3 was used to catalyze the hydrolysis of ammonia borane to produce hydrogen at different temperatures. The specific process is as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of the catalyst was the amount of the catalyst prepared in each example. 1 mmol of ammonia borane was added for reaction at 288 K, 293 K, and 303 K under atmospheric pressure respectively. The hydrogen production performance diagram and the Arrhenius curve diagram are as Figure 11 shown. The conditions for preparing the catalyst and the results of the catalytic reaction are shown in Table 6.

[0059] Table 6 Hydrogen production performance of each nanocatalyst prepared in Example 1, Comparative Example 2 and Comparative Example 3 for the hydrolysis of ammonia borane at different temperatures As can be seen from Table 6, it is calculated by the Arrhenius equation that Ni-MoO xThe apparent activation energy (Ea) of the / HTO catalytic system is 43.8 kJ·mol -1 . For comparison, in the same temperature range (288 K - 303 K), the Ea values of the non-supported Ni-MoO x NPs and Ni / HTO were measured to be 64.1 kJ·mol -1 and 71.9 kJ·mol -1 respectively. The results show that the decreasing trend of the activation energy is consistent with the law of the improvement of catalytic activity, indicating that the synergistic effect between Ni NPs, MoO x and the HTO support can effectively reduce the energy barrier of the ammonia borane hydrolysis reaction.

[0060] Example 16 Using the Ni-MoO x / HTO nanocatalyst prepared in Example 1 of the present invention, each nanocatalyst prepared in Comparative Example 2 and Comparative Example 3 was used to catalyze the hydrolysis of ammonia borane to produce hydrogen, and the specific process was as follows: The catalyst was placed in a 50 mL flask containing 4.46 mL of deionized water. The amount of the catalyst was the amount of the catalyst prepared in each example. 1 mmol of ammonia borane was added for reaction at 298 K under normal pressure, and the reaction was cycled 10 times. The hydrogen production performance graph and the cycle performance graph are as Figure 12 shown.

[0061] From Figure 12 it can be seen that after the Ni-MoO x / HTO nanocatalyst prepared in Example 1 was reused 10 times, the amount of gas produced by catalyzing the hydrolysis of ammonia borane did not decrease, and the activity remained good, and it was significantly superior to the Ni / HTO and Ni-MoO x catalysts. This difference confirms that the simultaneous introduction of the doping of MoO x and the HTO support can not only improve the catalytic activity of the catalyst, but also improve the cycle stability of the catalyst. By improving the stability of the catalyst to increase the utilization rate, the cost can be saved while reducing resource consumption.

[0062] The excellent activity and outstanding stability of the Ni-MoO x / HTO nanocatalyst prepared by the present invention are attributed to the synergistic effect between Ni species, MoO x and the HTO support, the ultrafine Ni metal nanoparticles, and the excellent chemical and thermal stability of the HTO support.

[0063] In summary, the method for preparing the catalyst of the present invention is simple in operation and low in cost. The obtained catalyst has the characteristics of small particle size and high electron density of metallic Ni, and has high catalytic activity and stability, and is a catalyst with great development prospects.

[0064] The embodiments of the present application have been described above in conjunction with the accompanying drawings. Specific examples have been used herein to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the core idea of the present application. However, the present application is not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection scope of the present application.

Claims

1. A preparation method of Ni-MoO x / HTO nanocatalyst, characterized in that It includes the following steps: S1. Mix Cs2CO3 and TiO2, grind them, and calcine them to obtain CsTO powder; S2. Disperse the CsTO powder in water, then add a hydrochloric acid solution for reaction, filter, wash, and dry to obtain the HTO support; S3. Disperse the HTO support in water, then add NiCl2·6H2O and Na2MoO4·2H2O, and ultrasonicate to obtain a suspension; S4. Add a reducing agent to the suspension for a reduction reaction until no bubbles are generated to obtain the Ni-MoO x / HTO nanocatalyst.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the Cs2CO3, the TiO2, and the hydrochloric acid solution is 1:5.3:37.

3.

3. The preparation method according to claim 2, characterized in that, The dosage ratio of the HTO support, the NiCl2·6H2O, and the Na2MoO4·2H2O is 10 mg - 50 mg: 11.88 mg: 0.001 mmol - 0.005 mmol.

4. The preparation method according to claim 1, characterized in that, The specific process of the calcination is as follows: Mix Cs2CO3 and TiO2 evenly, and place the powder obtained after grinding in a muffle furnace and heat it up to 800 °C at a heating rate of 5 °C·min -1 for constant temperature calcination, then cool it to obtain CsTO powder.

5. The preparation method according to claim 4, characterized in that, The time for the isothermal calcination is 18 h - 24 h.

6. The preparation method according to claim 1, characterized in that, The reducing agent includes sodium borohydride.

7. A Ni-MoO x / HTO nanocatalyst, characterized in that It is prepared by the preparation method according to any one of claims 1 - 6.

8. The Ni-MoO x / HTO nanocatalyst according to claim 7, characterized in that The Ni loading in the Ni-MoO x / HTO nanocatalyst is 5.5 wt% - 22.7 wt%.

9. Use of the Ni-MoO x / HTO nanocatalyst in the hydrolysis of ammonia borane for hydrogen production.

10. The application according to claim 9, wherein The Ni-MoO x The temperature for the hydrolysis of ammonia borane to produce hydrogen catalyzed by the / HTO nanocatalyst is 288K - 303K.

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