A single-atom catalyst for the preparation of SiH4 by disproportionation of SiHCl3 and its preparation method

Abstract

This invention discloses a single-atom catalyst for the disproportionation of SiHCl3 to SiH4 and its preparation method. The catalyst uses a transition metal as the active center, with single atoms dispersed on a high-temperature resistant support. High metal loading (0.5~5 wt%) and stable dispersion are achieved through coordination anchoring or high-temperature pyrolysis. This catalyst possesses single-atom active sites and strong interactions between the metal and the support, improving reactivity and SiH4 selectivity. The preparation method employs scalable technology, ensuring uniform distribution and stability of single atoms by optimizing the precursor ratio and heat treatment conditions. This catalyst achieves high SiHCl3 conversion and high SiH4 selectivity at relatively low temperatures (150~300℃), and has a long lifespan, making it suitable for continuous industrial production. It offers advantages such as high efficiency, low energy consumption, and long-term operation.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, specifically to a single-atom catalyst for the preparation of SiH4 by disproportionation of SiHCl3 and its preparation method. Background Technology

[0002] Silanes (SiH4) are widely used in semiconductor microelectronics (ICs), photovoltaic solar cells (PV), liquid crystal displays (LCDs), and polycrystalline silicon fabrication. Currently, the main methods for preparing SiH4 include the metal hydride method, the silicon-magnesium alloy method, and the trichlorosilane (SiHCl3) disproportionation method. The advantages of the SiHCl3 disproportionation method are high production efficiency, low power consumption, and low cost. While the initial investment in fixed equipment is relatively large, the raw material and processing costs are low, and the amount of byproducts is minimal. Commercial production of SiH4 typically uses the SiHCl3 disproportionation method.

[0003] The existing new silane method is a method to produce high-purity SiH4 by using a catalyst to catalyze the disproportionation reaction of chlorosilanes. The chlorosilane disproportionation reaction is as follows:

[0004]

[0005] The reactions in steps (2) and (3) above are known as chlorosilane disproportionation reactions. Both are based on the same principle and can be carried out under the same conditions (e.g., temperature and pressure) using the same catalyst. Currently, activated carbon-supported transition metal catalysts (e.g., activated carbon-supported Pt, Pd, Rh, Co, Cu, La, etc.) are commonly used catalysts for this reaction.

[0006] Traditional catalysts for the disproportionation reaction of chlorosilanes (such as supported metal particle catalysts) suffer from low activity, poor selectivity, and high reaction temperatures (typically >400℃), and are prone to deactivation due to metal agglomeration. Single-atom catalysts, due to their atomically dispersed active sites, can significantly improve atom utilization and reaction efficiency, but their application in the SiHCl3 disproportionation reaction has not been reported. Furthermore, existing single-atom catalysts have low loading and poor stability, making them difficult to meet industrial requirements. Therefore, developing a single-atom catalyst with high loading and high stability to achieve low-temperature, high-efficiency catalysis of the SiHCl3 disproportionation reaction has significant industrial value. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a single-atom catalyst for the preparation of SiH4 from disproportionated SiHCl3 and its preparation method, thereby solving the problems mentioned in the background art.

[0008] According to one aspect of this application, a single-atom catalyst for the preparation of SiH4 by disproportionation of SiHCl3 comprises:

[0009] Support: A high-temperature resistant material doped with SiC or Al2O3 prepared by atomic layer deposition (ALD) technology. The support has a high specific surface area and a uniform pore structure, with a specific surface area ≥200m² / g and a pore size of 2-50nm.

[0010] Active center: a transition metal dispersed on the support in the form of a single atom, selected from at least one of Pt, Pd, Rh, Co, Cu, and La;

[0011] The metal loading is 0.5-5 wt%. The transition metal single atoms are dispersed on the surface of the support by coordination anchoring or high-temperature pyrolysis and interact strongly with the functional groups on the surface of the support to inhibit the aggregation of metal atoms.

[0012] Preferably, the transition metal is Pt, Pd, or Rh, and the loading is 0.8-1.5 wt%.

[0013] Preferably, the support is a doped SiC material, and the SiC support is treated with oxygen plasma to introduce hydroxyl-OH functional groups to improve the anchoring ability of the metal precursor;

[0014] The support is a mesoporous Al2O3 material. The Al2O3 support is synthesized by the sol-gel method and then dried and calcined to obtain a support with a mesoporous structure and -OH functional groups on the surface.

[0015] A method for preparing the single-atom catalyst includes the following steps:

[0016] (1) Prepare doped SiC or Al2O3 supports using atomic layer deposition (ALD) or sol-gel method;

[0017] (2) The transition metal precursor is loaded onto the carrier by coordination anchoring or high-temperature pyrolysis, wherein the transition metal precursor is a metal-organic complex or a metal salt, wherein:

[0018] Coordination anchoring method: The support and the organometallic complex are mixed in a solvent, dried, and then heat-treated at 300-800℃ for 1-6 hours in an inert or reducing atmosphere to obtain a single-atom catalyst.

[0019] High-temperature pyrolysis method: The metal salt is mixed with the support and pyrolyzed at 600-800℃ in an inert atmosphere for 2-6 hours, so that the metal salt decomposes and releases single atoms and disperses on the surface of the support.

[0020] Preferably, the organometallic complex is Pt(acac)2, Pd(NO3)2 or RhCl3; the solvent is ethanol, methanol or water; and the heat treatment atmosphere is H2, N2, H2 / N2 mixture or Ar / H2 mixture.

[0021] Preferably, in step (2), the drying temperature of the coordination anchoring method is 60-80℃, the heat treatment temperature is 450-600℃, and the pyrolysis temperature of the high-temperature pyrolysis method is 700℃.

[0022] Preferably, in step (1), the carrier is treated with oxygen plasma to introduce hydroxyl groups or modified with amino groups; in step (2), the carrier is freeze-dried or vacuum-dried after impregnation.

[0023] An application of the single-atom catalyst for the disproportionation of SiHCl3 to prepare SiH4 involves loading the single-atom catalyst into a fixed-bed reactor, introducing a mixture of SiHCl3 and H2 gas at 150-300 °C, and carrying out a continuous reaction under normal pressure. The volume ratio of SiHCl3 to H2 is 1:3.

[0024] Preferably, the catalyst lifetime is ≥500h, the SiHCl3 conversion rate is ≥90%, and the SiH4 selectivity is ≥92%.

[0025] The advantages of this application compared to existing technologies are:

[0026] 1. High activity and selectivity: The strong interaction between the single atomic site and the support suppresses side reactions, and the selectivity of SiH4 is ≥92%.

[0027] 2. Low temperature and high efficiency: The reaction temperature is as low as 150~300℃, and energy consumption is reduced by more than 30%.

[0028] 3. Excellent stability: The high temperature resistance of the carrier and the strong metal-carrier bonding prevent atomic aggregation, with a lifespan of ≥500h.

[0029] 4. Industrialization potential: Atomic layer deposition (ALD) technology and controllable preparation methods are suitable for large-scale production. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of a method for preparing a single-atom catalyst for SiH4 by disproportionation of SiHCl3 according to an embodiment of this application. Detailed Implementation

[0031] To make the content of this application easier to understand, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0032] A single-atom catalyst for the preparation of SiH4 from disproportionated SiHCl3 comprises a support and active centers. The support is a high-temperature resistant material doped with SiC or Al2O3, prepared by atomic layer deposition (ALD) technology. The support has a high specific surface area and uniform porous structure, with a specific surface area ≥200 m² / g and a pore size of 2-50 nm. The active centers are transition metal single atoms dispersed on the support in single-atom form, selected from at least one of Pt, Pd, Rh, Co, Cu, and La. The metal loading is 0.5-5 wt%. The transition metal single atoms are dispersed on the support surface by coordination anchoring or high-temperature pyrolysis, and interact strongly with the functional groups on the support surface to inhibit metal atom aggregation. Among them, the SiC support is treated with oxygen plasma to introduce hydroxyl (-OH) functional groups to improve the anchoring ability of the metal precursor. The Al2O3 support is synthesized by sol-gel method, and then dried and calcined to obtain a support with a mesoporous structure and -OH functional groups on the surface.

[0033] like Figure 1 As shown, a method for preparing a single-atom catalyst includes the following steps:

[0034] (1) Prepare doped SiC or Al2O3 supports using atomic layer deposition (ALD) or sol-gel method;

[0035] (2) The transition metal precursor is loaded onto the carrier by coordination anchoring or high-temperature pyrolysis. The transition metal precursor is a metal-organic complex or a metal salt, wherein:

[0036] Coordination anchoring method: The support is mixed with a metal-organic complex (such as Pt(acac)2, Pd(acac)2, Rh(acac)3, Co(acac)2, Cu(OAc)2, La(NO3)3, etc.) in a suitable solvent (such as ethanol or methanol). The support is coordinated and anchored to the metal precursor through the -OH functional groups on the surface of the support. After drying, the mixture is heat-treated at 300-800℃ in an inert gas or reducing atmosphere to obtain a single-atom catalyst.

[0037] High-temperature pyrolysis method: Metal salts (such as RuCl3, Co(acac)2, Cu(OAc)2, etc.) are mixed with a support in a set ratio and directly calcined at 600-800℃ in N2 or an inert atmosphere, so that the metal salts decompose and release single atoms and disperse on the surface of the support.

[0038] The precursor ratio and heat treatment conditions were optimized to ensure that the metal was stably dispersed in the form of single atoms, with the loading controlled at 0.5-5wt%. The heat treatment conditions included calcination at 300-800℃ for 1-6h in an inert or reducing atmosphere.

[0039] An application of preparing SiH4 by disproportionation of SiHCl3 using a prepared single-atom catalyst involves loading the single-atom catalyst into a fixed-bed reactor, introducing a SiHCl3 and H2 mixed gas with a volume ratio of 1:3 at 150-300℃, and carrying out a continuous reaction under atmospheric pressure. In the reaction, the catalyst lifetime is ≥500h, the SiHCl3 conversion rate is ≥90%, and the SiH4 selectivity is ≥92%. Example 1

[0040] 1. Catalyst preparation: SiC support was prepared by atomic layer deposition (ALD) and hydroxyl groups were introduced to the surface by oxygen plasma treatment. Pt(acac)2 was dissolved in ethanol, impregnated with the support, dried at 80℃, and calcined at 500℃ for 4h in a H2 / N2 mixed gas to obtain a 1.2wt% Pt single-atom catalyst, labeled as Pt / SiC catalyst.

[0041] 2. Preparation of SiH4: A Pt / SiC catalyst was packed into a fixed-bed reactor, and a SiHCl3 / H2 mixed gas (volume ratio 1:3) was introduced at 180℃. The reaction results showed that the SiHCl3 conversion rate reached 98%, the SiH4 selectivity was 97%, and the catalyst lifetime was 600 h. Example 2

[0042] 1. Catalyst preparation: Mesoporous Al2O3 support was synthesized by sol-gel method, impregnated with Pd(NO3)2 solution and freeze-dried, and then reduced at 450℃ for 3h in H2 atmosphere to obtain 0.8wt% Pd single atom catalyst, labeled as Pd / Al2O3 catalyst.

[0043] 2. Preparation of SiH4: Under reaction conditions of 200℃, the Pd / Al2O3 catalyst catalyzes the disproportionation reaction of SiHCl3, achieving a SiHCl3 conversion rate of 93% and a SiH4 selectivity of 96%. The catalyst maintains stable catalytic performance within 550 h, without carbon deposition or metal agglomeration. Example 3

[0044] 1. Catalyst preparation: RhCl3 and amino-modified SiC support were refluxed in methanol for 12 h, dried under vacuum at 60 °C, and then heat-treated at 600 °C for 2 h in an Ar / H2 atmosphere to obtain a 1.5 wt% Rh single-atom catalyst, labeled as Rh / SiC catalyst.

[0045] 2. Preparation of SiH4: In the reaction at 220℃, the Rh / SiC catalyst exhibited a SiHCl3 conversion rate of 96% and a SiH4 selectivity of 95%. The proportion of SiCl4 generated by the side reaction was <2%, and the catalyst lifetime was 580 h. Example 4

[0046] 1. Catalyst preparation: Co(acac)2 and Al2O3 support were ball-milled and mixed by high-temperature pyrolysis and calcined at 700℃ for 5h in N2 atmosphere to obtain a 2wt% Co single-atom catalyst, labeled as Co / Al2O3 catalyst.

[0047] 2. Preparation of SiH4: At 250℃, the SiHCl3 conversion rate of the Co / Al2O3 catalyst was 90%, and the SiH4 selectivity was 94%. The catalyst maintained stable catalytic performance within 500 h, without carbon deposition or metal agglomeration. Example 5

[0048] 1. Catalyst preparation: Cu(OAc)2 was used as a precursor, and Cu single atoms were deposited on a SiC support by vapor phase migration method. After H2 reduction, the loading was 0.5 wt%, and it was labeled as Cu / SiC catalyst.

[0049] 2. Preparation of SiH4: At a low temperature of 150℃, the Cu / SiC catalyst achieved a SiHCl3 conversion rate of 95% and a SiH4 selectivity of 93%. The reaction energy consumption was reduced by 40% compared with traditional catalysts, and the catalyst lifetime was 500 hours. Example 6

[0050] 1. Catalyst preparation: La(NO3)3 was co-precipitated with Al2O3 support, calcined at 500℃, and then a 3wt% La single-atom catalyst was prepared by citric acid complexation-pyrolysis method, which was labeled as La / Al2O3 catalyst.

[0051] 2. Preparation of SiH4: In the reaction at 300℃, the conversion rate of SiHCl3 disproportionation catalyzed by La / Al2O3 catalyst was 91%, and the selectivity of SiH4 was 92%. The catalyst has strong resistance to chlorine poisoning and a catalyst lifetime of 530h.

[0052] Comparative Example 1

[0053] Unlike Example 1, the catalyst used was the most commonly used Pt / C catalyst, prepared by impregnation. High specific surface area activated carbon was selected, treated with H₂O₂ to increase surface oxygen-containing functional groups, washed until neutral, and dried at 120°C. The pretreated activated carbon was then impregnated in a chloroplatinic acid (H₂PtCl₆) solution (concentration 1-10 wt%) and stirred until homogeneous. It was washed with deionized water and vacuum dried to obtain the Pt / C catalyst. The reaction results showed that the SiHCl₃ conversion reached 90%, the SiH₄ selectivity was 85%, and the catalyst lifetime was 450 h.

[0054] Table 1 Comparison of catalyst performance

[0055]

[0056] It should be noted that this catalyst can be integrated into existing silane production facilities, significantly improving efficiency and product purity while reducing energy consumption, and is suitable for the large-scale preparation of photovoltaic and electronic-grade high-purity silanes.

[0057] The above are preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a single-atom catalyst for the disproportionation of SiHCl3 to SiH4 in the preparation of SiH4 from SiHCl3, characterized in that, include: The support is a high-temperature resistant SiC or Al2O3 doped material prepared by atomic layer deposition or sol-gel method, with a specific surface area ≥200m² / g and a pore size of 2-50nm; when the support is SiC doped, the SiC support is treated with oxygen plasma to introduce hydroxyl-OH functional groups to improve the anchoring ability of the metal precursor. Active center: a transition metal dispersed on the support in the form of a single atom, selected from at least one of Pt, Pd, Rh, Co, Cu, and La; The metal loading is 0.5-5 wt%. Transition metal single atoms are dispersed on the surface of the support through coordination anchoring or high-temperature pyrolysis and interact strongly with the functional groups on the surface of the support.

2. The application according to claim 1, characterized in that, The transition metal is Pt, Pd, or Rh, and the metal loading is 0.8-1.5 wt%.

3. The application according to any one of claims 1-2, characterized in that, The preparation method of the single-atom catalyst includes the following steps: (1) Prepare doped SiC or Al2O3 supports using atomic layer deposition or sol-gel method; (2) The transition metal precursor is loaded onto the carrier by coordination anchoring or high-temperature pyrolysis, wherein the transition metal precursor is a metal-organic complex or a metal salt, wherein: Coordination anchoring method: The support and the organometallic complex are mixed in a solvent, dried, and then heat-treated at 300-800℃ for 1-6 hours in an inert or reducing atmosphere to obtain a single-atom catalyst. High-temperature pyrolysis method: The metal salt is mixed with the support and pyrolyzed at 600-800℃ in an inert atmosphere for 2-6 hours, so that the metal salt decomposes and releases single atoms and disperses on the surface of the support.

4. The application according to claim 3, characterized in that: The organometallic complex is Pt(acac)2, Pd(NO3)2 or RhCl3; The solvent is ethanol or methanol; The heat treatment atmosphere is H2, N2, a mixture of H2 and N2, or a mixture of Ar and H2.

5. The application according to claim 3, characterized in that, In step (2): The drying temperature for the coordination anchoring method is 60-80℃, and the heat treatment temperature is 450-600℃. The pyrolysis temperature of the high-temperature pyrolysis method is 700℃.

6. The application according to claim 3, characterized in that, The drying process described in step (2) involves freeze drying or vacuum drying.

7. The application according to any one of claims 1-2, characterized in that, The single-atom catalyst was packed into a fixed-bed reactor, and a mixture of SiHCl3 and H2 gas was introduced at 150-300°C. The reaction was carried out continuously under normal pressure, with a volume ratio of SiHCl3 to H2 of 1:

3.

8. The application according to claim 7, characterized in that, Single-atom catalyst lifetime ≥ 500 h, SiHCl3 conversion ≥ 90%, SiH4 selectivity ≥ 92%.

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