Phosphorus-containing covalent organic framework material as well as preparation method and application thereof

Abstract

The invention relates to the field of polycrystalline silicon production, and discloses a phosphorus-containing covalent organic framework material as well as a preparation method and application thereof.The phosphorus-containing covalent organic framework material is prepared by synthesizing an organic monomer with a phosphorus-containing group and a rigid large-volume structure, enabling the organic monomer to be self-assembled with another rigid monomer through a reversible covalent bond, forming an ordered framework, and meanwhile, preparing the phosphorus-containing covalent organic framework material. Uniformly-distributed adsorption sites and micro-channels with the size smaller than 1 nm are generated in situ, and synergistic co-adsorption of PH3 and CH4 can be realized when the composite material is applied to a recycling and purifying process of recycle hydrogen.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polysilicon production, in particular to a phosphorus-containing covalent organic framework material and a preparation method and application thereof. BACKGROUND

[0002] The current recycling and purification process of circulating hydrogen is as follows: the reduction tail gas is first recovered by a low-pressure multi-stage condensing system to recover chlorosilane, and the non-condensable gas enters an absorption unit to remove hydrogen chloride by physical or chemical absorption. The hydrogen-rich gas stream is obtained at the top of the absorption tower, and then the hydrogen is deep purified by an activated carbon adsorption column. After removing the residual trace impurities, the hydrogen is returned to the reduction furnace for reaction. This process is relatively mature in the removal of chlorosilane and hydrogen chloride, but the trace removal of methane (CH4) and phosphine (PH3) is still a common bottleneck in the industry. The reason is that CH4 molecules are stable and have weak polarity, and only rely on weak dispersion to combine with conventional adsorbents (activated carbon, zeolite), with weak force. PH3 has weak polarity, but its kinetic diameter is small (about 0.36 nm), and its concentration is extremely low in a normal pressure high-purity hydrogen environment. Traditional microporous adsorbents have wide pore size distribution and lack specific active sites, resulting in weak competitive adsorption capacity and being easily inhibited by hydrogen dilution effect. The above impurities accumulate continuously in the closed loop, affecting the quality of polysilicon products, and thus seriously affecting the conversion efficiency of downstream batteries.

[0003] Covalent organic framework (COFs) materials have great potential in the field of gas separation due to their advantages of structure designability and precise preparation, large specific surface area, regular and ordered pore structure, and easy adjustment of pore size. For example, CN113634284A provides a preparation of a covalent organic framework catalyst and its application in removing PH3. The preparation method is as follows: mixing small molecule formaldehyde precursor, triaminobenzene ligand and first protic solvent to perform condensation reaction to obtain covalent organic framework carrier; then mixing the covalent organic framework carrier, nano metal oxide and second protic solvent to perform loading; finally mixing the loaded covalent organic framework material, sodium sulfate, sulfuric acid solution and third protic solvent to perform substitution reaction to obtain covalent organic framework catalyst. The catalyst can promote the adsorption of PH3 on the surface of the carrier and improve the oxidation of PH3, thereby realizing efficient removal of PH3. However, the preparation of the adsorbent adopts a post-modification method, which has problems such as complicated synthesis steps, uneven distribution of modification sites, and easy plugging of pores. Moreover, it can only achieve the removal of PH3. The existing technology also reports the application of functionalized COFs materials in methane storage, but does not involve the simultaneous deep removal of low-concentration PH3 and CH4 in photovoltaic circulating hydrogen.

[0004] Therefore, it is urgent to develop a microporous COFs adsorbent with specific adsorption sites and one-step synthesis to realize the simultaneous enhanced removal of PH3 and CH4, which is a key breakthrough for the polysilicon industry. SUMMARY

[0005] The present application aims to overcome the problems of the prior art, such as the difficulty in removing low-concentration PH3 and CH4 in recycled hydrogen, and provides a covalent organic framework material which has a good PH3 and CH4 removal effect when applied to the recycling and purification process of recycled hydrogen.

[0006] In order to achieve the above-mentioned purpose, one aspect of the present application provides a preparation method of a phosphorus-containing covalent organic framework material, which comprises: S1: performing a first contact reaction of a phosphorus source and an organic framework material monomer to prepare a phosphorus-containing organic framework material monomer; S2: performing a second contact reaction of the phosphorus-containing organic framework material monomer and a rigid condensation monomer in a solvent thermal system to obtain the phosphorus-containing covalent organic framework material; wherein the organic framework material monomer is selected from at least one of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 3,3'-dihydroxydiphenyl-4,4'-dicarboxylic acid and 1,3,5-tris(4-hydroxyphenyl)benzene; and the phosphorus source is selected from at least one of diphenyl chlorophosphate, diethyl chlorophosphate and phosphorus oxychloride.

[0007] The second aspect of the present application provides a phosphorus-containing covalent organic framework material prepared by the method of the first aspect of the present application.

[0008] The third aspect of the present application provides a recycling and purification process of recycled hydrogen, which comprises: using an adsorbent to adsorb and treat recycled hydrogen; The adsorbent is selected from the phosphorus-containing covalent organic framework material of the second aspect of the present application.

[0009] The fourth aspect of the present application provides an application of the phosphorus-containing covalent organic framework material of the second aspect of the present application in the field of polysilicon.

[0010] Through the above technical solution, an organic monomer with phosphorus-containing groups and rigid bulky structure is synthesized, which is self-assembled with another rigid monomer through reversible covalent bond, forming an ordered framework while generating in-situ uniform distribution of adsorption sites and microporous channels with a size of less than 1 nm; such microporous channels can realize efficient size screening and diffusion mass transfer of PH3 (~0.36 nm) and CH4 (~0.38 nm) with smaller size; the uniformly distributed adsorption sites are used to form P=O…H-O hydrogen bond with PH3, and after PH3 is locked, a local dipole array is induced, which produces induced dipole interaction with CH4, and can realize the synergistic co-adsorption of PH3 and CH4 when applied to the recycling and purification process of recycled hydrogen. DETAILED DESCRIPTION

[0011] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Each integer value within the stated ranges is incorporated into this disclosure as if each value is individually recited. The endpoints of the ranges of values (as well as the parameters described herein) shall be considered to be open-ended for purposes of interpreting the disclosure inherent in the range. Thus, even though a range of values is disclosed, a value outside the stated range can be used, and any stated value should be considered to be a minimum value.

[0012] In one aspect, the present application provides a method for preparing a phosphorus-containing covalent organic framework material, the method comprising: S1: performing a first contact reaction of a phosphorus source and an organic framework material monomer to prepare a phosphorus-containing organic framework material monomer; S2: performing a second contact reaction of the phosphorus-containing organic framework material monomer and a rigid condensation monomer in a solvothermal system to prepare the phosphorus-containing covalent organic framework material; wherein the organic framework material monomer is selected from at least one of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 3,3'-dihydroxybiphenyl-4,4'-dicarboxylic acid, and 1,3,5-tris(4-hydroxyphenyl)benzene; and the phosphorus source is selected from at least one of diphenyl chlorophosphate, diethyl chlorophosphate, and phosphorus oxychloride.

[0013] In the present application, preferably, the organic framework material monomer is selected from 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; the phosphorus source is selected from phosphorus oxychloride; and / or, the organic framework material monomer is selected from 3,3'-dihydroxybiphenyl-4,4'-dicarboxylic acid; the phosphorus source is selected from diphenyl chlorophosphate; and / or, the organic framework material monomer is selected from 1,3,5-tris(4-hydroxyphenyl)benzene; the phosphorus source is selected from diethyl chlorophosphate.

[0014] In the present application, the above method can be used to synthesize an organic monomer with both a phosphorus-containing group and a rigid bulky structure, which is self-assembled with another rigid monomer through a reversible covalent bond, forming an ordered framework while generating in-situ uniform distribution of adsorption sites and microporous channels with a size of less than 1 nm, realizing the synergistic co-adsorption of PH3 and CH4.

[0015] In the present application, the first contact reaction of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and phosphorus oxychloride in step S1 can be a nucleophilic substitution reaction, and preferably, the phosphorus-containing organic framework material monomer prepared in step S1 contains a structural unit as shown in the following formula: Formula (1): ; The reaction process equation is: C3N3( C6H4 NH2)3+ 3POCl3→ C3N3( C6H4 NH POCl2)3+ 3HCl; In the present application, the first contact reaction of 3,3'-dihydroxy-4,4'-dialdehyde biphenyl with diphenyl chlorophosphate in step S1 can be a nucleophilic substitution / esterification reaction, and preferably, the phosphorus-containing organic framework material monomer prepared in step S1 contains the following structural unit: Formula (2):

[0016] The reaction process equation is: C 14 H 10 O4+ 2(C6H5O)2POCl → C 14 H8O6P2(OC6H5)4+ 2HCl; In the present application, the first contact reaction of 1,3,5-tris(4-hydroxyphenyl) benzene with diethyl chlorophosphate in step S1 can be a nucleophilic substitution reaction, and preferably, the phosphorus-containing organic framework material monomer prepared in step S1 contains the following structural unit: Formula (3):

[0017] The reaction process equation is: C6H3(-C6H4-OH)3+ 3(C2H5O)2P(O)Cl→ C6H3(-C6H4-O-P(O)(OC2H5)2)3+ 3HCl; In the present application, by improving the combination of the phosphorus source and the organic framework material monomer, the adsorption performance of the subsequent material can be further improved. Therefore, in some preferred embodiments, the amount of the phosphorus source is 3-40 mol% based on the molar amount of the organic framework material monomer; more preferably, the amount of the phosphorus source is 5-30 mol% based on the molar amount of the organic framework material monomer.

[0018] In the present application, the second contact reaction between the phosphorus-containing organic framework material monomer and the rigid condensation monomer in step S2 may, for example, be: using an organic monomer with a specific geometric shape and rigid structure, constructing a long-range ordered or highly cross-linked two-dimensional or three-dimensional network structure with permanent pores through irreversible or reversible covalent condensation reaction, preferably, the rigid condensation monomer is selected from at least one of benzene-1,3,5-tricarboxaldehyde, p-xylylene and 4,4'-diphenyl dicarboxaldehyde.

[0019] In the present application, preferably, the rigid condensation monomer is selected from benzene-1,3,5-tricarboxaldehyde, and the reaction process equation is:

[0020] In the present application, preferably, the rigid condensation monomer is selected from p-xylylene, and the reaction process equation is: nC 14 H8O8P2(C6H5)4+ nC8H6O2→[C 14 H6O6P2(C6H5)4 C8H4O2] n + 2nH2O; In the present application, preferably, the rigid condensation monomer is selected from 4,4'-diphenyl dicarboxaldehyde, and the reaction process equation is: 2nC6H3(-C6H4-O-P(O)(OC2H5)2)3+ 3nOHC-C6H4-C6H4-CHO→ [C 114 H 108 O 24 P6] n + 6nH2O; In the present application, the amount of the phosphorus-containing organic framework material monomer and the rigid condensation monomer is controlled to prepare a phosphorus-containing covalent organic framework material with excellent adsorption performance, and therefore, in some preferred embodiments, the amount of the organic framework material monomer is 0.01-1 wt% based on the mass of the amount of the phosphorus source; more preferably, the amount of the organic framework material monomer is 0.3-0.7 wt% based on the mass of the amount of the phosphorus source.

[0021] In the present application, the solvothermal system provides a high-temperature, high-pressure, and uniform closed reaction environment, which not only promotes the reaction that is difficult to proceed thermodynamically, but more importantly, by enhancing the reversibility of the reaction, it guides the molecules to orderly assemble, so as to synthesize a phosphorus-containing covalent organic framework material with high crystallinity, high porosity and predetermined structure, preferably, the solvothermal system comprises 1,4-dioxane, mesitylene and acetic acid.

[0022] In some preferred embodiments, the volume ratio of the 1,4-dioxane to mesitylene is 3-4:1; the acetic acid is preferably in the form of an aqueous solution, and the concentration thereof may, for example, be 4-8 mol / L.

[0023] In the present application, in order to exclude the influence of moisture and oxygen, preferably, in step S1, the first contact reaction is carried out in the presence of an inert atmosphere selected from N2and / or Ar.

[0024] In the present application, preferably, the conditions of the first contact reaction include a temperature of 100-150 ℃ and a time of 8-15 h; more preferably, the conditions of the first contact reaction include a temperature of 110-130 ℃ and a time of 10-13 h.

[0025] In the present application, preferably, in step S2, the second contact reaction is carried out in an oxygen-free environment.

[0026] In the present application, preferably, the conditions of the second contact reaction include a temperature of 100-150 ℃ and a time of 60-80 h; more preferably, the conditions of the second contact reaction include a temperature of 110-130 ℃ and a time of 65-75 h.

[0027] In some preferred embodiments, step S1 further comprises a first post-treatment step; The first post-treatment comprises subjecting the reaction solution obtained in the first contact reaction to solid-liquid separation and collecting the solid phase A, and then subjecting to column chromatography purification treatment (the eluent may, for example, be at least one of dichloromethane, chloroform and ethyl acetate) to obtain the phosphorus-containing organic framework material monomer.

[0028] In the present application, preferably, in the first post-treatment, before the solid-liquid separation, the reaction solution is further subjected to ice-water quenching and neutralization treatment (the reagent for the neutralization treatment may, for example, be at least one of triethylamine, pyridine and N,N-diisopropylethylamine).

[0029] In other preferred embodiments, step S2 further comprises a second post-treatment step; The first post-treatment comprises subjecting the reaction solution obtained in the second contact reaction to solid-liquid separation and collecting the solid phase B, and then subjecting to washing treatment and drying treatment to obtain the phosphorus-containing covalent organic framework material.

[0030] According to some preferred embodiments, the washing agent used in the washing treatment is selected from tetrahydrofuran and / or N,N-dimethylformamide.

[0031] In this invention, preferably, the drying conditions include a temperature of 100-150 °C and a time of 8-20 h; more preferably, the drying conditions include a temperature of 110-130 °C and a time of 10-15 h.

[0032] The second aspect of the present invention provides a phosphorus-containing covalent organic framework material prepared by the method described in the first aspect of the present invention.

[0033] In this invention, preferably, the phosphorus-containing covalent organic framework material has a specific surface area of ​​500-1200 m². 2 / g, with a pore size of 0.60-1.0 nm; more preferably, the phosphorus-containing covalent organic framework material has a specific surface area of ​​700-1000 m² / g. 2 / g, with a pore size of 0.65-0.80 nm.

[0034] In this invention, the aforementioned phosphorus source, organic framework material monomer, and rigid polycondensation monomer, etc., can be obtained by purchasing commercially available products or by adopting conventional preparation methods in the field, and this invention does not limit them.

[0035] A third aspect of the present invention provides a process for recovering and purifying recycled hydrogen, the process comprising: treating recycled hydrogen by adsorption with an adsorbent; The adsorbent is selected from the phosphorus-containing covalent organic framework material described in the second aspect of this invention.

[0036] In this invention, in a preferred embodiment, the process for recovering and purifying circulating hydrogen includes: passing the circulating gas into a low-pressure multi-stage condensation system to recover chlorosilane, and then using an adsorbent to adsorb the remaining mixed gas (wherein, the volume hourly space velocity of the mixed gas can be, for example, 150-450 mL (gas) / min·g (adsorbent), the adsorption temperature is preferably 20-40 ℃, and the adsorption time is preferably 1-3 h).

[0037] The fourth aspect of this invention provides an application of the phosphorus-containing covalent organic framework material described in the second aspect of this invention in the field of polycrystalline silicon.

[0038] The above technical solution provides a phosphorus-containing covalent organic framework material with uniformly distributed modification sites and large adsorption capacity. It overcomes the problems of cumbersome post-modification synthesis steps, uneven distribution of modification sites, and easy pore blockage. It achieves synergistic co-adsorption of PH3 and CH4. In some preferred embodiments, the adsorption rates of PH3 and CH4 are not less than 95%.

[0039] The present invention will be described in detail below through examples. In the following examples, the organic framework material monomers: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; 3,3'-dihydroxy-4,4'-dialdehyde biphenyl was purchased from Zhengzhou Alpha Chemical Co., Ltd.; 1,3,5-tris(4-hydroxyphenyl)benzene was purchased from Zhengzhou Alpha Chemical Co., Ltd. Phosphorus sources: diphenyl chlorophosphate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; diethyl chlorophosphate was purchased from Haialadin Biochemical Technology Co., Ltd.; phosphorus oxychloride was purchased from Shandong Huize Chemical Technology Co., Ltd.

[0040] Example 1 This embodiment illustrates a method for preparing phosphorus-containing covalent organic framework materials, including: S1: In the presence of N2, 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was reacted with 4 mL of phosphorus oxychloride (6.58 g) at 120 °C for 12 h for the first contact reaction. After the reaction was completed, the reaction solution was quenched with ice water and neutralized to pH 6.5 with triethylamine reagent. The solution was then filtered and the solid phase A1 was collected and purified by column chromatography (eluent was dichloromethane) to obtain phosphorus-containing organic framework material monomer 1#. S2: 25 mg of phosphorus-containing organic framework material monomer 1# obtained from S1 and 12.15 mg of pyromellitic-1,3,5-tricarboxaldehyde were mixed, and then a solvothermal system of 1.5 mL of 1,4-dioxane / pyromellitic acid (volume ratio 4:1) and 0.3 mL of 6 M acetic acid aqueous solution was added. After ultrasonic dissolution to remove oxygen, the mixture was placed in an oven at 120 °C for a second contact reaction for 72 h. After the reaction was completed, the solid phase B1 was filtered and collected, then washed sequentially with anhydrous tetrahydrofuran and N,N-dimethylformamide, and extracted with tetrahydrofuran in a Soxhlet extractor for 24 h. Finally, it was vacuum dried at 120 °C for 12 h to prepare phosphorus-containing covalent organic framework material 1#.

[0041] Example 2 Following a similar preparation method as in Example 1, except that 30.2 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was used instead of 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 2.8 mL (4.61 g) of phosphorus oxychloride was used instead of 4 mL of phosphorus oxychloride; the remaining steps were the same as in Example 1, and phosphorus-containing covalent organic framework material 2# was prepared.

[0042] Example 3 Following a similar preparation method as in Example 1, except that 12 mg of 3,3'-dihydroxy-4,4'-dialdehyde biphenyl was used instead of 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 10 mL (13.00 g) of diphenylchlorophosphate was used instead of 4 mL of phosphorus oxychloride; the remaining steps were the same as in Example 1, and phosphorus-containing covalent organic framework material 3# was prepared.

[0043] Example 4 Following a similar preparation method as in Example 1, except that 15 mg of 3,3'-dihydroxy-4,4'-dialdehyde biphenyl was used instead of 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 6.4 mL of diphenylchlorophosphate (8.32 g) was used instead of 4 mL of phosphorus oxychloride; the remaining steps were the same as in Example 1, and phosphorus-containing covalent organic framework material 4# was prepared.

[0044] Example 5 Following a similar preparation method as in Example 1, except that 17.4 mg of 1,3,5-tris(4-hydroxyphenyl)benzene was used instead of 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 8 mL of diethyl chlorophosphate (9.6 g) was used instead of 4 mL of phosphorus oxychloride; the remaining steps were the same as in Example 1, and phosphorus-containing covalent organic framework material 5# was prepared.

[0045] Example 6 Following a similar preparation method as in Example 1, except that 16.5 mg of 1,3,5-tris(4-hydroxyphenyl)benzene was used instead of 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 5.4 mL of diethyl chlorophosphate (6.48 g) was used instead of 4 mL of phosphorus oxychloride; the remaining steps were the same as in Example 1, and phosphorus-containing covalent organic framework material 6# was prepared.

[0046] Comparative Example 1 This embodiment illustrates a method for preparing covalent organic framework materials, including: 23.4 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was mixed with 12.15 mg of mesitylenealdehyde, and then a solvothermal system of 1.5 mL of 1,4-dioxane / mesitylene (volume ratio 4:1) and 0.3 mL of 6 M acetic acid aqueous solution was added. After ultrasonic dissolution to remove oxygen, the mixture was placed in an oven at 120 °C for a second contact reaction for 72 h. After the reaction was completed, the solid phase B'1 was collected by filtration and then washed successively with anhydrous tetrahydrofuran and N,N-dimethylformamide. It was then extracted with tetrahydrofuran in a Soxhlet extractor for 24 h and finally vacuum dried at 120 °C for 12 h to prepare the covalent organic framework material 1'#.

[0047] Comparative Example 2 This embodiment illustrates a method for preparing covalent organic framework materials, including: (1) Take 25.2 mg of 1,3,5 Benzyl hydrazide and 27.9 mg of 2,5 Divinyl 1,4 Benzaldehyde was dissolved in 3 mL of 1,4-dimethylformaldehyde solution. The mixture of dioxane and mesitylene (volume ratio 1:1) was dissolved by sonication, and the two solutions were transferred to a Shrek tube. After homogenization by sonication, 0.6 mL of acetic acid solution (concentration 6 mol / L) was added. The reaction solution was degassed by three freeze-thaw cycles, and then placed in an oil bath at 120 °C for 72 h. (2) Using N,N The product of the oil bath reaction was washed with dimethylformamide, and the resulting precipitate was soaked in 10 mL of tetrahydrofuran. After 12 h, the precipitate was centrifuged and vacuum dried to obtain a yellow powder of COFBTH. DVa material; (3) 100 mg of COFBTH was added to each of the following solutions. DVa material and 25 mg of azobisisobutyronitrile were transferred to a clean, dry 25 mL Shrek tube, followed by the addition of 4 mL of 1,2-dioxanone. Ethylene dithiol was stirred at 80°C for 48 hours under a nitrogen atmosphere. The product was then washed with acetone, and the resulting solid phase was dried at 80°C for 12 hours to obtain covalent organic framework material 2'#.

[0048] Test Example 1 This test example is used to illustrate the morphological characteristics of the covalent organic framework materials prepared in the examples and comparative examples, including testing their specific surface area and pore size, as shown in Table 1. Test method: The specific surface area and pore size are tested using the BET method.

[0049] Table 1

[0050] Test Example 2 This test example is used to illustrate the adsorption performance of the covalent organic framework materials prepared in the examples and comparative examples in the recycling and purification process of cyclic hydrogen, as shown in Table 2. The process for recovering and purifying the circulating hydrogen includes: firstly, passing the circulating gas (with a PH3 concentration of 100 ppm and a CH4 concentration of 100 ppm) into a low-pressure multi-stage condensation system to recover chlorosilanes; then, using the covalent organic framework materials prepared in the examples and comparative examples to adsorb the remaining mixed gas (wherein, the mixed gas volume hourly space velocity is 300 mL (gas) / min·g (adsorbent), the adsorption temperature is 30 ℃, and the adsorption time is 2 h). Test method: The concentrations of pH3 and CH4 at the exhaust gas end were measured using spectrophotometry, and the adsorption rate was calculated according to the following formula: Adsorption rate = (Impurity before adsorption - Impurity after adsorption) / (Initial impurity content) × 100%; Table 2

[0051] As can be seen from the results in Table 2, compared with the comparative example, the phosphorus-containing covalent organic framework material prepared by the embodiments of the present invention has significantly better PH3 and CH4 removal effects when applied to the recycling and purification process of circulating hydrogen. In particular, the phosphorus-containing covalent organic framework material prepared in Example 1 has a PH3 adsorption rate of not less than 97% and a CH3 adsorption rate of not less than 96%.

[0052] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a phosphorus-containing covalent organic framework material, characterized in that, The method comprises: S1: a first contact reaction of a phosphorus source and an organic framework material monomer to prepare a phosphorus-containing organic framework material monomer; S2: a second contact reaction of the phosphorus-containing organic framework material monomer and a rigid condensation monomer in a solvothermal system to prepare the phosphorus-containing covalent organic framework material; The organic framework material monomer is selected from at least one of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 3,3'-dihydroxydiphenyl-4,4'-dicarboxylic acid and 1,3,5-tris(4-hydroxyphenyl)benzene; The phosphorus source is selected from at least one of diphenyl chlorophosphate, diethyl chlorophosphate and phosphorus oxychloride.

2. The production method according to claim 1, wherein, The amount of the organic framework material monomer is 0.01-1 wt% based on the mass of the amount of the phosphorus source; Preferably, the amount of the organic framework material monomer is 0.3-0.7 wt% based on the mass of the amount of the phosphorus source.

3. The preparation method of claim 1 or 2, wherein the amount of the rigid condensation monomer is 35-65 wt% based on the mass of the amount of the phosphorus-containing organic framework material monomer; Preferably, the amount of the rigid condensation monomer is 45-55 wt% based on the mass of the amount of the phosphorus-containing organic framework material monomer.

4. The production method according to any one of claims 1 to 3, wherein The rigid condensation monomer is selected from at least one of benzene-1,3,5-triformaldehyde, p-xylylene glycol and 4,4'-diphenyl glycol; And / or, the solvothermal system comprises 1,4-dioxane, mesitylene and acetic acid.

5. The production process according to any one of claims 1 to 4, wherein In step S1, the first contact reaction is performed in the presence of an inert atmosphere selected from N2 and / or Ar; And / or, the conditions of the first contact reaction include a temperature of 100-150 ℃ and a time of 8-15 h.

6. The production method according to any one of claims 1 to 5, wherein In step S2, the second contact reaction is performed in an oxygen-free environment; And / or, the conditions of the second contact reaction include a temperature of 100-150 ℃ and a time of 60-80 h.

7. The production process according to any one of claims 1 to 6, wherein Step S1 further comprises a first post-treatment step; The first post-treatment comprises solid-liquid separation of the reaction liquid obtained by the first contact reaction and collection of a solid phase A, and then column chromatography purification to obtain the phosphorus-containing organic framework material monomer.

8. The production process according to any one of claims 1 to 7, wherein Step S2 further comprises a second post-treatment step; The first post-treatment comprises solid-liquid separation of the reaction liquid obtained by the second contact reaction and collection of a solid phase B, and then washing treatment and drying treatment to obtain the phosphorus-containing covalent organic framework material.

9. The production method according to claim 8, wherein The washing treatment employs a washing agent selected from tetrahydrofuran and / or N,N-dimethylformamide; And / or, the conditions of the drying treatment include a temperature of 100-150 ℃ and a time of 8-20 h.

10. A phosphorus-containing covalent organic framework material prepared by the method of any one of claims 1-9.

11. The phosphorus-containing covalent organic framework material of claim 10, wherein, The phosphorus-containing covalent organic framework material has a specific surface area of 500-1200 m 2 / g, and a pore size of 0.60-1.0 nm; Preferably, the phosphorus-containing covalent organic framework material has a specific surface area of 700-1000 m 2 / g and a pore size of 0.65-0.80 nm.

12. A process for the recovery and purification of recycle hydrogen wherein, The process comprises adsorption treatment of the circulating hydrogen by an adsorbent; The adsorbent is selected from the phosphorus-containing covalent organic framework material of claim 10 or 11.

13. Use of the phosphorus-containing covalent organic framework material of claim 10 or 11 in the field of polysilicon.

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