Process for recovering hydrogen and silane from HJT solar cell production waste gas

Abstract

The invention discloses a process for recovering hydrogen and silane from HJT solar cell production waste gas, and belongs to the technical field of waste gas treatment, and the process comprises the following steps: the waste gas is input into a combined adsorption tower through a vacuum pump and a fan in sequence, and silane or hydrogen phosphide in the waste gas is removed; the adsorbed gas is fed into a deep-cooling cold box, and silane or hydrogen phosphide which is not thoroughly removed and nitrogen in the mixed gas are liquefied; hydrogen and a small amount of nitrogen are separated by the gas-liquid separator, separated high-nitrogen liquid flows back in the heat exchanger and exchanges heat with waste gas flowing forwards, and the high-nitrogen liquid flowing back is vaporized and then conveyed to the combined adsorption tower; and 5, hydrogen purification and recovery. By reasonably designing the waste gas treatment process and providing a novel molecular sieve configuration, hydrogen and silane gas are recovered from the waste gas discharged in HJT solar cell production and are purified and reused.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and particularly to a process for recovering hydrogen and silane from the waste gas produced in the production of HJT solar cells. Background Art

[0002] In the production process of traditional HJT solar cells, due to the use of special gases such as silane (SiH 4 ), phosphine (PH 3 ) in the amorphous silicon thin film deposition process section and the TCO deposition process section, and at the same time, a large amount of hydrogen is introduced into the reaction chamber as a carrier gas and a filling gas, the waste gas discharged during the production of HJT solar cells has the characteristics of strong toxicity, strong reducibility, flammability and explosiveness.

[0003] At present, the mainstream method in the industry for treating these waste gases is to use a plasma combustion type waste gas cabinet (plasma local Scrubber). Through a plasma generator, in the case of introducing air, hydrogen and oxygen in the air are burned, and the heat released by the combustion raises the temperature of the waste gas to above 600°C; at this temperature, silane and phosphine are thermally decomposed into hydrogen and elemental silicon and phosphorus. The chemical reaction equations are as follows: ; After the hydrogen in the waste gas is completely burned, the excess oxygen further reacts with the remaining silane, phosphine and silicon and phosphorus metal particles to form water and silicon and phosphorus oxides; the chemical reaction equations are as follows: ;

[0004] The waste gas after sufficient reaction enters the spray tower for washing. Water can adsorb the particulate matter in the waste gas and become silicon-containing or phosphorus-containing wastewater and be discharged to the wastewater treatment station.

[0005] The existing technology has the following problems: 1) When burning hydrogen using a plasma generator, special attention needs to be paid to controlling the flow rate of the introduced air to control the explosion limit of the mixed gas far from the explosion limit of hydrogen (4.0% - 75.6%). If the air flow rate does not match the amount of hydrogen in the waste gas, explosive hazards may occur.

[0006] 2) Oxide microparticles are generated after the decomposition and combustion of silane or phosphine, and finally form wastewater in the spray tower. Treating this part of the wastewater also requires concentration and evaporation, consuming a large amount of steam or electric energy.

[0007] 3) The materials cannot be recovered and utilized, resulting in waste.

[0008] Based on this, the present invention designs a process for recovering hydrogen and silane from the waste gas produced in the production of HJT solar cells to solve the above problems. Summary of the Invention

[0009] In view of the above-mentioned disadvantages of the prior art, the present invention provides a process for recovering hydrogen and silane from the waste gas generated in the production of HJT solar cells.

[0010] To achieve the above object, the present invention is realized through the following technical solutions: A process for recovering hydrogen and silane from the waste gas generated in the production of HJT solar cells, comprising the following steps: Step 1: During the production of HJT solar cells, the waste gas containing a mixture of silane or phosphine, hydrogen, nitrogen, etc. discharged from the machine is transported by a vacuum pump; Step 2: After the waste gas is preliminarily pressurized by a fan, it enters the combined adsorption tower, and the silane or phosphine component in the waste gas is removed. The combined adsorption tower is filled with an adsorbent; The adsorbent uses a modified molecular sieve, the framework uses a modified chabazite structure, the modified chabazite is subjected to electromagnetic radiation modification treatment, the pore orifice is designed as a bottleneck structure, and Cu is loaded on the inner wall of the pore channel + , boron atoms are doped to replace part of the aluminum sites to form Lewis acid sites, a polydimethylsiloxane coating is formed on the outer surface of the pore channel, and zirconium phosphate nanosheets are embedded in the framework; Step 3: The gas after adsorption is pressurized by a compressor and sent to a deep cooling box. A heat exchanger is arranged in the cooling box, and liquid nitrogen is used as an auxiliary cold source to liquefy the silane or phosphine that has not been completely removed in the combined adsorption tower and the nitrogen in the mixed gas; Step 4: The liquefied silane or phosphine and the nitrogen in the mixed gas are transported to the gas-liquid separator after the heat exchanger. The gas-liquid separator separates hydrogen + a small amount of nitrogen. The separated high-nitrogen liquid flows back in the heat exchanger and exchanges heat with the waste gas flowing in the forward direction. After the high-nitrogen liquid flowing back vaporizes, it is transported to the combined adsorption tower and used as the first-stage regeneration gas; Step 5: The hydrogen + a small amount of nitrogen separated by the gas-liquid separator enters the PSA cyclic adsorption tower, and the hydrogen is purified to 99.999%. The regeneration gas of the PSA cyclic adsorption tower flows back to the pipeline in front of the compressor for recycling.

[0011] Furthermore, the combined adsorption tower can be used in a two-tower switching mode. When tower A is operating, tower B is regenerated using the waste gas discharged from the cooling box. After regeneration, the waste gas is discharged into the silane combustion barrel for harmless subsequent treatment. After complete regeneration, it is switched to tower B for use and tower A is regenerated.

[0012] Furthermore, after the first-stage regeneration gas is regenerated, nitrogen is required to blow the combined adsorption tower once in the positive direction, and the dust-containing gas from the positive blow directly enters the silane combustion barrel.

[0013] Furthermore, the PSA cyclic adsorption tower is composed of multiple adsorption towers.

[0014] Further, in step two, after the waste gas is preliminarily pressurized to 30 - 80 Kpa by a blower, it enters the combined adsorption tower.

[0015] Further, in step three, the gas after adsorption is pressurized to 8 - 10 barg by a compressor and sent to a deep cryogenic refrigerator.

[0016] Further, in step three, at a low temperature of - 175 ~ - 185 °C, the silane or phosphine not completely removed by the combined adsorption tower and nitrogen in the mixed gas are liquefied.

[0017] Further, the preparation method of the modified molecular sieve is as follows: (1) Dissolve silica sol, aluminum sulfate, and sodium hydroxide in deionized water to form a uniform synthesis solution, and then carry out a crystallization reaction. The main pore diameter is larger than the molecular diameter of H 2 and smaller than the molecular diameters of SiH 4 and PH 3 . After washing, drying, and calcining, chabazite powder is obtained. The chabazite powder is exposed to electromagnetic radiation with a wavelength of 600 - 800 nm and a power of 12 - 20 W / cm for 5 - 10 minutes to obtain modified chabazite powder; (2) Weigh the modified chabazite powder and disperse it in a toluene solution of trimethylmethoxysilane, and carry out a reflux reaction to graft trimethylmethoxysilane onto the surface of the modified chabazite, further shrinking the pore mouth entrance, and then carry out washing and drying; (3) Prepare a copper chloride solution and a boric acid solution and mix them. Immerse the modified chabazite powder with modified pore orifices in the mixed solution, stir and exchange, and then dry and calcine to exchange Cu + into the inner wall of the pores of the modified chabazite, and boron atoms replace some aluminum sites to form Lewis acid sites; (4) Prepare a mixed solution containing zirconium nitrate and phosphoric acid, add the modified chabazite powder to the mixed solution, stir and react to in - situ generate zirconium phosphate nanosheets in the framework of the modified chabazite, and then dry; (5) Dissolve polydimethylsiloxane in n - hexane to prepare a PDMS solution, immerse the modified chabazite powder in the PDMS solution, so that a layer of PDMS solution is evenly coated on the surface of the modified chabazite, and finally cure to obtain the modified molecular sieve.

[0018] Further, in step (1), modified chabazite with a main pore diameter of 0.33 nm is obtained, and in step (2), the main pore diameter of the modified chabazite is shrunk to 0.30 nm.

[0019] Further, in step (4), the mass ratio of zirconium nitrate to phosphoric acid is 1:1.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By reasonably designing the waste gas treatment process and proposing a new configuration of molecular sieve, the present invention realizes the recovery of hydrogen and silane gas from the waste gas discharged during the production of HJT solar cells, and reuses them after purification. Using the above-mentioned modified molecular sieve as an adsorbent, silane and phosphine are highly selectively adsorbed, while hydrogen is allowed to pass through efficiently, and the purity of hydrogen can reach 99.5%.

[0021] 2. There is no open flame, no high temperature, no combustion, and no explosion risk during the preparation process of the present invention.

[0022] 3. The present invention can realize the recovery of silane or phosphine, as well as the recovery of hydrogen, online purification, and recycling.

[0023] 4. The system of the present invention is filled with nitrogen for protection, which is beneficial to reducing risks.

[0024] 5. Compared with the traditional waste gas treatment system, the present invention can not only save a large amount of materials for enterprises, reduce production costs, but also greatly reduce the silicon-containing waste generated during the production of HTJ batteries, with high environmental protection value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0026] Figure 1 It is a process flow diagram for recovering hydrogen and silane from the waste gas of HJT solar cell production of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0028] Example 1: In some embodiments, please refer to Figure 1 in the accompanying drawings of the specification. The process for recovering hydrogen and silane from the waste gas of HJT solar cell production adopts the method of compression + adsorption + cryogenic low temperature, and multi-stage separation with different principles is carried out for different components in the mixed waste gas. Specifically, it includes the following steps: Step 1. During the production process of HJT solar cells, the exhaust gas containing a mixture of silane or phosphine, hydrogen, nitrogen, etc., discharged from the machine (in the amorphous silicon thin film deposition and TCO deposition processes) is transported by a vacuum pump. Step 2. After the exhaust gas is preliminarily pressurized to 30 - 80 Kpa (G) by a blower, it enters the combined adsorption tower to remove the silane or phosphine components in the exhaust gas. The combined adsorption tower can be used with two towers switched. The combined adsorption tower is filled with an adsorbent. When Tower A is in operation, Tower B is regenerated using the exhaust gas discharged from the cold box. After regeneration, the exhaust gas is discharged into the silane combustion barrel for harmless subsequent treatment. After complete regeneration, it is switched to Tower B for use, and Tower A is regenerated in the same way. The adsorbent uses a modified molecular sieve, which can adsorb silane and phosphine with high selectivity and allow hydrogen to pass through efficiently.

[0029] The modified molecular sieve has the following characteristics: The framework adopts a modified chabazite structure, and by adjusting the silicon - aluminum ratio (Si / Al = 5), the main pore diameter is controlled at 0.33 nm, slightly larger than the diameter of H 2 molecule (0.289 nm), but smaller than that of SiH 4 (0.41 nm) and PH 3 (0.43 nm), achieving size screening.

[0030] The pore orifice is designed with a "bottleneck" structure, and the entrance shrinks to 0.30 nm to further block the entry of large molecules.

[0031] Metal - organic anchoring points: Copper (I) ions (Cu + ) are loaded on the inner wall of the pore channel, and PH 3 (containing lone pair electrons) is selectively adsorbed through π - complexation.

[0032] Lewis acid sites: Boron (B) atoms are doped to replace some aluminum sites to enhance the strong adsorption of SiH 4 (SiH 4 binds to the electron - deficient empty orbital of B).

[0033] Surface hydrogen - phobic treatment: A small amount of polydimethylsiloxane (PDMS) coating is added to the outer surface of the pore channel of the molecular sieve, and its low surface energy is used to reduce H 2 retention and improve the passing rate.

[0034] Flame - retardant design: Zirconium phosphate (ZrP) nanosheets are embedded in the framework, which decompose at high temperature to release phosphate radicals and inhibit the combustion of adsorbed gases.

[0035] Harmless treatment: The molecular sieve saturated with adsorption can be decomposed by soaking in sodium hydroxide solution to decompose SiH 4 / PH 3, harmless silicate / phosphate is generated.

[0036] In summary, the design of this modified molecular sieve can achieve the efficient separation of H 2 and SiH 4 / PH 3 through the dual mechanisms of "pore size screening + chemical adsorption".

[0037] Step 3: The gas after adsorption is pressurized to 8 - 10 barg by a compressor and sent to a deep cooling box. A heat exchanger is installed in the cooling box. The heat exchanger adopts a low-temperature plate fin heat exchanger and uses liquid nitrogen as an auxiliary cold source. At a low temperature of -175~-185°C, a small amount of silane or phosphine that was not completely removed by the combined adsorption tower and nitrogen in the mixed gas are liquefied. Step 4: The liquefied small amount of silane or phosphine and nitrogen in the mixed gas are transported to the gas-liquid separator after the heat exchanger. The gas-liquid separator separates hydrogen + a small amount of nitrogen. The separated high-nitrogen liquid flows back in the heat exchanger and exchanges heat with the waste gas flowing in the forward direction. After the high-nitrogen liquid flowing back vaporizes, it is transported to the combined adsorption tower and used as the first-stage regeneration gas. Furthermore, after the first-stage regeneration gas completes the regeneration, nitrogen is required to blow the combined adsorption tower once in the positive direction. The dust-containing gas from the positive blow directly enters the silane combustion barrel. This process is used to prevent possible large particles from damaging the compressor. Step 5: The hydrogen + a small amount of nitrogen separated by the gas-liquid separator enters the PSA cyclic adsorption tower. After the hydrogen + a small amount of nitrogen is cyclically adsorbed by the PSA (Pressure Swing Adsorption) cyclic adsorption tower, the hydrogen is purified to a purity of 99.999%. The PSA cyclic adsorption tower consists of multiple (≥3 stages) adsorption towers. The characteristic of its adsorbent is that when the gas enters it, nitrogen will be adsorbed by the adsorbent, and hydrogen can pass through normally. The regeneration gas of the PSA cyclic adsorption tower flows back to the front of the compressor for recycling.

[0038] The present invention realizes the recovery and purification of hydrogen and silane gas from the waste gas discharged during the production of HJT solar cells by reasonably designing the waste gas treatment process and proposing a new configuration of molecular sieve for reuse.

[0039] During the preparation process of the present invention, there is no open flame, no high temperature, no combustion, and no explosion risk.

[0040] The present invention can realize the recovery of silane or phosphine, as well as the recovery, on-line purification, and recycling of hydrogen.

[0041] The system of the present invention is filled with nitrogen for protection, which is beneficial to reducing risks.

[0042] Compared with the traditional waste gas treatment system, the present invention can not only save a large amount of materials for enterprises, reduce production costs, but also greatly reduce the silicon-containing waste generated during the production of HTJ batteries, with high environmental protection value.

[0043] Example 2: The preparation method of the modified molecular sieve is as follows: (1) Dissolve 15 g of 40% silica sol, 3.42 g of aluminum sulfate, and 0.28 g of sodium hydroxide in 60 mL of deionized water to form a uniform synthesis solution. Then transfer it to a stainless steel autoclave with a polytetrafluoroethylene liner, seal it, and place it in an oven. Crystallize at 160 °C for 5 days. The silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron are connected by sharing oxygen atoms to form chabazite crystals with a specific pore structure. Its silicon-aluminum ratio is 5, and the main pore diameter is about 0.33 nm (slightly larger than the diameter of H 2 molecule (0.289 nm), but smaller than SiH 4 (0.41 nm) and PH 3 (0.43 nm). After washing, dry at 100 °C for 10 hours, and finally calcine at 535 °C for 5 hours to remove the template agent to obtain chabazite powder. Expose the chabazite powder to electromagnetic radiation with a wavelength of 600 nm and a power of 20 W / cm for 5 minutes to obtain modified chabazite powder.

[0044] (2) Weigh 30 g of modified chabazite powder and disperse it in a toluene solution of trimethylmethoxysilane with a concentration of 0.7 mol / L. Reflux at 71 °C for 5 hours to graft trimethylmethoxysilane onto the surface of the modified chabazite, reducing the pore entrance to 0.30 nm. After the reaction, wash the modified chabazite powder with an organic solvent to remove the unreacted silane reagent, and then dry at 105 °C for 1 h.

[0045] (3) Prepare a 3.5 wt% cuprous chloride solution and a 2 wt% boric acid solution, mix them, and immerse the modified chabazite powder with modified pore openings in the mixed solution. Stir and exchange at 55 °C for 13 hours, then dry at 105 °C for 1 h, and finally calcine at 450 °C for 2 hours to exchange copper (I) ions onto the inner wall of the modified chabazite pores, and boron atoms replace some aluminum sites to form Lewis acid sites.

[0046] (4) Prepare a mixed solution containing zirconium nitrate and phosphoric acid, with a mass ratio of zirconium nitrate to phosphoric acid of 1:1. Add the modified chabazite powder to the mixed solution and stir at 88 °C for 5 hours to in-situ generate zirconium phosphate nanosheets in the modified chabazite framework, and then dry at 105 °C for 1 h; (5) Dissolve polydimethylsiloxane (PDMS) in n - hexane to prepare a 12 wt% PDMS solution. Immerse the modified chabazite powder in the PDMS solution so that a layer of PDMS solution is evenly coated on the surface of the modified chabazite. Finally, cure it at 80 °C for 2 hours to obtain the modified molecular sieve.

[0047] Use the above - mentioned modified molecular sieve as an adsorbent to highly selectively adsorb silane and phosphine, while allowing hydrogen to pass through efficiently, and the hydrogen purity can reach 99.5%.

[0048] The present invention adopts a redesigned molecular sieve structure, selectively adsorbs and separates silane, has a long service life, and can efficiently separate SiH 4 , PH 3 and hydrogen, and has good use effects.

[0049] Example 3: The difference from Example 2 is that in step (1), after preparing the chabazite powder, expose the chabazite powder to electromagnetic radiation with a wavelength of 800 nm and a power of 12 W / cm² for 10 minutes to obtain the modified chabazite powder. Use this modified molecular sieve as an adsorbent to highly selectively adsorb silane and phosphine, while allowing hydrogen to pass through efficiently, and the hydrogen purity can reach 99.2%.

[0050] Example 4: The difference from Example 2 is that in step (1), after preparing the chabazite powder, expose the chabazite powder to electromagnetic radiation with a wavelength of 700 nm and a power of 15 W / cm² for 8 minutes to obtain the modified chabazite powder. Use this modified molecular sieve as an adsorbent to highly selectively adsorb silane and phosphine, while allowing hydrogen to pass through efficiently, and the hydrogen purity can reach 99.6%.

[0051] Comparative Example 1: The difference from Example 2 is that in step (1), after preparing the chabazite powder, no electromagnetic radiation is carried out. Use this modified molecular sieve as an adsorbent, and the hydrogen purity can reach 94.4%.

[0052] The above - mentioned examples are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present invention in each example.

Claims

1. A process for recovering hydrogen and silane from waste gas produced by HJT solar cells, characterized in that: The following steps are involved: Step 1: During the HJT solar cell production process, the waste gas discharged from the machine containing silane or phosphine, hydrogen, and nitrogen mixture is transported through a vacuum pump; Step 2: After the exhaust gas is initially pressurized by a fan, it enters a combined adsorption tower to remove silane or phosphine components in the exhaust gas, and the combined adsorption tower is filled with adsorbent; The adsorbent adopts a modified molecular sieve, the framework adopts a modified chabazite, the modified chabazite is treated by electromagnetic radiation modification, the pore opening is designed as a bottleneck structure, and Cu is loaded on the inner wall of the pore + , boron atoms are doped to replace some aluminum sites to form Lewis acid sites, a polydimethylsiloxane coating is formed on the outer surface of the pores, and zirconium phosphate nanosheets are embedded in the skeleton; Step 3: The adsorbed gas is pressurized by a compressor and sent to a deep cold box. A heat exchanger is arranged in the cold box, and liquid nitrogen is used as an auxiliary cold source to liquefy the silane or phosphine that is not completely removed by the combined adsorption tower and the nitrogen in the mixed gas; Step 4: The liquefied silane or phosphine and the nitrogen in the mixed gas are transported to the gas-liquid separator after the heat exchanger. The gas-liquid separator separates the hydrogen + a small amount of nitrogen. The separated high-nitrogen liquid refluxes in the heat exchanger and exchanges heat with the waste gas flowing in. The refluxed high-nitrogen liquid is vaporized and transported to the combined adsorption tower to be used as the first-stage regeneration gas. Step 5: The hydrogen + a small amount of nitrogen separated by the gas-liquid separator enters the PSA circulating adsorption tower, the hydrogen is purified, and the regenerated gas of the PSA circulating adsorption tower flows back to the pipeline in front of the compressor.

2. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: The combined adsorption tower can be switched between two towers. When Tower A is running, Tower B uses the exhaust gas discharged from the cold box for regeneration. After regeneration, the exhaust gas is discharged into the silane combustion barrel for subsequent harmless treatment. After the regeneration is complete, Tower B is switched to use and Tower A is regenerated.

3. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: After the regeneration of the first stage regeneration gas is completed, nitrogen needs to be used to blow the combined adsorption tower forward, and the dust-containing gas blown directly enters the silane combustion barrel.

4. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: The PSA cycle adsorption tower is composed of multiple stages of adsorption towers.

5. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: In step 2, the exhaust gas is initially pressurized to 30~80Kpa by a fan and then enters the combined adsorption tower.

6. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: In step three, the adsorbed gas is pressurized to 8~10barg by a compressor and sent to a cryogenic cold box.

7. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: In step three, at a low temperature of -175 to -185°C, the silane or phosphine that has not been completely removed by the combined adsorption tower and the nitrogen in the mixed gas are liquefied.

8. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 1, characterized in that: The preparation method of the modified molecular sieve is as follows: (1) dissolving silica sol, aluminum sulfate and sodium hydroxide in deionized water to form a uniform synthetic solution, followed by a crystallization reaction, wherein the main pore diameter is larger than the molecular diameter of H2 and smaller than the molecular diameters of SiH4 and PH3, washing, drying and calcining to obtain chabazite powder, and exposing the chabazite powder to electromagnetic radiation having a wavelength of 600-800 nm and a power of 12-20 watts / cm2 for 5-10 minutes to obtain modified chabazite powder; (2) Weighing the modified chabazite powder, dispersing it in a toluene solution of trimethylmethoxysilane, and subjecting it to a reflux reaction to graft the trimethylmethoxysilane onto the surface of the modified chabazite, thereby further shrinking the pore entrance, and then washing and drying it; (3) Prepare cuprous chloride solution and boric acid solution and mix them, immerse the pore-modified modified chabazite powder in the mixed solution, stir and exchange, then dry and calcine to make Cu + Exchanged to the inner wall of the modified chabazite pores, boron atoms replace part of the aluminum sites to form Lewis acid sites; (4) preparing a mixed solution containing zirconium nitrate and phosphoric acid, adding the modified chabazite powder to the mixed solution, stirring the solution to react, so that zirconium phosphate nanosheets are in situ generated in the modified chabazite framework, and then drying; (5) Dissolve polydimethylsiloxane in n-hexane to prepare a PDMS solution, immerse the modified chabazite powder in the PDMS solution, evenly coat the surface of the modified chabazite with a layer of PDMS solution, and finally solidify to obtain the modified molecular sieve.

9. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 8, characterized in that: Step (1) obtains a modified chabazite with a main pore diameter of 0.33 nm, and step (2) shrinks the main pore diameter of the modified chabazite to 0.30 nm.

10. The process for recovering hydrogen and silane from waste gas produced by HJT solar cells according to claim 8, characterized in that: In step (4), the mass ratio of zirconium nitrate to phosphoric acid is 1:1.

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