A process for treating slurry in polysilicon production
By performing gas-liquid separation, solid-liquid separation, and acid hydrolysis on polysilicon production slurry, and combining organic ethers and metal chloride salts as additives, the problem of ineffective recovery of silicon powder and high-boiling-point substances in the slurry was solved, achieving efficient material recovery and cost reduction in the slurry system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XINJIANG DAQO NEW ENERGY CO LTD
- Filing Date
- 2024-04-15
- Publication Date
- 2026-07-17
AI Technical Summary
In the polysilicon production process, silicon powder, high-boiling-point substances and metal chlorides contained in the slurry cannot be effectively recovered, resulting in high material and alkali consumption in the system and high production costs.
The slurry is treated through steps such as gas-liquid separation, solid-liquid separation, acid hydrolysis, pressure filtration, drying, and sieving. Combined with organic ethers and chloride metal salts as additives, the light and heavy components in the slurry are separated and recovered. The silica powder is then hydrolyzed in an acidic environment to produce trichlorosilane and silicon tetrachloride.
It achieves efficient recovery and utilization of the gas, solid, and liquid phases in the slurry, reduces production costs and alkali consumption, improves material recovery rate, and reduces the amount of waste residue and waste liquid to be treated.
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Figure CN118343768B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polysilicon technology, specifically relating to a process for treating slurry in polysilicon production. Background Technology
[0002] Currently, in the cold hydrogenation production process of polysilicon, a small amount of silicon powder is carried out by the fluidized bed. After washing and settling in the downstream system's washing tower, a large amount of slurry containing high-boiling-point substances and silicon powder is discharged to the slurry treatment section. The slurry undergoes gas-liquid separation, with the gas phase condensed and recovered, and the liquid phase buffered in a receiving tank. After filtration and separation, the solid phase is dried and hydrolyzed in an alkaline environment, producing a large amount of acid gas, silicon dioxide, metal salts, and sodium silicate. The gas phase is neutralized by alkaline leaching before being discharged. The wastewater is neutralized and then subjected to solid-liquid separation using a filter press. The solid phase is treated as waste residue, and the treated wastewater is discharged externally.
[0003] The slurry treatment involves simple gas-solid-liquid three-phase separation, followed by drying of the solid and liquid phases using a dryer. Utilizing the different boiling points of the material components, the lighter liquid components are recovered after heating, while the large amounts of high-boiling-point substances (pentachloro, hexachlorosilane, and siloxane) and metal chlorides are hydrolyzed. However, the slurry contains silicon powder, high-boiling-point substances (pentachloro, hexachlorosilane), and metal chlorides. While silicon powder has some recycling value, the high-boiling-point substances (pentachloro, hexachlorosilane, and siloxane) also contain significant amounts of silicon and chlorine. These hydrolyzed materials are treated as waste, leading to high system material consumption, high alkali consumption, and persistently high production costs.
[0004] In view of this, the present invention proposes a new process for treating slurry in polysilicon production, which can improve the material recycling rate of the slurry system. Summary of the Invention
[0005] The purpose of this invention is to provide a process for treating slurry in polysilicon production, which can improve the material classification and processing capabilities of the slurry process and the amount of material recycled.
[0006] To achieve the above objectives, the technical solution adopted is as follows:
[0007] A process for treating slurry in polysilicon production includes the following steps:
[0008] After gas-liquid separation of the slurry, a solid-liquid mixed phase and a gas phase are obtained;
[0009] After solid-liquid separation, the solid-liquid mixture is separated into a solid phase and a liquid phase.
[0010] The solid phase is dried, acidically hydrolyzed, pressure filtered, dried again, and sieved to obtain a solid phase containing silicon powder; the solid phase containing silicon powder is reacted with hydrogen chloride to form a synthesis reaction, the gas phase after the reaction is cooled, and the liquid phase after cooling is recovered to the distillation system.
[0011] The liquid phase is first treated to remove light-element compounds to recover trichlorosilane and silicon tetrachloride; then, an additive is added to the treated liquid phase to react and separate a liquid phase containing pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane; subsequently, the separated liquid phase is subjected to a cracking reaction with hydrogen chloride to generate trichlorosilane and silicon tetrachloride, which are then recovered, while the unreacted phase is subjected to alkaline hydrolysis.
[0012] Furthermore, the solid-liquid mixture is subjected to solid-liquid separation at a temperature below 15°C.
[0013] Furthermore, the solid-liquid mixture is subjected to solid-liquid separation at a temperature below 10°C.
[0014] Furthermore, the cooled gas phase is recovered into the hydrogen system.
[0015] Furthermore, the auxiliaries are organic ethers or metal chloride salts.
[0016] Furthermore, the organic ether is at least one of 18-crown-6 ether and 15-crown-4 ether;
[0017] The chloride metal salts mentioned are sodium chloride, barium chloride, or potassium chloride.
[0018] Furthermore, the catalyst for the pyrolysis reaction is an amine salt or an amine salt resin.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0020] This invention discloses a slurry treatment process for polycrystalline silicon production, which improves slurry processing capacity and enables the recovery and reuse of all three phases (gas, solid, and liquid). Light components (trichlorosilane and silicon tetrachloride) in the liquid phase are recovered, while heavy components (pentachlorosilane and hexachlorosilane) are cracked, and those that fail to decompose are hydrolyzed. The recovered solid silicon powder reacts with hydrogen chloride to produce trichlorosilane and silicon tetrachloride. This process also consumes hydrogen chloride, further reducing material consumption in the polycrystalline silicon production process. Simultaneously, the hydrolysis of solid silicon changes the environment from alkaline to acidic, effectively reducing the amount of alkali used and thus lowering production costs. The hydrolyzed waste residue is transformed from solid waste into recyclable production raw materials, and the waste liquid is fully recovered and reused, further reducing the amount of solid waste and treatment costs, and ultimately lowering production costs. Attached Figure Description
[0021] Figure 1This is a process flow diagram of a polysilicon production slurry treatment process according to the present invention. Detailed Implementation
[0022] To further illustrate the slurry treatment process in polycrystalline silicon production according to the present invention and to achieve the intended purpose of the invention, the following detailed description, in conjunction with preferred embodiments, details the specific implementation, structure, features, and effects of the slurry treatment process in polycrystalline silicon production proposed by the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0023] The following will provide a more detailed description of a slurry treatment process in polycrystalline silicon production according to the present invention, with reference to specific embodiments:
[0024] The technical solution of this invention can improve the material classification and processing capacity and the amount of material recovered and utilized in slurry processes. It enables the recovery and utilization of all three phases (gas, solid, and liquid) in the slurry system, achieving waste gas recovery, waste liquid recovery, waste liquid conversion, waste solid separation, and utilization. This increases the material recovery rate of the slurry process, reduces alkali consumption in the slurry system, reduces the amount of solid waste generated in the slurry system, and reduces costs through slurry treatment. The technical solution of this invention is as follows:
[0025] A process for treating slurry in polysilicon production includes the following steps:
[0026] After gas-liquid separation of the slurry, a solid-liquid mixed phase and a gas phase are obtained;
[0027] After solid-liquid separation, the solid-liquid mixture is separated into a solid phase and a liquid phase.
[0028] The solid phase is dried, acidically hydrolyzed, pressure filtered, dried again, and sieved to obtain a solid phase containing silicon powder; the solid phase containing silicon powder is reacted with hydrogen chloride to form a synthesis reaction, the gas phase after the reaction is cooled, and the liquid phase after cooling is recovered to the distillation system.
[0029] The liquid phase is first treated to remove light-element compounds to recover trichlorosilane and silicon tetrachloride; then, an additive is added to the treated liquid phase to react and separate a liquid phase containing pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane; subsequently, the separated liquid phase is subjected to a cracking reaction with hydrogen chloride to generate trichlorosilane and silicon tetrachloride, which are then recovered, while the unreacted phase is subjected to alkaline hydrolysis.
[0030] Preferably, the solid-liquid mixture is subjected to solid-liquid separation at a temperature below 15°C.
[0031] More preferably, the solid-liquid mixture is subjected to solid-liquid separation at a temperature below 10°C.
[0032] In the above technical solution, the temperature limit for separating solid-liquid mixtures can be limited by selecting a lower-grade refrigerant, thereby reducing energy consumption.
[0033] Preferably, the cooled gas phase is recovered into the hydrogen system.
[0034] Preferably, the auxiliary agent is an organic ether or a metal chloride salt.
[0035] More preferably, the organic ether is at least one of 18-crown-6 ether and 15-crown-4 ether;
[0036] The chloride metal salts mentioned are sodium chloride, barium chloride, or potassium chloride.
[0037] Preferably, the catalyst for the pyrolysis reaction is an amine salt or an amine salt resin.
[0038] Example 1.
[0039] This invention re-establishes the slurry processing flow. The gas phase is condensed and recovered to the hydrogen system for reuse. The liquid phase is separated into light and heavy components. The light components are recovered, and the heavy components are treated to remove metal ions, then converted and cracked to obtain light components, which are recovered for distillation. Unreacted components are hydrolyzed. The solid phase is hydrolyzed under certain conditions, filtered, and the silicon slag is dried and recovered. After sieving, usable silicon powder is obtained. The silicon powder reacts with hydrogen chloride in a synthesis furnace under certain conditions to obtain trichlorosilane and silicon tetrachloride. The reaction gas phase is condensed and compressed, the liquid phase is recovered to the distillation system for purification and reuse, and the gas phase is sent to the hydrogen system, compressed, and returned to cold hydrogenation for reuse.
[0040] Combination Figure 1 The specific operating steps are as follows:
[0041] The slurry residue from the cold hydrogenation slurry is separated into gas and liquid phases in a buffer tank, with the gas phase being recovered and reused in the hydrogen system. The solid-liquid mixture is separated into solid and liquid phases by filtration and pressing at a temperature not exceeding 15°C.
[0042] (1) Solid phase treatment
[0043] ① The solid phase is dried. The small amount of liquid contained in the solid phase is dried into a gas phase, which is then used for waste gas treatment.
[0044] ② Acidic hydrolysis: After drying, hydrolysis is carried out under acidic conditions (hydrochloric acid).
[0045] In existing technologies, alkaline hydrolysis is commonly used to treat solid phases. However, alkaline hydrolysis easily produces alkaline metal precipitates such as aluminum hydroxide and iron hydroxide, and silicon also readily reacts to form sodium silicate, which dissolves in water. This results in a higher impurity content and a lower effective silicon content in the recovered solid phase after hydrolysis.
[0046] This invention employs acidic hydrolysis, ensuring that most metal salts dissolve in water while minimizing reactions between elemental silicon and other substances. Under acidic conditions, silicon powder does not react with water, effectively preserving the silicon content in the solid impurities. Simultaneously, the large amount of metal impurities reacts with water to generate metal salts and hydrogen chloride, further reducing emissions and thus lowering production costs.
[0047] Hydrogen chloride dissolves in water, forming a hydrochloric acid solution system. Metal salts mainly exist in the form of chloride salts and are soluble in hydrochloric acid solution systems. Once saturated with hydrogen chloride, it becomes insoluble in water. This undissolved hydrogen chloride gas phase is leached and then sent to the downstream section for further alkaline leaching. After passing the leaching process, the gas phase is vented.
[0048] ③ Filtration: The liquid phase rich in hydrochloric acid solution, chloride solution and silica powder is filtered by a filter press. The silica powder is reduced to silica slag. The filtered water is neutralized and then reused.
[0049] ④ Drying and sieving: After drying, the moisture in the silicon slag is removed. After sieving, some impurities inside the silicon slag are discharged from the system. The remaining slag has a silicon content of about 70%. The rest are insoluble salts and some silicon alloys.
[0050] ⑤ Synthesis reaction, separation and cooling: The sieved silicon powder is added to the synthesis furnace and reacts again with hydrogen chloride at around 300℃ to produce trichlorosilane and silicon tetrachloride. The reaction gas phase is filtered, compressed and condensed, the liquid phase is recovered to the distillation system for purification and reuse, and the unreacted gas phase and some by-product hydrogen are recovered to the hydrogen system. After multi-stage compression, it is returned to the high-pressure hydrogen system for cold hydrogenation and reuse.
[0051] (2) Liquid phase treatment: The liquid phase after solid-liquid separation is transferred to the liquid phase treatment system. The liquid phase contains trichlorosilane, silicon tetrachloride, pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane. The specific treatment is as follows:
[0052] ① Light components removal: Taking advantage of the different boiling points of the various material components, the light components trichlorosilane and silicon tetrachloride are recovered and reused through distillation, and the condensed liquid phase is recovered for cold hydrogenation treatment.
[0053] ② Removal of metallic impurities: The heavy components pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane are treated with additives to remove metallic impurities. The additives and metallic impurities can react to form heavy components. After impurity removal, the light components are further treated by distillation to separate the pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane from the heavy components. The heavy components are then subjected to slag discharge and alkaline hydrolysis.
[0054] Additives for removing metallic impurities include organic ethers and metal chloride salts that undergo coordination reactions in chloride ion systems.
[0055] I. Reaction Mechanism of Organic Ethers: One of the most important properties of crown ethers is their ability to selectively complex metal ions. Under certain conditions, crown ethers can form relatively stable host-guest complexes with certain positively charged metal ions (such as alkali metals, alkaline earth elements belonging to the lanthanides and actinides) and ammonium ions. The main factors affecting whether crown ethers can complex with metal ions and the stability of the complexes are whether the diameter of the crown ether pore is compatible with the diameter of the cation, and the type of bonding atoms in the crown ether.
[0056] The structure of crown ether-metal ion complexes was investigated based on X-ray structural analysis of crystalline complexes, and the results showed that:
[0057] 1) When the diameter of the cation matches the size of the crown ether ring cavity, the cation is located exactly in the middle of the cavity, and the coordinated bonding atoms are all equidistant from the cation, forming a 1:1 complex.
[0058] 2) When the crown ether cavity is smaller than that of the cation, it is found that a 2:1 or 3:2 complex is generated or formed between the crown ether and the cation, that is, a 2:1 sandwich structure or a 3:2 double-layer sandwich structure is formed.
[0059] The diameter of the inner cavity of common crown ethers and the diameter of alkali metal ions are shown in Table 1.
[0060] Table 1. Matching relationship between crown ether lumen diameter and alkali metal ion size
[0061] Crown ethers Inner diameter / pm cation Cation diameter / pm 12 crowns - 4 120-150 Li+ 120 15 crowns - 5 170-220 Na+ 190 18 crowns - 6 260-320 K+ 266 21 crowns - 7 340-430 Rb+ 296 24 crowns - 8 >400 Cs+ 334
[0062] The radii of common metal ions are shown in Table 2.
[0063] Table 2
[0064]
[0065]
[0066] Different ethers are selected based on the table above to remove different metal ions. The metal ions removed in this invention are mainly iron, aluminum, and calcium ions. 18-crown-6 ether or 15-crown-4 ether can be selected according to the crown ether pore diameter, or a 1:1 ratio of the two can be used to remove metal ions. The specific addition ratio in the solution needs to be adjusted promptly based on the reaction temperature and the composition of the material, according to the removal effect.
[0067] II. Metal chloride salts that undergo coordination reactions in chloride ion systems:
[0068] Reaction Mechanism: In the chlorosilane system, a large number of chloride ions are present. Some metal chloride salts undergo coordination reactions with metal chlorides in the chlorosilane liquid phase, i.e., metal chloride salts form complexes with metal impurities. The metal impurities to be removed are mainly iron, aluminum, and calcium ions, which form precipitated metal complex salts after the addition of some metal chloride salts. In this reaction system, iron, aluminum, and calcium ions are the central ions, and chloride ions act as ligands, forming coordination compounds with the added metal chloride cations. The molar ratio of the added metal chloride salt to the metal chloride to be removed in this reaction is 1:1. The specific reaction mechanism is shown below (taking aluminum chloride as an example):
[0069] CL-+ALCL3——ALCL4 - That is, chloride ions react with aluminum trichloride to form tetrachloroaluminate ions.
[0070] To ensure effective removal, the metal salt in the chlorosilane solution must be added in excess. Common metal chloride salts include sodium chloride, barium chloride, and potassium chloride.
[0071] ③ Cracking and Conversion: Hydrogen chloride is introduced into the liquid phase after heavy components have been removed. Under the action of a catalyst, pentachlorosilane and hexachlorosilane are catalytically cracked into trichlorosilane and silicon tetrachloride. The trichlorosilane and silicon tetrachloride are treated as light components and recovered for distillation by condensation. Pentachlorosilane and hexachlorosilane do not react with hydrogen chloride and are treated as heavy components. After being removed from the reaction system, they are subjected to alkaline hydrolysis.
[0072] Catalysts for the pyrolysis reaction include amine salts and resins containing amine salt functional groups, which are conventional catalysts in the field. The organic amines in the amine salts include: tributylamine, isotributylamine, nitrogen-2-dimethylaniline, aromatic tertiary amines, etc., and the inorganic acid anions are sulfate ions. Various tertiary amines have different catalytic effects. The resin, as a carrier, can achieve different effects when different functional groups are attached. In this invention, the resin needs to be attached with amine salt functional groups to achieve the catalytic conversion effect.
[0073] Example 2.
[0074] The specific steps are as follows:
[0075] Combination Figure 1 The specific operating steps are as follows:
[0076] The slurry residue from the cold hydrogenation slurry is separated into gas and liquid phases in a buffer tank, with the gas phase being recovered and reused in the hydrogen system. The solid-liquid mixture is separated into solid and liquid phases by filtration and pressing at a temperature not exceeding 10°C.
[0077] (1) Solid phase treatment
[0078] ① The solid phase is dried. The small amount of liquid contained in the solid phase is dried into a gas phase, which is then used for waste gas treatment.
[0079] ② Acidic hydrolysis: After drying, hydrolysis is carried out under acidic conditions (hydrochloric acid).
[0080] ③ Filtration: The liquid phase rich in hydrochloric acid solution, chloride solution and silica powder is filtered by a filter press. The silica powder is reduced to silica slag. The filtered water is neutralized and then reused.
[0081] ④ Drying and sieving: After drying, the moisture in the silicon slag is removed. After sieving, some impurities inside the silicon slag are discharged from the system. The remaining slag has a silicon content of about 70%. The rest are insoluble salts and some silicon alloys.
[0082] ⑤ Synthesis reaction, separation and cooling: The sieved silicon powder is added to the synthesis furnace and reacted again with hydrogen chloride at 300±20℃ to produce trichlorosilane and silicon tetrachloride. The reaction gas phase is filtered, compressed and condensed, the liquid phase is recovered to the distillation system for purification and reuse, and the unreacted gas phase and some by-product hydrogen are recovered to the hydrogen system. After multi-stage compression, it is returned to the high-pressure hydrogen system for cold hydrogenation and reuse.
[0083] (2) Liquid phase treatment: The liquid phase after solid-liquid separation is transferred to the liquid phase treatment system. The liquid phase contains trichlorosilane, silicon tetrachloride, pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane. The specific treatment is as follows:
[0084] ① Light components removal: Taking advantage of the different boiling points of the various material components, the light components trichlorosilane and silicon tetrachloride are recovered and reused through distillation, and the condensed liquid phase is recovered for cold hydrogenation treatment.
[0085] ② Removal of metallic impurities: The heavy components pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane are treated with additives (18-crown-6 ether and 15-crown-4 ether in a 1:1 mass ratio) to remove metallic impurities. The additives and metallic impurities can react to form heavy components. After impurity removal, the light components are further treated by distillation to separate the pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane from the heavy components. The heavy components are then subjected to slag discharge and alkaline hydrolysis.
[0086] ③ Cracking and Conversion: Hydrogen chloride is introduced into the liquid phase after heavy components have been removed. Under the action of a catalyst, pentachlorosilane and hexachlorosilane are catalytically cracked into trichlorosilane and silicon tetrachloride. The trichlorosilane and silicon tetrachloride are treated as light components and recovered for distillation by condensation. Pentachlorosilane and hexachlorosilane do not react with hydrogen chloride and are treated as heavy components. After being removed from the reaction system, they are subjected to alkaline hydrolysis.
[0087] The catalyst for the pyrolysis reaction is the amine salt of tributylamine.
[0088] Example 3.
[0089] The operation steps of Example 3 are the same as those of Example 2, except that:
[0090] The auxiliary agent for removing metal impurities in liquid phase treatment is a metal chloride salt, specifically sodium chloride (addition amount is 2.5 g / ml).
[0091] The catalyst for the pyrolysis reaction is the amine salt of isotributylamine.
[0092] Example 4.
[0093] The operation steps of Example 4 are the same as those of Example 2, except that:
[0094] The auxiliary agent for removing metal impurities in liquid phase treatment is a metal chloride salt, specifically potassium chloride (addition amount is 1.25 g / ml).
[0095] The catalyst for the pyrolysis reaction is the amine salt of nitrogen-nitrogen dimethylaniline.
[0096] Example 5.
[0097] The operation steps of Example 5 are the same as those of Example 2, except that:
[0098] The auxiliary agent for removing metal impurities in liquid phase treatment is a metal chloride salt, specifically barium chloride (addition amount is 0.625 g / ml).
[0099] The catalyst for the cracking reaction is the amine salt of an aromatic tertiary amine.
[0100] The recovery effects of Examples 2-5 were measured. After using this process, the liquid phase recovery rate in the slurry system reached over 99%, with 100% recovery of light components (trichlorosilane and silicon tetrachloride) and 95% conversion and cracking of heavy components (pentachlorosilane and hexachlorosilane). Pentachlorosilane and hexachlorosilane effectively separated the chlorosilane system. The silicon powder recovery rate in the slurry reached 90% after pressure filtration. The remaining 10% of silicon powder was lost due to its small particle size, which prevented efficient interception. The water content of 90% of the silicon powder was approximately 20-25%. After drying, approximately 75%-80% of the total silicon powder could be recycled and screened. During screening, approximately 20% of the silicon powder was unsuitable for use as raw material in the synthesis furnace due to particle size issues. After screening, approximately 55%-65% of the total silicon powder could be used as raw material in the synthesis furnace. The remaining dried silicon powder can be sold as low-content silicon.
[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A process for treating slurry in polysilicon production, characterized in that, Includes the following steps: After gas-liquid separation of the slurry, a solid-liquid mixed phase and a gas phase are obtained; After solid-liquid separation, the solid-liquid mixture is separated into a solid phase and a liquid phase. The solid phase is dried, acidically hydrolyzed, pressure filtered, dried again, and sieved to obtain a solid phase containing silicon powder; the solid phase containing silicon powder is reacted with hydrogen chloride to form a synthesis reaction, the gas phase after the reaction is cooled, and the liquid phase after cooling is recovered to the distillation system. The liquid phase is first treated to remove light-element compounds to recover trichlorosilane and silicon tetrachloride; then, an additive is added to the treated liquid phase to react and separate a liquid phase containing pentachlorosilane, hexachlorosilane, pentachlorosiloxane, and hexachlorosiloxane; subsequently, the separated liquid phase is subjected to a cracking reaction with hydrogen chloride to generate trichlorosilane and silicon tetrachloride, which are then recovered, while the unreacted phase is subjected to alkaline hydrolysis.
2. The processing technology according to claim 1, characterized in that, The solid-liquid mixture is subjected to solid-liquid separation at a temperature below 15°C.
3. The processing technology according to claim 2, characterized in that, The solid-liquid mixture is subjected to solid-liquid separation at a temperature below 10°C.
4. The processing technology according to claim 1, characterized in that, The gas phase after the cooling reaction is recovered into the hydrogen system.
5. The processing technology according to claim 1, characterized in that, The aforementioned additives are organic ethers and metal chloride salts.
6. The processing technology according to claim 5, characterized in that, The organic ethers mentioned are at least one of 18-crown-6 ether and 15-crown-4 ether; The chloride metal salts mentioned are sodium chloride, barium chloride, or potassium chloride.
7. The processing technology according to claim 1, characterized in that, The catalyst for the pyrolysis reaction is an amine salt.