A porous adsorption material for removing trace propane from monofluoromethane, and its preparation method and application

Abstract

The present invention discloses a porous adsorption material for removing trace propane from monofluoromethane, and its preparation method and application, which belongs to the field of electronic special gas impurity removal and purification. The method comprises the following steps: (1) carbonizing fruit shell particles; (2) impregnating the carbonized fruit shell particles obtained in step (1) in a metal salt solution; (3) activating the carbonized fruit shell particles impregnated with the metal salt obtained in step (2) with carbon dioxide at high temperature to form pores, thereby obtaining a porous adsorption material. The porous carbon adsorbent prepared by the present invention using renewable natural biomass fruit shells has a uniform pore size distribution, can preferentially adsorb propane, has an extremely high adsorption capacity for trace propane, can purify monofluoromethane to above 6N in one step, far exceeding commercial coconut shell activated carbon CTC100, and meets the application demand for efficient removal of trace propane from monofluoromethane. Therefore, the material has important application prospects in the field of electronic special gas purification technology.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic special gas impurity removal and purification, and in particular to a porous adsorption material for removing trace propane from monofluoromethane to prepare ultra-high-purity monofluoromethane, as well as a preparation method and application thereof. Background Art

[0002] With the rapid development of the electronics industry, electronic specialty gases, as essential supporting gases for the semiconductor industry, have become increasingly important. These gases have a wide range of applications in fields such as semiconductor manufacturing, display panel manufacturing, photovoltaic energy, and fiber-optic communications. They are widely used as key raw materials in processes such as etching, doping, vapor deposition, and ion implantation. Consequently, these gases are often called the "blood" and "food" of the electronics industry. Their purity and cleanliness directly impact the quality, integration, and yield of optoelectronic and microelectronic components. Monofluoromethane, also known as HFC-41, with the chemical formula CH3F, is a highly effective etching gas characterized by its non-toxicity, environmental friendliness, and high efficiency. It is widely used in the etching process for semiconductors and electronic products. To ensure the production and quality of electronic products such as chips, CH3F purity is typically required to exceed 99.999% or even 99.9999%. Therefore, deep purification of CH3F is an extremely important and challenging process in the semiconductor chip industry. The purity of crude CH3F product is generally 99.9%, and it usually contains organic impurities such as methane (CH4), ethylene (C2H4), ethane (C2H6), propylene (C3H6), propane (C3H8), and hexafluoroethane (C2F6). These organic impurities are produced by the cracking process in the CH3F production process. In order to obtain ultra-high-purity CH3F products, the trace impurities in CH3F must be deeply removed. The adsorption method can selectively remove low-concentration and ultra-low-concentration gas impurities at room temperature and pressure, so it is also considered a feasible method for producing ultra-pure electronic gases. The core of the adsorption method is the adsorbent. Common solid adsorption materials include porous carbon materials, MOFs, and molecular sieves. The existing technologies for the purification of impurities in monofluoromethane are mainly reported as follows:

[0003] Chinese invention patent application CN201410391684.2 discloses an adsorbent modification method. The adsorbent modified by ion exchange, ball milling, or impregnation of type A molecular sieve, type X molecular sieve, type Y molecular sieve, SiO2, Al2O3, or activated carbon AC can effectively remove organic impurities from crude monofluoromethane, resulting in an ultra-high-purity CH3F product with a purity of ≥99.999%.

[0004] Chinese invention patent application CN202111676741.8 discloses a method for preparing a carbon adsorbent. Six-membered ring monosaccharide is used as raw material, and the carbon adsorbent is prepared through hydrothermal carbonization and high-temperature pyrolysis. After CH3F and C3H8 are introduced into the prepared adsorbent, CH3F with a purity of 6N can be obtained.

[0005] Chinese invention patent application CN202211417636.7 discloses a modified adsorbent and its application in removing C2F6 from CH3F. Activated carbon is modified using cucurbituril, and the resulting adsorbent can remove C2F6 from CH3F to below 20 ppb.

[0006] Porous carbon materials offer excellent stability, well-developed pores, easy modification, and low production costs, holding them in great demand for electronic gas purification. However, the porous carbon materials currently used to purify specialty electronic gases are mostly commercial activated carbons with a wide pore size distribution, resulting in poor recognition and capture of specific molecules. This makes it difficult to remove trace amounts of C3H8 impurities from CH3F, making CH3F electronic gas difficult to meet the application requirements of the electronics industry. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention provides a granular porous carbon material with a uniform pore size distribution and an ultra-high adsorption capacity for trace propane, and a method for preparing the same. By utilizing renewable natural biomass fruit shells as a carbon source and employing a high-temperature activation-pore-forming-catalytic graphitization method and application, the porous carbon material undergoes physical activation and pore formation. Metal ions that catalyze the formation of graphite structures, thereby shrinking the pores, are utilized to precisely adjust the pore size of the porous carbon material. This porous carbon adsorbent, KC, exhibits a high adsorption selectivity for C3H8 in CH3F and an extremely high adsorption capacity for trace amounts of C3H8, enabling a single-step purification of CH3F to above 6N.

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] A method for preparing a porous adsorption material comprises the following steps:

[0010] (1) carbonizing the fruit shell particles to obtain carbonized fruit shell particles;

[0011] (2) impregnating the carbonized fruit shell particles obtained in step (1) in a metal salt solution to obtain metal salt-impregnated carbonized fruit shell particles; the metal salt is any one of iron salt, cobalt salt, nickel salt and manganese salt, or a combination of two or more thereof;

[0012] (3) The carbonized fruit shell particles impregnated with metal salts obtained in step (2) are activated and porous using carbon dioxide at high temperature to obtain a porous adsorption material, which is labeled as KC.

[0013] Preferably, the metal salt in step (2) is an iron salt.

[0014] Preferably, the fruit shells described in step (1) include but are not limited to walnut shells, olive shells, coconut shells, date shells, peach shells, etc.

[0015] Preferably, the fruit shell particles in step (1) have a size of 2 to 80 meshes.

[0016] Preferably, the carbonization temperature in step (1) is 200-500° C., and the duration is 0.5-8 h.

[0017] Preferably, the concentration of the metal salt solution in step (2) is 0.01 to 5 mol / L.

[0018] Preferably, the immersion time in step (2) is 1 to 24 hours.

[0019] Preferably, the solid-liquid ratio of the impregnation in step (2) is 1:0.5 to 1:20 g / mL, and the temperature is 20 to 80°C.

[0020] Preferably, in step (2), after immersion, the mixture is filtered and dried, and the drying temperature is 50 to 200° C. and the drying time is 2 to 24 hours.

[0021] Preferably, the heating rate of high-temperature activation in step (3) is 1 to 10°C / min.

[0022] Preferably, the activation temperature in step (3) is 750-1000° C., and the activation time is 15-180 min.

[0023] Preferably, the concentration of carbon dioxide in step (3) is 1% to 100%.

[0024] A porous adsorption material prepared by any of the preparation methods described above.

[0025] The porous adsorption material described above is used to remove propane from a propane-containing mixed gas.

[0026] Preferably, the mixed gas contains monofluoromethane and propane, wherein the concentration of propane is 1 to 2000 ppm; the removal process uses nitrogen as the carrier gas, the adsorption temperature is 273 to 323 K, and the adsorption pressure is 0.01 to 3 bar.

[0027] Preferably, the flow rate of the mixed gas is 0.5 to 20 mL / min.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) The present invention uses natural biomass waste fruit shells as a carbon source, which is green, environmentally friendly, renewable, and has low production costs.

[0030] (2) The adsorbent of the present invention has a uniform and appropriate pore size distribution and has molecular recognition ability for C3H8, so that it has a strong ability to remove trace amounts of C3H8 in CH3F.

[0031] (3) The adsorbent of the present invention utilizes the synergistic effect of high-temperature carbon dioxide activation and metal salt catalytic graphitization to precisely control the pore size of the porous carbon material within the angstrom range.

[0032] (4) Compared with existing adsorbents, the adsorbent of the present invention can adsorb up to 1.04 mmol / g of C3H8 at a concentration of 1000 ppm at room temperature. The yield of CH3F with a purity of more than 6N obtained by one-step adsorption purification is 2975.7 mL / g, which is much higher than the 0.46 mmol / g and 1024.9 mL / g of commercial coconut shell CTC100 activated carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a typical pore size distribution diagram of commercial coconut shell activated carbon CTC100 and the adsorbent obtained in the present invention.

[0034] Figure 2 The adsorption isotherms of C3H8 and CH3F at 298K for commercial coconut shell activated carbon CTC100 and the adsorbents obtained in various embodiments of the present invention are shown.

[0035] Figure 3 The adsorption breakthrough curves of commercial coconut shell activated carbon CTC100 and the adsorbents obtained in various embodiments of the present invention for 100 ppm of C3H8. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. However, the scope of protection claimed by the present invention is not limited to the scope described in the embodiments.

[0037] Example 1

[0038] (1) crushing the walnut shells and collecting walnut shell particles of 10 to 20 mesh, and then carbonizing the obtained walnut shell particles at 200° C. for 8 h to obtain carbonized walnut shell particles;

[0039] (2) The carbonized walnut shell particles obtained in step (1) were immersed in 5 mol / L Fe 3+ The solution has a solid-liquid ratio of 1:0.5 and is stirred and immersed at 20°C for 1 hour. The solution is filtered and dried at 200°C for 2 hours to obtain carbonized walnut shell particles impregnated with iron salt.

[0040] (3) The carbonized walnut shell particles impregnated with iron salt in step (2) were heated to 750°C at a heating rate of 1°C / min, and then activated with 100% carbon dioxide for 180 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-1.

[0041] Example 2

[0042] (1) crushing the olive shells and collecting the olive shell particles of 20-30 mesh, and then carbonizing the obtained olive shell particles at 300° C. for 6 h to obtain carbonized olive shell particles;

[0043] (2) The carbonized olive shell particles obtained in step (1) were immersed in 2 mol / L Co 2+ The solution has a solid-liquid ratio of 1:2 and is stirred and immersed at 30°C for 4 hours. The solution is filtered and dried at 150°C for 4 hours to obtain carbonized olive shell particles impregnated with cobalt salt.

[0044] (3) The carbonized olive shell particles impregnated with cobalt salt in step (2) were heated to 850°C at a heating rate of 2°C / min, and then activated with 75% carbon dioxide for 120 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-2.

[0045] Example 3

[0046] (1) crushing the coconut shell and collecting 30-40 mesh coconut shell particles, and then carbonizing the obtained coconut shell particles at 400° C. for 1 h to obtain carbonized coconut shell particles;

[0047] (2) The carbonized coconut shell particles obtained in step (1) were immersed in 0.1 mol / L Ni 2+ The solution has a solid-liquid ratio of 1:10 and is stirred and immersed at 80°C for 12 hours. The solution is filtered and dried at 100°C for 6 hours to obtain carbonized coconut shell particles impregnated with nickel salt.

[0048] (3) The carbonized coconut shell particles impregnated with nickel salt in step (2) were heated to 900°C at a heating rate of 5°C / min, and then activated with 50% carbon dioxide for 60 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-3.

[0049] Example 4

[0050] (1) crushing the jujube shells and collecting jujube shell particles of 40-50 mesh, and then carbonizing the obtained jujube shell particles at 500° C. for 0.5 h to obtain carbonized jujube shell particles;

[0051] (2) The carbonized jujube shell particles obtained in step (1) were immersed in 0.01 mol / L Mn 2+The solution has a solid-liquid ratio of 1:20 and is stirred and immersed at 60°C for 24 hours, filtered, and dried at 50°C for 24 hours to obtain carbonized jujube shell particles impregnated with manganese salt;

[0052] (3) The carbonized jujube shell particles impregnated with manganese salt in step (2) were heated to 1000° C. at a heating rate of 10° C. / min, and then activated with 1% carbon dioxide for 15 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-4.

[0053] Example 5

[0054] (1) crushing peach shells and collecting peach shell particles of 50-80 mesh, and then carbonizing the obtained peach shell particles at 300° C. for 6 h to obtain carbonized peach shell particles;

[0055] (2) Immerse the carbonized peach shell particles obtained in step (1) in 0.5 mol / L Ni 2+ and Mn 2+ The solution was prepared in a ratio of 1:9, with a solid-liquid ratio of 1:8, and stirred at 50°C for 6 hours. The mixture was filtered and dried at 70°C for 6 hours to obtain carbonized peach shell particles impregnated with two metal salts.

[0056] (3) The carbonized peach shell particles impregnated with the metal salt in step (2) were heated to 950°C at a heating rate of 2°C / min, and then activated with 15% carbon dioxide for 0.5 h. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-5.

[0057] Example 6

[0058] (1) crushing apricot shells and collecting apricot shell particles of 2-10 mesh, and then carbonizing the apricot shell particles at 350° C. for 5 h to obtain carbonized apricot shell particles;

[0059] (2) The carbonized apricot shell particles obtained in step (1) were immersed in 1 mol / L Fe 3+ 、Co 2+ and Ni 2+ The solution was prepared in a ratio of 1:1:1, with a solid-liquid ratio of 1:9, and stirred at 30°C for 12 hours. The mixture was filtered and dried at 80°C for 12 hours to obtain carbonized apricot shell particles impregnated with three metal salts.

[0060] (3) The carbonized apricot shell particles impregnated with the metal salt in step (2) were heated to 800°C at a heating rate of 5°C / min, and then activated with 60% carbon dioxide for 180 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as KC-6.

[0061] Comparative Example 1

[0062] (1) crushing the walnut shells and collecting walnut shell particles of 10 to 20 mesh, and then carbonizing the obtained walnut shell particles at 200° C. for 8 h to obtain carbonized walnut shell particles;

[0063] (2) The carbonized walnut shell particles obtained in step (1) were immersed in 5 mol / L Zn 2+ The solution has a solid-liquid ratio of 1:0.5 and is stirred and immersed at 20°C for 1 hour. The solution is filtered and dried at 200°C for 2 hours to obtain zinc salt-impregnated carbonized walnut shell particles.

[0064] (3) The carbonized walnut shell particles impregnated with zinc salt in step (2) were heated to 750° C. at a heating rate of 1° C. / min, and then activated with 100% carbon dioxide for 180 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as Comparative Example 1.

[0065] Comparative Example 2

[0066] (1) crushing the coconut shell and collecting 30-40 mesh coconut shell particles, and then carbonizing the obtained coconut shell particles at 400° C. for 1 h to obtain carbonized coconut shell particles;

[0067] (2) immersing the carbonized coconut shell particles obtained in step (1) in deionized water with a solid-liquid ratio of 1:10, and stirring and immersing at 80° C. for 12 h, filtering, and drying at 100° C. for 6 h to obtain washed carbonized coconut shell particles;

[0068] (3) The washed carbonized coconut shell particles in step (2) were heated to 900° C. at a heating rate of 5° C. / min, and then activated with 50% carbon dioxide for 60 min. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as Comparative Example 2.

[0069] Comparative Example 3

[0070] (1) crushing the olive shells and collecting the olive shell particles of 20-30 mesh, and then carbonizing the obtained olive shell particles at 300° C. for 6 h to obtain carbonized olive shell particles;

[0071] (2) The carbonized olive shell particles obtained in step (1) were immersed in 2 mol / L Co 2+ The solution has a solid-liquid ratio of 1:2 and is stirred and immersed at 30°C for 4 hours. The solution is filtered and dried at 150°C for 4 hours to obtain carbonized olive shell particles impregnated with cobalt salt.

[0072] (3) The carbonized olive shell particles impregnated with cobalt salt in step (2) were heated to 850°C at a heating rate of 2°C / min, and then activated with nitrogen for 120 minutes. After cooling to room temperature, a porous carbon adsorbent was obtained, which was recorded as Comparative Example 3.

[0073] The pore size distribution of commercial coconut shell activated carbon CTC100 and typical porous carbon adsorbent KC was analyzed using the ASAP 2460 multi-station fully automatic specific surface and pore size analyzer from Micromeritics, USA. The results are shown in Figure 1 The results show that the pore size of the porous carbon adsorbent KC prepared by the present invention is concentrated in At high temperature, carbon dioxide can activate the fruit shell carbon to produce a rich pore structure, and the added metal ions can catalyze the amorphous carbon to form a graphite structure to achieve pore shrinkage, thereby producing a porous carbon adsorbent KC with a uniform pore size distribution, which has excellent molecular recognition and capture capabilities for trace amounts of C3H8.

[0074] The adsorption isotherms of C3H8 and CH3F at 298K for commercial coconut shell activated carbon CTC100, porous carbon adsorbents prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were measured using a 3Flex three-station gas adsorption instrument from Micromeritics, USA. The results are shown in Figure 2 The results show that the propane adsorption capacities of the porous carbon adsorbents prepared in each example at a C3H8 concentration of 1000 ppm are 1.04, 0.95, 0.99, 1.00, 0.96, and 0.92 mmol / g, respectively, which are much higher than the 0.46 mmol / g of commercial coconut shell activated carbon CTC100, and also much higher than the 0.49, 0.53, and 0.34 mmol / g of the comparative examples.

[0075] The outlet C3H8 concentration was detected by GC-6600 gas chromatograph and flame ionization detector (FID). A 5 mm stainless steel packed column was used, filled with 200 mg of adsorbent. Nitrogen was used as the carrier gas, and a six-port valve was used for sample introduction. The inlet gas was a C3H8 / CH3F mixture with a concentration of 100 ppm and a flow rate of 10 mL / min. The carrier gas flow rate was 20 mL / min. The column temperature was 323 K, and the detector temperature was 523 K.

[0076] Depend on Figure 3It can be seen that for C3H8 gas with a concentration of 100 ppm, the time for the KC prepared in each embodiment to produce CH3F with a purity of 6N or above is 60.07, 60.01, 60.05, 60.02, 59.94 and 60.16 min, respectively, and the yield is 2975.7, 2966.7, 2956.2, 2971.2, 2924.7 and 2950.2 mL / g, respectively. The time for each comparative example to produce CH3F with a purity of 6N or above is 23.97, 24.12 and 12.18 min, respectively, and the yield is 1095.5, 1132.0 and 530.5 mL / g, respectively, which is much lower than the KC prepared in each embodiment. At the same time, the time and yield of CH3F with a purity of 6N or above produced by the KC prepared in each example are much higher than 23.60 min and 1024.9 mL / g of the commercial coconut shell activated carbon CTC100, indicating that the porous carbon adsorbent KC prepared in each example has an excellent removal effect on trace C3H8, and the yield of ultra-high purity CH3F is significantly higher than that of the commercial coconut shell activated carbon CTC100.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An application of a porous adsorption material for removing propane from a propane-containing mixed gas, characterized in that: The mixed gas contains monofluoromethane and propane, wherein the concentration of propane is 1-2000 ppm; the removal process uses nitrogen as a carrier gas, the adsorption temperature is 273-323 K, and the adsorption pressure is 0.01-3 bar; the pore size of the porous adsorption material is concentrated at 6.4 Å; the porous adsorption material has excellent molecular recognition and capture capabilities for C3H8; The preparation method of the porous adsorption material comprises the following steps: (1) carbonizing the fruit shell particles to obtain carbonized fruit shell particles; (2) impregnating the carbonized fruit shell particles obtained in step (1) in a metal salt solution to obtain metal salt-impregnated carbonized fruit shell particles; the metal salt is any one of iron salt, cobalt salt, nickel salt and manganese salt, or a combination of two or more thereof; (3) The carbonized fruit shell particles impregnated with the metal salt obtained in step (2) are activated and pore-formed using carbon dioxide at 750-1000° C. to obtain a porous adsorption material.

2. The use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The metal salt described in step (2) is an iron salt.

3. The use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The fruit shells described in step (1) are one or more of walnut shells, olive shells, coconut shells, jujube shells and peach shells; and the particle size of the fruit shells is 2-80 meshes.

4. The use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The carbonization temperature in step (1) is 200-500°C, and the duration is 0.5-8 h.

5. The use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The concentration of the metal salt solution in step (2) is 0.01 to 5 mol / L; the immersion time is 1 to 24 h; the immersion solid-liquid ratio is 1:0.5 to 1:20, and the temperature is 20 to 80°C.

6. Use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The heating rate of high-temperature activation in step (3) is 1-10°C / min; the activation time is 15-180 min; and the carbon dioxide concentration is 1%-100%.

7. Use of a porous adsorption material according to claim 1 for removing propane from a propane-containing mixed gas, characterized in that: The flow rate of the mixed gas is 0.5-20 mL / min.

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