Adsorbent, preparation method thereof and Ru purification method

Abstract

The invention discloses an adsorbent, a preparation method thereof and a Ru purification method, and the preparation method comprises the following steps: carrying out three-stage high-temperature hydrothermal treatment on an HY molecular sieve to obtain a pretreated molecular sieve; reacting the pretreated molecular sieve with a hydrochloric acid solution, and then filtering, washing and drying to obtain the adsorbent. The Ru purification method comprises the following steps: loading the adsorbent prepared by the preparation method into a chemical adsorption tower, and introducing spent fuel post-treatment tail gas into the chemical adsorption tower, so that the adsorbent adsorbs RuO4 in the tail gas and reacts with the RuO4. The adsorbent has the advantages of high adsorption capacity, high adsorption efficiency and the like; ru in spent fuel post-treatment tail gas can be effectively purified, and the treatment effect is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear industry, and in particular relates to an adsorbent and a preparation method thereof, and a Ru purification method. Background Art

[0002] Ruthenium (Ru) is a high-yield, long-lived fission element in spent fuel. In reactors, Ru is a high-yield fission product and is highly mobile in the environment. According to the World Nuclear Association, each nuclear power reactor produces an average of over 40 kilograms of radioactive Ru annually.

[0003] To recover U and Pu from nuclear fuel, the fragmented elements, including Ru, must be separated. However, during aqueous spent fuel reprocessing, the purification of ruthenium remains a significant challenge due to the wide variety of Ru nitroxyl salts and the interconversion of various ruthenium salt complexes. This complex multi-ion, multi-valent, and multi-element aqueous reprocessing process presents a significant challenge. Furthermore, RuO4, a Ru compound, is the only volatile metal nuclide in spent fuel reprocessing. If the extraction process fails to completely remove Ru, the entrainment of gaseous RuO4 in the exhaust gas may lead to excessive radioactivity.

[0004] During dry reprocessing, Ru, a key fission product, behaves significantly differently from other fission products. Due to its high volatility, ruthenium typically evaporates at the beginning of the process as ruthenium tetroxide (RuO4) under high-temperature conditions. This volatility not only contaminates subsequent processing steps but also poses a potential threat to the environment and operational safety. Therefore, the capture and purification of volatile ruthenium has become an important research direction in dry reprocessing.

[0005] Chemical adsorption is the preferred method for capturing volatile ruthenium tetroxide (RuO4) due to its high selectivity, efficiency and stability. RuO4 is highly oxidizing and volatile. By reacting it with chemical adsorption materials, it can be fixed into a stable chemical form (such as ruthenium oxide or ruthenium salt), significantly reducing the risk of volatilization. Compared with physical adsorption, chemical adsorption exhibits better performance under high temperature and low concentration conditions, and the adsorbed Ru is not easy to desorb. In addition, chemical adsorption materials (such as metal oxides, alkaline adsorbents) have the characteristics of flexible design and strong targeting. They can optimize the adsorption mechanism by regulating the active sites to meet the strict requirements for Ru capture in the post-processing process. This method is not only conducive to improving process safety and capture efficiency, but also facilitates subsequent processing and storage, and has important application value.

[0006] However, current chemical adsorption methods employ chemical adsorption materials (such as metal oxides and alkaline adsorbents) that suffer from low adsorption capacity and efficiency. Furthermore, RuO₄ produced in the nuclear industry is not only highly oxidizing and volatile, but also radioactive, placing higher demands on the selectivity and durability of purification materials. Therefore, developing a technology that can efficiently capture and purify RuO₄ is of great theoretical significance and has significant engineering application value. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide an adsorbent and a preparation method thereof, as well as a Ru purification method. The adsorbent of the present invention has the advantages of high adsorption capacity and adsorption efficiency, and can effectively purify Ru in spent fuel post-processing tail gas with excellent treatment effect.

[0008] The technical solution of the present invention to solve the above technical problems is:

[0009] According to a first aspect of the present invention, there is provided a method for preparing an adsorbent, comprising:

[0010] The HY molecular sieve is subjected to a three-stage high-temperature hydrothermal treatment to obtain a pretreated molecular sieve;

[0011] The pretreated molecular sieve is reacted with a hydrochloric acid solution, and then filtered, washed, and dried to obtain an adsorbent.

[0012] Optionally, the three-stage high-temperature hydrothermal treatment includes:

[0013] Heating the HY molecular sieve to a first temperature at a first heating rate, and continuously introducing a first mixed gas comprising air and water vapor at a first flow rate, and maintaining the temperature for a period of time to obtain a treated HY molecular sieve;

[0014] Heating the first-stage treated HY molecular sieve to a second temperature at a second heating rate, and continuously introducing a second mixed gas comprising air and water vapor at a second flow rate, and maintaining the temperature for a period of time to obtain a second-stage treated HY molecular sieve, wherein the second temperature is greater than the first temperature, and the second flow rate is greater than the first flow rate;

[0015] The second-stage treated HY molecular sieve is heated to a third temperature at a third heating rate, and a third mixed gas including air and water vapor is continuously introduced at a third flow rate, and kept warm for a period of time to obtain a pretreated molecular sieve, wherein the third temperature is greater than the second temperature, and the third flow rate is greater than the second flow rate.

[0016] Optionally, the first heating rate is 10-12 K / min, the second heating rate is 12-14 K / min, and the third heating rate is 15-18 K / min.

[0017] Optionally, the first temperature is 900-910K, the second temperature is 950-960K, and the third temperature is 1050-1060K.

[0018] Optionally, the first flow rate is 34-36 cm 3 / min, the second flow rate is 44-46cm 3 / min, the third flow rate is 54-56cm 3 / min.

[0019] Optionally, the HY molecular sieve is a zeolite molecular sieve having a Faujasite-type crystal structure, and its silicon-aluminum ratio is 10-12.

[0020] Optionally, the volume ratio of air and water vapor in the first mixed gas is 1:(0.9~1.1), the volume ratio of air and water vapor in the second mixed gas is 1:(1.4~1.6), and the volume ratio of air and water vapor in the third mixed gas is 1:(1.9~2.1).

[0021] Optionally, the mixing ratio of the pretreated molecular sieve and the hydrochloric acid solution is 15-18 g:120 mL.

[0022] Optionally, the reaction temperature of the pretreated molecular sieve and the hydrochloric acid solution is 70-75° C., and the reaction time is 5-6 hours.

[0023] Optionally, the concentration of the hydrochloric acid solution is 5-6 mol / L.

[0024] According to a second aspect of the present invention, there is provided an adsorbent, which is prepared using the above-mentioned preparation method.

[0025] According to a third aspect of the present invention, there is provided a Ru purification method comprising:

[0026] The adsorbent prepared by the above-mentioned preparation method is loaded into a chemical adsorption tower, and the spent fuel post-processing tail gas is introduced into the chemical adsorption tower, so that the adsorbent adsorbs RuO4 in the tail gas and reacts.

[0027] Optionally, the tail gas flow rate is 55-58m 3 / h.

[0028] Optionally, the reaction temperature is 110-112°C.

[0029] Beneficial effects of the present invention:

[0030] The adsorbent and preparation method of the present invention are based on HY molecular sieve, and through three-stage high-temperature hydrothermal treatment and hydrochloric acid solution treatment, a high-adsorption capacity USY molecular sieve adsorbent with regular pores and supercage structure can be prepared. The pore size and supercage structure diameter are consistent with the van der Waals size of RuO4 clusters (diameter is about ) is highly matched, has strong selective adsorption performance for RuO4, can effectively capture RuO4 molecules to prevent them from escaping, and at the same time provide them with stable adsorption sites, greatly improving the adsorbent's treatment and purification effect on Ru in spent fuel post-processing exhaust gas. Moreover, within the pores and supercage structures of the adsorbent, RuO4 clusters interact with the inner surface of the molecular sieve through van der Waals forces (including dispersion forces and induction forces). This effect enables RuO4 to be stably adsorbed in the USY molecular sieve with high adsorption capacity. There are a certain amount of acidic centers (such as The adsorbent has a large number of sites (including Lewis acid sites and Lewis acid sites) that can further enhance adsorption performance through hydrogen bonding or electrostatic interactions with RuO4 molecules, increasing both the adsorption efficiency and the amount of RuO4 adsorbed. Furthermore, the adsorbent possesses an extremely high specific surface area and pore volume, providing a large number of effective adsorption sites for the dispersion and multi-point adsorption of RuO4 molecules, thereby increasing adsorption capacity. Furthermore, the adsorbent exhibits excellent stability in high temperatures and chemical environments, maintaining high RuO4 adsorption efficiency for extended periods under harsh conditions, demonstrating excellent durability and a long lifespan.

[0031] The Ru purification method of the present invention uses the USY molecular sieve adsorbent with high adsorption capacity specially prepared by the preparation method described above, which can play a significant adsorption role in the process of treating spent fuel post-processing tail gas, effectively purify Ru in the spent fuel post-processing tail gas, and has excellent treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 4 is a graph showing the adsorption amount of ruthenium tetroxide by the adsorbent in an embodiment of the present invention at different hydrochloric acid solution treatment times. DETAILED DESCRIPTION

[0033] To help those skilled in the art better understand the technical solutions of the present invention, the following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0034] In view of the problems of low adsorption capacity and low adsorption efficiency in the prior art of treating spent fuel post-processing tail gas using a chemical adsorption method, the present invention discloses a method for preparing an adsorbent, comprising: subjecting an HY molecular sieve to a three-stage high-temperature hydrothermal treatment to obtain a pretreated molecular sieve; reacting the pretreated molecular sieve with a hydrochloric acid solution, followed by filtering, washing, and drying to obtain an adsorbent.

[0035] Furthermore, the present invention also discloses an adsorbent, which is prepared using the above-mentioned preparation method.

[0036] Furthermore, the present invention also discloses a Ru purification method, which comprises: loading the adsorbent prepared by the preparation method described above into a chemical adsorption tower, introducing spent fuel post-processing tail gas into the chemical adsorption tower, and allowing the adsorbent to adsorb RuO4 in the tail gas and react.

[0037] Example 1

[0038] This embodiment discloses a method for preparing an adsorbent, comprising:

[0039] Step S1, subjecting HY molecular sieve (i.e., hydrogen-type Y-type zeolite molecular sieve) to a three-stage high-temperature hydrothermal treatment to obtain a pretreated molecular sieve;

[0040] In step S2, the pretreated molecular sieve is reacted with a hydrochloric acid solution, and then filtered, washed, and dried to obtain a USY molecular sieve (i.e., ultra-stable Y zeolite) adsorbent with a high adsorption capacity.

[0041] After the high-temperature hydrothermal treatment in step S1, the framework aluminum in the HY molecular sieve can be removed, and an ultra-stable Y molecular sieve (i.e., a pretreated molecular sieve) with high crystallinity and high hydrothermal stability can be initially prepared. However, the framework aluminum removed in step S1 still exists in the pores of the pretreated molecular sieve in the form of non-framework aluminum, which affects the adsorption performance of the molecular sieve. The present method further treats the pretreated molecular sieve with hydrochloric acid to dissolve the non-framework aluminum produced during the high-temperature hydrothermal treatment and remove this non-framework aluminum, further improving the SiO2 / Al2O3 ratio of the molecular sieve and simultaneously increasing the micropore volume and mesopore volume of the adsorbent.

[0042] In this embodiment, the SiO2 / Al2O3 of HY molecular sieve is 10-12, and the specific surface area is 600-630m 2 / g, pore volume is 0.4~0.6cm 3 / g, pore size 0.32~0.41nm.

[0043] In some embodiments, the three-stage high-temperature hydrothermal treatment comprises:

[0044] One-stage high-temperature hydrothermal treatment: placing the HY molecular sieve in a fixed-bed reactor, controlling the temperature through a tube furnace program, heating the HY molecular sieve to a first temperature at a first heating rate, and continuously introducing a first mixed gas including air and water vapor at a first flow rate, and keeping the temperature for a period of time to obtain a first-stage treated HY molecular sieve;

[0045] Second-stage high-temperature hydrothermal treatment: placing a first-stage HY molecular sieve in a fixed-bed reactor, controlling the temperature through a tube furnace program, heating the first-stage treated HY molecular sieve to a second temperature at a second heating rate, and continuously introducing a second mixed gas including air and water vapor at a second flow rate, and maintaining the temperature for a period of time to obtain a second-stage treated HY molecular sieve, wherein the second temperature is greater than the first temperature, and the second flow rate is greater than the first flow rate;

[0046] Three-stage high-temperature hydrothermal treatment: placing the second-stage HY molecular sieve in a fixed bed reactor, controlling the temperature through a tubular furnace program, heating the second-stage treated HY molecular sieve to a third temperature at a third heating rate, and continuously introducing a third mixed gas including air and water vapor at a third flow rate, and keeping the temperature for a period of time to obtain the pretreated molecular sieve, wherein the third temperature is greater than the second temperature, and the third flow rate is greater than the second flow rate.

[0047] Specifically, by adopting the above-mentioned high-temperature hydrothermal treatment from the first to the third stage, the following effects can be achieved:

[0048] 1. Gradual dealumination

[0049] Controlling the dealumination rate: Heating in stages can avoid excessive dealumination caused by a single high-temperature treatment, which can cause the molecular sieve structure to collapse or the pores to become clogged.

[0050] Improve structural stability: Gradual dealumination helps reduce stress concentration in the crystal structure and maintain the crystal phase integrity and pore connectivity of the molecular sieve.

[0051] 2. Improve acid distribution

[0052] Regulation of acidic centers: Through hydrothermal treatment at different temperature stages, framework aluminum or non-framework aluminum can be selectively removed to optimize the distribution and strength of acidic centers, thereby improving adsorption performance.

[0053] Avoid excessive loss of acidity: High temperature treatment can easily lead to the loss of acid sites. Segmented treatment helps to more accurately regulate the retention and enhancement of acidity.

[0054] 3. Avoid structural collapse

[0055] Protecting the pore structure: A one-time high-temperature treatment may cause drastic changes in the molecular sieve structure, while a staged temperature increase treatment can alleviate the damage to the molecular sieve skeleton caused by thermal stress and maintain the integrity of the pores and specific surface area.

[0056] Enhanced adaptability: Segmented processing helps molecular sieves with different silicon-aluminum ratios better adapt to high temperature conditions and improve their structural stability.

[0057] 4. Improve subsequent activity and selectivity

[0058] Improved uniformity: Segmented treatment can make the degree of dealumination inside and outside the molecular sieve more uniform, thereby improving the uniformity of the catalytic active centers.

[0059] Optimization for specific applications: Temperature and time regulation of the three-stage treatment can optimize the activity and selectivity of the zeolite according to the target reaction (such as cracking, isomerization, hydrogenation, etc.).

[0060] In some embodiments, the first heating rate is 10-12 K / min, the second heating rate is 12-14 K / min, and the third heating rate is 15-18 K / min. The three-stage high-temperature hydrothermal treatment, through gradual heating and dealumination, can effectively improve the physicochemical properties of the HY molecular sieve while maximally preserving its structural integrity and acidic characteristics, providing better performance for Ru chemical adsorption.

[0061] In some embodiments, the first temperature is 900-910K, which initially removes non-framework aluminum. Non-framework aluminum typically exists in unstable forms, such as surface-adsorbed aluminum oxide or aluminum hydroxyl clusters, located in the molecular sieve pores or on the outer surface, and is weakly bound. At low temperatures of 900-910K, water vapor primarily attacks these loosely bound non-framework aluminum, removing it through hydrolysis or dissolution. At this stage, the framework structure is not significantly destroyed, so the framework aluminum is retained. This initial removal of non-framework aluminum can reduce impurities and enhance pore stability, laying the foundation for subsequent processing.

[0062] The second temperature is 950-960K. The dealumination at this stage is mainly aimed at the aluminum at the weak acid sites or structural defects in the framework. As the temperature rises, at a medium temperature of 950-960K, the hydrothermal conditions intensify, the Al-O-Si bonds in the molecular sieve framework begin to break, and part of the framework aluminum is separated from the framework and converted into non-framework aluminum (such as hydroxyaluminum), thereby further removing part of the framework aluminum. At this time, the removed aluminum may include two parts: one is the original residual non-framework aluminum, and the other is the aluminum newly detached from the framework, which can generate more medium-strength acid sites while maintaining the stability of the molecular sieve framework structure.

[0063] The third temperature is 1050-1060K, which can selectively remove framework aluminum and non-framework aluminum. Specifically, it includes: at a high temperature of 1050-1060K, water vapor attacks the framework more violently, causing more framework aluminum to detach, thereby achieving deep removal of framework aluminum. This process is achieved by deep hydrolysis of Al-O-Si bonds, which can significantly reduce the aluminum content of the molecular sieve; at the same time, high temperature may accelerate the migration or dissolution of non-framework aluminum, further reducing its residual amount and achieving simultaneous removal of non-framework aluminum. In other words, at this high temperature of 1050-1060K, framework aluminum can be efficiently removed, and non-framework aluminum may be selectively removed by extending the treatment time or adjusting the water vapor partial pressure, thereby further enhancing the dealumination effect, optimizing the framework structure and strong acid site distribution of the molecular sieve, and improving its high-temperature stability and adsorption performance.

[0064] During the three-stage high-temperature hydrothermal treatment process, the key factors affecting the selectivity mechanism of aluminum include: 1) the influence of the temperature gradient. The dynamic effect of the temperature gradient is that low temperatures preferentially remove non-framework aluminum, while medium and high temperatures gradually attack framework aluminum. 2) The influence of treatment conditions. The aluminum removal path is adjusted by parameters such as water vapor concentration, treatment time, and pressure. For example, short-term high temperature may mainly remove framework aluminum, while long-term treatment may also reduce non-framework aluminum. 3) The structural reorganization effect. After dealumination, the zeolite may undergo local structural reorganization (such as defect repair or partial recrystallization), affecting the selectivity of subsequent dealumination.

[0065] In some embodiments, the first flow rate is 34-36 cm 3 / min, the second flow rate is 44~46cm 3 / min, the third flow rate is 54~56cm 3 / min.

[0066] In this embodiment, the first flow rate is preferably 35 cm 3 / min, the holding time is 1 hour; the second flow rate is preferably 45cm 3 / min, the holding time is 1 hour; the third flow rate is preferably 55cm 3 / min, and the holding time is 1 hour. The relative crystallinity of the pretreated HY molecular sieve can be increased to 109%, but subsequent high-temperature hydrothermal treatment cannot further improve the crystallinity.

[0067] In some embodiments, the HY molecular sieve has a three-dimensional pore structure, a silicon-aluminum ratio of 10 to 12, that is, SiO2 / Al2O3=10 to 12, and a specific surface area of 600 to 630 m 2 / g, pore volume is 0.4~0.6cm 3 / g, pore size 0.32~0.41nm.

[0068] In this embodiment, the HY molecular sieve is a zeolite molecular sieve having a Faujasite type crystal structure, which can be prepared by conventional hydrothermal synthesis, which will not be described in detail here. The HY molecular sieve has a strong acidic active center, a silicon-aluminum ratio of 10, and a specific surface area of 600 m 2 / g, the average pore size is 0.32nm, and the unit cell constant of the molecular sieve is

[0069] In some embodiments, the volume ratio of air to water vapor in the first mixed gas is 1:(0.9-1.1), which helps to initially remove non-framework aluminum and enhance pore stability; the volume ratio of air to water vapor in the second mixed gas is 1:(1.4-1.6) to further remove part of the framework aluminum and generate more medium-strength acid sites; the volume ratio of air to water vapor in the third mixed gas is 1:(1.9-2.1) to selectively remove framework aluminum and further enhance the dealumination effect.

[0070] In this embodiment, the volume ratio of air to water vapor in the first mixed gas is preferably 1:1; the volume ratio of air to water vapor in the second mixed gas is preferably 1:1.5; and the volume ratio of air to water vapor in the third mixed gas is preferably 1:2.

[0071] In some embodiments, the mixing ratio of the pretreated molecular sieve and the hydrochloric acid solution is 15-18 g:120 mL. Too high or too low a mixing ratio of the hydrochloric acid solution to the pretreated molecular sieve will affect the treatment effect and reduce the structural stability of the pretreated molecular sieve.

[0072] In some embodiments, the reaction temperature of the pretreated molecular sieve and the hydrochloric acid solution is 70-75° C. and the reaction time is 5-6 hours, which can enhance the stability of the molecular sieve framework structure.

[0073] In some embodiments, the concentration of the hydrochloric acid solution is 5 to 6 mol / L. Experiments have found that the concentration of hydrochloric acid treatment affects the dealumination of the Y molecular sieve (i.e., the pretreated molecular sieve). Treatment with a hydrochloric acid concentration of 5 to 6 mol / L can increase the adsorption capacity of the molecular sieve. However, treatment with excessively high hydrochloric acid concentrations, although the silicon-to-aluminum ratio, mesopore specific surface area, and mesopore volume increase, reduces the micropore specific surface area, which in turn affects the adsorption performance.

[0074] In some embodiments, filtering, washing, and drying are specifically as follows: first filtering with a filter, then washing with water until neutral, and then drying at 120° C. for 40 minutes.

[0075] This embodiment also discloses an adsorbent, which is prepared using the above-mentioned preparation method.

[0076] The preparation method of the adsorbent in this embodiment is based on HY molecular sieve. By adopting three-stage high-temperature hydrothermal treatment and hydrochloric acid solution treatment, a high-adsorption capacity USY molecular sieve adsorbent with regular pores and supercage structure can be prepared. The pore size and supercage structure diameter are consistent with the van der Waals size of RuO4 clusters (diameter is about ) is highly matched, has strong selective adsorption performance for RuO4, can effectively capture RuO4 molecules to prevent their escape, and at the same time provide them with stable adsorption sites, greatly improving the adsorbent's treatment and purification effect on Ru in spent fuel reprocessing exhaust gas.

[0077] Moreover, in the pores and supercage structure of the adsorbent, RuO4 clusters interact with the inner surface of the molecular sieve through van der Waals forces (including dispersion forces and induction forces). This interaction enables RuO4 to be stably adsorbed in the USY molecular sieve with high adsorption capacity. There are a certain amount of acidic centers (such as acid sites and Lewis acid sites), which can further enhance the adsorption performance through hydrogen bonds or electrostatic interactions with RuO4 molecules, thereby improving the adsorption efficiency and adsorption amount of RuO4 molecules.

[0078] At the same time, the adsorbent has extremely high specific surface area and pore volume, which provides a large number of effective adsorption sites for the dispersion and multi-point adsorption of RuO4 molecules, thereby improving the adsorption capacity.

[0079] Example 2

[0080] This embodiment discloses a Ru purification method for purifying Ru in spent fuel post-processing tail gas, the method comprising:

[0081] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described above is loaded into a chemical adsorption tower, and the spent fuel post-processing tail gas is introduced into the chemical adsorption tower, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0082] In some embodiments, the tail gas flow rate is 55-58 m 3 / h. Too high or too low is not good. The specific flow rate selection is related to the airspeed, which will not be elaborated here.

[0083] In some embodiments, the temperature for the reaction between the adsorbent and RuO4 in the tail gas is 110-112° C. High temperature is beneficial for chemical adsorption, but too high a temperature results in high energy consumption, and further increasing the temperature has little effect on adsorption.

[0084] The Ru purification method of this embodiment uses the USY molecular sieve adsorbent with a high adsorption capacity specially prepared by the preparation method described in Example 1. In the process of treating the spent fuel post-processing tail gas, it can exert a significant adsorption effect, effectively purify the Ru in the spent fuel post-processing tail gas, and achieve excellent treatment results.

[0085] Example 3

[0086] This embodiment discloses an adsorbent and a preparation method thereof, the preparation method comprising the steps of:

[0087] Step S1, subjecting HY molecular sieve with SiO2 / Al2O3=10 to a three-stage high-temperature hydrothermal treatment to obtain a pretreated molecular sieve.

[0088] Specifically, first, the HY molecular sieve was placed in a fixed bed reactor, and the temperature was controlled by a tube furnace program. The HY molecular sieve was heated to 900K at a heating rate of 10K / min and then heated to 35cm 3 A first mixed gas of air and water vapor in a volume ratio of 1:1 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a first-stage treated HY molecular sieve;

[0089] Then, a section of HY molecular sieve was placed in a fixed bed reactor, and the temperature was controlled by a tube furnace program. The temperature of the treated HY molecular sieve was raised to 950K at a heating rate of 13K / min and heated at 45cm 3 A second mixed gas of air and water vapor in a volume ratio of 1:1.5 was continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a second-stage treated HY molecular sieve;

[0090] Three-stage high-temperature hydrothermal treatment: The second-stage HY molecular sieve is placed in a fixed-bed reactor, and the temperature is controlled by a tube furnace program. The second-stage treated HY molecular sieve is heated to 1050K at a heating rate of 16K / min and heated at 55cm 3 A third mixed gas of air and water vapor in a volume ratio of 1:2 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a pretreated molecular sieve.

[0091] Step S2, reacting the pretreated molecular sieve with 6 mol / L hydrochloric acid solution in a mixing ratio of 18 g: 120 mL, the reaction temperature is 75 ° C, the time is 5 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0092] This embodiment discloses a Ru purification method, which includes the following steps:

[0093] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 2 was loaded into the chemical adsorption tower and heated at 55m 3 The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 110°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0094] Example 4

[0095] This embodiment discloses an adsorbent and a preparation method thereof. Compared with Example 3, the preparation method differs in that the method includes a three-stage high-temperature hydrothermal treatment process, as follows:

[0096] First, the HY molecular sieve was placed in a fixed bed reactor and the temperature was controlled by a tube furnace program. The HY molecular sieve was heated to 905K at a heating rate of 10K / min and heated to 35cm 3 A first mixed gas of air and water vapor in a volume ratio of 1:1 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a first-stage treated HY molecular sieve;

[0097] Then, a section of HY molecular sieve was placed in a fixed bed reactor, and the temperature was controlled by a tube furnace program. The temperature of the treated HY molecular sieve was raised to 955K at a heating rate of 13K / min and heated at 45cm 3 A second mixed gas of air and water vapor in a volume ratio of 1:1.5 was continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a second-stage treated HY molecular sieve;

[0098] Three-stage high-temperature hydrothermal treatment: The second-stage HY molecular sieve is placed in a fixed-bed reactor, and the temperature is controlled by a tube furnace program. The second-stage treated HY molecular sieve is heated to 1055K at a heating rate of 16K / min and heated at 55cm 3 A third mixed gas of air and water vapor in a volume ratio of 1:2 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a pretreated molecular sieve.

[0099] Step S2, reacting the pretreated molecular sieve with 6 mol / L hydrochloric acid solution in a mixing ratio of 18 g: 120 mL, the reaction temperature is 75 ° C, the time is 5 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0100] This embodiment discloses a Ru purification method, which includes the following steps:

[0101] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 3 above was loaded into the chemical adsorption tower and heated at 55m 3The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 110°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0102] Example 5

[0103] This embodiment discloses an adsorbent and a preparation method thereof. Compared with Example 3, the preparation method differs in step S2, which is as follows:

[0104] Step S2, reacting the pretreated molecular sieve with 5 mol / L hydrochloric acid solution in a mixing ratio of 16 g: 120 mL, the reaction temperature is 72 ° C, the time is 5 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0105] This embodiment discloses a Ru purification method, which includes the following steps:

[0106] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 4 above was loaded into the chemical adsorption tower and heated at 55m 3 The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 110°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0107] Example 6

[0108] This embodiment discloses an adsorbent and a preparation method thereof. Compared with Example 3, the preparation method differs in step S2, which is as follows:

[0109] Step S2, reacting the pretreated molecular sieve with 5.5 mol / L hydrochloric acid solution in a mixing ratio of 17 g: 120 mL, the reaction temperature is 70 ° C, the time is 5 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0110] This embodiment discloses a Ru purification method, which includes the following steps:

[0111] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 5 above was loaded into the chemical adsorption tower and heated at 55m 3 The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 110°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0112] Example 7

[0113] This embodiment discloses an adsorbent and a preparation method thereof. Compared with Example 3, the preparation method differs in that the method includes a three-stage high-temperature hydrothermal treatment process, as follows:

[0114] First, the HY molecular sieve was placed in a fixed bed reactor and the temperature was controlled by a tube furnace program. The HY molecular sieve was heated to 908K at a heating rate of 10K / min and heated to 34cm 3 A first mixed gas of air and water vapor in a volume ratio of 1:0.9 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a first-stage treated HY molecular sieve;

[0115] Then, a section of HY molecular sieve was placed in a fixed bed reactor, and the temperature was controlled by a tube furnace program. The temperature of the treated HY molecular sieve was raised to 950K at a heating rate of 12K / min and heated at 44cm 3 A second mixed gas of air and water vapor in a volume ratio of 1:1.4 was continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a second-stage treated HY molecular sieve;

[0116] Three-stage high-temperature hydrothermal treatment: The second-stage HY molecular sieve is placed in a fixed-bed reactor, and the temperature is controlled by a tube furnace program. The second-stage treated HY molecular sieve is heated to 1050K at a heating rate of 15K / min and heated at 54cm 3 A third mixed gas having a volume ratio of air to water vapor of 1:1.9 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a pretreated molecular sieve.

[0117] Step S2, reacting the pretreated molecular sieve with 5.5 mol / L hydrochloric acid solution in a mixing ratio of 15 g: 120 mL, the reaction temperature is 73 ° C, the time is 5.5 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0118] This embodiment discloses a Ru purification method, which includes the following steps:

[0119] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 3 above was loaded into the chemical adsorption tower and heated at 56 m 3 The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 111°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0120] Example 8

[0121] This embodiment discloses an adsorbent and a preparation method thereof. Compared with Example 3, the preparation method differs in that the method includes a three-stage high-temperature hydrothermal treatment process, as follows:

[0122] First, the HY molecular sieve was placed in a fixed bed reactor and the temperature was controlled by a tube furnace program. The HY molecular sieve was heated to 910K at a heating rate of 12K / min and heated to 36cm 3 A first mixed gas of air and water vapor in a volume ratio of 1:1.1 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a first-stage treated HY molecular sieve;

[0123] Then, a section of HY molecular sieve was placed in a fixed bed reactor, and the temperature was controlled by a tube furnace program. The temperature of the treated HY molecular sieve was raised to 960K at a heating rate of 14K / min and heated at 46cm 3 A second mixed gas of air and water vapor in a volume ratio of 1:1.6 was continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a second-stage treated HY molecular sieve;

[0124] Three-stage high-temperature hydrothermal treatment: The second-stage HY molecular sieve is placed in a fixed-bed reactor, and the temperature is controlled by a tube furnace program. The second-stage treated HY molecular sieve is heated to 1060K at a heating rate of 18K / min and heated at 56cm 3 A third mixed gas having a volume ratio of air to water vapor of 1:2.1 is continuously introduced at a flow rate of / min, kept warm for 1 hour, and then taken out to obtain a pretreated molecular sieve.

[0125] Step S2, reacting the pretreated molecular sieve with 5.5 mol / L hydrochloric acid solution in a mixing ratio of 15 g: 120 mL, the reaction temperature is 74 ° C, the time is 6 hours, and then filtered, washed with water to neutrality, and then dried at 120 ° C for 40 minutes to obtain a USY molecular sieve adsorbent with high adsorption capacity.

[0126] This embodiment discloses a Ru purification method, which includes the following steps:

[0127] The high adsorption capacity USY molecular sieve adsorbent prepared by the preparation method described in Example 3 above was loaded into the chemical adsorption tower and heated at 58 m 3 The spent fuel post-processing tail gas is introduced into the chemical adsorption tower at a flow rate of 1000 t / h. The temperature in the chemical adsorption tower is controlled at 112°C, so that the adsorbent adsorbs RuO4 in the tail gas and reacts, thereby achieving Ru purification.

[0128] Comparative Example 1

[0129] This comparative example is basically the same as Example 3, except that the three-stage high-temperature hydrothermal treatment is replaced by a one-stage high-temperature hydrothermal treatment.

[0130] Comparative Example 2

[0131] This comparative example is basically the same as Example 3, except that the three-stage high-temperature hydrothermal treatment is replaced by one-stage high-temperature hydrothermal treatment and two-stage high-temperature hydrothermal treatment.

[0132] Comparative Example 3

[0133] This comparative example is basically the same as Example 3, except that the hydrochloric acid solution is replaced by deionized water.

[0134] test:

[0135] The pore structure characteristics such as specific surface area and pore volume of the adsorbent samples of Examples 3 to 8 and Comparative Examples 1 to 3 were analyzed by N2 adsorption-desorption experiments. The equipment used in the experiment was a Micromeritics ASAP2460 automatic physical adsorption instrument. Before the test, the samples were degassed in a nitrogen atmosphere at 573K for 5 hours. The adsorption isotherm was measured at 77K using high-purity nitrogen as the adsorbent. The specific surface area (SBET) of the samples was calculated by the Brunauer-Emmett-Teller (BET) method, and the micropore volume was calculated by the t-plot method.

[0136] In addition, a blank control group was set up: HY molecular sieve. The results are shown in Tables 1 and 2.

[0137] Table 1

[0138]

[0139]

[0140] As can be seen from Table 1, the adsorbents prepared in Examples 3 to 8 have a higher specific surface area. That is, the preparation method of the adsorbent in the present invention can greatly increase the specific surface area of the molecular sieve by treating the HY molecular sieve. The increase in specific surface area can provide more channels and pores, making it easier for molecules to diffuse into the interior of the molecular sieve, thereby accelerating the adsorption rate and improving the adsorption efficiency.

[0141] Table 2

[0142] <![CDATA[Micropore volume m 3 / g]]> Example 3 0.389 Example 4 0.381 Example 5 0.386 Example 6 0.380 Example 7 0.383 Example 8 0.382 Comparative Example 1 0.326 Comparative Example 2 0.337 Comparative Example 3 0.342 Blank control group 0.308

[0143] It can be seen from Table 2 that the adsorbents prepared in Examples 3 to 8 have a higher micropore volume. The higher micropore volume can further increase the adsorption capacity of RuO4, that is, the method of the present invention can increase the adsorption capacity of RuO4.

[0144] The following is the adsorption test of RuO4:

[0145] Simulate the tail gas containing RuO4 from a post-processing facility as the test object (non-radioactive Ru was used for the experiment, the RuO4 content was 0.124 vol%, and the flow rate was 55m3 / h, temperature is 110 ° C), the adsorbents prepared in Examples 3 to 8 and Comparative Examples 1 to 3 are respectively used to purify RuO4 in the above-mentioned tail gas according to the Ru purification method described in Example 3, wherein the initial mass of the adsorbent in each group is 50 g, and the adsorption treatment time is 1 hour.

[0146] In addition, a blank control group was set up: HY molecular sieve.

[0147] After testing, the adsorption amount of RuO4 by each group of adsorbents was compared, and the results are shown in Table 3.

[0148] Table 3

[0149] <![CDATA[Adsorption amount of RuO4, mL / g]]> Example 3 1.24 Example 4 1.19 Example 5 1.17 Example 6 1.21 Example 7 1.20 Example 8 1.22 Comparative Example 1 0.92 Comparative Example 2 1.13 Comparative Example 3 0.77 Blank control group 0.37

[0150] As can be seen from Table 3, the adsorbents prepared in Examples 3 to 8 have a significantly greater adsorption capacity for RuO4. In other words, the method of the present invention can greatly improve the adsorption of Ru in the spent fuel post-processing tail gas, and the purification effect is significant.

[0151] In addition, based on the preparation method of the adsorbent described in Example 3, the effects of different hydrochloric acid solution concentrations on the adsorption performance of the molecular sieve were compared, and the results are shown in Table 4.

[0152] Table 4

[0153] Hydrochloric acid solution concentration mol / L <![CDATA[Adsorption amount of RuO4, mL / g]]> 0 0.77 1 0.83 2 0.88 3 0.93 4 0.97 5 1.19 6 1.24 7 1.13 8 1.11

[0154] It can be seen from Table 4 that when the concentration of hydrochloric acid solution is 6 mol / L, the adsorption capacity of the adsorbent is the highest. Further increasing the hydrochloric acid concentration, although the silicon-aluminum ratio, mesopore specific surface area and mesopore volume increase, the micropore specific surface area decreases, which in turn affects the adsorption performance.

[0155] Based on the preparation method of the adsorbent described in Example 3, the effects of different hydrochloric acid solution treatment times on the adsorption performance of the adsorbent were compared. The results are shown in Table 5. Figure 1 shown.

[0156] Table 5

[0157]

[0158]

[0159] From Table 5, Figure 1 It can be seen that with the extension of the hydrochloric acid solution treatment time, the adsorption performance of the adsorbent first increases and then gradually decreases, which indicates that further increasing the treatment time, although the silicon-aluminum ratio, mesopore specific surface area and mesopore volume increase, the micropore specific surface area decreases, which affects the adsorption performance.

[0160] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing an adsorbent, characterized in that: include: The HY molecular sieve is subjected to a three-stage high-temperature hydrothermal treatment to obtain a pretreated molecular sieve; The pretreated molecular sieve is reacted with a hydrochloric acid solution, and then filtered, washed, and dried to obtain an adsorbent.

2. The method for preparing an adsorbent according to claim 1, wherein: The three-stage high-temperature hydrothermal treatment comprises: Heating the HY molecular sieve to a first temperature at a first heating rate, and continuously introducing a first mixed gas comprising air and water vapor at a first flow rate, and maintaining the temperature for a period of time to obtain a treated HY molecular sieve; Heating the first-stage treated HY molecular sieve to a second temperature at a second heating rate, and continuously introducing a second mixed gas comprising air and water vapor at a second flow rate, and maintaining the temperature for a period of time to obtain a second-stage treated HY molecular sieve, wherein the second temperature is greater than the first temperature, and the second flow rate is greater than the first flow rate; The second-stage treated HY molecular sieve is heated to a third temperature at a third heating rate, and a third mixed gas including air and water vapor is continuously introduced at a third flow rate, and kept warm for a period of time to obtain a pretreated molecular sieve, wherein the third temperature is greater than the second temperature, and the third flow rate is greater than the second flow rate.

3. The method for preparing an adsorbent according to claim 2, wherein: The first heating rate is 10-12 K / min, the second heating rate is 12-14 K / min, and the third heating rate is 15-18 K / min.

4. The method for preparing an adsorbent according to claim 2, wherein: The first temperature is 900-910K, the second temperature is 950-960K, and the third temperature is 1050-1060K.

5. The method for preparing an adsorbent according to claim 2, wherein: The first flow rate is 34 to 36 cm 3 / min, the second flow rate is 44 to 46 cm 3 / min, and the third flow rate is 54 to 56 cm 3 / min.

6. The method for preparing an adsorbent according to claim 2, wherein: The HY molecular sieve is a zeolite molecular sieve with a Faujasite-type crystal structure, and its silicon-aluminum ratio is 10-12.

7. The method for preparing an adsorbent according to claim 2, wherein: The volume ratio of air to water vapor in the first mixed gas is 1:(0.9~1.1), the volume ratio of air to water vapor in the second mixed gas is 1:(1.4~1.6), and the volume ratio of air to water vapor in the third mixed gas is 1:(1.9~2.1).

8. The method for preparing an adsorbent according to any one of claims 1 to 7, characterized in that: The mixing ratio of the pretreated molecular sieve and the hydrochloric acid solution is 15-18 g:120 mL.

9. The method for preparing an adsorbent according to any one of claims 1 to 7, characterized in that: The reaction temperature of the pretreated molecular sieve and the hydrochloric acid solution is 70-75° C., and the reaction time is 5-6 hours.

10. The method for preparing an adsorbent according to any one of claims 1 to 7, characterized in that: The concentration of the hydrochloric acid solution is 5-6 mol / L.

11. An adsorbent, characterized in that The preparation method is described in any one of claims 1 to 10.

12. A Ru purification method, characterized in that: include: The adsorbent prepared by the preparation method according to any one of claims 1 to 10 is loaded into a chemical adsorption tower, and the spent fuel post-processing tail gas is introduced into the chemical adsorption tower to allow the adsorbent to adsorb RuO4 in the tail gas and react.

13. The Ru purification method according to claim 12, characterized in that: The flow rate of the tail gas is 55-58 m3 / h.

14. The Ru purification method according to claim 12, characterized in that: The reaction temperature is 110-112°C.

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