A copper-manganese composite oxide natural gas demercuration adsorbent, and a preparation method and application thereof

Abstract

The present application belongs to the technical field of preparation of mercury-removal adsorbent, and provides a copper-manganese composite oxide natural gas mercury-removal adsorbent, a preparation method and application thereof. The preparation method comprises the following steps: mixing a copper salt, a manganese salt, water and a complexing agent solution to obtain a mixed solution; mixing the mixed solution and a potassium permanganate solution, and then performing a hydrothermal reaction to obtain a reaction product; sequentially performing centrifugation, suction filtration and washing, and drying on the reaction product to obtain a solid precipitate; placing the solid precipitate in an acid solution to perform etching; and sequentially performing suction filtration and washing, drying, and calcination on the etched solid precipitate to obtain the copper-manganese composite oxide natural gas mercury-removal adsorbent. The preparation method is simple, low in cost, short in production cycle and high in efficiency, and the prepared copper-manganese composite oxide natural gas mercury-removal adsorbent can be used for deep purification and mercury removal of mercury-containing natural gas through a fixed bed adsorption mode, so that efficient removal of mercury under a complex natural gas wet gas atmosphere can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of mercury removal adsorbents, and particularly relates to a copper-manganese composite oxide natural gas mercury removal adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Gaseous elemental mercury (Hg 0 ) is a global harmful pollutant, due to its high volatility, toxicity, bioaccumulation and global migration, which leads to Hg 0 difficult to be inhibited, thus causing great harm to human health and ecological system. It is well known that coal-fired flue gas is one of the main sources of mercury emission, and a large number of related technologies such as adsorption and catalytic oxidation have been widely used to improve the removal efficiency of Hg 0 in coal-fired flue gas. However, due to the lack of emission restrictions on natural gas combustion flue gas, the removal of mercury in natural gas is usually ignored. Natural gas is mainly C1-C4 hydrocarbon gas containing a small amount of H2S, CO2, H2O and mercury and other impurities, and the mercury in natural gas mainly comes from gas source rock. Because mercury and oil and gas have similar activity and reservoir conditions, and organic matter has good mercury accumulation properties, mercury is accumulated in natural gas reservoirs in the form of volatile matter along with natural gas. In recent years, the demand for natural gas as a residential and transportation fuel has increased significantly. Since the greenhouse gas generated after natural gas combustion is only half of that of coal and two-thirds of that of oil, the role of natural gas in reducing greenhouse gas emissions and promoting renewable energy integration is undoubtedly crucial. Due to the high annual production of natural gas, it is necessary to remove mercury in natural gas before combustion to reduce mercury emissions. In addition, in the natural gas gathering and processing system, mercury is easy to form amalgam with aluminum in low-temperature heat exchangers, thereby corroding the equipment and causing explosion accidents due to perforation. With the progress of mining technology and the depletion of shallow oil and gas fields, oil and gas exploitation of deeper reservoirs and high-temperature reservoirs will be the only way for the oil industry, which greatly increases the content of mercury and other impurities in oil and gas. Therefore, efficient removal of Hg 0 in natural gas is an important problem in the natural gas chemical industry.

[0003] Current natural gas mercury removal processes include low-temperature separation, solution absorption, anion resin, membrane separation and chemical adsorption. Low-temperature separation process is applied to the dehydration and dealkylation process of natural gas. Glycol (hydrate inhibitor) is injected into the raw gas before entering the heat exchanger. After J-T valve throttling refrigeration, gas-liquid separation is carried out in the low-temperature separator, and then mercury is enriched in glycol. Such a way has poor mercury removal effect, difficult equipment cleaning, huge energy consumption, and mercury entering the condensate and water, which will cause secondary pollution. Solution absorption technology is to use potassium permanganate, nitric acid and other oxidizing agents to oxidize mercury into mercury ions and then absorb them into the solution. This method has small adsorption capacity, low economic efficiency, and high corrosion of absorption liquid, which is easy to cause secondary pollution to the environment. Anion resin mercury removal is to use anion exchange resin with granular or spherical shape to combine with natural gas to remove mercury. This technology is not mature and has low treatment capacity. Membrane separation technology is to use the principle of semi-permeable membrane to remove mercury from natural gas. The operation conditions are relatively strict, liquid substances cannot exist during the operation process, and the treatment capacity is limited. Chemical adsorption method is to remove mercury by fixed bed adsorbent. Due to high economic efficiency, excellent mercury removal effect and environmental friendliness, this is the mainstream way of natural gas mercury removal at home and abroad.

[0004] According to the different positions of mercury removal units, mercury removal processes can be divided into dry gas mercury removal and wet gas mercury removal. Dry gas mercury removal is to place the mercury removal adsorption tower after the dehydration and deacidification unit, and to carry out dehydration and deacidification purification process before mercury removal. Wet gas mercury removal is to place the mercury removal adsorption tower before the dehydration and deacidification device, and to directly remove mercury from the raw gas. Compared with dry gas mercury removal, wet gas mercury removal can effectively remove mercury from the source and prevent secondary pollution, but it has high requirements for the performance of adsorbent. Since wet gas mercury removal does not go through dehydration and deacidification, the atmosphere contains a certain amount of H2S, CO2 and H2O. At present, some effective adsorbents such as modified activated carbon, noble metal carrier materials, metal sulfides and immobilized ionic liquids have been used for the removal of Hg 0 from natural gas. However, due to the leaching of sulfur, the capillary condensation of carbon in the wet gas stream, the high price of noble metal materials and the low resistance to H2O and acid gas, these adsorbents are mostly suitable for dry gas atmosphere, and there is little research on natural gas mercury removal in wet gas atmosphere.

[0005] The operating conditions of mercury removal in natural gas purification process are different from those of flue gas mercury removal. For example, natural gas mercury removal is usually carried out at room temperature, which is much lower than flue gas mercury removal, which requires the adsorbent to have low-temperature activity. The natural gas wet gas mercury removal process is in a reducing atmosphere, unlike the flue gas atmosphere which has oxygen to supplement the consumed active oxygen species, which requires the natural gas mercury removal adsorbent to have high oxygen storage capacity. Due to high adsorption capacity, strong metal ion affinity and ability to remove trace concentration of metals, metal oxides (such as FeO x , MnO x and CuOx ) have been widely studied. Among them, manganese oxides are abundant in reserves, low in price, and environmentally friendly, and have been widely used in catalytic oxidation, pollution control and other fields due to their adjustable valence state and high oxygen abundance. Copper-based adsorbents have also been widely studied and applied in mercury removal processes. In a hydrogen sulfide atmosphere, it promotes the formation of active sulfur sites (S*) on the surface of the adsorbent, which reacts with H 0 to generate stable HgS.

[0006] At present, the existing technology discloses the following copper-based or manganese-based adsorbents. For example, a Chinese patent application with publication number CN 117342615 A discloses a hydrothermally oriented doped MnCux composite oxide and its preparation method and application. It uses potassium permanganate, copper nitrate and citric acid as precursors to prepare a copper-manganese composite oxide, which has high VOCs elimination activity. However, the complexation of citric acid and manganese salt is not sufficient during the preparation process, and the reducing citric acid and the strongly oxidizing potassium permanganate will directly react with each other. A Chinese patent with publication number CN 110124663 A discloses a catalyst for catalytic oxidation of VOCs and its preparation method and application. It prepares a manganese-based composite metal oxide through a hydrothermal reaction, which shows good VOCs catalytic activity. However, citric acid only plays the role of a reducing agent in this process and cannot effectively complex. A Chinese patent with publication number CN 106179395 A discloses a high-performance CO oxidation and NO x elimination storage material preparation method, which uses a hydrothermal reaction to prepare a Cu-Mn oxide. However, adding copper nitrate after adding potassium permanganate will weaken the complexation of copper ions and citric acid, which is not conducive to the dispersion of copper. Therefore, how to provide a simple, efficient and excellent performance natural gas mercury removal adsorbent preparation method has become a problem that needs to be solved by those skilled in the art. SUMMARY

[0007] Therefore, the present application provides a copper-manganese composite oxide natural gas mercury removal adsorbent and its preparation method and application, which aims to solve the technical problem of low adsorption activity of existing natural gas mercury removal adsorbents in wet gas mercury removal.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] The present application provides a preparation method of a copper-manganese composite oxide natural gas mercury removal adsorbent, comprising the following steps:

[0010] S1, mixing a copper salt, a manganese salt, water and a complexing agent solution to obtain a mixed solution;

[0011] S2, mixing the mixed solution and a potassium permanganate solution and then performing a hydrothermal reaction to obtain a reaction product;

[0012] S3, sequentially centrifuging, suction-filtering, washing and drying the reaction product to obtain a solid precipitate;

[0013] S4, etching the solid precipitate in an acid solution;

[0014] S5, sequentially suction-filtering, washing, drying and calcining the etched solid precipitate to obtain the copper-manganese composite oxide natural gas mercury removal adsorbent.

[0015] Further, in the step S1, the amount ratio of the copper salt, the manganese salt, the water and the complexing agent solution is 0.1-1 g:1-10 g:10-50 mL:10-20 mL.

[0016] The mixing temperature is 60-80°C, and the mixing time is 3-10 h. The mixing is performed by stirring at a stirring speed of 400-600 rpm.

[0017] Further, in the step S1, the copper salt includes one or more of copper nitrate, copper sulfate, copper chloride and copper carbonate.

[0018] The manganese salt includes one or more of manganese nitrate, manganese sulfate and manganese chloride.

[0019] The complexing agent solution includes a complexing agent and ethanol, and the mass-volume ratio of the complexing agent and ethanol is 0.1-1 g:10-20 mL. The complexing agent includes citric acid and / or ascorbic acid.

[0020] Further, in the step S2, the hydrothermal reaction temperature is 90-120°C, and the hydrothermal reaction time is 10-48 h.

[0021] Further, in the step S2, the mixing temperature is 60-80°C, and the mixing time is 1-5 h. The mixing is performed by stirring at a stirring speed of 600-800 rpm.

[0022] The concentration of the potassium permanganate solution is 0.05-0.2 g / mL, and the volume ratio of the potassium permanganate solution and the complexing agent solution is 1-5:1-2.

[0023] Further, in the step S3, the drying temperature is 90-100°C, and the drying time is 10-18 h.

[0024] Further, in the step S4, the concentration of the acid solution is 0.5-2 mol / L, and the acid solution includes a sulfuric acid solution, a nitric acid solution or an acetic acid solution. The etching time is 20-50 min.

[0025] Further, in the step S5, the drying temperature is 100-120°C, and the drying time is 5-20 h.

[0026] The calcination temperature is 400–500℃, and the calcination time is 1–5 hours.

[0027] This invention provides a copper-manganese composite oxide natural gas mercury removal adsorbent prepared by the above preparation method.

[0028] The present invention also provides the application of the above-mentioned copper-manganese composite oxide natural gas mercury removal adsorbent in natural gas mercury removal under a humid atmosphere.

[0029] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention first fully complexes divalent copper salt, divalent manganese salt, and a complexing agent under high-speed stirring, then adds potassium permanganate to initiate the reaction. Based on the preparation of copper-manganese oxides through a redox reaction, this method maximizes the chelation and dispersion of copper and manganese ions, promoting the generation of oxygen vacancies. Although the amount of divalent copper salt added in this invention is relatively low, the complexing agent enables efficient dispersion of copper, effectively creating active oxygen sites and reducing preparation costs. Simultaneously, the acid etching post-treatment introduces more defect sites, which is highly beneficial for mercury removal in a reducing, humid natural gas atmosphere. Furthermore, this preparation method features a short production cycle and high efficiency. The prepared copper-manganese composite oxide natural gas mercury removal adsorbent can be used for deep purification and mercury removal from mercury-containing natural gas via fixed-bed adsorption, thereby achieving efficient mercury removal in complex humid natural gas atmospheres. Attached Figure Description

[0031] Figure 1 SEM image of the adsorbent prepared in Example 1;

[0032] Figure 2 SEM image of the adsorbent prepared in Example 2;

[0033] Figure 3 SEM image of the adsorbent prepared in Example 3;

[0034] Figure 4 SEM image of the adsorbent prepared in Example 4;

[0035] Figure 5 SEM image of the adsorbent prepared in Example 5;

[0036] Figure 6 SEM image of the adsorbent prepared in Comparative Example 1;

[0037] Figure 7 SEM image of the adsorbent prepared in Comparative Example 2;

[0038] Figure 8 SEM image of the adsorbent prepared in Comparative Example 3;

[0039] Figure 9 SEM image of the adsorbent prepared in Comparative Example 4;

[0040] Figure 10 The image shows the SEM image of the adsorbent prepared in Comparative Example 5. Detailed Implementation

[0041] This invention provides a method for preparing a copper-manganese composite oxide natural gas mercury removal adsorbent, comprising the following steps:

[0042] S1. Mix copper salt, manganese salt, water and complexing agent solution to obtain a mixed solution;

[0043] S2. Mix the mixed solution and potassium permanganate solution and then carry out a hydrothermal reaction to obtain the reaction product;

[0044] S3. The reaction products are centrifuged, filtered, washed and dried sequentially to obtain a solid precipitate.

[0045] S4. Etch the solid precipitate in an acid solution.

[0046] S5. The etched solid precipitate is sequentially filtered, washed, dried, and calcined to obtain the copper-manganese composite oxide natural gas mercury removal adsorbent.

[0047] In this invention, in step S1, the ratio of copper salt, manganese salt, water, and complexing agent solution is 0.1-1g:1-10g:10-50mL:10-20mL, preferably 0.2-0.8g:2-8g:15-45mL:12-18mL, and more preferably 0.4-0.6g:4-6g:20-30mL:14-16mL;

[0048] The mixing temperature is 60-80℃, preferably 65-75℃, and more preferably 70℃; the mixing time is 3-10h, preferably 4-8h, and more preferably 5-6h; the mixing is carried out by stirring, and the stirring speed is 400-600rpm, preferably 450-550rpm, and more preferably 500rpm.

[0049] In this invention, in step S1, the copper salt includes one or more of copper nitrate, copper sulfate, copper chloride and copper carbonate, preferably one or more of copper nitrate, copper sulfate and copper chloride, and more preferably copper nitrate and / or copper sulfate.

[0050] Manganese salts include one or more of manganese nitrate, manganese sulfate and manganese chloride, preferably manganese nitrate and / or manganese sulfate, and more preferably manganese sulfate;

[0051] The complexing agent solution comprises a complexing agent and ethanol, and the mass-volume ratio of the complexing agent and ethanol is 0.1-1 g:10-20 mL, preferably 0.2-0.8 g:12-18 mL, and further preferably 0.4-0.6 g:14-16 mL; and the complexing agent comprises citric acid and / or ascorbic acid, and preferably is citric acid.

[0052] In the present application, in the step S2, the hydrothermal reaction is performed at a temperature of 90-120°C, preferably 95-115°C, and further preferably 100-110°C, and for a time of 10-48 h, preferably 20-40 h, and further preferably 30 h.

[0053] In the present application, in the step S2, the mixing is performed at a temperature of 60-80°C, preferably 65-75°C, and further preferably 70°C, and for a time of 1-5 h, preferably 2-4 h, and further preferably 3 h; the mixing is performed by stirring at a rotation speed of 600-800 rpm, preferably 650-750 rpm, and further preferably 700 rpm.

[0054] The concentration of the potassium permanganate solution is 0.05-0.2 g / mL, preferably 0.1-0.16 g / mL, and further preferably 0.12-0.15 g / mL; and the volume ratio of the potassium permanganate solution and the complexing agent solution is 1-5:1-2, preferably 2-4:1.2-1.8, and further preferably 3:1.4-1.6.

[0055] In the present application, in the step S3, the drying is performed at a temperature of 90-100°C, preferably 92-98°C, and further preferably 94-96°C, and for a time of 10-18 h, preferably 12-16 h, and further preferably 14-15 h.

[0056] In the present application, in the step S4, the acid solution has a concentration of 0.5-2 mol / L, preferably 0.8-1.6 mol / L, and further preferably 1.0-1.4 mol / L; the acid solution comprises a sulfuric acid solution, a nitric acid solution or an acetic acid solution, preferably a sulfuric acid solution or a nitric acid solution, and further preferably a sulfuric acid solution; and the etching is performed for a time of 20-50 min, preferably 25-40 min, and further preferably 30-35 min.

[0057] In the present application, in the step S4, the solid precipitate is ground before the etching.

[0058] In the present application, in the step S5, the drying is performed at a temperature of 100-120°C, preferably 105-115°C, and further preferably 110°C, and for a time of 5-20 h, preferably 8-16 h, and further preferably 10-15 h.

[0059] The calcination temperature is 400-500℃, preferably 420-480℃, and more preferably 440-460℃; and the calcination time is 1-5h, preferably 2-4h, and more preferably 3h.

[0060] The application provides a copper-manganese composite oxide natural gas mercury removal adsorbent prepared by the preparation method.

[0061] The application also provides application of the copper-manganese composite oxide natural gas mercury removal adsorbent in natural gas mercury removal in a moisture atmosphere.

[0062] The technical solutions provided by the application will be described in detail below in combination with examples, but they should not be understood as limitations to the protection scope of the application.

[0063] Example 1

[0064] In a beaker, 20mL of deionized water was added, and then 0.5364g of copper nitrate and 4.4389g of manganese sulfate were sequentially added to the beaker and stirred at 500r / min at 60℃; 0.8957g of citric acid was added to 20mL of anhydrous ethanol to obtain a citric acid solution, and the citric acid solution was added to the above solution and stirred at 600r / min at 60℃ for 5h to obtain a mixed solution. 2.9224g of potassium permanganate was dissolved in 30mL of deionized water and stirred to obtain a potassium permanganate solution.

[0065] The potassium permanganate solution was added dropwise to the mixed solution, and the mixture was stirred at 700r / min at 70℃ for 3h, then transferred to a tetrafluoro lining, sealed and placed in a stainless steel reaction kettle, and subjected to hydrothermal reaction in a 100℃ oven for 24h.

[0066] The reaction product after hydrothermal reaction was centrifuged, filtered and washed, and then heated in a 110℃ oven for 10h to remove excess water to obtain a solid precipitate. The solid precipitate was ground to 200 mesh and etched in 20mL of 1mol / L nitric acid solution for 30min.

[0067] The sample after acid etching was filtered and washed, and then heated in a 110℃ oven for 10h, and then the dried sample was placed in a tube furnace and calcined at 450℃ for 2h to obtain a copper-manganese composite oxide natural gas mercury removal adsorbent.

[0068] Figure 1 is a SEM image of the adsorbent prepared in this example, and Figure 1 It can be seen that the morphology of the adsorbent is nanorod-shaped with a length of several hundred nanometers.

[0069] Example 2

[0070] In a beaker, 20 mL of deionized water was added, and 0.5364 g of copper nitrate, 4.4389 g of manganese sulfate were sequentially added to the beaker, and fully stirred at 60°C and 500 r / min; 0.8211 g of ascorbic acid was added to 10 mL of anhydrous ethanol to fully dissolve to obtain an ascorbic acid solution, and the ascorbic acid solution was added to the above solution, and stirred at 80°C and 600 r / min for 5 h to obtain a mixed solution. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and fully stirred to obtain a potassium permanganate solution.

[0071] The potassium permanganate solution was added dropwise to the mixed solution, fully stirred at 70°C and 700 r / min for 2 h, then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to hydrothermal reaction in a 100°C oven for 30 h.

[0072] The reaction product after hydrothermal reaction was centrifuged, filtered and washed, heated in a 100°C oven for 12 h to remove excess water to obtain a solid precipitate. The solid precipitate was ground to 200 mesh or less, and etched in 10 mL of 0.5 mol / L sulfuric acid solution for 25 min.

[0073] The sample precipitate after acid etching was filtered and washed, and dried in a 110°C oven for 10 h. The dried sample was then placed in a tube furnace and calcined at 450°C for 2 h to obtain a copper-manganese composite oxide natural gas demercuration adsorbent.

[0074] Figure 2 The SEM image of the adsorbent prepared in this example is shown in FIG. 1. Figure 2 As can be seen, the morphology of the adsorbent exhibits nanorod-like structures with a length of several hundred nanometers.

[0075] Example 3

[0076] In a beaker, 20 mL of deionized water was added, and 0.5364 g of copper nitrate, 4.4389 g of manganese sulfate were sequentially added to the beaker, and fully stirred at 60°C and 500 r / min; 0.8957 g of citric acid was added to 10 mL of anhydrous ethanol to fully dissolve to obtain a citric acid solution, and the citric acid solution was added to the above solution, and stirred at 70°C and 500 r / min for 5 h to obtain a mixed solution. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and fully stirred to obtain a potassium permanganate solution.

[0077] The potassium permanganate solution was added dropwise to the mixed solution, fully stirred at 70°C and 700 r / min for 3 h, then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to hydrothermal reaction in a 110°C oven for 18 h.

[0078] The reaction product after hydrothermal reaction was centrifuged, washed by suction filtration, heated in a 110°C oven for 18h, and the excess water was removed to obtain a solid precipitate. The solid precipitate was ground to 200 mesh, and etched in 20mL of 1.5mol / L acetic acid solution for 35min.

[0079] The sample precipitate after acid etching was washed by suction filtration, heated in a 110°C oven for 10h, and then the dried sample was placed in a tube furnace and calcined at 450°C for 2h to obtain a copper-manganese composite oxide natural gas mercury removal adsorbent.

[0080] Figure 3 is the SEM image of the adsorbent prepared in this example, and Figure 3 It can be obtained that the morphology of the adsorbent is in the aggregated state of nanorods and nanoparticles.

[0081] Example 4

[0082] In a beaker, 20mL of deionized water was added, and 0.5364g of copper nitrate, 4.4389g of manganese sulfate were sequentially added to the beaker, and stirred at 60°C at a speed of 500r / min; 0.8211g of ascorbic acid was added to 20mL of anhydrous ethanol, and dissolved to obtain an ascorbic acid solution, and the ascorbic acid solution was added to the above solution, and stirred at 80°C at a speed of 400r / min for 5h to obtain a mixed solution. 2.9224g of potassium permanganate was dissolved in 30mL of deionized water, and stirred to obtain a potassium permanganate solution.

[0083] The potassium permanganate solution was added dropwise to the mixed solution, and stirred at 70°C at a speed of 700r / min for 2h, and then transferred to a tetrafluoro lining, sealed and placed in a stainless steel reaction kettle, and subjected to hydrothermal reaction in a 100°C oven for 24h.

[0084] The reaction product after hydrothermal reaction was centrifuged, washed by suction filtration, heated in a 90°C oven for 16h, and the excess water was removed to obtain a solid precipitate. The solid precipitate was ground to 200 mesh, and etched in 20mL of 1mol / L acetic acid solution for 30min.

[0085] The sample precipitate after acid etching was washed by suction filtration, heated in a 110°C oven for 10h, and then the dried sample was placed in a tube furnace and calcined at 450°C for 3h to obtain a copper-manganese composite oxide natural gas mercury removal adsorbent.

[0086] Figure 4 is the SEM image of the adsorbent prepared in this example, and Figure 4 It can be obtained that the morphology of the adsorbent is in the aggregated state of nanorods and nanoparticles.

[0087] Example 5

[0088] In a beaker, 20 mL of deionized water was added, and 0.5543 g of copper nitrate, 4.6526 g of manganese nitrate were sequentially added to the beaker, and fully stirred at 60°C and a speed of 500 r / min; 0.8211 g of ascorbic acid was added to 10 mL of anhydrous ethanol to fully dissolve to obtain an ascorbic acid solution, and the ascorbic acid solution was added to the above solution, and stirred at 80°C and a speed of 600 r / min for 5 h to obtain a mixed solution. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and fully stirred to obtain a potassium permanganate solution.

[0089] The potassium permanganate solution was added dropwise to the mixed solution, fully stirred at 70°C and a speed of 700 r / min for 3 h, then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to a hydrothermal reaction in a 100°C oven for 30 h.

[0090] The reaction product after the hydrothermal reaction was centrifuged, filtered and washed, heated in a 100°C oven for 12 h to remove excess water to obtain a solid precipitate. The solid precipitate was ground to 200 mesh, and etched in 10 mL of an acetic acid solution with a concentration of 1.5 mol / L for 35 min.

[0091] The sample precipitate after acid etching was filtered and washed, heated in a 110°C oven for 10 h, and then the dried sample was placed in a tube furnace and calcined at 450°C for 3 h to obtain a copper-manganese composite oxide natural gas mercury removal adsorbent.

[0092] Figure 5 is an SEM image of the adsorbent prepared in this example, and Figure 5 It can be seen that the morphology of the adsorbent is nanorod-shaped with a length of several hundred nanometers.

[0093] Comparative Example 1

[0094] In this comparative example, no complexing agent was used and no acid etching was performed, and the specific steps were as follows:

[0095] In a beaker, 20 mL of deionized water was added, and 0.5543 g of copper nitrate, 4.6526 g of manganese nitrate were sequentially added to the beaker, and fully stirred at 60°C and a speed of 500 r / min; 0.8211 g of ascorbic acid was added to 10 mL of anhydrous ethanol to fully dissolve to obtain an ascorbic acid solution, and the ascorbic acid solution was added to the above solution, and stirred at 80°C and a speed of 600 r / min for 5 h to obtain a mixed solution. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and fully stirred to obtain a potassium permanganate solution.

[0096] The potassium permanganate solution was added dropwise to the mixed solution, fully stirred at 70°C and a speed of 700 r / min for 3 h, then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to a hydrothermal reaction in a 100°C oven for 24 h.

[0097] The reaction product after hydrothermal reaction was centrifuged, suction filtered and washed, heated in a 110°C oven for 12h, and the excess water was removed to obtain a solid precipitate, which was the adsorbent.

[0098] Figure 6 The SEM image of the adsorbent prepared in this comparative example is shown in FIG. 2, from which it can be seen that the morphology of the adsorbent is nanorod-like. Figure 6

[0099] Comparative Example 2

[0100] The same as Example 1, except that benzoic acid was used instead of citric acid.

[0101] Figure 7 The SEM image of the adsorbent prepared in this comparative example is shown in FIG. 4, from which it can be seen that the morphology of the adsorbent is shorter nanorod. Figure 7

[0102] Comparative Example 3

[0103] In this comparative example, no acid etching was performed, and the specific steps were as follows:

[0104] In a beaker, 20 mL of deionized water was added, and 0.5364 g of copper nitrate, 4.4389 g of manganese sulfate were sequentially added to the beaker, and stirred at 500 r / min at 60°C; 0.8211 g of ascorbic acid was added to 10 mL of anhydrous ethanol, and dissolved to obtain an ascorbic acid solution, which was added to the above solution, and stirred at 500 r / min at 70°C for 5h to obtain a mixed solution. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and stirred to obtain a potassium permanganate solution.

[0105] The potassium permanganate solution was added dropwise to the mixed solution, and stirred at 700 r / min at 70°C for 3h, then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to hydrothermal reaction in a 90°C oven for 24h.

[0106] The reaction product after hydrothermal reaction was centrifuged, suction filtered and washed, heated in a 110°C oven for 18h, and the excess water was removed to obtain a solid precipitate, which was the adsorbent.

[0107] Figure 8 The SEM image of the adsorbent prepared in this comparative example is shown in FIG. 6, from which it can be seen that the morphology of the adsorbent is elongated and dense nanorod. Figure 8

[0108] Comparative Example 4

[0109] In this comparative example, no complexing agent was used, and the specific steps were as follows:

[0110] ​​​In a beaker, 20 mL of deionized water was added, and 0.5364 g of copper nitrate, 4.4389 g of manganese sulfate were sequentially added to the beaker, and a mixed solution was obtained by stirring at 500 r / min at 60°C. 2.9224 g of potassium permanganate was dissolved in 30 mL of deionized water, and a potassium permanganate solution was obtained by stirring.

[0111] The potassium permanganate solution was added dropwise to the mixed solution, and the solution was stirred at 700 r / min at 70°C for 3 h, and then transferred to a tetrafluoro lining, sealed in a stainless steel reaction kettle, and subjected to a hydrothermal reaction in a 100°C oven for 24 h.

[0112] The reaction product after the hydrothermal reaction was centrifuged, filtered and washed, and heated in a 90°C oven for 16 h to remove excess water to obtain a solid precipitate. The solid precipitate was ground to 200 mesh or less, and etched in 20 mL of a 1.5 mol / L nitric acid solution for 30 min.

[0113] The sample precipitate after acid etching was filtered and washed, and heated in a 110°C oven for 10 h, and then the dried sample was placed in a tube furnace and calcined at 450°C for 2 h to obtain the adsorbent.

[0114] Figure 9 The SEM image of the adsorbent prepared in this comparative example is shown in FIG. 1, and it can be seen that the morphology of the adsorbent is a short nanorod. Figure 9

[0115] Comparative Example 5

[0116] The same as Example 2, except that 1 mol / L sodium hydroxide solution was used instead of 0.5 mol / L sulfuric acid solution.

[0117] Figure 10 The SEM image of the adsorbent prepared in this comparative example is shown in FIG. 1, and it can be seen that the morphology of the adsorbent is a short nanorod. Figure 10

[0118] Performance Test

[0119] The adsorbent was granulated, and 0.17 mL of adsorbent particles between 40 and 60 mesh were placed in a fixed bed quartz tube for mercury removal from simulated natural gas. CH4 was introduced into the fixed bed as Hg 0 ​​The carrier gas was introduced into the reactor, and 15% CO2, 5% H2O, 200 ppm H2S, and N2 as the balance gas were introduced into the reactor, and the total gas flow rate was 1000 mL / min. The evaluation time was 2 h. The effects of various adsorbents are shown in Table 1. As shown in Table 1, the adsorbent prepared in the present application has extremely high mercury removal efficiency under a complex reducing natural gas atmosphere, which is greatly improved compared with the comparative examples. Under a reducing atmosphere, the adsorbent is difficult to obtain oxygen from the environment to oxidize elemental mercury into divalent mercury, and only relies on the active oxygen of the adsorbent itself. The adsorbent provided in the present application has abundant active oxygen sites, and the lattice oxygen and surface active oxygen of the adsorbent itself have extremely high conversion efficiency under the support of abundant oxygen vacancy defects, and therefore exhibit good mercury removal efficiency.

[0120] The mercury removal efficiency is calculated in the following manner:

[0121]

[0122] wherein, is the inlet mercury content (μg·m -3 ); is the outlet mercury content (μg·m -3 ); and η is the mercury removal efficiency.

[0123] Table 1: Mercury removal efficiency of adsorbents

[0124] Sample Import mercury content (pg m -3 ) <![CDATA[Mercury content at the outlet (μg·m -3 )]]> Mercury removal efficiency (%) Example 1 100.5 0.1 99.9 Example 2 100.4 0.4 99.6 Example 3 99.8 0.8 99.2 Example 4 99.7 0.7 99.3 Example 5 100.1 0.7 99.3 Comparative Example 1 99.7 4.8 95.1 Comparative Example 2 99.6 5.3 94.7 Comparative Example 3 100.1 3.5 96.5 Comparative Example 4 99.9 3.3 96.7 Comparative Example 5 100.2 3.1 96.9

[0125] Pilot test

[0126] The adsorbent of Example 1 was subjected to a pilot test in a certain natural gas purification plant, the inlet natural gas temperature was about 35℃, and the Hg 0 removal efficiency was tested by using a VM 3000 mercury tester. The results are shown in Table 2.

[0127] Table 2: Pilot test results of Example 1

[0128] Test Units Inlet Outlet 2h value Removal rate (%) Hg 0 ]]> pg.mL -3 ]] ～100 0.1 99.9

[0129] As shown in Table 2, under actual working conditions, the Hg 0 removal rate can be maintained at 99.9%. Therefore, the adsorbent prepared in the present application has excellent Hg 0 oxidation activity under the condition of coexistence of water and sulfur at room temperature.

[0130] The above description is only preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. The application of a copper-manganese composite oxide natural gas mercury removal adsorbent in natural gas mercury removal under a humid atmosphere, characterized in that, The preparation method of copper-manganese composite oxide natural gas mercury removal adsorbent includes the following steps: S1. Mix copper salt, manganese salt, water and complexing agent solution to obtain a mixed solution; S2. Mix the mixed solution and potassium permanganate solution and then carry out a hydrothermal reaction to obtain the reaction product; S3. The reaction products are centrifuged, filtered, washed and dried sequentially to obtain a solid precipitate. S4. Etch the solid precipitate in an acid solution. S5. The etched solid precipitate is sequentially filtered, washed, dried, and calcined to obtain the copper-manganese composite oxide natural gas mercury removal adsorbent.

2. The application according to claim 1, characterized in that, In step S1, the ratio of copper salt, manganese salt, water and complexing agent solution is 0.1-1g: 1-10g: 10-50mL: 10-20mL; The mixing temperature is 60-80℃, the mixing time is 3-10 hours, and the mixing is carried out by stirring at a speed of 400-600 rpm.

3. The application according to claim 2, characterized in that, In step S1, the copper salt includes one or more of copper nitrate, copper sulfate, copper chloride, and copper carbonate. Manganese salts include one or more of manganese nitrate, manganese sulfate, and manganese chloride; The complexing agent solution comprises a complexing agent and ethanol, with a mass-to-volume ratio of 0.1–1 g to 10–20 mL; the complexing agent comprises citric acid and / or ascorbic acid.

4. The application according to any one of claims 1 to 3, characterized in that, In step S2, the hydrothermal reaction temperature is 90–120°C, and the hydrothermal reaction time is 10–48 h.

5. The application according to claim 4, characterized in that, In step S2, the mixing temperature is 60-80℃, the mixing time is 1-5 hours, the mixing is carried out by stirring, and the stirring speed is 600-800 rpm. The concentration of potassium permanganate solution is 0.05–0.2 g / mL, and the volume ratio of potassium permanganate solution to complexing agent solution is 1–5:1–2.

6. The application according to claim 1, 2, 3 or 5, characterized in that, In step S3, the drying temperature is 90-100℃ and the drying time is 10-18h.

7. The application according to claim 6, characterized in that, In step S4, the concentration of the acid solution is 0.5–2 mol / L, and the acid solution includes sulfuric acid solution, nitric acid solution, or acetic acid solution; the etching time is 20–50 min.

8. The application according to claim 1, 2, 3, 5 or 7, characterized in that, In step S5, the drying temperature is 100-120℃ and the drying time is 5-20h. The calcination temperature is 400–500℃, and the calcination time is 1–5 hours.

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