A catalyst cloth bag loaded with graphene modified copper-manganese composite catalyst and a preparation method and application thereof

Abstract

The application belongs to the field of environmental catalysis, and particularly relates to a catalyst cloth bag of a graphene-modified copper-manganese composite catalyst, a preparation method and application thereof. The graphene-modified copper-manganese composite catalyst is prepared by adding potassium permanganate and a divalent manganese salt into a graphene oxide suspension, stirring uniformly for the first time, adding citric acid and a divalent copper salt, stirring uniformly for the second time, and then placing the mixed solution in a condition of 130-150 DEG C for hydrothermal treatment for 10-14 hours. The graphene-modified copper-manganese composite catalyst is loaded on the catalyst cloth bag and applied to low-temperature catalytic oxidation of CO in an industrial environment. The catalyst cloth bag of the graphene-modified copper-manganese composite catalyst reaches a conversion rate of more than 90% at 90 DEG C in a dry state, and reaches a conversion rate of more than 90% at 100 DEG C in a wet state (RH=70%), which indicates that the catalyst cloth bag of the graphene-modified copper-manganese composite catalyst can maintain high-efficiency catalysis of CO at a low temperature and good moisture resistance.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalysis, specifically relating to a catalyst bag for a graphene-modified copper-manganese composite catalyst, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] CO has become one of the six major standard air pollutants, causing significant damage to the natural environment and human health. Many aspects of daily life and industrial production require CO removal, and one of the most effective ways to remove CO is to use catalysts to oxidize CO into CO2. Currently, catalysts are widely used in areas such as automotive exhaust treatment, industrial flue gas treatment, and fuel cells (PEMFC).

[0004] In recent years, numerous scholars have demonstrated that noble metal (Au, Pt, Pd)-based catalysts possess high catalytic activity. However, their high cost and susceptibility to poisoning and deactivation limit their long-term application. Copper-manganese composite catalysts, a type of non-noble metal catalyst, offer advantages over currently commercially available noble metal-based catalysts, including lower cost, better stability, stronger resistance to poisoning, and easier regeneration.

[0005] Therefore, copper-manganese composite catalysts can serve as a good alternative to precious metal catalysts for the catalytic oxidation of CO. However, copper-manganese composite catalysts still suffer from low CO oxidation efficiency at low temperatures and poor moisture resistance.

[0006] To improve the catalytic effect of catalysts, scientists have supported powdered or particulate catalysts on various carrier surfaces, such as carbon black, silica gel, refractory bricks, diatomaceous earth, molecular sieves, cordierite, ceramics, and filter bags. However, traditional loading methods, such as coating and hydrothermal growth, suffer from problems such as easy catalyst detachment, uneven loading, or difficulty in loading. Therefore, achieving efficient loading of copper-manganese composite catalysts for the catalytic oxidation of CO is an urgent problem to be solved. Summary of the Invention

[0007] To overcome the above problems, this invention provides a catalyst bag with a graphene-modified copper-manganese composite catalyst, its preparation method, and its application. The graphene-modified copper-manganese composite catalyst provided by this invention can achieve efficient CO oxidation at low temperatures and maintain good catalytic performance even in high humidity environments. By utilizing ball milling and tumbling-vibration assisted impregnation technology to load the graphene-modified copper-manganese composite catalyst onto the surface and interior of a polyester filter bag fiber, the problems of easy catalyst detachment, uneven loading, or difficulty in loading existing in traditional loading methods are solved. Simultaneously, the catalyst bag with the graphene-modified copper-manganese composite catalyst can still maintain efficient catalytic oxidation of CO at low temperatures and good moisture resistance.

[0008] In a first aspect, the present invention provides a method for preparing a graphene-modified copper-manganese composite catalyst, the method comprising:

[0009] Potassium permanganate and divalent manganese salt were added to the graphene oxide suspension. After the first stirring was thorough, citric acid and divalent copper salt were added. After the second stirring was thorough, the mixed solution was placed at 130-150℃ and hydrothermally treated for 10-14 hours. The solution was obtained after the reaction was completed.

[0010] In a second aspect, the present invention provides a graphene-modified copper-manganese composite catalyst prepared by the above-described preparation method.

[0011] A third aspect of the present invention provides a method for preparing a catalyst bag for a graphene-modified copper-manganese composite catalyst, the method comprising:

[0012] S1. Place the cloth bag in anhydrous ethanol solution for ultrasonic treatment, and then dry it; immerse the dried cloth bag in NaOH solution for a period of time; wash and dry the immersed cloth bag to obtain the pretreated cloth bag.

[0013] S2. The graphene-modified copper-manganese composite catalyst was ground using a planetary ball mill. After grinding, deionized water was added to prepare a graphene-modified copper-manganese composite catalyst suspension.

[0014] S3. Place the pretreated filter bag from S1 and the graphene-modified copper-manganese composite catalyst suspension from S2 into a rotary shaker and shake at a speed of 40-50 r / min for 18-22 h. After shaking, wash and dry to obtain the catalyst filter bag of the graphene-modified copper-manganese composite catalyst.

[0015] In a fourth aspect, the present invention provides a catalyst bag for a graphene-modified copper-manganese composite catalyst prepared by the above-described preparation method.

[0016] In a fifth aspect of the invention, a catalyst bag containing either the graphene-modified copper-manganese composite catalyst of the second aspect or the supported graphene-modified copper-manganese composite catalyst of the fourth aspect is provided for low-temperature catalytic oxidation of CO in an industrial environment.

[0017] A sixth aspect of the present invention provides a catalyst bag for the graphene-modified copper-manganese composite catalyst of the second aspect or the supported graphene-modified copper-manganese composite catalyst of the fourth aspect, applied to the synergistic catalytic oxidation of CO and toluene in an industrial environment.

[0018] The beneficial effects of this invention are:

[0019] (1) The graphene-modified copper-manganese composite catalyst provided by this invention can achieve efficient catalytic oxidation of CO under low-temperature conditions and maintain good catalytic performance under high humidity conditions. This is mainly due to: the strong conductivity of graphene promotes the interaction and electron transfer between copper oxide and manganese oxide, thereby generating more oxygen vacancies; secondly, the large specific surface area of ​​graphene is beneficial to improving the microstructure of the copper-manganese composite catalyst and the uniform dispersion of the metal active components, thus generating more adsorption sites on the surface of the composite catalyst. In addition, during the hydrothermal process, the oxygen-containing group bonds of the graphene oxide molecules break due to heat, which reduces the hydrophilicity of the composite catalyst, thus exhibiting good moisture resistance.

[0020] (2) This invention uses commercially available polyester dust collector bags as catalyst bags. Polyester dust collector bags have high strength, wear resistance, and poor moisture absorption. Furthermore, the continuous operating temperature of commercially available polyester materials is approximately 120°C, and the instantaneous operating temperature is 150°C, which meets the temperature requirements for flue gas emissions. However, because polyester is a hydrophobic material, loading the catalyst onto the polyester fabric is quite difficult. This invention uses a planetary ball mill to process the powdered copper-manganese composite catalyst to achieve a nanoscale particle size. The smaller particle size of the copper-manganese composite catalyst, under the action of a rotating vibrator, is more easily adsorbed by the polyester dust collector bags. The capillary pressure generated by the surface tension of the polyester dust collector bags allows the graphene-modified copper-manganese composite catalyst to penetrate into the capillary. Therefore, the copper-manganese composite catalyst is more firmly loaded onto the polyester dust collector bags, solving the problems of easy catalyst detachment, uneven loading, or difficulty in loading that exist in traditional loading methods.

[0021] (3) The catalyst bag with graphene-modified copper-manganese composite catalyst achieved a conversion rate of over 90% at 90℃ under dry conditions and over 90% at 100℃ under wet conditions (RH = 70%). This indicates that the catalyst bag with graphene-modified copper-manganese composite catalyst can maintain high efficiency of CO catalysis and good moisture resistance under low temperature conditions. Attached Figure Description

[0022] Figure 1 The images shown are scanning electron microscope (SEM) images of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 of this invention and the copper-manganese composite catalyst prepared in Comparative Example 1, wherein a is an SEM image of the copper-manganese composite catalyst prepared in Comparative Example 1, b is an SEM image of the graphene-modified copper-manganese composite catalyst prepared in Example 1, c is an SEM image of the graphene-modified copper-manganese composite catalyst prepared in Example 2, d is an SEM image of the graphene-modified copper-manganese composite catalyst prepared in Example 3, e is an SEM image of the graphene-modified copper-manganese composite catalyst prepared in Example 4, and f is an SEM image of the graphene-modified copper-manganese composite catalyst prepared in Example 5.

[0023] Figure 2 The results show the catalytic CO oxidation performance of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 and the copper-manganese composite catalyst prepared in Comparative Example 1 under dry conditions.

[0024] Figure 3 The results show the catalytic CO oxidation performance of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 and the copper-manganese composite catalyst prepared in Comparative Example 1 under wet conditions (RH=70%).

[0025] Figure 4 The graph shows the lifetime test results of the graphene-modified copper-manganese composite catalyst prepared in Example 4 and the copper-manganese composite catalyst prepared in Comparative Example 1 under dry conditions.

[0026] Figure 5 The graph shows the lifetime test results of the graphene-modified copper-manganese composite catalyst prepared in Example 4 and the copper-manganese composite catalyst prepared in Comparative Example 1 under wet conditions (RH = 70%).

[0027] Figure 6 These are scanning electron microscope images of the ball milling process before and after in Example 6, where a is before ball milling and b is after ball milling.

[0028] Figure 7 XRD patterns of commercially available filter bags (without catalyst support) and the catalyst filter bags of the graphene-modified copper-manganese composite catalyst prepared in this example.

[0029] Figure 8 Scanning electron microscope image of a filter bag for a copper-manganese composite catalyst without graphene loading;

[0030] Figure 9 Scanning electron microscope image of a copper-manganese composite catalyst with graphene support and modification.

[0031] Figure 10 Distribution of C, O, Mn and Cu elements on polyester dust collector bag fibers in a catalyst bag for supporting graphene-modified copper-manganese composite catalyst.

[0032] Figure 11 Scanning electron microscope (SEM) image of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared by the traditional hydrothermal method.

[0033] Figure 12 The image shows the catalytic CO oxidation performance of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry and wet (RH = 70%) conditions.

[0034] Figure 13 The image shows the lifetime test results of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry conditions.

[0035] Figure 14 The image shows the lifetime test results of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 under wet conditions (RH = 70%).

[0036] Figure 15 The image shows the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 undergoing five cycles of catalytic testing in a dry environment.

[0037] Figure 16 The graph shows the test results of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry conditions, with the air flow rate as a function of the catalyst.

[0038] Figure 17 This is a schematic diagram showing the results of using the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 for the synergistic treatment of CO and toluene. Detailed Implementation

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] A first typical embodiment of the present invention provides a method for preparing a graphene-modified copper-manganese composite catalyst, the method comprising:

[0042] Potassium permanganate and divalent manganese salt were added to the graphene oxide suspension. After the first stirring was thorough, citric acid and divalent copper salt were added. After the second stirring was thorough, the mixed solution was placed at 130-150℃ and hydrothermally treated for 10-14 hours. The solution was obtained after the reaction was completed.

[0043] In one or more embodiments, the method for preparing the graphene oxide suspension utilizes the method for preparing the graphene oxide suspension in Chinese Patent CN202210877766.2, specifically including:

[0044] Negative electrode graphite obtained from the dismantling of fully discharged waste batteries was placed in a 2-4 mol / L NaOH solution and stirred; then, it was filtered, washed, and dried; the obtained graphite powder was placed in a quartz reactor for microwave shock, Ar was introduced under closed conditions, and the power and temperature of the solid-state microwave source were adjusted; after multiple microwave shock cycles, the graphite powder was treated with a modified Hummers method to obtain a graphene oxide suspension.

[0045] Furthermore, the solid-state microwave source has a power of 1000W and a maximum temperature of 1200℃; the impact mode involves cooling for 30 seconds after reaching the maximum temperature, and then continuing to heat up, for a total of 5 to 20 cycles; after each impact, the expanded graphite powder is removed and placed in a drying oven for later use.

[0046] Furthermore, for every 1g of decommissioned graphite, the required flow rate of Ar is 300-1000mL / min;

[0047] Further, the specific steps of the improved Hummers method are as follows: microwave-treated expanded graphite is mixed and stirred with concentrated sulfuric acid at a solid-liquid ratio of 1:(20-40), in g:mL; during stirring, H3PO4 is added dropwise to the solution, with a volume ratio of concentrated sulfuric acid to phosphoric acid of (6-8):1; then, solid KMnO4 is added to the mixture in ten portions, with an interval of 5-7 minutes between each addition, and a mass ratio of KMnO4 to expanded graphite of 6:1; subsequently, the mixture is stirred for 2 hours each in an ice bath and at 35°C; after stirring, an appropriate amount of deionized water is added, and the temperature is raised to 80°C and stirring is continued for 1 hour; finally, after stirring, H2O2 (mass fraction of solute is 30%) is added dropwise, with a required volume ratio of concentrated H2SO4 to H2O2 of (1-3):1; after washing with water 5-7 times, a graphene oxide suspension is obtained, with a suspension concentration of 1-3 mg / mL.

[0048] In one or more embodiments, the divalent manganese salt is one of MnSO4·H2O, MnCl2·4H2O or Mn(CH3COO)2·4H2O, preferably MnSO4·H2O.

[0049] In one or more embodiments, the divalent manganese salt is one of Cu(NO3)2·3H2O, CuCl2·2H2O or Cu(CH3COO)2, preferably Cu(NO3)2·3H2O.

[0050] In one or more embodiments, the mass ratio of graphene oxide, potassium permanganate, divalent manganese salt, citric acid, and divalent copper salt is 1–5:132:53:18:28–140, preferably 1–5:132:53:18:28, 1–5:132:53:18:56, 1–5:132:53:18:84, 1–5:132:53:18:112, or 1–5:132:53:18:140, and more preferably 4:132:53:18:28.

[0051] In one or more embodiments, after the second stirring is uniform, the mixed solution is placed at 140°C for hydrothermal treatment for 12 hours.

[0052] A second typical embodiment of the present invention provides a graphene-modified copper-manganese composite catalyst prepared by the above preparation method.

[0053] A third typical embodiment of the present invention provides a method for preparing a catalyst bag for a graphene-modified copper-manganese composite catalyst, the method comprising:

[0054] S1. Place the cloth bag in anhydrous ethanol solution for ultrasonic treatment, and then dry it; immerse the dried cloth bag in NaOH solution for a period of time; wash and dry the immersed cloth bag to obtain the pretreated cloth bag.

[0055] S2. The graphene-modified copper-manganese composite catalyst was ground using a planetary ball mill. After grinding, deionized water was added to prepare a graphene-modified copper-manganese composite catalyst suspension.

[0056] S3. Place the pretreated filter bag from S1 and the graphene-modified copper-manganese composite catalyst suspension from S2 into a rotary shaker and shake at a speed of 40-50 r / min for 18-22 h. After shaking, wash and dry to obtain the catalyst filter bag of the graphene-modified copper-manganese composite catalyst.

[0057] In one or more embodiments, the filter bag is a polyester dust collector bag, the polyester material has a continuous operating temperature of 120°C and an instantaneous operating temperature of 150°C, and its temperature range meets the flue gas emission temperature requirements.

[0058] In one or more embodiments, the ultrasonic treatment power in step S1 is 150-240W, preferably 180W, and the drying conditions are 95-105℃, preferably 100℃.

[0059] In one or more embodiments, the concentration of the NaOH solution in step S1 is 1 to 20 g / L, preferably 15 g / L.

[0060] In one or more embodiments, in step S1, the dried cloth bag is immersed in NaOH solution and treated at 80°C to 100°C for 1 to 2 hours; preferably, it is treated at 90°C for 1 hour.

[0061] In one or more embodiments, in step S1, the washing conditions are water washing at room temperature, and the drying conditions are 95-105°C, preferably 100°C.

[0062] In one or more embodiments, in step S2, the grinding conditions are: a rotation speed of 300-400 r / min, grinding for 1.5-2.5 h; preferably 300 r / min, grinding for 2 h.

[0063] In one or more embodiments, in step S2, the concentration of the graphene-modified copper-manganese composite catalyst is 1 to 20 g / L, preferably 10 g / L.

[0064] In one or more embodiments, in step S3, the mass ratio of the graphene-modified copper-manganese composite catalyst to the pretreated filter bag is 1 to 4:10, preferably 3:11.

[0065] In one or more embodiments, in step S3, the oscillation is performed at a rotation speed of 45 r / min for 20 h.

[0066] In one or more embodiments, in step S3, the washing conditions are: rinsing the surface residual suspension 3 to 5 times with deionized water.

[0067] In one or more embodiments, in step S3, the drying conditions are 95–105°C, preferably 100°C.

[0068] A fourth typical embodiment of the present invention provides a catalyst bag for a copper-manganese composite catalyst supported on graphene prepared by the above preparation method.

[0069] The fifth typical embodiment of the present invention provides a catalyst bag for the low-temperature catalytic oxidation of CO in an industrial environment, which is either a graphene-modified copper-manganese composite catalyst as described in the second aspect or a supported graphene-modified copper-manganese composite catalyst as described in the fourth aspect.

[0070] In one or more embodiments, the temperature for the low-temperature catalytic oxidation of CO is 90–140°C.

[0071] In one or more embodiments, the concentration of CO in the industrial flue gas is 0 to 10,000 ppm, preferably 5,000 ppm, based on the total volume of the industrial flue gas.

[0072] Based on the total volume of industrial flue gas as 100%, the H2O content in the industrial flue gas is 0-5%, preferably 3 vol%.

[0073] The sixth and fourth typical embodiments of the present invention provide a catalyst bag for the graphene-modified copper-manganese composite catalyst of the second aspect or the supported graphene-modified copper-manganese composite catalyst of the fourth aspect, applied to the synergistic catalytic oxidation of CO and toluene in an industrial environment.

[0074] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0075] Example 1: Preparation of graphene-modified copper-manganese composite catalyst

[0076] Negative electrode graphite obtained from fully discharged waste batteries was placed in 2L of NaOH solution (2mol / L) and stirred for 1h to remove some DMF impurities. The graphite in the solution was then filtered, washed until the solution pH reached 7, and dried at 90℃ for 12h. Next, 0.5g of the alkali-treated graphite powder was weighed and placed in a quartz reactor. An infrared thermocouple was installed, and Ar was introduced (300mL / min) under sealed conditions. The solid-state microwave source power was then adjusted to 1000W, with a maximum temperature of 1200℃. The shock mode involved cooling for 30s after each temperature limit was reached, followed by further heating, for a total of 10 cycles. After each shock, the graphite sample was removed and placed in a drying oven for later use. A suitable amount of pretreated expanded graphite was placed in a beaker and treated using a modified Hummers method to obtain a graphene oxide suspension. The procedure is as follows: First, microwave-treated expanded graphite is placed in a beaker, and concentrated H2SO4 (98%) is added. The mixture is stirred continuously for 30 minutes in an ice bath, with a solid-liquid ratio of expanded graphite to concentrated sulfuric acid of 1:30 (g:mL). During stirring, H3PO4 is added dropwise to the solution, with a phosphoric acid to concentrated sulfuric acid volume ratio of 1:7.5. Then, solid KMnO4 is added to the mixture in ten portions, with a 6-minute interval between each addition, and a KMnO4 to expanded graphite mass ratio of 6:1. The mixture is then stirred for 2 hours in an ice bath and at 35°C. After stirring, an appropriate amount of deionized water is added, and the temperature is raised to 80°C with continued stirring for 1 hour. Finally, after stirring, H2O2 (30% solute by mass) is added dropwise, with a required concentrated H2SO4 to H2O2 volume ratio of 3:1. The mixture is then washed 5–7 times with water to obtain a graphene oxide suspension. The concentration of the graphene oxide suspension is set to 2 mg / mL for later use. Compared to commercially available flake graphite, waste anode graphite has a larger interlayer spacing. When waste graphite is subjected to microwave shock, the graphite expands due to heat. At the same time, residual electrolyte impurities decompose due to heat, and the generated gas further induces an increase in the interlayer spacing. Therefore, high-quality graphene oxide suspensions can be prepared using waste graphite as a carbon source.

[0077] Add 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O to 5 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring, add 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O. After the second stirring, place the mixed solution at 140 °C for hydrothermal treatment for 12 h. After the reaction is complete, the graphene-modified copper-manganese composite catalyst is obtained.

[0078] Example 2

[0079] The preparation method of the graphene oxide suspension is the same as that in Example 1.

[0080] 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O were added to 10 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring was thorough, 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O were added. After the second stirring was thorough, the mixed solution was placed at 140 °C and hydrothermally treated for 12 h. After the reaction was completed, the graphene-modified copper-manganese composite catalyst was obtained.

[0081] Example 3

[0082] The preparation method of the graphene oxide suspension is the same as that in Example 1.

[0083] 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O were added to 15 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring was thorough, 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O were added. After the second stirring was thorough, the mixed solution was placed at 140 °C and hydrothermally treated for 12 h. After the reaction was completed, the graphene-modified copper-manganese composite catalyst was obtained.

[0084] Example 4

[0085] The preparation method of the graphene oxide suspension is the same as that in Example 1.

[0086] 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O were added to 20 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring was thorough, 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O were added. After the second stirring was thorough, the mixed solution was placed at 140 °C and hydrothermally treated for 12 h. After the reaction was completed, the graphene-modified copper-manganese composite catalyst was obtained.

[0087] Example 5

[0088] The preparation method of the graphene oxide suspension is the same as that in Example 1.

[0089] 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O were added to 25 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring was thorough, 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O were added. After the second stirring was thorough, the mixed solution was placed at 140 °C and hydrothermally treated for 12 h. After the reaction was completed, the graphene-modified copper-manganese composite catalyst was obtained.

[0090] Comparative Example 1

[0091] Add 1.32g potassium permanganate and 0.53g MnSO4·H2O to 20mL of deionized water. After the first stirring, add 0.18g citric acid and 0.28g Cu(NO3)2·3H2O. After the second stirring, place the mixed solution at 140℃ for hydrothermal treatment for 12h. After the reaction is complete, the copper-manganese composite catalyst is obtained.

[0092] The scanning electron microscope (SEM) images of the copper-manganese composite catalyst prepared in Comparative Example 1 and the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 are as follows: Figure 1 a to f in the series, from Figure 1 As can be seen from a, the copper-manganese composite catalyst mainly comprises two structures: nanospheres and nanoneedles. With the addition of graphene ( Figure 1 In the middle (b-f), the nanoneedles on the surface of the copper-manganese composite catalyst gradually disappear. Graphene is coated on the catalyst surface (e.g., Figure 1 As the graphene content increases, the silver nanorods (marked in the middle) gradually become more uniformly distributed on the surface. However, in Example 5 (Figure f), the excessive amount of graphene resulted in a tendency for aggregation.

[0093] Experimental Example 1

[0094] The catalytic performance of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 and the copper-manganese composite catalyst prepared in Comparative Example 1 was studied for CO.

[0095] The specific test method is as follows: 0.2 g (40-60 mesh) of catalyst was placed in a quartz reactor (inner diameter 6 mm, outer diameter 10 mm), and the catalyst was fixed with quartz wool. 200 mL of synthetic air was mixed with 200 mL of CO gas (1 vol% CO + N2), and the resulting mixed gas (5000 ppm CO + 10 vol% O2 + N2 equilibrium gas, corresponding to a WHSV of 120,000 mL / (gh)) was introduced into the reactor, with the gas flow rate controlled by a mass flow meter. A tubular furnace with programmed temperature rise was used to control the catalytic bed temperature, with a heating range of 40–250 °C and a heating rate of 5 °C / min for each test. CO and CO2 concentrations were measured using a gas chromatograph (Beijing Ruili SP-3420A) equipped with an FID detector. Considering the high humidity in some practical applications, it is necessary to investigate the effect of humidity on catalytic oxidation performance. Therefore, a water vapor generator was added to the catalytic test system to control the relative humidity. Water vapor is generated using air as the carrier gas, with the vaporization temperature controlled between 110 and 120°C. Deionized water is injected into the vaporization pipeline using a micro-injection pump and mixed with CO gas before being introduced into the catalytic bed. The relative humidity of the reaction gas is controlled by adjusting the deionized water injection rate.

[0096] like Figure 2The results show the catalytic performance tests of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 and the copper-manganese composite catalyst prepared in Comparative Example 1 under dry conditions for CO oxidation. The results show that the copper-manganese composite catalyst prepared in Comparative Example 1 has poor catalytic activity, achieving 90% CO oxidation only at 210℃. However, in Examples 1-5, the catalytic activity of the graphene-modified copper-manganese composite catalysts gradually improved with the addition of graphene. Specifically, the graphene-modified copper-manganese composite catalyst prepared in Example 4 achieved a 92% CO conversion rate at 120℃. However, with further increases in graphene content, the catalytic performance of the graphene-modified copper-manganese composite catalyst prepared in Example 5 decreased.

[0097] like Figure 3 As shown, the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5 and the copper-manganese composite catalyst prepared in Comparative Example 1 exhibit the same catalytic performance under wet (RH = 70%) conditions as under dry conditions. The graphene-modified copper-manganese composite catalyst prepared in Example 4 still shows the best catalytic performance, achieving a conversion rate of 90% at 126℃. The comparison reveals that humidity did not significantly negatively impact the catalytic performance of the graphene-modified copper-manganese composite catalysts prepared in Examples 1-5, indicating that the catalysts possess good moisture resistance.

[0098] Figure 4 and Figure 5 The lifetime test results of the graphene-modified copper-manganese composite catalyst prepared in Example 4 and the copper-manganese composite catalyst prepared in Comparative Example 1 are shown under dry and wet (RH = 70%) conditions, respectively. Figure 4 The results showed that the catalytic performance of the graphene-modified copper-manganese composite catalyst prepared in Example 4 remained above 90% for 12 hours, indicating that it has excellent stability. Figure 5 The results show that, under wet conditions, although the catalytic performance of the graphene-modified copper-manganese composite catalyst prepared in Example 4 decreased within 12 hours, the catalyst performance could be restored after the water vapor in the reaction gas was removed. This indicates that the catalyst has good resistance to moisture and good stability.

[0099] Example 6

[0100] A catalyst bag for supporting the graphene-modified copper-manganese composite catalyst was prepared using the graphene-modified copper-manganese composite catalyst prepared in Example 4.

[0101] The methods include:

[0102] S1. Commercially available polyester dust collector bags are cut and sewn to obtain bags with a diameter of 34mm, a height of 110mm, and a weight of 11g. The bags are then subjected to ultrasonic treatment in anhydrous ethanol solution and subsequently dried. The ultrasonic treatment power is 180W, and the drying conditions are 100℃. The dried bags are then immersed in a 15g / L NaOH solution and treated at 90℃ for 1 hour. The immersed bags are then washed and dried to obtain pre-treated bags.

[0103] S2. The graphene-modified copper-manganese composite catalyst prepared in Example 4 was ground using a planetary ball mill. The grinding conditions were: 300 r / min for 2 h. After grinding, 300 mL of deionized water was added to prepare a suspension of graphene-modified copper-manganese composite catalyst.

[0104] S3. Place the pretreated filter bag from S1 and the graphene-modified copper-manganese composite catalyst suspension from S2 into a rotary shaker and shake at 45 r / min for 20 h. After shaking, wash and dry. The washing conditions are: rinse the surface of residual suspension 3-5 times with deionized water, and the drying conditions are 100℃. After washing and drying, the catalyst filter bag loaded with graphene-modified copper-manganese composite catalyst is obtained.

[0105] Scanning electron microscope (SEM) images before and after ball milling in step S2 are as follows: Figure 6 As shown in a and b, from Figure 6 As can be seen, after ball milling, the particle size of the graphene-modified copper-manganese composite catalyst is significantly reduced. The smaller-sized copper-manganese composite catalyst is more easily adsorbed by the polyester dust collector bag under the action of the rotating shaker.

[0106] The XRD patterns of the filter bag for the unmodified copper-manganese composite catalyst and the filter bag for the graphene-modified copper-manganese composite catalyst prepared in this example are shown in the figure. Figure 7 As shown, from Figure 7 As can be seen, the graphene-modified copper-manganese composite catalyst has been successfully loaded onto polyester dust collector bags.

[0107] The scanning electron microscope (SEM) images of the graphene-modified copper-manganese composite catalyst prepared in this embodiment before and after loading the graphene-modified copper-manganese composite catalyst onto the catalyst bag are shown below. Figure 8 and Figure 9 As shown, from Figure 9 As can be seen, there are no obvious catalyst particles on the surface of the polyester dust collector bag fibers.

[0108] The distribution of C, O, Mn, and Cu elements on the polyester dust collector bag fibers in the catalyst bag prepared in this embodiment, which is a graphene-modified copper-manganese composite catalyst, is shown in the figure below.Figure 10 As shown, from Figure 10 As can be seen, C, O, Mn, and Cu elements are uniformly dispersed on the surface of the polyester dust collector bag fibers. This indicates that the catalyst may have penetrated into the interior of the polyester dust collector bag fibers. Figure 9 and Figure 10 It can be confirmed that the graphene-modified copper-manganese composite catalyst is firmly loaded onto the polyester dust collector bag.

[0109] Comparative Example 2

[0110] Preparation of catalyst bags for graphene-modified copper-manganese composite catalysts prepared by conventional hydrothermal methods:

[0111] Commercially available polyester dust collector bags were cut and sewn to obtain bags with a diameter of 34mm, a height of 110mm, and a weight of 11g. These bags were then subjected to ultrasonic treatment in anhydrous ethanol solution, followed by drying. The ultrasonic treatment power was 180W, and the drying conditions were 100℃. The dried bags were then immersed in a 15g / L NaOH solution and treated at 90℃ for 1 hour. The immersed bags were then washed and dried to obtain pre-treated bags.

[0112] Add 1.32 g of potassium permanganate and 0.53 g of MnSO4·H2O to 20 mL of graphene oxide suspension with a concentration of 2 mg / mL. After the first stirring, add 0.18 g of citric acid and 0.28 g of Cu(NO3)2·3H2O. After a second stirring, place the treated polyester dust collector bag in the prepared solution and sonicate for 2 hours to ensure full contact between the catalyst and the fabric. Then, place the fabric and the suspension simultaneously in a hydrothermal reactor and treat at 140℃ for 12 hours. Finally, wash and dry the treated polyester fabric to obtain the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared by the traditional hydrothermal method.

[0113] The scanning electron microscope (SEM) image of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared by the conventional hydrothermal method in this comparative example is shown below. Figure 11 As shown, from Figure 11 As can be seen, the graphene-modified copper-manganese composite catalyst is unevenly deposited on the surface of the polyester dust collector bag fibers. In this case, during the catalytic oxidation of CO, the flue gas velocity is relatively high, and the catalyst is easily detached from the surface, thus becoming deactivated. In addition, the catalyst deposited on the fiber surface may block the flow channels of the flue gas.

[0114] Experimental Example 2

[0115] Using the same test conditions as in Experimental Example 1, the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 and the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared by conventional hydrothermal method in Comparative Example 2 were tested for their catalytic oxidation performance under dry and wet conditions (RH = 70%).

[0116] Figure 12 The graphs show the catalytic CO oxidation performance of the catalyst bag containing the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry and wet (RH = 70%) conditions. The results indicate that under dry conditions, the catalyst bag containing the graphene-modified copper-manganese composite catalyst prepared in Example 6 achieves a CO conversion rate of 90% at 90°C. When the humidity increases to 70%, the presence of water vapor leads to competitive adsorption between water molecules and reactant molecules (CO or O2), resulting in a slight decrease in catalyst performance; however, it can still achieve a CO conversion rate of 90% at 100°C. Furthermore, regardless of whether under dry conditions or RH = 70%, the T90 of the catalyst bag containing the graphene-modified copper-manganese composite catalyst prepared in Example 6 is within the operating temperature range of polyester fabric and is lower than the temperature of the flue gas, indicating that CO purification in the flue gas can be achieved without external energy supply.

[0117] Figure 13 The figure shows the lifetime test results of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry conditions. The results show that under the conditions of 90℃ and 34286mL / (g·h), the catalytic performance of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 is stable at over 90% within 11h.

[0118] Figure 14 The image shows the lifetime test results of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared in Example 6 under wet conditions (RH = 70%). The results indicate that the catalytic performance of the catalyst bag for the graphene-modified copper-manganese composite catalyst prepared in Example 6 decreases with increasing humidity, but the catalyst performance can be restored after the water vapor is turned off. The results demonstrate that the catalyst has good moisture resistance and stability.

[0119] Figure 15 This is a test graph showing the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry conditions for five cycles of catalytic degradation. The results show that within five cycles, the Te of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6... 90 There were no significant changes, indicating that it is applicable to industrial processes that require repeated start-ups and shutdowns.

[0120] Figure 16 The graph shows the test results of the airflow rate for the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 under dry conditions; the space velocity was gradually increased by increasing the gas flow rate (flow rates from smallest to largest were 400, 500, 600, 800, and 1000 mL / min). As the space velocity increased from 34286 to 85715 mL / (g·h), the Te of the catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 increased. 90 The temperature was increased from 90°C to 105°C. With increasing space velocity, the catalyst performance decreased slightly, possibly due to the shorter contact time between reactant molecules and the catalyst.

[0121] Experimental Example 3: Co-catalysis

[0122] The catalyst bag of the graphene-modified copper-manganese composite catalyst prepared in Example 6 was used for the synergistic treatment of CO and toluene. The specific operation method was as follows: 5000 ppm CO, 200 ppm toluene, 10 vol% O2, and N2 (equilibrium gas) were simultaneously introduced into the reactor. The total flow rate of the reaction gas was 400 mL / min, controlled by a mass flow meter. The temperature range for catalytic testing was 40–250 °C, with a heating rate of 5 °C / min. The concentrations of toluene and CO were detected by gas chromatography, measured every 10 °C. The catalyst was held at each temperature for 10 min, and the values ​​were recorded. The results are as follows: Figure 17 As shown.

[0123] The results show that when 5000 ppm CO and 200 ppm toluene are simultaneously introduced, the catalyst bag supported on graphene-modified copper-manganese composite catalyst can achieve a CO conversion rate of 94% at 120℃ and a toluene conversion rate of 91.25% at 160℃. This indicates that the graphene-modified copper-manganese composite catalyst of this invention has the potential for synergistic removal of multiple pollutants from flue gas in typical industries.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene-modified copper-manganese composite catalyst, characterized in that, The preparation method includes: Add potassium permanganate and divalent manganese salt to the graphene oxide suspension. After stirring evenly for the first time, add citric acid and divalent copper salt. After stirring evenly for the second time, place the mixed solution at 130~150℃ for hydrothermal treatment for 10~14h. The solution is obtained after the reaction is complete. The mass ratio of graphene oxide, potassium permanganate, divalent manganese salt, citric acid, and divalent copper salt is 1~5:132:53:18:28~140.

2. The preparation method according to claim 1, characterized in that, The divalent manganese salt is one of MnSO4·H2O, MnCl2·4H2O or Mn(CH3COO)2·4H2O; Alternatively, the divalent copper salt is one of Cu(NO3)2·3H2O, CuCl2·2H2O, or Cu(CH3COO)2; Alternatively; the mass ratio of graphene oxide, potassium permanganate, divalent manganese salt, citric acid, and divalent copper salt is 1~5:132:53:18:28, 1~5:132:53:18:56, 1~5:132:53:18:84, 1~5:132:53:18:112, or 1~5:132:53:18:140; Alternatively, after the second stirring is thorough, the mixed solution is placed at 140°C for hydrothermal treatment for 12 hours.

3. The preparation method according to claim 2, characterized in that, The divalent manganese salt is MnSO4·H2O; Alternatively, the divalent copper salt is Cu(NO3)2·3H2O; Alternatively, the mass ratio of graphene oxide, potassium permanganate, divalent manganese salt, citric acid, and divalent copper salt is 4:132:53:18:

28.

4. A method for preparing a catalyst bag for a graphene-modified copper-manganese composite catalyst, characterized in that, The method includes: S0. The graphene-modified copper-manganese composite catalyst is prepared by the preparation method of any one of claims 1-3. S1. Place the cloth bag in anhydrous ethanol solution for ultrasonic treatment, and then dry it; immerse the dried cloth bag in NaOH solution for a period of time; wash and dry the immersed cloth bag to obtain the pretreated cloth bag. S2. The graphene-modified copper-manganese composite catalyst was ground using a planetary ball mill. After grinding, deionized water was added to prepare a graphene-modified copper-manganese composite catalyst suspension. S3. Place the pretreated filter bag from S1 and the graphene-modified copper-manganese composite catalyst suspension from S2 into a rotary shaker and shake at a speed of 40-50 r / min for 18-22 h. After shaking, wash and dry to obtain the catalyst filter bag of the graphene-modified copper-manganese composite catalyst.

5. The preparation method according to claim 4, characterized in that, The filter bag is a polyester dust collector bag; Alternatively, in step S1, the ultrasonic treatment power is 150~240W, and the drying conditions are 95~105℃; Alternatively, the concentration of the NaOH solution in step S1 is 1~20 g / L; Alternatively, in step S1, the dried cloth bag is immersed in NaOH solution and treated at 80℃~100℃ for 1~2 hours; Alternatively, in step S1, the washing conditions are water washing at room temperature, and the drying conditions are 95~105℃.

6. The preparation method according to claim 5, characterized in that, In step S1, the ultrasonic treatment power is 180W, and the drying condition is 100℃. Alternatively, the concentration of the NaOH solution in step S1 is 15 g / L; Alternatively, in step S1, the dried cloth bag is immersed in NaOH solution and treated at 90°C for 1 hour; Alternatively, in step S1, the drying condition is 100°C.

7. The preparation method according to claim 4, characterized in that, In step S2, the grinding conditions are: rotation speed of 300~400 r / min, grinding time of 1.5~2.5 h; Alternatively, in step S2, the concentration of the graphene-modified copper-manganese composite catalyst is 1~20 g / L.

8. The preparation method according to claim 7, characterized in that, The grinding conditions were: 300 r / min for 2 hours; Alternatively, in step S2, the concentration of the graphene-modified copper-manganese composite catalyst is 10 g / L.

9. The preparation method according to claim 4, characterized in that, In step S3, the device oscillates at a speed of 45 r / min for 20 hours. Alternatively, in step S3, the washing conditions are: rinsing the surface residual suspension 3 to 5 times with deionized water; Alternatively, in step S3, the drying conditions are 95~105℃.

10. The preparation method according to claim 9, characterized in that, In step S3, the drying condition is 100°C.

11. The catalyst bag for the graphene-modified copper-manganese composite catalyst prepared by the preparation method according to any one of claims 4 to 10.

12. The application of the catalyst bag of the graphene-modified copper-manganese composite catalyst according to claim 11 in the low-temperature catalytic oxidation of CO in an industrial environment.

13. The application of the catalyst bag of the graphene-modified copper-manganese composite catalyst according to claim 11 in the synergistic catalytic oxidation of CO and toluene in an industrial environment.

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