A Ce-Cu denitration catalyst derived from metal-organic framework, its preparation method and application

Abstract

The present invention discloses a metal-organic framework-derived Ce-Cu denitration catalyst, its preparation method and application. The preparation method includes: dissolving 1,3,5-benzenetricarboxylic acid in absolute ethanol, and then successively adding polyvinylpyrrolidone, N,N-dimethylformamide, copper nitrate and cerium nitrate for solvothermal reaction. After the reaction is completed, it is cooled, and then centrifuged and dried in sequence to obtain a Ce-Cu metal-organic framework precursor; 2) calcining the Ce-Cu metal-organic framework precursor, and taking it out after cooling to obtain the metal-organic framework-derived Ce-Cu denitration catalyst. The application refers to using the Ce-Cu denitration catalyst for the selective catalytic reduction of NOx by CO. Compared with the prior art, the denitration catalyst prepared by the present invention has strong catalytic ability, high NOx conversion rate, strong N2 selectivity, and the catalyst is simple to prepare, can simultaneously remove CO and NOx in atmospheric pollutants, and has strong anti-poisoning ability.

Description

Technical Field

[0001] The selective catalytic reduction of the present invention belongs to the technical field, and particularly relates to a Ce-Cu denitration catalyst derived from metal-organic framework, its preparation method and application. Background Art

[0002] During the combustion of fossil fuels, atmospheric pollutants such as carbon monoxide (CO) and nitrogen oxides (NO x ) will inevitably be generated. If directly discharged into the atmosphere without treatment, it will cause air pollution problems such as photochemical smog, acid rain, ozone layer depletion, and haze, and will also endanger human health. Selective catalytic reduction (SCR) technology is one of the most effective NO x removal means, and its core is the catalyst used. The SCR technology currently used has technologies such as NH3-SCR, CO-SCR, H2-SCR, and HC-SCR according to different types of reducing agents. Among them, the reducing agent used in the CO-SCR technology is CO, which can be directly obtained from industrial flue gas, and can simultaneously remove NO and CO in the flue gas, realizing waste treatment with waste. Compared with the NH3-SCR technology, CO-SCR can avoid problems such as ammonia leakage, ammonia escape, and equipment corrosion, thereby reducing the operation and maintenance costs.

[0003] Metal-organic framework materials (MOFs) are a new type of compound. Due to their ultra-high specific surface area, strong adsorption capacity, and high structural tunability, they are widely used in the fields of batteries, capacitors, adsorption, and catalysis. Using MOFs as the precursor of the catalyst, nanostructured metal oxides with diverse structures, regular morphologies, uniform sizes, and controllable compositions can be prepared.

[0004] However, the flue gas contains impurity gases such as oxygen (O2), sulfur dioxide (SO2), and H2O, which will compete for active sites with CO and NO x during the selective catalytic process, sulfonate the surface active metal oxides, and at the same time, O2 will also react with CO, consuming the reaction gas concentration, resulting in a decrease in catalytic activity, further reducing the catalyst life, and having an adverse impact on the CO-SCR reaction. Therefore, developing a catalyst with high activity, high selectivity, high resistance, and high stability is the key to determining the performance of the CO-SCR reaction. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a Ce-Cu denitration catalyst derived from a metal-organic framework.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: including,

[0009] Add a polyvinylpyrrolidone solution, N,N-dimethylformamide, a copper nitrate solution, and a cerium nitrate solution to an anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid in sequence for a solvothermal reaction. After the reaction is completed, cool it, and then perform centrifugation and vacuum drying in sequence to obtain a Ce-Cu metal-organic framework precursor, wherein the molar ratio of Ce to Cu is 0.5-2:3-4.5;

[0010] The Ce-Cu metal-organic framework precursor is calcined at 300-500 °C for 1-8 h, and the heating rate is 1-5 °C / min -1 , and take it out after cooling when the calcination is completed, and then the metal-organic framework-derived Ce-Cu denitration catalyst is obtained.

[0011] As a preferred scheme of the preparation method of the Ce-Cu denitration catalyst derived from the metal-organic framework of the present invention, wherein: the solution used in the solvothermal reaction is anhydrous ethanol.

[0012] As a preferred scheme of the preparation method of the Ce-Cu denitration catalyst derived from the metal-organic framework of the present invention, wherein: the concentration of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 18-22 g / L, and the dosage of the polyvinylpyrrolidone solution corresponding to every 50 ml of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 8-12 ml, and the dosage of the corresponding N,N-dimethylformamide is 45-55 ml, wherein the concentration of the polyvinylpyrrolidone solution is 8-12 g / L.

[0013] As a preferred scheme of the preparation method of the Ce-Cu denitration catalyst derived from the metal-organic framework of the present invention, wherein: the dosage of the copper nitrate solution corresponding to every 50 ml of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 30-45 ml, and the dosage of the corresponding cerium nitrate solution is 5-20 ml, wherein the concentrations of the copper nitrate solution and the cerium nitrate solution are both 0.1 mol / L.

[0014] As a preferred scheme of the preparation method of the Ce-Cu denitration catalyst derived from the metal-organic framework of the present invention, wherein: the temperature of the solvothermal reaction is 60-120 °C, and the time is 16-24 h.

[0015] As a preferred embodiment of the preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to the present invention, wherein: the rotation speed of the centrifugation is 3000-8000 rpm, and the time is 1-10 min.

[0016] As a preferred embodiment of the preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to the present invention, wherein: the temperature of the vacuum drying is 60-90 °C, and the time is 6-12 h.

[0017] Another object of the present invention is to provide a Ce-Cu denitration catalyst derived from metal-organic framework.

[0018] Another object of the present invention is to provide an application of a Ce-Cu denitration catalyst derived from metal-organic framework in the selective catalytic reduction of NO by CO x in.

[0019] To solve the above technical problems, the present invention provides the following technical solutions: including,

[0020] The catalyst is used for the selective catalytic reduction of NO in the flue gas to be treated by CO x .

[0021] As a preferred embodiment of the application of the Ce-Cu denitration catalyst derived from metal-organic framework according to the present invention in the selective catalytic reduction of NO by CO x in, wherein: the flue gas to be treated contains NO,

[0022] CO, SO2, O2 and H2O, wherein, the CO concentration is 1000-10000 ppm, the SO2 concentration is 0-200 ppm, the O2 concentration is 0-20000 ppm, and the volume fraction of H2O is 0%-20%.

[0023] Advantages of the present invention:

[0024] (1) The present invention uses a partial pyrolysis method to prepare a Ce-Cu denitration catalyst derived from metal-organic framework. The partial pyrolysis can calcine part of the organic ligands, increase the exposure degree of the active centers, and greatly retain the large specific surface area of Ce-Cu BTC, overcoming the defect that the active metals in the original Ce-Cu BTC are hindered by the organic ligands, resulting in a decrease in the accessibility of the active centers and difficulty in meeting its actual application.

[0025] (2) Applying the Ce-Cu denitration catalyst derived from metal-organic framework prepared by the present invention to the selective catalytic reduction of NO by CO x to synergistically remove pollutants and treat waste with waste. The results confirm that the Ce-Cu BTC-X catalyst prepared by the present invention can efficiently and rapidly remove CO and NO in the waste gas x, compared with the traditional selective catalytic reduction of NO by ammonia x technology, the present invention can improve the conversion efficiency of NO x , reduce the reaction window, and also enable NO x to be better removed under high O2 concentration and high H2O volume fraction, with a wider application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0027] Figure 1 XRD crystal structure diagram of the metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention.

[0028] Figure 2 SEM morphology diagram of the metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention.

[0029] Figure 3 XPS full-spectrum diagram of the metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention.

[0030] Figure 4 The metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention is used for selective catalytic reduction of NO x CO conversion rate result diagram at 100 - 350 °C.

[0031] Figure 5 The metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention is used for selective catalytic reduction of NO x NO conversion rate result diagram at 100 - 350 °C.

[0032] Figure 6 The metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination temperatures in Example 2 of the present invention is used for selective catalytic reduction of NO x N2 selectivity result diagram at 100 - 350 °C.

[0033] Figure 7 The metal-organic framework-derived Ce-Cu denitration catalyst prepared at different calcination times in Example 3 of the present invention is used for selective catalytic reduction of NO xCO conversion rate results graph at 100 - 350 °C.

[0034] Figure 8 The metal - organic framework - derived Ce - Cu denitration catalyst prepared with different calcination times in Example 3 of the present invention is used for selective catalytic reduction of NO x NO conversion rate results graph at 100 - 350 °C.

[0035] Figure 9 The metal - organic framework - derived Ce - Cu denitration catalyst prepared with different molar ratios of Ce and Cu in Example 4 of the present invention is used for selective catalytic reduction of NO x CO conversion rate results graph at 100 - 350 °C.

[0036] Figure 10 The metal - organic framework - derived Ce - Cu denitration catalyst prepared with different molar ratios of Ce and Cu in Example 4 of the present invention is used for selective catalytic reduction of NO x NO conversion rate results graph at 100 - 350 °C.

[0037] Figure 11 Selective catalytic reduction of NO at different space velocities in Example 5 of the present invention x CO conversion rate results graph at 100 - 350 °C.

[0038] Figure 12 Selective catalytic reduction of NO at different space velocities in Example 5 of the present invention x NO conversion rate results graph at 100 - 350 °C.

[0039] Figure 13 Selective catalytic reduction of NO at different CO concentrations in Example 6 of the present invention x CO conversion rate results graph at 100 - 350 °C.

[0040] Figure 14 Selective catalytic reduction of NO at different CO concentrations in Example 6 of the present invention x NO conversion rate results graph at 100 - 350 °C.

[0041] Figure 15 Selective catalytic reduction of NO at different O2 concentrations in Example 7 of the present invention x Effect.

[0042] Figure 16 Selective catalytic reduction of NO at different SO2 concentrations in Example 8 of the present invention x Effect.

[0043] Figure 17 Selective catalytic reduction of NO at different H2O volume fractions in Example 9 of the present inventionx Effect.

[0044] Figure 18 For Example 10 of the present invention, when SO2 and H2O coexist, selective catalytic reduction of NO at different SO2 concentrations x Effect. Specific Embodiments

[0045] To make the above objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the embodiments of the specification.

[0046] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0047] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0048] Unless otherwise specified, the raw materials used in the present invention are all commonly available in the market.

[0049] Example 1

[0050] This example provides a preparation method of a Ce-Cu denitration catalyst derived from a metal-organic framework. Specifically:

[0051] 1) 1 g of 1,3,5-benzenetricarboxylic acid was added to 50 mL of absolute ethanol and dissolved. Then, 10 mL of polyvinylpyrrolidone solution (10 g / L), 50 mL of N,N-dimethylformamide, 40 mL of copper nitrate absolute ethanol solution (0.1 mol / L), and 10 mL of cerium nitrate absolute ethanol solution (0.1 mol / L) were added in sequence. The mixture was transferred to a reaction kettle and subjected to hydrothermal reaction at 80 °C for 20 h. After the reaction ended and cooled to room temperature, centrifugation was carried out (6000 rpm, 5 min). After centrifugation, it was washed several times with absolute ethanol and then transferred to a vacuum drying oven at 80 °C for drying for 8 h to obtain a Ce-Cu metal-organic framework precursor;

[0052] 2) The Ce-Cu metal-organic framework precursor was transferred to a crucible and calcined in a muffle furnace at a heating rate of 1 °C / min -1 to 350 °C for 6 h. After cooling, it was taken out to obtain a metal-organic framework-derived Ce-Cu denitration catalyst.

[0053] Example 2

[0054] This example is used to explore the influence of different calcination temperatures on the performance of the prepared catalyst. Different from Example 1, the calcination temperatures in step 2) are adjusted to 300 °C, 350 °C, 400 °C, 450 °C, 500 °C and no calcination respectively. The processes of the remaining steps are all referred to Example 1. The catalysts prepared under different calcination temperature conditions in this example are respectively denoted as CeCu - BTC - 300, CeCu - BTC - 350, CeCu - BTC - 400, CeCu - BTC - 450, CeCu - BTC - 500, CeCu - BTC - Uncalcined.

[0055] Figure 1 is the XRD crystal structure diagram of metal - organic framework - derived Ce - Cu denitration catalysts at different calcination temperatures. For the unpyrolyzed BTC precursor, its diffraction peaks correspond well to the simulated Cu - BTC diffraction peaks, and the addition of Ce does not significantly change its crystal structure. With the increase of the calcination temperature, the characteristic diffraction peaks of CuO and CeO2 gradually appear. The diffraction peaks at 35.4°, 38.6° and 48.7° respectively belong to the (002), (111) and (20 - 2) crystal planes of CuO (PDF#48 - 1548), and the diffraction peaks at 28.6°, 47.3° and 56.1° respectively belong to the (111), (220) and (311) crystal planes of CeO2 (PDF#34 - 0394).

[0056] Figure 2 is the SEM morphology diagram of metal - organic framework - derived Ce - Cu denitration catalysts at different calcination temperatures. It can be seen that the prepared composite catalyst has a polyhedron structure, and with the increase of the calcination temperature, wrinkles gradually appear on the surface.

[0057] Figure 3 is the XPS full - spectrum diagram of metal - organic framework - derived Ce - Cu denitration catalysts at different calcination temperatures. It can be seen that Cu, Ce, O, and C exist in all samples, and a small amount of N is due to the addition of N,N - dimethylformamide or nitrate during the preparation of the samples.

[0058] Application test

[0059] The catalytic effect of the prepared catalyst is tested. Specifically, 0.05 mL of the prepared catalyst is measured and placed in a fixed - bed reactor. The reaction gas concentration is adjusted (CO: 2000 ppm, NO: 1000 ppm), the gas flow rate is 100 ml / min, and N2 is used as the balance gas, so that the space velocity is 120000 h -1, while using a programmed temperature increase to heat the quartz tube from room temperature to 350 °C. Starting from 100 °C, measure the concentrations of CO, NO, NO₂, and N₂O in the tail gas every 25 °C, and calculate the conversion rate and selectivity. The calculation formulas for the conversion rate and selectivity are as follows:

[0060]

[0061] In the formula, in represents the concentration before the reaction, and out represents the concentration after the reaction.

[0062] Perform application tests on the catalysts obtained at different calcination temperatures in this example. The results are shown in Table 1 and Figures 4 - 6 as follows.

[0063] Table 1

[0064] Catalyst CO conversion rate % at 275°C NO conversion rate % at 275°C <![CDATA[N2 Selectivity % at 275℃]]> CeCu - BTC - Uncalcined 1.0 12.6 95.6 CeCu - BTC - 300 63.8 45.6 90.8 CeCu - BTC - 350 83.3 100.0 100.0 CeCu - BTC - 400 77.7 100.0 100.0 CeCu - BTC - 450 73.0 66.3 92.9 CeCu - BTC - 500 50.3 59.1 92.7

[0065] From the above results, it can be seen that when the calcination temperature is 350 °C and 400 °C, both the NO conversion rate and selectivity can reach 100% at 275 °C. However, the CO conversion rate is higher when calcined at 350 °C. This is because an appropriate calcination temperature increases the exposure degree of the active metal in the MOF-derived catalyst, thereby improving the pollutant conversion rate. The CO conversion rate and NO conversion rate of the catalysts prepared without calcination, at 300 °C, and at higher calcination temperatures (450 °C and 500 °C) are lower. This is because a lower calcination temperature results in insufficient exposure of the active centers, while a higher calcination temperature causes the structure of the MOF-derived catalyst to collapse.

[0066] Example 3

[0067] This example is used to explore the influence of different calcination times on the performance of the prepared catalysts. The difference from Example 1 is that the calcination times in step 2) are adjusted to 1 h, 3 h, 6 h, and 8 h respectively, and the rest of the process steps refer to Example 1. The catalysts obtained under different calcination temperature conditions in this example are denoted as CeCu-BTC-350-1h, CeCu-BTC-350-3h, CeCu-BTC-350-6h, and CeCu-BTC-350-8h respectively.

[0068] Refer to the method of Example 2 to perform application tests on the catalysts obtained at different calcination times in this example. The results are shown in Table 2 and Figure 7 and Figure 8 as follows.

[0069] Table 2

[0070] Catalyst CO conversion rate % at 275°C NO conversion rate % at 275°C CeCu - BTC - 350 - 1h 57.4 58.9 CeCu - BTC - 350 - 3h 58.6 99.0 CeCu - BTC - 350 - 6h 83.3 100.0 CeCu - BTC - 350 - 8h 41.3 77.7

[0071] From Table 6 and Figure 7 and Figure 8It can be seen that when the calcination time is 1 h and 3 h, since the organic ligands are not calcined sufficiently and the exposure degree of the active centers is insufficient, the CO conversion rate and the NO conversion rate are still insufficient. When the calcination time is 6 h, the catalyst has a CO conversion rate of 83.3% and a NO conversion rate of 100%. When the calcination time is further increased to 8 h, the catalytic activity decreases significantly. This is because excessive calcination time causes a large amount of organic ligands to burn out, resulting in the collapse of the catalyst structure.

[0072] Example 4

[0073] This example is used to explore the influence of the molar ratio of different Ce and Cu substances in the catalyst on the performance of the prepared catalyst. The difference from Example 1 is that the dosages of the copper nitrate absolute ethanol solution (0.1 mol / L) and the cerium nitrate absolute ethanol solution (0.1 mol / L) in step 1) are adjusted (see Table 3 for details). The processes of the remaining steps are all referred to Example 1, and the catalysts prepared under different molar ratios of Ce and Cu in this example are obtained, which are respectively denoted as Cu-BTC, Ce 0.25 Cu 4.75 -BTC, Ce 0.5 Cu 4.5 -BTC, Ce1Cu4-BTC, Ce2Cu3-BTC, Ce 2.5 Cu 2.5 -BTC, Ce3Cu2-BTC, Ce4Cu1-BTC, Ce-BTC.

[0074] Table 3

[0075] Catalyst Dosage of cerium nitrate (mL) Dosage of copper nitrate (mL) Cu - BTC 0 50 <![CDATA[Ce 0.25 Cu 4.75 -BTC]]> 2.5 47.5 <![CDATA[Ce 0.5 Cu 4.5 -BTC]]> 5 45 <![CDATA[Ce1Cu4-BTC]]> 10 40 <![CDATA[Ce2Cu3-BTC]]> 20 30 <![CDATA[Ce 2.5 Cu 2.5 -BTC]]> 25 25 <![CDATA[Ce3Cu2-BTC]]> 30 20 <![CDATA[Ce4Cu1-BTC]]> 40 10 Ce - BTC 50 0

[0076] Referring to the method of Example 2, the catalysts obtained with different molar ratios of Ce and Cu in this example are subjected to application tests. The results are shown in Table 4 and Figure 9 Figure 10 as follows.

[0077] Table 4

[0078] Catalyst CO conversion rate % at 275°C NO conversion rate % at 275°C Cu - BTC 92.0 36.2 <![CDATA[Ce 0.25 Cu 4.75 -BTC]]> 77.2 64.3 <![CDATA[Ce 0.5 Cu 4.5 -BTC]]> 79.0 73.7 <![CDATA[Ce1Cu4-BTC]]> 83.3 100.0 <![CDATA[Ce2Cu3-BTC]]> 61.7 96.2 <![CDATA[Ce 2.5 Cu 2.5 -BTC]]> 51.7 92.0 <![CDATA[Ce3Cu2-BTC]]> 49.7 84.6 <![CDATA[Ce4Cu1-BTC]]> 36.6 80.0 Ce - BTC 3.4 12.6

[0079] From Table 4 and Figure 9 , Figure 10 it can be seen that the CO conversion rate increases with the increase of the proportion of Cu, but the NO conversion rate is the highest when the molar ratio of Ce to Cu is optimal. When the molar ratio of Ce to Cu is 1:4, the NO conversion rate can reach 100%. This proves that the appropriate ratio of active elements has the most excellent synergistic effect, thus having the optimal catalytic activity.

[0080] Example 5

[0081] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different space velocities. x Specifically:

[0082] 0.05 mL of the catalyst prepared in Example 1 was measured and placed in a fixed-bed reactor. The reaction gas concentration was adjusted (CO: 2000 ppm, NO: 1000 ppm), and the gas flow rates were 50, 100, and 120 mL / min respectively. N2 was used as the balance gas, so that the volume space velocities were 60000, 120000, and 144000 h -1 , respectively. At the same time, the quartz tube was heated from room temperature to 350 °C by programmed heating. Starting from 100 °C, the concentrations of CO and NO in the tail gas were measured every 25 °C, and the conversion rate was calculated. The test results are shown in Table 5 and Figures 11 - 12 as follows.

[0083] Table 5

[0084] <![CDATA[Air speed / h -1 > CO conversion rate % at 275°C NO conversion rate % at 275°C 60000 95.1 100.0 120000 83.3 100.0 144000 62.1 85.0

[0085] As can be seen from the results shown in Table 5 and Figures 11 - 12 as follows, the conversion rates of CO and NO gradually decrease with the increase of the space velocity. However, when the space velocity is 144000 h -1 , the CO conversion rate can still reach 95% and the NO x conversion rate can reach 100%. This result shows that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention has a high adaptability to the space velocity. Therefore, in actual application, it is not necessary to control the reaction gas flow rate in advance.

[0086] Example 6

[0087] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different CO concentrations. x Specifically:

[0088] 0.05 mL of the catalyst prepared in Example 1 was measured and placed in a fixed-bed reactor. The reaction gas concentration was adjusted (CO: 1000 - 10000 ppm, NO: 1000 ppm), and the gas flow rate was 100 mL / min. N2 was used as the balance gas, so that the volume space velocity was 120000 h -1 , respectively. At the same time, the quartz tube was heated from room temperature to 350 °C by programmed heating. Starting from 100 °C, the concentrations of CO and NO in the tail gas were measured every 25 °C, and the conversion rate was calculated. The test results are shown in Table 6 and Figure 13 and Figure 14 as follows.

[0089] Table 6

[0090]

[0091]

[0092] Table 6 and Figure 13 、 Figure 14 From the results of, it can be seen that the NO conversion rate gradually increases with the increase of CO concentration. When the CO concentration exceeds 2000 ppm, the NO conversion rate can reach 100%. However, the CO conversion rate gradually decreases with the increase of CO concentration. This result shows that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention still has high catalytic activity at a relatively low CO concentration.

[0093] Example 7

[0094] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different O2 concentrations. Specifically: x of the effect, specifically:

[0095] Measure 0.05 mL of the catalyst prepared in Example 1 and place it in a fixed-bed reactor. Adjust the reaction gas concentration (CO: 2000 ppm, NO: 1000 ppm, O2: 0 - 20000 ppm), the gas flow rate is 50 ml / min, and N2 is used as the balance gas to make the volume space velocity 60000 h -1 , and at the same time, use programmed heating to heat the quartz tube from room temperature to 200 °C for constant temperature testing. Measure the CO and NO concentrations in the tail gas and calculate the conversion rate. The test results are as Figure 15 shown.

[0096] Figure 15 The results show that the CO conversion rate gradually increases with the increase of O2 concentration. When the O2 concentration is 20000 ppm, the CO conversion rate reaches 100%; the NO conversion rate gradually decreases with the increase of O2 concentration, but it can still maintain a 100% conversion rate when the O2 concentration is 15000 ppm. This result shows that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention still has high catalytic activity at an O2 concentration of 15000 ppm.

[0097] Example 8

[0098] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different SO2 concentrations. x of the effect, specifically:

[0099] Measure 0.05 mL of the catalyst prepared in Example 1 and place it in a fixed-bed reactor. Adjust the reaction gas concentration (CO: 2000 ppm, NO: 1000 ppm, SO2: 0 - 200 ppm), the gas flow rate is 50 ml / min, and N2 is used as the balance gas to make the volume space velocity 60000 h -1 , and at the same time, use programmed heating to heat the quartz tube from room temperature to 200 °C for constant temperature testing. Measure the NO concentration in the tail gas and calculate the conversion rate. The test results are asFigure 16 as shown

[0100] Figure 16 The results show that the NO conversion rate gradually decreases with the increase of SO2 concentration, but can still maintain a relatively high conversion rate when the SO2 concentration is 50 ppm. This result indicates that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention has certain SO2 resistance.

[0101] Example 9

[0102] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different H2O volume fractions. Specifically: x as follows

[0103] 0.05 mL of the catalyst prepared in Example 1 was measured and placed in a fixed-bed reactor. The reaction gas concentration was adjusted (CO: 2000 ppm, NO: 1000 ppm, H2O: 0 - 20%), the gas flow rate was 50 ml / min, and N2 was used as the balance gas, so that the volume space velocity was 60000 h -1 , and at the same time, the quartz tube was heated from room temperature to 200 °C by programmed heating for constant temperature testing. The NO concentration in the tail gas was measured, and the conversion rate was calculated. The test results are as Figure 17 shown

[0104] Figure 17 The results show that the NO conversion rate gradually decreases with the increase of H2O volume fraction, but can still maintain a relatively high conversion rate when the H2O volume fraction is 5%. This result indicates that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention has certain H2O resistance.

[0105] Example 10

[0106] This example is used to explore the effect of the catalyst of the present invention on the selective catalytic reduction of NO at different SO2 concentrations when SO2 and H2O coexist. Specifically: x as follows

[0107] 0.05 mL of the catalyst prepared in Example 1 was measured and placed in a fixed-bed reactor. The reaction gas concentration was adjusted (CO: 2000 ppm, NO: 1000 ppm, H2O: 5%, SO2: 0 - 200 ppm), the gas flow rate was 50 ml / min, and N2 was used as the balance gas, so that the volume space velocity was 60000 h -1 , and at the same time, the quartz tube was heated from room temperature to 200 °C by programmed heating for constant temperature testing. The NO concentration in the tail gas was measured, and the conversion rate was calculated. The test results are as Figure 18 shown

[0108] Figure 18The results show that the NO conversion rate does not change significantly with the increase of SO2 concentration (0 - 100 ppm). When the SO2 concentration is 200 ppm, the NO conversion rate can still remain above 80%. Moreover, after turning off SO2 and H2O, the NO conversion rate can recover to about 90%. This result indicates that the metal-organic framework-derived Ce-Cu denitration catalyst of the present invention has a high NO conversion rate in the coexistence of H2O and SO2.

[0109] The results of Examples 5 - 10 show that the catalyst prepared by the present invention has good catalytic effects under conditions of high space velocity, low reducing gas concentration, different oxygen concentrations, different sulfur dioxide concentrations, and the presence of moisture. In actual application scenarios, it is not necessary to adjust the above parameters in advance to ensure a high pollutant removal efficiency.

[0110] In summary, the present invention uses partial pyrolysis to prepare a metal-organic framework-derived Ce-Cu denitration catalyst. Partial pyrolysis can calcine some organic ligands, increasing the exposure degree of active centers and greatly retaining the large specific surface area of Ce-Cu BTC. It overcomes the defect that the active metal in the original Ce-Cu BTC is hindered by organic ligands, resulting in a reduction in the accessibility of its active centers and difficulty in meeting its actual application requirements.

[0111] Apply the metal-organic framework-derived Ce-Cu denitration catalyst prepared by the present invention to the selective catalytic reduction of NO by CO x to synergistically remove pollutants and treat waste with waste. The results confirm that the Ce-Cu BTC-X catalyst prepared by the present invention can efficiently and rapidly remove CO and NO in waste gas. x , compared with the traditional selective catalytic reduction of NO by ammonia x technology, the present invention can improve the NO x conversion efficiency, lower the reaction window, and also enable NO x to be better removed under high O2 concentration and high H2O volume fraction, with a wider application range.

[0112] It should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of a Ce-Cu denitration catalyst derived from metal-organic frameworks, characterized in that: Including, Add a polyvinylpyrrolidone solution, N,N-dimethylformamide, a copper nitrate solution, and a cerium nitrate solution to an anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid in sequence for a solvothermal reaction. After the reaction is completed, cool it, and then perform centrifugation and vacuum drying in sequence to obtain a Ce-Cu metal-organic framework precursor, wherein the molar ratio of Ce to Cu is 1:4; The Ce-Cu metal-organic framework precursor is calcined at 350 - 400 °C for 6 h with a heating rate of 1 - 5 °C min -1 . After cooling down upon completion of calcination, it is taken out to obtain the metal-organic framework-derived Ce-Cu denitration catalyst.

2. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to claim 1, characterized in that: The solution used in the solvothermal reaction is anhydrous ethanol.

3. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to claim 1, characterized in that: The concentration of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 18-22 g / L. The dosage of the polyvinylpyrrolidone solution corresponding to every 50 ml of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 8-12 ml, and the dosage of N,N-dimethylformamide corresponding thereto is 45-55 ml, wherein the concentration of the polyvinylpyrrolidone solution is 8-12 g / L.

4. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to any one of claims 1 or 3, characterized in that: The dosage of the copper nitrate solution corresponding to every 50 ml of the anhydrous ethanol solution of 1,3,5-benzenetricarboxylic acid is 30-45 ml, and the dosage of the cerium nitrate solution corresponding thereto is 5-20 ml, wherein the concentrations of the copper nitrate solution and the cerium nitrate solution are both 0.1 mol / L.

5. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to claim 2, wherein: The temperature of the solvothermal reaction is 60-120 °C, and the time is 16-24 h.

6. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to claim 1, characterized in that: The rotation speed of the centrifugation is 3000-8000 rpm, and the time is 1-10 min.

7. The preparation method of the Ce-Cu denitration catalyst derived from metal-organic framework according to claim 1, characterized in that: The temperature of the vacuum drying is 60-90 °C, and the time is 6-12 h.

8. A Ce-Cu denitrification catalyst derived from a metal-organic framework prepared by the preparation method according to any one of claims 1 to 7.

9. Application of the Ce-Cu denitration catalyst derived from metal-organic framework as claimed in claim 8 in the selective catalytic reduction of NO by CO x is characterized in that: The catalyst is used for selectively catalytically reducing NO in the flue gas to be treated by CO x .

10. The application according to claim 9, characterized in that: The flue gas to be treated contains NO, CO, SO2, O2 and H2O, wherein the CO concentration is 1000-10000 ppm, the SO2 concentration is 0-200 ppm, the O2 concentration is 0-20000 ppm, and the volume fraction of H2O is 0%-20%.

Images