Cu-fe-ti-based catalytic filter tube, method of making and use thereof

Abstract

The application discloses a Cu-Fe-Ti-based catalytic filter tube, a preparation method and application thereof, and a preparation method of the catalytic filter tube, and steps of the preparation method are as follows: S1: crushing, grinding and screening of siderite; S2: dispersing a copper source, a titanium source and the screened siderite in S1 in deionized water to obtain a mixed solution; S3: adding ammonia water into the mixed solution in S2 until complete precipitation, and then performing stirring, aging, filtration, washing, drying and calcination to obtain a catalyst; S4: grinding the catalyst in S3 and dispersing the catalyst in deionized water to obtain a catalyst slurry, immersing a filter tube into the catalyst slurry, and then performing drying and calcination to obtain the Cu-Fe-Ti-based catalytic filter tube. The Cu-Fe-Ti-based catalytic filter tube prepared by the application has good denitration activity and water resistance and sulfur resistance, and shows more than 90% of NO conversion rate in the range of 200-400 DEG C; under the condition that H2O and SO2 exist simultaneously at 225 DEG C, the NO conversion rate can be stably kept above 85% in continuous operation for 4h.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic filter tube, in particular to a Cu-Fe-Ti-based catalytic filter tube, a preparation method and application thereof. BACKGROUND

[0002] The catalytic filter core technology combines fine filtration with catalytic removal, and is a new multifunctional material integrating mechanical filtration and selective catalytic reduction of dust. The catalytic filter core is formed by densely interlaced fibers, and the developed pore structure provides sufficient attachment points for the loading of SCR denitration catalyst. When the dust-containing exhaust gas passes through the catalytic filter core, the dust is intercepted on the outside of the filter core, and the NO x inside the catalyst is catalytically reduced to N2 and H2O. When matched with front-end dry desulfurization, SO2, dust, NO x , hydrogen chloride, hydrogen fluoride and other pollutants in the flue gas can be removed at the same time. The problems of complex process, large occupied area and high operation and maintenance cost existing in the traditional series technology are effectively solved. Moreover, the catalytic filter core has the advantages of high temperature resistance and corrosion resistance, and the internal SCR catalyst is not easily poisoned by harmful substances such as SO2 and alkali metals, and has a long service life. At present, the catalytic filter core is equipped with V-W / Ti-based catalyst, but the vanadium-titanium-based catalyst has the disadvantages of high and narrow temperature window, easy poisoning by alkali metals / H2O / SO2 and biological toxicity, etc. Therefore, it has high practical significance and application value to develop a catalytic filter core with high activity, wide temperature range, low cost and green environmental protection. SUMMARY

[0003] Based on the technical problems existing in the background technology, the present application provides a Cu-Fe-Ti-based catalytic filter tube, a preparation method and application thereof. The catalytic filter tube has high denitration activity and water and sulfur resistance, and has the advantages of low production cost, simple operation, green environmental protection and good application prospect.

[0004] The preparation method of the Cu-Fe-Ti-based catalytic filter tube provided by the present application comprises the following steps:

[0005] S1: crushing, grinding and screening of siderite;

[0006] S2: dispersing copper source, titanium source and the screened siderite of S1 in deionized water to obtain a mixed solution;

[0007] S3: adding ammonia water to the mixed solution of S2 until complete precipitation, and then stirring, aging, filtering, washing, drying and calcining to obtain a catalyst;

[0008] S4: grinding the catalyst of S3 and dispersing it in deionized water to obtain a catalyst slurry, immersing the filter tube in the catalyst slurry, and then drying and calcining to obtain a Cu-Fe-Ti-based catalytic filter tube.

[0009] Preferably, the siderite contains the following mass fractions of elements: Fe 25-35%, O 25-30%, Si 20-30%.

[0010] Preferably, the mass ratio of the copper source, the siderite and the titanium source is 0.05-0.25:0.1-0.2:1.

[0011] Preferably, the copper source is anhydrous copper sulfate; the titanium source is anhydrous titanium sulfate.

[0012] Preferably, the volume-mass ratio of ammonia water to the titanium source is 1.3-1.5 mL:1 g.

[0013] Preferably, the temperature for drying in S3 is 100-110°C, and the time is 12-24h; the temperature for calcining is 350-450°C, and the time is 3-5h.

[0014] Preferably, the temperature for drying in S4 is 100-110°C, and the time is 12-24h; the temperature for calcining is 350-450°C, and the time is 3-5h.

[0015] Preferably, the target loading of the filter tube in S4 is that the mass growth rate of the filter tube after drying is 20-35 Wt.%.

[0016] The Cu-Fe-Ti-based catalytic filter tube prepared by the above method.

[0017] The application of the above Cu-Fe-Ti-based catalytic filter tube in denitration.

[0018] The beneficial technical effects of the application are:

[0019] (1) The Cu-Fe-Ti catalytic filter tube prepared by the application has good denitration activity and water and sulfur resistance. It shows more than 90% NO conversion rate in the range of 200-400°C; under the condition of the simultaneous existence of H2O and SO2 at 225°C, the NO conversion rate can still be stably maintained at more than 85% after continuous operation for 4h.

[0020] (2) The application uses TiO2 with strong chemical stability and large specific surface area as the carrier, and Cu and siderite as the active sources to construct a Cu-Fe-Ti composite denitration catalyst. After high-temperature calcination of siderite, a large number of nanometer cracks are generated with the decomposition of FeCO3, which increases the specific surface area of the catalyst and significantly enhances the adsorption performance. In the isolated system of Fe-Ti two phases, the introduction of the third phase element Cu will disturb the original electronic circulation between Fe-Ti, thereby forming a new balance among Fe-Cu-Ti three phases. The existence of Cu causes the deviation of Ti 4+ species electron cloud, and makes Ti 4+ species lose electrons more easily from Fe2+ Species "plunder" more electrons, forming a larger electron cloud density; according to the law of conservation of charge, Fe 2+ Species will form a lack of electron environment, thus promoting more Fe 3+ Species generated. This will improve the oxidation performance and acidity of the catalyst surface, thus improving the catalyst denitration effect at lower temperatures. At the same time, Cu 2+ Species will also get some electrons, making more CuO-Cu2O structure formation, promoting the formation of catalyst surface adsorbed oxygen. When SO2 exists, part of Fe 3+ As "sacrifice site" will preferentially react with SO2 to form Fe2(SO4)3, which will weaken the oxidation ability of the catalyst to some extent, but SO 2 4 - Will enhance the acidity of Fe site, ensure that the catalyst still has good denitration performance in the presence of SO2.

[0021] (3) The Cu-Fe-Ti catalytic filter tube is synthesized by impregnation method with ceramic fiber filter tube as substrate, which has high temperature resistance and corrosion resistance. The unique fibrous support structure can effectively improve the dispersity and loading rate of the catalyst, and effectively weaken the poisoning effect of H2O / SO2 / alkali metal on the catalyst inside the filter core.

[0022] (4) The raw material of the application has low price, and the preparation method is simple, without secondary pollution, etc., which provides a new idea for comprehensive utilization of siderite mineral resources and industrial promotion of catalytic filter core process. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 TEM image of the catalyst proposed by the application;

[0024] Figure 2 XRD image of the catalyst proposed by the application;

[0025] Figure 3 SEM image of the catalytic filter tube proposed by the application; (a) before loading catalyst, (b) after loading catalyst;

[0026] Figure 4 Catalytic activity comparison chart of Cu-Fe-Ti powder catalyst and Cu-Ti and Fe-Ti catalysts proposed by the application;

[0027] Figure 5 Catalytic activity curve of the catalytic filter tube proposed by the application with reaction temperature change;

[0028] Figure 6A comparison chart of water and sulfur resistance performance of Cu-Fe-Ti catalytic filter tube and Cu-Ti and Fe-Ti catalytic filter tube at 225°C is provided for the present application. DETAILED DESCRIPTION

[0029] The present application will be further illustrated below in conjunction with specific examples.

[0030] Example 1

[0031] The preparation method steps of the Cu-Fe-Ti-based catalytic filter tube provided by the present application are as follows:

[0032] S1: sieve the sintered magnetite after crushing and grinding to a standard sample sieve of 200 meshes;

[0033] S2: dissolve CuSO4·5H2O and Ti(SO4)2 in deionized water, then add sintered magnetite powder to obtain a mixed solution; the mass ratio of copper sulfate pentahydrate, sintered magnetite and titanium sulfate anhydrous in the mixed solution is 0.15:0.135:1;

[0034] S3: vigorously stir the mixed solution in S2 and add ammonia water until complete precipitation, continue stirring for 0.5 h, age for 2 h, and then filter to obtain a solid mixture;

[0035] S4: place the solid in S3 in an oven, dry at 105°C for 12 h, then take it out, place it in a muffle furnace and calcine at 350°C for 4 h, cool it down, and then put it into a jar mill, grind at a speed of 120 r / min for 4 h;

[0036] S5: add the catalyst in S4 into deionized water to make a uniform slurry, then put it into a filter tube, ultrasonic, dry, calcine at 350°C for 4 h to obtain a Cu-Fe-Ti-based catalytic filter tube with a target loading of 30 wt.%.

[0037] The performance test method of the catalytic filter tube is carried out on a fixed bed reactor with continuous flow of reaction gas, the total flow rate of the reaction gas is 300 mL / min, the gas composition includes [NO] = [NH3] = 500 ppm, 3 vol.% O2, 10 vol.% H2O (when used), [SO2] = 100 ppm (when used), and the balance gas is Ar. When testing the activity of the Cu / Fe / Ti catalytic filter tube, the surface filtration speed is controlled at 1.5 m / min. The NO x concentration at the inlet and outlet of the reaction gas is monitored online by an Austria Madur GA-12Plus type flue gas analyzer.

[0038] NO x The conversion rate is obtained by the following formula:

[0039]

[0040] where [NO] in and [NO] out represent the inlet and outlet concentration of NO, ppm, respectively.

[0041] Example 2

[0042] The test surface filtration speed in the test method of this example is 0.6 m / min, and the rest of the conditions are the same as in Example 1.

[0043] Example 3

[0044] The raw material used in this example S2 is Ti(SO4)2+siderite, and the rest of the conditions are the same as in Example 1.

[0045] Example 4

[0046] The raw material used in this example S2 is CuSO4·5H2O+siderite, and the rest of the conditions are the same as in Example 1.

[0047] The TEM image of the powder Cu-Fe-Ti catalyst prepared by the present application is shown in Figure 1 After calcination, a large number of nanoscale cracks are generated by the decomposition of siderite on the TiO2 carrier, and CuOx microcrystals are uniformly distributed on the surface of the catalyst. To determine the active components of the catalyst, XRD crystal phase analysis of the Cu-Fe-Ti catalyst proposed by the present application is shown in Figure 2 After calcination at 350℃, the XRD spectrum shows obvious characteristic peaks of anatase TiO2, and the FeCO3 crystal phase is converted into the highly active α-Fe2O3 phase. In addition, CuOx mainly exists in the form of CuO and Cu2O, and the lower peak intensity indicates that CuOx is well dispersed on the surface of the catalyst. From Figure 3 As seen in the comparison chart before and after loading the Cu-Fe-Ti catalyst on the ceramic filter tube, the catalyst particles after ball milling are uniformly loaded on the ceramic fiber, which ensures a high air permeability of the catalytic filter tube while improving the exposure rate and utilization rate of the active sites of the catalyst.

[0048] Figure 4 The comparison chart of the catalytic activity of the Cu-Fe-Ti powder catalyst proposed by the present application with Cu-Ti and Fe-Ti catalysts. The test results show that the Cu-Fe-Ti catalyst has the best low-temperature effect, with a NO conversion rate of more than 90% within 175-375℃, and a NO conversion rate close to 100% within 200-350℃. The catalytic activity curve of the catalytic filter tube prepared in Examples 1-4 of the present application with the change of reaction temperature is shown in Figure 5The results are shown in Figure 1. It can be seen that the Cu-Fe-Ti-based catalytic filter tube prepared in Example 1 has 100% NO conversion in the range of 250-375°C. In Example 2, the range of 100% NO conversion of the Cu-Fe-Ti-based catalytic filter tube is extended to 200-400°C after the face velocity is reduced to 0.6 m / min. The Cu-Ti and Fe-Ti catalytic filter tubes corresponding to Examples 3 and 4 have lower denitration effect than the Cu-Fe-Ti-based catalytic filter tube under the same conditions.

[0049] Figure 6 The curves of the influence of H2O and SO2 on the catalytic activity of the catalytic filter tubes prepared in Examples 1, 3 and 4 at a reaction temperature of 225°C are shown in Figure 2. It can be seen that the Cu-Fe-Ti-based catalytic filter tube always maintains a NO removal rate of more than 85% under the condition of continuously passing 10 vol.% H2O and 100 ppm SO2 at 225°C for 4 h, and has good water and sulfur resistance.

Claims

1. A method for preparing Cu-Fe-Ti based catalytic filter tubes, characterized in that, The steps are as follows: S1: Crushing, grinding and screening of siderite; S2: Disperse the copper source, titanium source and the siderite after S1 sieving in deionized water to obtain a mixed solution; S3: Add ammonia to the S2 mixture until complete precipitation, and obtain the catalyst after stirring, aging, filtration, washing, drying and calcination; S4: After grinding the S3 catalyst, disperse it in deionized water to obtain a catalyst slurry. Immerse the filter tube in the catalyst slurry, and then dry and calcine it to obtain the Cu-Fe-Ti based catalytic filter tube. The mass ratio of copper source, siderite, and titanium source is 0.05-0.25:0.1-0.2:1; The calcination temperature in S3 is 350-450 ℃, and the time is 3-5 h.

2. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, Siderite contains the following elements in mass fractions: Fe 25-35%, O 25-30%, Si 20-30%.

3. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, The copper source is anhydrous copper sulfate; the titanium source is anhydrous titanium sulfate.

4. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, The volume-to-mass ratio of ammonia to titanium source is 1.3-1.5 mL:1 g.

5. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, The drying temperature in S3 is 100-110 ℃, and the time is 12-24 h.

6. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, The drying temperature in S4 is 100-110 ℃, and the time is 12-24 h; the calcination temperature is 350-450 ℃, and the time is 3-5 h.

7. The method for preparing the Cu-Fe-Ti based catalytic filter tube according to claim 1, characterized in that, The target load of the filter tube in S4 is: the mass growth rate of the filter tube after drying is 20-35 Wt.

8. The Cu-Fe-Ti based catalytic filter tube prepared by the method according to any one of claims 1-7.

9. The application of the Cu-Fe-Ti based catalytic filter tube as described in claim 8 in denitrification.

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