Cu-Fe-Ti-based catalytic filter tube as well as preparation method and application thereof

Abstract

The invention discloses a Cu-Fe-Ti-based catalytic filter tube as well as a preparation method and application thereof. The preparation method of the catalytic filter tube comprises the following steps: S1, crushing, grinding and screening siderite; s2, dispersing a copper source, a titanium source and siderite screened in S1 into deionized water to obtain a mixed solution; s3, adding ammonia water into the mixed solution in the S2 until the mixed solution is completely precipitated, stirring, aging, filtering, washing, drying and calcining to obtain a catalyst; and S4, grinding the catalyst in S3, dispersing the ground catalyst in deionized water to obtain catalyst slurry, putting the filter tube into the catalyst slurry for dipping, and then drying and calcining to obtain the Cu-Fe-Ti-based catalytic filter tube. The Cu-Fe-Ti-based catalytic filter tube prepared by the invention has good denitration activity and water and sulfur resistance, and shows the NO conversion rate of more than 90% within the range of 200-400 DEG C; when the catalyst is continuously operated for 4 hours at 225 DEG C in the presence of H2O and SO2 at the same time, the NO conversion rate can still be stably kept at 85% or above.

Description

Technical Field

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

[0002] The catalytic filter element technology combines fine filtration with catalytic removal. It is a new multifunctional material that integrates mechanical filtration and dust removal with selective catalytic denitration. The catalytic filter element is made of dense fibers stacked in an interlaced manner. The developed pore structure provides sufficient attachment points for the loading of the SCR denitration catalyst. When the dusty exhaust gas passes through the catalytic filter element, the dust is intercepted on the outside of the filter element, and NO x It will be catalytically reduced to N2 and H2O by the internal catalyst. When matched with the front-end dry desulfurization, it can remove SO2, dust, NO in the flue gas at the same time. x , hydrogen chloride, hydrogen fluoride and other pollutants. It effectively solves the problems of cumbersome processes, large floor space, high operation and maintenance costs in traditional series technology. In addition, the catalytic filter element is also resistant to high temperature and corrosion, 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 element is equipped with VW / Ti series catalysts, but the disadvantages of vanadium-titanium catalysts are increasingly prominent, such as high and narrow temperature windows, susceptibility to alkali metal / H2O / SO2 poisoning and biological toxicity. Therefore, the development of a catalytic filter element with high activity, wide temperature range, low cost, and green environmental protection has high practical significance and application value. Summary of the invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a Cu-Fe-Ti based catalytic filter tube, a preparation method and an application thereof. The catalytic filter tube has high denitrification activity and water and sulfur resistance, and has low production cost, simple operation, and is green and environmentally friendly, and has good application prospects.

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

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

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

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

[0008] S4: Grind the S3 catalyst and disperse it in deionized water to obtain a catalyst slurry. Dip the filter tube into the catalyst slurry, and then dry and calcine to obtain a Cu-Fe-Ti based catalytic filter tube.

[0009] Preferably, the siderite contains the following elements in mass fractions: 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; and the titanium source is anhydrous titanium sulfate.

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

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

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

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

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

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

[0018] Beneficial technical effects of the present invention:

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

[0020] (2) The present invention uses TiO2 with strong chemical stability and large specific surface area as a carrier, and Cu and siderite as active sources to construct a Cu-Fe-Ti composite denitrification catalyst. After high-temperature calcination of siderite, it decomposes with FeCO3 to produce a large number of nanocracks, which increases the specific surface area of ​​the catalyst and significantly enhances the adsorption performance. In an isolated system of Fe-Ti two phases, the introduction of the third phase element Cu will disrupt the original electron cycle between Fe and Ti, thereby forming a new balance between the three phases of Fe-Cu-Ti. The presence of Cu causes Ti 4+ The deviation of the electron cloud of the species makes Ti 4+ Species from Fe2+ The species "plunders" more electrons, forming a larger electron cloud density; according to the law of conservation of charge, the Fe 2+ The electron-deficient environment will be formed around the species, thus promoting more Fe 3+ This will improve the oxidation performance and acidity of the catalyst surface, thereby enhancing the denitrification effect of the catalyst at a lower temperature. 2+ Species will also gain some electrons, allowing the formation of more CuO-Cu2O structures and promoting the formation of oxygen adsorbed on the catalyst surface. 3+ It will act as a "sacrificial site" to preferentially react with SO2 to form Fe2(SO4)3, which will weaken the oxidation ability of the catalyst to a certain extent. 2 4 - It will enhance the acidity at the Fe site, ensuring that the catalyst still has good denitrification performance in the presence of SO2.

[0021] (3) The present invention uses a high temperature and corrosion resistant ceramic fiber filter tube as a matrix and synthesizes a Cu-Fe-Ti catalytic filter tube by an impregnation method. Its unique fibrous support structure can effectively improve the dispersion and loading rate of the catalyst and effectively reduce the poisoning effect of H2O / SO2 / alkali metal on the catalyst inside the filter element.

[0022] (4) The raw materials of the present invention are low in price, the preparation method is simple, and there is no secondary pollution. This provides a new idea for the comprehensive utilization of siderite mineral resources and the industrial promotion of catalytic filter element technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 TEM image of the catalyst proposed in the present invention;

[0024] Figure 2 The XRD diagram of the catalyst proposed in the present invention;

[0025] Figure 3 The SEM images of the catalytic filter tube proposed in the present invention; (a) before loading the catalyst, (b) after loading the catalyst;

[0026] Figure 4 A comparison chart of the catalytic activities of the Cu-Fe-Ti powder catalyst proposed in the present invention and Cu-Ti and Fe-Ti catalysts;

[0027] Figure 5 This is a curve diagram showing the catalytic activity of the catalytic filter tube proposed by the present invention changing with the reaction temperature;

[0028] Figure 6The present invention provides a comparison chart of the water and sulfur resistance of the Cu-Fe-Ti catalytic filter tube and the Cu-Ti and Fe-Ti catalytic filter tubes at 225°C. DETAILED DESCRIPTION

[0029] The present invention will be further explained below in conjunction with specific embodiments.

[0030] Example 1

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

[0032] S1: crush and grind the siderite and then sieve it through a 200-mesh standard sample sieve;

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

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

[0035] S4: The solid in S3 was placed in an oven, dried at 105°C for 12 h, taken out, and calcined at 350°C for 4 h in a muffle furnace. After cooling, the solid was placed in a pot-type ball mill and ground at 120 r / min for 4 h.

[0036] S5: The catalyst in S4 is added to deionized water to prepare a uniform slurry, which is then placed in a filter tube. After ultrasonic treatment, the slurry is dried and calcined at 350° C. for 4 h to obtain a Cu-Fe-Ti based catalytic filter tube with a target loading of 30 wt.%.

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

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

[0039]

[0040] Among them, [NO] in and [NO] out Represent the inlet and outlet concentrations of NO, ppm, respectively.

[0041] Example 2

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

[0043] Example 3

[0044] The raw materials used in Example S2 are Ti(SO4)2+siderite, and the other conditions are the same as those in Example 1.

[0045] Example 4

[0046] The raw materials used in Example S2 are CuSO4·5H2O+siderite, and the other conditions are the same as those in Example 1.

[0047] The TEM image of the powdered Cu-Fe-Ti catalyst prepared by the present invention is as follows: Figure 1 As shown. After calcination, the siderite on the TiO2 carrier decomposes to produce a large number of nanocracks, and the CuOx microcrystals are evenly distributed on the catalyst surface. In order to determine the active components of the catalyst, the Cu-Fe-Ti catalyst proposed in the present invention was subjected to XRD crystal phase analysis. Figure 2 As shown. After calcination at 350℃, the XRD spectrum shows obvious anatase TiO2 characteristic peaks, and the FeCO3 crystal phase transforms into a highly active α-Fe2O3 phase. In addition, CuOx mainly exists in the form of CuO and Cu2O. The lower peak intensity indicates that CuOx is well dispersed on the catalyst surface. Figure 3 From the comparison chart before and after the ceramic filter tube is loaded with Cu-Fe-Ti catalyst, it can be seen that the catalyst particles after ball milling are evenly loaded on the ceramic fiber, which improves the exposure rate and utilization rate of the catalyst active sites while ensuring the high air permeability of the catalytic filter tube.

[0048] Figure 4 The catalytic activity comparison diagram of the Cu-Fe-Ti powder catalyst proposed in the present invention and the 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% in the range of 175-375°C and a NO conversion rate of nearly 100% in the range of 200-350°C. The catalytic activity of the catalytic filter tube prepared in Examples 1-4 of the present invention changes with the reaction temperature. Figure 5As shown. It can be seen that the Cu-Fe-Ti based catalytic filter tube prepared in Example 1 has a 100% NO conversion rate in the range of 250-375°C. In Example 2, after reducing the surface velocity to 0.6 m / min, the range of 100% NO conversion rate of the Cu-Fe-Ti based catalytic filter tube is expanded to 200-400°C. The catalytic filter tubes prepared with Cu-Ti and Fe-Ti catalysts corresponding to Examples 3 and 4 have lower denitration effects than the Cu-Fe-Ti based catalytic filter tube under the same conditions.

[0049] Figure 6 The catalytic activity of the catalytic filter tubes prepared in Example 1, Example 3 and Example 4 is affected by H2O and SO2 at a reaction temperature of 225°C. It can be seen that when 10 vol.% H2O and 100 ppm SO2 are introduced continuously at 225°C for 4 hours, the Cu-Fe-Ti based catalytic filter tube always maintains a NO removal rate of more than 85%, and has good water and sulfur resistance.

Claims

1. A method for preparing a Cu-Fe-Ti based catalytic filter tube, characterized in that: The steps are as follows: S1: Crushing, grinding and screening of siderite; S2: dispersing the copper source, titanium source and the siderite screened in S1 in deionized water to obtain a mixed solution; S3: adding ammonia water to the mixed solution of S2 until complete precipitation, stirring, aging, filtering, washing, drying and calcining to obtain a catalyst; S4: Grind the S3 catalyst and disperse it in deionized water to obtain a catalyst slurry, immerse the filter tube in the catalyst slurry, and then dry and calcine to obtain a Cu-Fe-Ti based catalytic filter tube.

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 mass ratio of the copper source, the siderite and the titanium source is 0.05-0.25:0.1-0.2:

1.

4. 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.

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

6. 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°C and the time is 12-24h; the calcination temperature is 350-450°C and the time is 3-5h.

7. 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°C and the time is 12-24h; the calcination temperature is 350-450°C and the time is 3-5h.

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

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

10. Use of the Cu-Fe-Ti based catalytic filter tube according to claim 9 in denitration.

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