Medium-low temperature phosphorus-containing cerium-manganese-copper-tin composite denitration catalyst and preparation method thereof

Abstract

The invention discloses a medium and low temperature type phosphorus-containing cerium manganese copper tin composite denitration catalyst. The catalyst is composed of cerium phosphate, manganese oxide, copper oxide and tin oxide. The preparation method of the catalyst comprises the following steps: 1, adding cerous nitrate into a pyrophosphoric acid aqueous solution, and uniformly stirring to obtain a solution A; 2, adding urea to obtain a solution B; 3, carrying out hydrothermal reaction to obtain a phosphate product C; 4, pouring manganese acetate, copper acetate and a tin tetrachloride solution into the phosphate product C for dipping to obtain a compound D; and 5, drying and roasting the compound D to obtain the catalyst. The catalyst disclosed by the invention has excellent catalytic activity, a wide temperature window and a relatively high removal rate on nitrogen oxides in medium and low temperature regions; according to the invention, a hydrothermal synthesis method is combined with an impregnation method, so that the catalyst has larger specific surface area and surface acidity, the activity of the catalyst is improved, the catalyst has better water resistance and sulfur resistance, the preparation process is simple, the raw materials are easy to obtain, and the catalyst is easy to popularize and apply.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a medium-low temperature type phosphorus-containing cerium-manganese-copper-tin composite denitration catalyst and a preparation method thereof. Background Art

[0002] Nitrogen oxides are mainly generated by the high-temperature combustion of fossil fuels in the air. The nitrogen oxides generated by the combustion of mineral fuels (oil, coal, and natural gas) account for more than 90%. With the rapid development of industry, excessive nitrogen oxides emitted from automobile exhaust and coal-fired flue gas have caused great pollution to the atmosphere, and the concentration of nitrogen oxides has increased year by year; NO can produce chemical smog under sunlight, which poses a great threat to the human respiratory system; at the same time, it can damage the atmosphere and indirectly form acid rain. NH 3 -SCR is the most widely used and mature NOx removal technology. Its catalyst VW-Ti has a high denitrification rate and good sulfur resistance. However, its temperature window (350℃~400℃) is narrow. When the temperature is higher than 400℃, a large amount of N 2 O causes secondary pollution, the denitrification effect of low-temperature catalysts is poor, and the active component V of the catalyst is a toxic substance. In view of this, the research and development of new non-vanadium system catalysts is very necessary.

[0003] Chinese patent CN1166438C discloses a nitrogen oxide purification catalyst, the main components of which are Fe-Mo / ZSM-5 molecular sieve. -1 ~80000h -1 The removal rate of nitrogen oxides at a temperature of 400°C reached more than 96%, and the catalyst was not deactivated after 50 hours, but its activity was low below 400°C. Chinese patent CN101642715A discloses a cerium pyrophosphate catalyst, which has a high denitration efficiency above 350°C, but has poor catalytic activity below 350°C. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a medium-low temperature type phosphorus-containing cerium manganese copper-tin composite denitrification catalyst in view of the above-mentioned deficiencies of the prior art. 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 The composition effectively increases the specific surface area and surface acidity of the catalyst, ensuring that the catalyst has excellent catalytic activity and a wide temperature window, solving the problems of poor low-temperature removal effect and narrow temperature window in existing denitrification catalysts.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a medium-low temperature type phosphorus-containing cerium manganese copper-tin composite denitrification catalyst, characterized in that the catalyst is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.06~0.14.

[0006] The above-mentioned medium-low temperature type phosphorus-containing cerium manganese copper tin composite denitrification catalyst is characterized in that the CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.08.

[0007] At the same time, the present invention also discloses a method for preparing the above-mentioned medium-low temperature type phosphorus-containing cerium manganese copper-tin composite denitrification catalyst, characterized in that the method comprises the following steps:

[0008] Step 1, dissolving cerous nitrate in deionized water and stirring evenly, then adding into a container filled with pyrophosphoric acid aqueous solution and stirring evenly to obtain solution A;

[0009] Step 2: adding urea to the solution A obtained in step 1 until it is completely dissolved to obtain solution B; the molar ratio of pyrophosphoric acid and cerous nitrate in the pyrophosphoric acid aqueous solution in step 1 to the urea added in step 2 is 0.5:1:10;

[0010] Step 3: Place the solution B obtained in step 2 in a hydrothermal reactor, perform a hydrothermal reaction at 110°C to 150°C for 12h to 48h, filter the hydrothermal reaction system after cooling to room temperature, wash the filtered precipitate product with water, dry it in an oven at 80°C to 130°C for 10h to 48h, and then heat it to 400°C to 600°C at a heating rate of less than 20°C / min and calcine it for 4h to 6h to obtain a phosphate product C, i.e., CePO 4 ;

[0011] Step 4: dissolving manganese acetate, copper acetate and tin tetrachloride in deionized water and stirring evenly, then pouring into the phosphate product C in the evaporating dish for impregnation, and after complete impregnation, placing the evaporating dish in an oven at 35° C. to 60° C. and continuing to impregnate for 12 h to 48 h to obtain a composite D;

[0012] Step 5: Place the composite D obtained in step 4 in an oven at 80°C to 130°C and dry for 10h to 48h, then heat to 400°C to 600°C at a heating rate of less than 20°C / min and calcine for 4h to 6h to obtain a phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst.

[0013] The above method is characterized in that the temperature of the hydrothermal reaction in step three is 130° C. and the time is 20 hours.

[0014] The above method is characterized in that the drying temperature in step 3 is 120° C. and the drying time is 16 hours.

[0015] The above method is characterized in that the calcination temperature in step 3 is 500° C. and the calcination time is 4 hours.

[0016] The above method is characterized in that the immersion temperature in step 4 is 40° C. and the time is 24 hours.

[0017] The above method is characterized in that the drying temperature in step 5 is 120° C. and the drying time is 16 hours.

[0018] The above method is characterized in that the temperature of the continued roasting in step 5 is 500° C. and the time is 4 hours.

[0019] The above method is characterized in that the nitrogen oxide conversion rate of the phosphorus-cerium-manganese-copper-tin composite denitrification catalyst in step 5 reaches more than 90% in the medium and low temperature range of 100°C to 400°C.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The catalyst of the present invention is controlled by cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 The composition effectively increases the specific surface area and surface acidity of the catalyst, ensuring that the catalyst has excellent catalytic activity and a wide temperature window, and has a high removal rate for nitrogen oxides in the medium and low temperature range of 100°C to 400°C.

[0022] 2. The catalyst composition of the present invention does not contain any toxic V-containing components, thus avoiding damage to the environment and being safer and more environmentally friendly.

[0023] 3. The present invention prepares cerium phosphate (CePO) by hydrothermal synthesis 4) carrier, and then combined with the impregnation method to prepare the phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst. This preparation method is conducive to the dispersion of the active components, so that the catalyst has a larger specific surface area and surface acidity, which is conducive to improving the activity of the catalyst. Therefore, the catalyst has a higher removal rate for nitrogen oxides in the medium and low temperature range of 100℃ to 400℃, and the stability is similar to that of N 2 The selectivity is high. In addition, the catalyst has good water resistance and sulfur resistance.

[0024] 4. The present invention uses relatively low-priced rare earth elements cerium, tin, manganese oxide and copper oxide as active components, has a simple process, and the raw materials are easily obtained, and is easy to promote and apply.

[0025] 5. The catalyst of the present invention has a nitrogen oxide removal rate of more than 90% in the medium and low temperature range (100°C to 400°C) without causing secondary pollution. In the presence of 5% water vapor, the catalyst continuously reacts at 250°C for 50 hours, and the activity of the catalyst remains above 90%. The catalyst has good water and sulfur resistance.

[0026] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0027] Example 1

[0028] The composite denitration catalyst of this embodiment is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.06.

[0029] The preparation method of the composite denitration catalyst of this embodiment comprises the following steps:

[0030] Step 1, dissolving 6.51 g, i.e. 0.015 mol, of cerium nitrate in deionized water and stirring evenly, then adding the mixture into a container containing a pyrophosphoric acid aqueous solution and stirring evenly to obtain a solution A; the pyrophosphoric acid aqueous solution contains 1.34 g, i.e. 0.0075 mol, of pyrophosphoric acid;

[0031] Step 2: Add 6.00 g (0.1 mol) of urea to the solution A obtained in step 1 until it is completely dissolved to obtain a solution B;

[0032] Step 3: Place the solution B obtained in step 2 in a hydrothermal reactor, perform a hydrothermal reaction at 130°C for 20 hours, cool to room temperature, filter the hydrothermal reaction system, wash the filtered precipitate product with water, dry it in a 120°C oven for 16 hours, and then heat it to 500°C at a heating rate of less than 20°C / min and calcine it for 4 hours to obtain a phosphate product C, i.e., CePO 4 ;

[0033] Step 4: Dissolve 1.12 g of manganese acetate, 0.75 g of copper acetate and 0.31 g of tin tetrachloride in 4 mL of deionized water and stir evenly, then use a rubber-tipped dropper to drop into 3.00 g of phosphate product C in an evaporating dish for impregnation. After complete impregnation, place the evaporating dish in an oven at 40° C. and continue to impregnate for 24 hours to obtain a composite D;

[0034] Step 5: Place the composite D obtained in step 4 in an oven at 120° C. and dry for 16 h, then heat to 500° C. at a heating rate of less than 20° C. / min and calcine for 4 h to obtain a phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst.

[0035] Comparative Example 1

[0036] The catalyst of this comparative example is composed of cerium phosphate CePO 4 composition.

[0037] The preparation method of the composite denitration catalyst of this embodiment is different from that of embodiment 1 in that only step 3 is performed, and the phosphate product C obtained in step 3, i.e., CePO 4 As a catalyst.

[0038] Example 2

[0039] The composite denitration catalyst of this embodiment is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.08.

[0040] The preparation method of the composite denitration catalyst of this embodiment is different from that of Embodiment 1 in that the mass of tin tetrachloride in step 4 is 0.41 g.

[0041] Example 3

[0042] The composite denitration catalyst of this embodiment is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.1.

[0043] The preparation method of the composite denitration catalyst of this embodiment is different from that of Embodiment 1 in that the mass of tin tetrachloride in step 4 is 0.52 g.

[0044] Example 4

[0045] The composite denitration catalyst of this embodiment is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.12.

[0046] The preparation method of the composite denitration catalyst of this embodiment is different from that of Embodiment 1 in that the mass of tin tetrachloride in step 4 is 0.62 g.

[0047] Example 5

[0048] The composite denitration catalyst of this embodiment is composed of cerium phosphate CePO 4 、Manganese oxide Mn 2 O 3 , copper oxide CuO and tin oxide SnO 2 Composition, of which CePO 4 , Mn 2 O 3 , CuO, SnO 2 The mass ratio is 1:0.12:0.1:0.14.

[0049] The preparation method of the composite denitration catalyst of this embodiment is different from that of Embodiment 1 in that the mass of tin tetrachloride in step 4 is 0.72 g.

[0050] Example 6

[0051] The difference between this embodiment and embodiment 1 is that in step 3, the temperature of the hydrothermal reaction is 110°C, the time is 48 hours, the drying temperature is 80°C, the time is 48 hours, and the calcination temperature is 400°C, and the time is 6 hours; in step 4, the immersion temperature is 35°C, and the time is 48 hours; in step 5, the drying temperature is 80°C, the time is 48 hours, and the calcination temperature is 400°C, and the time is 6 hours.

[0052] Example 7

[0053] The difference between this embodiment and embodiment 1 is that in step 3, the temperature of the hydrothermal reaction is 150°C, the time is 12 h, the drying temperature is 130°C, the time is 10 h, and the calcination temperature is 600°C, and the time is 4 h; in step 4, the immersion temperature is 60°C, and the time is 12 h; in step 5, the drying temperature is 130°C, the time is 10 h, and the calcination temperature is 600°C, and the time is 4 h.

[0054] (1) Catalyst activity detection

[0055] The catalysts prepared in Examples 1 to 7 of the present invention and Comparative Example 1 were tableted and ground, and particles with a particle size of 40 to 80 mesh were screened out for activity testing. The test conditions were: NO volume content of 1000 ppm, NH 3 The volume content is 1000ppm, O 2 The volume content is 5%, the volume content of water vapor is 5%, the reaction temperature is 100℃~400℃, and the space velocity is 40000h -1 , the activity test results are shown in Table 1 below.

[0056] Table 1 Catalyst activity for reducing nitrogen oxides at different temperatures

[0057]

[0058] It can be seen from Table 1 above that the catalysts prepared in Examples 1 to 7 have a high efficiency at a space velocity of 40,000 h -1 The removal rate of nitrogen oxides is more than 90% in the temperature range of 100℃ to 400℃, indicating that the catalyst has a higher catalytic activity in the presence of water vapor.

[0059] (2) Catalyst stability test

[0060] The catalysts prepared in Examples 1 to 7 of the present invention and Comparative Example 1 were tableted and ground, and particles with a particle size of 40 to 80 mesh were screened out for stability testing. The test conditions were: NO volume content was 1000 ppm, NH 3 The volume content is 1000ppm, SO 2 The volume content is 100ppm, O 2 Volume content is 5%, air velocity is 40000h-1 , the volume content of water vapor is 5%, and the temperature is 250°C. The reaction is continued for 50 hours. The results show that compared with Comparative Example 1, the conversion rate of nitrogen oxides prepared by the catalysts of Examples 1 to 7 is still maintained at more than 90%, indicating that the catalyst of the present invention has good stability, water resistance and sulfur resistance.

[0061] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A medium-low temperature type phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst, characterized in that: The catalyst consists of cerium phosphate CePO4, manganese oxide Mn2O3, copper oxide CuO and tin oxide SnO2, wherein the mass ratio of CePO4, Mn2O3, CuO and SnO2 is 1:0.12:0.1:0.06-0.

14.

2. A medium-low temperature type phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst according to claim 1, characterized in that: The mass ratio of CePO4, Mn2O3, CuO and SnO2 is 1:0.12:0.1:0.

08.

3. A method for preparing the medium-low temperature type phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: Step 1, dissolving cerous nitrate in deionized water and stirring evenly, then adding into a container filled with pyrophosphoric acid aqueous solution and stirring evenly to obtain solution A; Step 2: adding urea to the solution A obtained in step 1 until it is completely dissolved to obtain solution B; the molar ratio of pyrophosphoric acid and cerous nitrate in the pyrophosphoric acid aqueous solution in step 1 to the urea added in step 2 is 0.5:1:10; Step 3, placing the solution B obtained in step 2 in a hydrothermal reaction kettle, performing a hydrothermal reaction at 110°C to 150°C for 12h to 48h, filtering the hydrothermal reaction system after cooling to room temperature, washing the filtered precipitated product with water, drying it in an oven at 80°C to 130°C for 10h to 48h, and then heating it to 400°C to 600°C at a heating rate of less than 20°C / min and calcining it for 4h to 6h to obtain a phosphate product C, i.e., CePO4; Step 4: dissolving manganese acetate, copper acetate and tin tetrachloride in deionized water and stirring evenly, then pouring into the phosphate product C in the evaporating dish for impregnation, and after complete impregnation, placing the evaporating dish in an oven at 35° C. to 60° C. and continuing to impregnate for 12 h to 48 h to obtain a composite D; Step 5: Place the composite D obtained in step 4 in an oven at 80°C to 130°C and dry for 10h to 48h, then heat to 400°C to 600°C at a heating rate of less than 20°C / min and calcine for 4h to 6h to obtain a phosphorus-containing cerium-manganese-copper-tin composite denitrification catalyst.

4. The method according to claim 3, characterized in that: The temperature of the hydrothermal reaction in step 3 is 130° C. and the time is 20 h.

5. The method according to claim 3, characterized in that: The drying temperature in step 3 is 120° C. and the drying time is 16 h.

6. The method according to claim 3, characterized in that The calcination temperature in step 3 is 500° C. and the calcination time is 4 h.

7. The method according to claim 3, characterized in that The temperature for continued immersion in step 4 is 40° C. and the time is 24 hours.

8. The method according to claim 3, characterized in that The drying temperature in step 5 is 120° C. and the drying time is 16 hours.

9. The method according to claim 3, characterized in that: The calcination temperature in step 5 is 500° C. and the calcination time is 4 h.

10. The method according to claim 3, characterized in that The phosphorus-cerium-manganese-copper-tin composite denitration catalyst described in step 5 has a nitrogen oxide conversion rate of more than 90% in the medium and low temperature range of 100° C. to 400° C.

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