A manganese-based intercalation type ultra-low temperature denitration catalyst and preparation method thereof

Abstract

The present invention relates to a manganese-based intercalation type ultra-low temperature denitration catalyst, wherein the manganese-based intercalation type ultra-low temperature denitration catalyst uses a layered material as a carrier, and the layered material is loaded with manganese ions and iron ions; the manganese ions are located between the layers of the layered material, and the iron ions are located outside the layers of the layered material; the layered material is niobate HNb3O8. The beneficial effects of the present invention are as follows: the present invention selects a three-dimensional layered material with a certain interlayer spacing, and the narrow interlayer channel of the layered material is ≤0.4nm; through delamination-ion exchange, Mn (manganese oxide) is confined in the narrow interlayer channel of the layered material, and the larger molecular sulfur dioxide in the side reaction during denitration cannot enter the interlayer channel, reducing the contact between sulfur dioxide and Mn, and then loading Fe with water resistance on the surface and in the stacking pores by an impregnation method, and a water-resistant and sulfur-resistant dual-function low-temperature denitration catalyst is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection management, especially to the field of ultra-low temperature denitrification with terminal flue gas temperature less than 180°C in waste incineration power plants, cement kilns, steel sintering flue gas, etc. The present invention relates to the preparation of a manganese-based intercalation type ultra-low temperature denitrification catalyst that is resistant to water and sulfur poisoning. Background Art

[0002] With the tightening of environmental protection standards, flue gas denitrification in areas such as waste incineration power plants, cement kilns, and steel sintering flue gas with terminal flue gas temperatures less than 180°C has been put on the agenda. At present, my country has formed SCR denitrification technology and its catalyst system with good application effects in the range of 180-420°C, which effectively solves the flue gas denitrification needs of thermal power and coking industries. However, with the increasingly stringent environmental protection requirements, denitrification in many non-electric industries will face new challenges. In this context, carrying out SCR denitrification treatment on the "clean" flue gas after "dust removal-desulfurization" treatment can effectively alleviate the bottleneck problem of catalyst poisoning caused by the complexity of flue gas components. There is no need to change the boiler body, and the overall cost of the denitrification device can be greatly reduced. Because it is located after the dust removal device, the flue gas has the characteristics of low temperature (≤180°C) and low dust (or low sulfur), which solves the problems of catalyst blockage and wear, reduces maintenance costs, and increases service life.

[0003] The most studied ultra-low temperature denitrification catalyst is the Mn series. The problem with Mn series catalysts is that they are poorly resistant to sulfur and water at low temperatures: first, SO2 and Mn easily form manganese sulfate, which is difficult to decompose at low temperatures, resulting in a decrease in catalyst activity; second, SO2, NH3, H2O, etc. form ammonium bisulfate at low temperatures, which is deposited on the catalyst surface and causes the catalyst to deactivate.

[0004] Domestic application and development of ultra-low temperature denitrification catalysts mainly focuses on MnOx-based catalysts. Usually, by adding additives such as Ce, Cu, La, etc., SO2 preferentially reacts with the additives rather than the active component manganese to form sulfate, thereby improving the catalyst's resistance to water and sulfur poisoning. However, as the additives are consumed, the catalyst life will decrease significantly. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a manganese-based intercalation type ultra-low temperature denitration catalyst and a preparation method thereof.

[0006] This manganese-based intercalation type ultra-low temperature deNOx catalyst uses a layered material as a carrier, and the layered material is loaded with manganese ions and iron ions; before loading, the manganese ions are divalent manganese ions, and the iron ions are trivalent iron ions, and after loading, they exist in the form of MnxOy and FexOy; the manganese ions are located between the layers of the layered material, and the iron ions are located outside the layers of the layered material; the layered material is niobate HNb3O8.

[0007] Preferably, the interlayer spacing of HNb3O8 is 1.13 nm.

[0008] like Figure 1 As shown, the preparation method of this manganese-based intercalation type ultra-low temperature denitration catalyst comprises the following steps:

[0009] Step 1, introducing organic ammonium ions between HNb3O8 layers through intercalation reaction: HNb3O8 is dispersed in water, and an intercalation agent is added to carry out an intercalation reaction; the solid product is filtered and washed to neutrality, and then dried to obtain organic ammonium intercalated niobium acid;

[0010] Step 2, the organic ammonium intercalated niobate is subjected to ion exchange with manganese ions to introduce manganese ions into the interlayer: the organic ammonium intercalated niobate is dispersed in water, and a metal salt of manganese ions is added to perform ion exchange; after the ion exchange is completed, the solid product is filtered, washed and dried, and finally calcined to obtain manganese oxide intercalated niobate;

[0011] Step 3: Loading iron ions by impregnation: dispersing manganese oxide intercalated niobate into water, adding an iron source and then impregnating; after the impregnation, drying and calcining the obtained solid product to finally obtain a manganese-based intercalated ultra-low temperature denitrification catalyst.

[0012] Preferably, the intercalation agent selected for the intercalation reaction in step 1 is tetramethylammonium hydroxide or tetraethylammonium hydroxide, and the molar ratio of the selected intercalation agent to HNb3O8 is 0.2-1; the intercalation reaction time is 1-7 days, and the reaction temperature is 20-60°C.

[0013] Preferably, in step 1, the intercalation agent is 25 wt% tetramethylammonium hydroxide, the ratio of the amount of the intercalation agent to the amount of HNb3O8 is 0.5, the intercalation reaction time is 5 days, the intercalation reaction temperature is 30°C, and the filtered solid product is dried at 105°C for 12 hours.

[0014] Preferably, the metal salt of manganese ion selected in step 2 is manganese acetate, manganese sulfate or manganese nitrate; the molar ratio of the metal salt of manganese ion to the organic ammonium intercalated niobate is 1 to 3; the ion exchange time is 1 to 3 days, and the ion exchange temperature is 20 to 60° C.; the calcination temperature is 300 to 450° C., and the calcination time is 0.5 to 2 h.

[0015] Preferably, the metal salt of manganese ion in step 2 is manganese nitrate, the molar ratio of the metal salt of manganese ion to the organic ammonium intercalated niobate is 1.5, the ion exchange time is 3 days, and the ion exchange temperature is 30°C; the calcination temperature is 450°C, the calcination time is 2h, the drying temperature of the product obtained by ion exchange is 105°C, and the drying time is 12h.

[0016] Preferably, in step 3, the iron source is ferric sulfate or ferric nitrate (preferably trivalent iron ions, and if divalent iron ions are not hydrolyzed, they may enter the interlayer); the molar ratio of the iron source to the manganese oxide intercalated niobate is 0.1 to 1; the impregnation temperature is 20 to 60° C., and the impregnation time is 1 to 12 hours; in step 3, the impregnated solid product is calcined at 300 to 450° C. for 0.5 to 2 hours.

[0017] Preferably, in step 3, the iron source is ferric nitrate; the molar ratio of the iron source to the manganese oxide intercalated niobate is 0.5; the impregnation temperature is 30°C, and the impregnation time is 6 hours; in step 3, the impregnated solid product is calcined at 400°C for 1 hour; the interlayer spacing of the obtained manganese-based intercalated ultra-low temperature denitration catalyst is less than or equal to 1.16nm, wherein the layer thickness of HNb3O8 is 0.75nm, and the interlayer spacing of HNb3O8 is ≤0.41nm. For manganese oxide confined within this interlayer spacing, sulfur dioxide (size 0.411nm) cannot quickly enter the interlayer during denitration, while NO (0.317nm) and NH3 (0.26nm) can react in the interlayer, ensuring that the manganese oxide is not inactivated by sulfation.

[0018] The application of this manganese-based intercalation type ultra-low temperature denitrification catalyst in waste incineration power plants, cement kilns, and steel sintering flue gas: The manganese-based intercalation type ultra-low temperature denitrification catalyst is used as a denitrification catalyst in the denitrification of low-temperature flue gas with a temperature of less than or equal to 180°C.

[0019] The beneficial effects of the present invention are:

[0020] The present invention selects a three-dimensional layered material with a certain interlayer spacing, and the narrow interlayer channel of the layered material is ≤0.4nm; through delamination-ion exchange, Mn (manganese oxide) is confined in the narrow interlayer channel of the layered material, and larger molecular sulfur dioxide in the side reaction during denitrification cannot enter the interlayer channel, thereby reducing the contact between sulfur dioxide and Mn, and then Fe with water resistance is loaded on the surface and in the stacking pores through an impregnation method, thereby obtaining a water-resistant and sulfur-resistant dual-function low-temperature denitrification catalyst.

[0021] The calcination temperature affects the interlayer spacing. Generally speaking, after the exchange, the temperature is high, the arrangement and shape of ions between the layers will be different, and the interlayer spacing will become smaller. The present invention can control the interlayer spacing of the manganese-based intercalation type ultra-low temperature deNOx catalyst by controlling the calcination temperature.

[0022] Traditional vanadium oxides easily oxidize sulfur dioxide into sulfur trioxide to form ammonium bisulfate deposited on the catalyst surface. The present invention does not adopt the traditional method of adding sacrificial additives, but starts from the carrier structure, selects a suitable carrier to load the active component Mn, so that NO and NH3 can enter the reaction, but SO2 cannot enter quickly, ensuring that manganese oxide is not deactivated by sulfation; and then by loading iron (iron oxide) instead of vanadium, the generation of ammonium bisulfate is reduced, while improving the selectivity, the resistance of the entire catalyst system to sulfur and water poisoning is increased, thereby improving the life of the catalyst and the reaction selectivity. The catalyst has good application prospects in ultra-low temperature fields (≤180°C) such as waste incineration power plants, cement kilns, and steel sintering flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram of the preparation process of manganese-based intercalation ultra-low temperature deNOx catalyst. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0025] Embodiment 1

[0026] 1 g of niobic acid was dispersed in 100 ml of water, 0.5 ml of 25 wt% tetramethylammonium hydroxide solution was added, and the mixture was stirred at 30° C. for 5 days, filtered and washed until neutral, and dried at 105° C. for 12 h to obtain organic ammonium intercalated niobic acid.

[0027] 1g of organic ammonium intercalated niobate was dispersed in 100ml of manganese nitrate (3.75mmol Mn 2+ ) in an aqueous solution, stirred at 30°C for 3 days, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 450°C for 2h to obtain manganese oxide intercalated niobate, at which time the interlayer spacing was 0.988nm.

[0028] 1g of manganese oxide intercalated niobic acid was dispersed in 100ml of ferric nitrate (1.25mmol Fe 3+ ) aqueous solution, stirred at 30°C for 6h, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 400°C for 1h to obtain the final manganese oxide intercalated ultra-low temperature denitrification catalyst.

[0029] Embodiment 2

[0030] Disperse 1 g into 100 ml of water, add 0.5 ml of 25 wt% tetraethylammonium hydroxide solution, stir at 30°C for 5 days, filter and wash until neutral, and dry at 105°C for 12 hours to obtain organic ammonium intercalated niobate.

[0031] Disperse 1g of organic ammonium intercalated niobate into 100ml of manganese sulfate (3.75mmol Mn 2+ ) in an aqueous solution, stirred at 30°C for 3 days, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 400°C for 2h to obtain manganese oxide intercalated niobate, at which time the interlayer spacing was 1.017nm.

[0032] 1g of manganese oxide intercalated niobic acid was dispersed in 100ml of ferric sulfate (1.25mmol Fe 3+ ) aqueous solution, stirred at 30°C for 6h, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 400°C for 1h to obtain the final manganese oxide intercalated ultra-low temperature denitrification catalyst.

[0033] Embodiment 3

[0034] 1 g of niobic acid was dispersed in 100 ml of water, 1 ml of 25 wt% tetramethylammonium hydroxide solution was added, and the mixture was stirred at 30° C. for 5 days, filtered and washed until neutral, and dried at 105° C. for 12 h to obtain organic ammonium intercalated niobic acid.

[0035] Disperse 1g of organic ammonium intercalated niobic acid into 100ml of manganese nitrate (5mmol Mn 2+ ) in an aqueous solution, stirred at 30°C for 3 days, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 350°C for 2h to obtain manganese oxide intercalated niobate, at which time the interlayer spacing is 1.100nm.

[0036] 1g of manganese oxide intercalated niobate was dispersed in 100ml of ferric nitrate (2.5mmol Fe 3+ ) aqueous solution, stirred at 30°C for 6h, filtered and washed thoroughly, dried at 105°C for 12h, and calcined at 400°C for 1h to obtain the final manganese oxide intercalated ultra-low temperature denitrification catalyst.

[0037] Summarize:

[0038] The types and amounts of intercalation agents used in Examples 1 to 3 are different, so the amounts of Mn ions exchanged subsequently are also different. The less intercalation agent, the less Mn exchanged. When the solid product of ion exchange between organic ammonium intercalated niobate and manganese ions is calcined, the abilities of organic ammonium ions and Mn ions to combine with HNb3O8 layered materials are different. The temperature of calcining the intercalation reaction product is different. At a low temperature, the interlayer spacing of the obtained organic ammonium intercalated niobate is larger, and at a high temperature, the interlayer spacing of the obtained organic ammonium intercalated niobate is smaller.

Claims

1. A method for preparing a manganese-based intercalation type ultra-low temperature denitration catalyst, characterized in that: The finally obtained manganese-based intercalation type ultra-low temperature denitration catalyst uses a layered material as a carrier, and the layered material is loaded with manganese ions and iron ions; the manganese ions are located between the layers of the layered material, and the iron ions are located outside the layers of the layered material; the layered material is HNb3O8, and the interlayer spacing of HNb3O8 in the finally obtained manganese-based intercalation type ultra-low temperature denitration catalyst is ≤0.41nm; the ultra-low temperature refers to a temperature less than or equal to 180°C; the preparation method of the manganese-based intercalation type ultra-low temperature denitration catalyst comprises the following steps: Step 1, introducing organic ammonium ions between HNb3O8 layers through intercalation reaction: HNb3O8 is dispersed in water, and an intercalation agent is added to carry out an intercalation reaction; the solid product is filtered and washed to neutrality, and then dried to obtain organic ammonium intercalated niobium acid; Step 2, ion exchange between organic ammonium intercalated niobate and manganese ions: dispersing organic ammonium intercalated niobate in water, adding metal salt of manganese ions for ion exchange; after the ion exchange, filtering, washing and drying the solid product, and finally calcining at a calcination temperature of 300 to 450° C. for 0.5 to 2 hours to obtain manganese oxide intercalated niobate; Step 3: Loading iron ions by impregnation: dispersing manganese oxide intercalated niobate into water, adding an iron source and then impregnating; after the impregnation, drying the obtained solid product, calcining at 300-450° C. for 0.5-2 h, and finally obtaining a manganese-based intercalated ultra-low temperature denitrification catalyst.

2. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 1, characterized in that: In step 1, the intercalation agent selected for the intercalation reaction is tetramethylammonium hydroxide or tetraethylammonium hydroxide, and the molar ratio of the selected intercalation agent to HNb3O8 is 0.2-1; the intercalation reaction time is 1-7 days, and the reaction temperature is 20-60°C.

3. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 2, characterized in that: In step 1, the intercalation agent is a 25wt% tetramethylammonium hydroxide solution, the ratio of the amount of the intercalation agent to the amount of HNb3O8 is 0.5, the intercalation reaction time is 5 days, the intercalation reaction temperature is 30°C, and the solid product filtered in step 1 is dried at 105°C for 12h.

4. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 2, characterized in that: The metal salt of manganese ion selected in step 2 is manganese acetate, manganese sulfate or manganese nitrate; the molar ratio of the metal salt of manganese ion to the organic ammonium intercalated niobate is 1 to 3; the ion exchange time is 1 to 3 days, and the ion exchange temperature is 20 to 60°C.

5. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 4, characterized in that: In step 2, the metal salt of manganese ion is manganese nitrate, the molar ratio of the metal salt of manganese ion and the organic ammonium intercalated niobate is 1.5, the ion exchange time is 3 days, in step 2, the ion exchange temperature is 30°C; the calcination temperature is 450°C, the calcination time is 2h, the drying temperature of the product obtained by ion exchange is 105°C, and the drying time is 12h.

6. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 4, characterized in that: In step 3, the iron source is ferric sulfate or ferric nitrate; the molar ratio of the iron source to the manganese oxide intercalated niobate is 0.1 to 1; the immersion temperature is 20 to 60° C., and the immersion time is 1 to 12 hours.

7. The method for preparing the manganese-based intercalation type ultra-low temperature denitration catalyst according to claim 6, characterized in that: In step 3, the iron source is ferric nitrate; the molar ratio of the iron source to the manganese oxide intercalated niobate is 0.5; the impregnation temperature is 30°C, and the impregnation time is 6 hours; in step 3, the impregnated solid product is calcined at 400°C for 1 hour; the layer thickness of HNb3O8 in the obtained manganese-based intercalated ultra-low temperature deNOx catalyst is 0.75nm.

8. An application of a manganese-based intercalation type ultra-low temperature denitration catalyst obtained by the preparation method of the manganese-based intercalation type ultra-low temperature denitration catalyst as claimed in claim 1 in waste incineration power plants, cement kilns or steel sintering flue gas, characterized in that: The manganese-based intercalation type ultra-low temperature denitration catalyst is used as a denitration catalyst in low-temperature flue gas denitration at a temperature of less than or equal to 180°C.

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