Preparation method of CO oxidation catalyst, obtained catalyst and application

Abstract

The invention relates to a preparation method of a CO oxidation catalyst, the obtained catalyst and application, in particular to the field of catalysts.The preparation method comprises the steps that ferric salt, alkali, water and auxiliaries are mixed and then subjected to a hydrothermal reaction, and the CO oxidation catalyst is obtained through solid-liquid separation; wherein the auxiliary agent comprises one or a combination of at least two of formamide, acetamide and nicotinamide. According to the preparation method provided by the invention, the specific auxiliary agent is introduced in the preparation process, so that the preparation of the high-performance CO oxidation catalyst is realized, the obtained catalyst has relatively low activation temperature, good stability and efficient catalytic effect, and catalytic oxidation of CO can be carried out at the temperature of more than or equal to 100 DEG C.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a method for preparing a CO oxidation catalyst, the obtained catalyst and uses thereof, and in particular to a method for preparing a size-adjustable CO oxidation catalyst, the obtained catalyst and uses thereof. Background Art

[0002] Currently, the catalytic oxidation of carbon monoxide (CO) is an important reaction in the field of catalysis. Its importance is reflected in two aspects.

[0003] On the one hand, this reaction is often used as a model probe reaction to elucidate some basic catalytic science issues such as catalyst structure-activity relationship and reaction active sites.

[0004] On the other hand, the flue gas generated by the sintering process of steel plants contains a large amount of carbon monoxide. Steel plants generally use SDA desulfurization (or activated carbon desulfurization) and SCR denitrification. The inlet temperature of the SCR denitrification catalyst is required to be greater than 280°C, while the flue gas temperature after passing through the GGH heat exchanger is about 250°C. Mixed coal gas needs to be added to increase the temperature by about 30°C, which consumes a lot of coal gas.

[0005] For example, CN118416690A discloses a system and method for removing CO from sintering flue gas, which belongs to the field of pollutant emission reduction and waste heat utilization in the sintering process, and includes a semi-dry desulfurization process reactor, a GGH heat exchanger, a precious metal catalytic oxidation reactor, a hot blast furnace, and an SCR reactor connected in sequence. The precious metal catalytic oxidation reactor is connected to the SCR reactor through a heat exchanger, and the SCR reactor is connected to the GGH heat exchanger. This scheme effectively solves the problem of CO removal from flue gas according to the characteristics of sintering flue gas; this scheme adjusts the temperature of the flue gas after CO catalytic oxidation according to the process characteristics of sintering flue gas temperature, CO concentration, flue gas desulfurization and denitrification, so as to stabilize the temperature entering the SRC reactor, and at the same time make full use of the heat of CO catalytic oxidation reaction.

[0006] The smoke contains about 6000mg / m 3 If catalytic oxidation technology is used to treat carbon monoxide, the heat released when carbon monoxide is oxidized to carbon dioxide can heat the flue gas and save the use of mixed coal gas. Therefore, the development of efficient CO oxidation catalysts has attracted much attention.

[0007] However, traditional catalyst preparation methods have problems such as wide particle size distribution, uneven size, and difficulty in achieving high control of multi-dimensional structure, which limits the improvement of catalyst performance and the expansion of its application range. Therefore, a preparation method is urgently needed to regulate the size of the catalyst while ensuring the stability of the catalyst morphology. Summary of the invention

[0008] In view of the problems existing in the prior art, the object of the present invention is to provide a method for preparing a CO oxidation catalyst, the obtained catalyst and its use, so as to solve the problems of poor catalytic performance and wide and non-uniform catalyst particle size distribution of the current catalyst for CO oxidation catalysis.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing a CO oxidation catalyst, the preparation method comprising:

[0011] The iron salt, alkali, water and an additive are mixed, and then a hydrothermal reaction is carried out, and a CO oxidation catalyst is obtained by solid-liquid separation;

[0012] Wherein, the auxiliary agent includes one or a combination of at least two of formamide, acetamide or nicotinamide.

[0013] The preparation method provided by the present invention realizes the preparation of a high-performance CO oxidation catalyst by introducing a specific auxiliary agent during the preparation process. The obtained catalyst has a low activation temperature, good stability and a high-efficiency catalytic effect, and can catalytically oxidize CO at a temperature of ≥100°C.

[0014] As a preferred technical solution of the present invention, the iron salt includes one or a combination of at least two of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, hydrated ferric chloride, hydrated ferric sulfate, hydrated ferric nitrate or hydrated ferric acetate.

[0015] As a preferred technical solution of the present invention, the alkali includes one or a combination of at least two of sodium hydroxide, ammonia water, potassium hydroxide, urea, sodium carbonate or sodium bicarbonate.

[0016] As a preferred technical solution of the present invention, the mass ratio of the alkali to the iron salt is (1-2):(1-3).

[0017] As a preferred technical solution of the present invention, the mass ratio of the auxiliary agent to the iron salt is (1-2):(1-3).

[0018] As a preferred technical solution of the present invention, the mass ratio of water to iron salt is (20-100):1.

[0019] As a preferred technical solution of the present invention, the temperature of the hydrothermal reaction is 50-500°C.

[0020] Preferably, the hydrothermal reaction time is 2-48h.

[0021] In a second aspect, the present invention provides a CO oxidation catalyst, which is obtained by the preparation method described in the first aspect.

[0022] In a third aspect, the present invention provides a CO catalytic oxidation method, which comprises: performing catalytic oxidation using the CO oxidation catalyst obtained by the preparation method described in the first aspect.

[0023] As a preferred technical solution of the present invention, the starting temperature of the catalytic oxidation is ≥100°C.

[0024] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0025] (1) The preparation method provided by the present invention regulates the growth process of the catalyst by controlling the type and amount of the additive. The addition of the additive can form a chemical bond with the surface of the iron atom, reduce the surface energy of the crystal face during the crystallization process, and then control the size of the catalyst growing during the forming process, thereby enhancing the catalyst size effect, thereby achieving the purpose of enhancing the catalytic activity of the catalyst, and achieving a higher oxidation of CO at a lower temperature.

[0026] (2) The CO oxidation catalyst obtained by the present invention has a good catalytic effect on CO. By controlling the type and addition amount of the auxiliary agent, the CO oxidation catalysts of different particle sizes have different catalytic effects. Among them, the 20nm CO oxidation catalyst can be oxidized and catalyzed at a temperature ≥100°C, and 100% conversion of CO can be achieved at a temperature of 180°C; the 50nm CO oxidation catalyst can be oxidized and catalyzed at a temperature ≥130°C, and 100% conversion of CO can be achieved at a temperature of 210°C; the 80nm CO oxidation catalyst can be oxidized and catalyzed at a temperature ≥150°C, and 100% conversion of CO can be achieved at a temperature of 240°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a SEM photograph of the CO oxidation catalyst obtained in Example 1 of the present invention (corresponding to a particle size of 80 nm);

[0028] Figure 2 is a SEM photograph of the CO oxidation catalyst obtained in Example 4 of the present invention (corresponding to a particle size of 50 nm);

[0029] Figure 3 is a SEM photograph of the CO oxidation catalyst obtained in Example 5 of the present invention (corresponding to a particle size of 20 nm);

[0030] Figure 4 is the XRD diagram of the CO oxidation catalyst obtained in Examples 1, 4 and 5 of the present invention;

[0031] Figure 5 is a catalytic CO oxidation activity diagram of the CO oxidation catalysts obtained in Examples 1, 4, and 5 of the present invention;

[0032] Figure 6 This is a stability test chart of the CO oxidation catalyst obtained in Example 1 of the present invention.

[0033] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0034] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0035] This embodiment provides a method for preparing a CO oxidation catalyst, the preparation method comprising:

[0036] The iron salt, alkali, water and an additive are mixed, and then a hydrothermal reaction is carried out, and a CO oxidation catalyst is obtained by solid-liquid separation;

[0037] In the present invention, the iron salt, alkali, water and auxiliary agent can be mixed by direct mixing, or the iron salt and part of the water are configured as an iron salt solution, the alkali and part of the water are configured as an alkaline solution, and then the iron salt solution, the alkaline solution and the auxiliary agent are mixed, or the iron salt and water are configured as a solution, and then the alkali and the auxiliary agent are added to the solution, etc., and the mixing process is to ensure that the solution is mixed evenly after mixing. The specific mixing can be carried out by stirring, oscillating, ultrasonic, shearing and the like.

[0038] The iron salt includes one or a combination of at least two of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, hydrated ferric chloride, hydrated ferric sulfate, hydrated ferric nitrate or hydrated ferric acetate.

[0039] Illustratively, the combination of iron salts includes: a combination of ferric chloride and ferric sulfate, a combination of ferric sulfate and ferric nitrate, a combination of ferric nitrate and ferric acetate, and the like.

[0040] Wherein, the alkali includes one or a combination of at least two of sodium hydroxide, ammonia water, potassium hydroxide, urea, sodium carbonate or sodium bicarbonate.

[0041] In the present invention, the mass concentration of the ammonia water used is 3-50 mg / mL, for example, it can be 3 mg / mL, 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, 40 mg / mL, 45 mg / mL or 50 mg / mL, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0042] Illustratively, the combination of bases includes: a combination of sodium hydroxide and aqueous ammonia, a combination of potassium hydroxide and urea, a combination of urea and sodium carbonate, a combination of sodium carbonate and sodium bicarbonate, and the like.

[0043] Wherein, the auxiliary agent includes one or a combination of at least two of formamide, acetamide or nicotinamide.

[0044] Exemplarily, combinations of adjuvants include: a combination of formamide and acetamide, a combination of acetamide and nicotinamide, a combination of formamide and nicotinamide, a combination of formamide, acetamide and nicotinamide, and the like.

[0045] Among them, the mass ratio of the base and the iron salt is (1-2):(1-3), for example, it can be 1:1, 1:2, 1:3, 2:1 or 2:3, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0046] Among them, the mass ratio of the auxiliary agent to the iron salt is (1-2):(1-3), for example, it can be 1:1, 1:2, 1:3, 2:1 or 2:3, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0047] Within the mass ratio range of the auxiliary agent to the iron salt defined in the present invention, as the amount of amide added increases, the particle size of the obtained CO oxidation catalyst gradually increases.

[0048] Wherein, the mass ratio of water to iron salt is (20-100):1, for example, it can be 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1 or 100:1, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0049] In the present invention, the mass ratio of alkali to iron salt, the mass ratio of auxiliary agent to iron salt, and the mass ratio of water to iron salt are all mass ratios to the corresponding hydrated iron salt.

[0050] Wherein, the temperature of the hydrothermal reaction is 50-500°C, for example, it can be 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0051] Wherein, the time of the hydrothermal reaction is 2-48h, for example, it can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0052] The CO oxidation catalyst obtained by solid-liquid separation can be selectively washed with water and / or alcohol, then dried, and then optionally ground or pulverized to obtain CO oxidation catalyst powder.

[0053] Furthermore, the present invention provides a CO oxidation catalyst, which is obtained by the above-mentioned preparation method.

[0054] The obtained CO oxidation catalyst can be selectively loaded on a carrier for use, and the carrier used is, for example, a cordierite carrier.

[0055] Illustratively, the process of loading the CO oxidation catalyst on the cordierite carrier is as follows: the CO oxidation catalyst is coated on the cordierite carrier, and then calcined to obtain the catalyst.

[0056] Wherein, the calcination temperature is 400-600°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0057] The calcination time is 4-6h, for example, 4h, 4.2h, 4.4h, 4.6h, 4.8h, 5h, 5.2h, 5.4h, 5.6h, 5.8h or 6h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0058] Wherein, the calcination is carried out in an air atmosphere.

[0059] Furthermore, the present invention provides a CO catalytic oxidation method, which comprises: using the CO oxidation catalyst obtained by the above-mentioned preparation method to perform catalytic oxidation.

[0060] Wherein, the starting temperature of the catalytic oxidation is ≥100°C.

[0061] Further, in order to illustrate the good catalytic effect of the CO oxidation catalyst prepared by the present invention on CO, the following practical examples are used for illustration, as follows:

[0062] Example 1

[0063] This embodiment provides a method for preparing a CO oxidation catalyst, which is as follows:

[0064] 5 g of ferric nitrate nonahydrate and 3.6 g of urea were mixed and added to 150 mL of polytetrafluoroethylene liner, followed by 120 mL of deionized water, and completely dissolved by magnetic stirring. After complete dissolution, stirring was continued for 10 min, and then 5 g of formamide liquid was added dropwise to the mixture. After the addition was completed, stirring was continued for 30 min to fully mix and dissolve;

[0065] The polytetrafluoroethylene liner was then sealed in a stainless steel high-pressure hydrothermal autoclave and reacted at 120°C for 24 hours. After the reaction, the temperature was naturally lowered to room temperature (25°C). The reaction solution was taken out, and the solid-liquid separation of the reaction solution was performed by high-speed centrifugation. The reaction solution was then washed three times by alternating centrifugation with deionized water and ethanol.

[0066] The final sample was placed in a drying oven at 80° C. and dried overnight. After drying, it was taken out and ground into powder to obtain a CO oxidation catalyst.

[0067] Example 2

[0068] This embodiment provides a method for preparing a CO oxidation catalyst, which is as follows:

[0069] 5g of ferric sulfate nonahydrate and 5g of sodium hydroxide were mixed and added to 150mL of polytetrafluoroethylene liner, followed by 120mL of deionized water, and completely dissolved by magnetic stirring. After complete dissolution, stirring was continued for 10min, and then 2.5g of acetamide liquid was added dropwise to the mixture. After the addition was completed, stirring was continued for 30min to fully mix and dissolve;

[0070] The polytetrafluoroethylene liner was then sealed in a stainless steel high-pressure hydrothermal autoclave and reacted at 80°C for 48 hours. After the reaction was completed, the temperature was naturally lowered to room temperature (25°C). The reaction solution was taken out, and the solid-liquid separation of the reaction solution was performed by high-speed centrifugation. The reaction solution was then washed three times by alternating centrifugation with deionized water and ethanol.

[0071] The final sample was placed in a drying oven at 80° C. and dried overnight. After drying, it was taken out and ground into powder to obtain a CO oxidation catalyst.

[0072] Example 3

[0073] This embodiment provides a method for preparing a CO oxidation catalyst, which is as follows:

[0074] 5g of ferric chloride hexahydrate and 10g (ammonia water, mass concentration of 40mg / mL) were mixed and added to 150mL of polytetrafluoroethylene liner, followed by 120mL of deionized water, and completely dissolved by magnetic stirring. After complete dissolution, stirring was continued for 10min, and then 1.25g of nicotinamide liquid was added dropwise to the mixture. After the addition was completed, stirring was continued for 30min to fully mix and dissolve;

[0075] The polytetrafluoroethylene liner was then sealed in a stainless steel high-pressure hydrothermal autoclave and reacted at 500°C for 2 hours. After the reaction, the temperature was naturally lowered to room temperature (25°C). The reaction solution was taken out, and the solid-liquid separation of the reaction solution was performed by high-speed centrifugation. The reaction solution was then washed three times by alternating centrifugation with deionized water and ethanol.

[0076] The final sample was placed in a drying oven at 80° C. and dried overnight. After drying, it was taken out and ground into powder to obtain a CO oxidation catalyst.

[0077] Example 4

[0078] The only difference from Example 1 is that the added amount of formamide liquid is controlled to be 2.5 g.

[0079] Example 5

[0080] The only difference from Example 1 is that the added amount of formamide liquid is controlled to be 1.25 g.

[0081] Example 6

[0082] The only difference from Example 1 is that the amount of formamide added is increased to 15 g.

[0083] Comparative Example 1

[0084] The only difference from Example 1 is that the auxiliary agent formamide is not added.

[0085] Comparative Example 2

[0086] The only difference from Example 1 is that formamide is replaced by an equal amount of dimethylacetamide.

[0087] Comparative Example 3

[0088] The only difference from Example 1 is that formamide is replaced by an equal amount of polyvinyl pyrrolidone.

[0089] Comparative Example 4

[0090] The only difference from Example 1 is that formamide is replaced by an equal amount of polyacrylamide.

[0091] Among them, SEM detection and XRD analysis were performed on Example 1, Example 4 and Example 5. The SEM photo of the CO oxidation catalyst obtained in Example 1 is as follows: Figure 1As shown, the SEM photo of the CO oxidation catalyst obtained in Example 4 is as follows Figure 2 As shown, the SEM photo of the CO oxidation catalyst obtained in Example 5 is as follows Figure 3 As shown, Figure 4 1 is the XRD diagram of the CO oxidation catalyst obtained in Examples 1, 4 and 5 of the present invention.

[0092] The CO oxidation catalyst prepared in the above example was uniformly loaded onto the cordierite carrier by a coating machine, then dried at 120°C for 12 hours, and then calcined at 500°C in air for 5 hours for anchoring. The prepared cordierite catalyst was loaded into a skid-mounted reaction device for a gradient temperature catalytic reaction (the space velocity was controlled at 15000 h / min during the process). -1 The reaction gas used in the reaction is the tail gas from the steel plant, which is introduced into the skid-mounted device through a side line pipeline for reaction. The catalytic results and related catalyst indicators are shown in Table 1. The catalytic results of Example 1, Example 4, and Example 5 are shown in Table 1. Figure 5 and Figure 6 As shown, it can be seen that the catalyst has excellent catalytic effect and service life.

[0093] Table 1

[0094]

[0095]

[0096] Combined with Table 1, Figure 5 and Figure 6 In the scheme provided by the present invention, under hydrothermal conditions, ferric hydroxide will gradually polymerize to form a crystal nucleus, and as the polymerized ferric hydroxide increases, chemical bonding occurs to generate iron oxide, and the hydroxyl group is removed. As the polymerized iron oxide increases, the crystal size gradually increases. During the crystal growth process, the pH will change the crystal forming method to obtain iron oxide with different morphologies. During the crystal growth process, the crystal will always tend to grow in a situation with lower surface binding energy. In the present invention, an amide-containing auxiliary agent is added to the reaction solution, which can bond with hydrogen ions in the solution under the crystal growth conditions, accelerate the formation of ferric hydroxide, and promote the growth of crystals, thereby ensuring that the obtained CO oxidation catalyst has a good carbon monoxide catalytic oxidation effect.

[0097] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0098] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0099] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a CO oxidation catalyst, characterized in that: The preparation method comprises: The iron salt, alkali, water and an additive are mixed, and then a hydrothermal reaction is carried out, and a CO oxidation catalyst is obtained by solid-liquid separation; Wherein, the auxiliary agent includes one or a combination of at least two of formamide, acetamide or nicotinamide.

2. The preparation method according to claim 1, characterized in that The iron salt includes one or a combination of at least two of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, hydrated ferric chloride, hydrated ferric sulfate, hydrated ferric nitrate or hydrated ferric acetate.

3. The preparation method according to claim 1, characterized in that: The alkali includes one or a combination of at least two of sodium hydroxide, ammonia water, potassium hydroxide, urea, sodium carbonate or sodium bicarbonate.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the alkali to the iron salt is (1-2):(1-3).

5. The preparation method according to claim 1, characterized in that: The mass ratio of the auxiliary agent to the iron salt is (1-2):(1-3).

6. The preparation method according to claim 1, characterized in that: The mass ratio of water to iron salt is (20-100):

1.

7. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 50-500°C; Preferably, the hydrothermal reaction time is 2-48h.

8. A CO oxidation catalyst, characterized in that The CO oxidation catalyst is obtained by the preparation method according to any one of claims 1 to 7.

9. A CO catalytic oxidation method, characterized in that: The CO catalytic oxidation method comprises: performing catalytic oxidation using a CO oxidation catalyst obtained by the preparation method according to any one of claims 1 to 7.

10. The CO catalytic oxidation method according to claim 9, characterized in that: The starting temperature of the catalytic oxidation is ≥100°C.

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