阅读说明：本技术 一种弱晶化整体式锰氧化物催化剂的制备方法及其产品 (Preparation method of weak crystallization monolithic manganese oxide catalyst and product thereof ) 是由 崔大祥 孙瑞涛 赵昆峰 童琴 蔡婷 袁静 于 2020-12-17 设计创作，主要内容包括：本发明公布了一种弱晶化整体式锰氧化物催化剂的制备方法及其产品,利用电沉积方法,以醋酸锰为前驱体,以SDBS为表面活性剂,在整体式泡沫镍基底上原位生长弱晶化锰氧化物。氨水调节前驱体溶液的pH值,提高了催化剂的沉积率,采用SDBS表面活性剂改变了原位生长过程中活性组分与载体之间的相互作用。所得催化剂兼具了弱晶化和低脱落率特性,具有很好的应用前景。(The invention discloses a preparation method of a weakly crystallized monolithic manganese oxide catalyst and a product thereof. The ammonia water is used for adjusting the pH value of the precursor solution, the deposition rate of the catalyst is improved, and the interaction between the active component and the carrier in the in-situ growth process is changed by adopting the SDBS surfactant. The obtained catalyst has the characteristics of weak crystallization and low shedding rate, and has good application prospect.)

1. a preparation method of a weak crystallization monolithic manganese oxide catalyst is characterized in that manganese acetate and a surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) are mixed as a precursor solution by an electrodeposition method, and then weak crystallization manganese oxide is grown in situ on a foamed nickel substrate after ammonia water is added and stirred, and the method comprises the following steps:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water, preparing 0.2M manganese compound solution, magnetically stirring for 30 minutes, adding Sodium Dodecyl Benzene Sulfonate (SDBS) to ensure that the concentration of the doped surfactant in the solution is 0.1M, stirring for 2 hours, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours again to obtain solution A;

(4) putting 40ml of the solution A into a small beaker, respectively connecting a platinum electrode and a calomel electrode with a counter electrode and a reference electrode of an electrochemical workstation, and connecting the cut foam nickel with a working electrode;

(5) simultaneously immersing the foamed nickel, the platinum electrode and the calomel electrode into the small beaker filled with the solution A in the step (4), setting the deposition voltage to be 1.5V and the deposition time to be 600s by adopting a constant-voltage electrodeposition method, starting deposition, and depositing manganese on the foamed nickel;

(6) taking the foam nickel deposited with manganese, placing the foam nickel in a glass dish, and drying the foam nickel in a drying oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foam nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the weak crystallization integral manganese oxide catalyst.

2. A weakly crystallized monolithic manganese oxide catalyst characterized by being prepared according to the method of claim 1.

Technical Field

The invention relates to a preparation method of an integral catalyst, in particular to a preparation method of a weak crystallization integral manganese oxide catalyst and a product thereof.

Background

The problem of air pollution is more and more emphasized by people, and the problem of air pollution will affect the living environment of human beings and the health of human beings, so how to effectively reduce air pollution is an urgent problem to be solved. At present, the catalytic method is an effective method for solving the problem of air pollution, and the catalytic method is to convert harmful gas into other substances so as to reduce the air pollution, so that how to prepare an effective pollution-free catalyst and modify the catalyst are widely concerned by the industry.

At present, the monolithic catalyst is widely used for harmful gas catalysts, the monolithic catalyst combines a catalytic active material with a carrier, and has strong interaction with the carrier, because compared with the traditional powder catalyst, the monolithic catalyst is not easy to fall off and agglomerate, and is beneficial to recovery.

Manganese-based catalysts catalyze catalysts with a high content of harmful gases, such as catalytic combustion of propane, removal of benzene, Selective Catalytic Reduction (SCR) of nitric oxide, etc., and thus manganese is considered as a very potential element among transition metal elements. Particularly, the weakly crystallized manganese oxide has more Mn and O defect sites, so that the performance of the weakly crystallized manganese oxide is remarkably improved compared with the manganese oxide with high crystallization degree. Therefore, the weak crystallization is manganese oxide, and is an effective means for improving the catalytic performance of the manganese oxide.

However, the formation of monolithic catalysts often requires high temperature treatment to remove the binder and pore former and enhance the interaction of the active components with the monolithic support. Therefore, weak crystallization and low exfoliation rate are difficult to be compatible. The electrochemical deposition method adopted by the invention is in-situ growth preparation, and the surfactant is used for modifying the manganese-based catalyst so as to reinforce the acting force between the catalyst and the carrier and reduce the falling rate of the catalyst.

Disclosure of Invention

The invention aims to solve the problems of weak crystallization and low shedding rate of an integral catalyst and provides a preparation method of a weak crystallization integral manganese oxide catalyst.

Yet another object of the present invention is to: provides a weak crystallization monolithic manganese oxide catalyst product prepared by the method.

The purpose of the invention is realized by the following scheme: a preparation method of a weak crystallization monolithic manganese oxide catalyst comprises the following steps of mixing manganese acetate and a surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) as a precursor solution by an electrodeposition method, adding ammonia water, stirring, growing the weak crystallization manganese oxide on a foam nickel substrate in situ, and enhancing the interaction between a carrier and the weak crystallization manganese oxide to reduce the falling rate of active components, wherein the preparation method comprises the following steps:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water, preparing 0.2M manganese compound solution, magnetically stirring for 30 minutes, adding Sodium Dodecyl Benzene Sulfonate (SDBS) to ensure that the concentration of the doped surfactant in the solution is 0.1M, stirring for 2 hours, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours again to obtain solution A;

(4) putting 40ml of the solution A into a small beaker, respectively connecting a platinum electrode and a calomel electrode with a counter electrode and a reference electrode of an electrochemical workstation, and connecting the cut foam nickel with a working electrode;

(5) simultaneously immersing foamed nickel, a platinum electrode and a calomel electrode into the small beaker filled with the solution A in the step (4), setting the deposition voltage to be 1.5V and the deposition time to be 600s by adopting a constant-voltage electrodeposition method, starting deposition, and depositing manganese on the foamed nickel;

(6) taking off the foam nickel deposited with manganese, placing the foam nickel in a glass dish, and drying the foam nickel in an oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foam nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the weak crystallization integral manganese oxide catalyst.

The invention also provides a weakly crystallized monolithic manganese oxide catalyst prepared by the method.

The method for calculating the falling rate of the catalyst comprises the following steps: the method comprises the steps of adopting an integral manganese-based catalyst, weighing the catalyst loaded with 0.01g, carrying out ultrasonic treatment for 60 minutes, drying the catalyst, weighing the mass of the catalyst, and calculating the falling amount, wherein the falling rate of the catalyst added with the SDBS is only 1%.

The preparation mechanism of the invention is as follows: and (3) adopting an electrochemical method, taking manganese acetate as a precursor, adding ammonia water and an SDBS surfactant, and growing weak crystallized manganese on the integral foam nickel carrier in situ. The addition of ammonia makes the deposition of manganese oxide easier during electrodeposition. The SDBS surfactant changes the acting force of the catalyst and the carrier and improves the falling problem of the catalyst. The product of the weakly crystallized monolithic manganese oxide catalyst prepared by the method has the characteristics of weak crystallization and low shedding rate, and has a good application prospect in the field of catalysis.

The invention has the following advantages:

1, the product weak crystallization monolithic manganese oxide catalyst obtained by the method has the characteristics of weak crystallization and low shedding rate, and has a good application prospect in the field of catalysis.

And 2, adding ammonia water into the precursor solution, which is beneficial to the generation of intermediate products, thereby improving the deposition rate of manganese.

3, the surfactant SDBS modifies the catalyst, improves the interaction of the active component and the carrier, and improves the falling problem of the monolithic catalyst.

4, the used materials are manganese and nickel, and the general catalyst is noble metal elements such as platinum, rubidium, palladium and the like, so that the production cost of the catalyst is reduced.

Drawings

FIG. 1 is a Raman diagram of catalysts of examples and comparative examples 1 to 3, 651cm^-1The absorption peak is a tensile vibration absorption peak of the Mn-O bond.

Detailed Description

The following examples illustrate the invention in detail: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

Examples

A weak crystallization monolithic manganese oxide catalyst is prepared by mixing manganese acetate and a surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) as a precursor solution by an electrodeposition method, adding ammonia water, stirring, and growing a weak crystallization manganese oxide in situ on a foamed nickel substrate, wherein the weak crystallization monolithic manganese oxide catalyst is prepared by the following steps:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water to prepare a 0.2M manganese acetate solution, measuring 40ml of precursor solution in a 50ml beaker, magnetically stirring for 30 minutes, adding Sodium Dodecyl Benzene Sulfonate (SDBS) to enable the concentration of the SDBS solution to be 0.1M, stirring for 2 hours, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours to obtain a solution A;

(4) connecting a foamed nickel electrode, a platinum electrode and a calomel electrode to a working electrode, a counter electrode and a reference electrode of an electrochemical workstation in sequence;

(5) simultaneously immersing the connected nickel foam, the platinum electrode and the calomel electrode into a small beaker filled with the solution A, keeping the heights of the nickel foam, the platinum electrode and the calomel electrode uniform, adopting a constant voltage electrodeposition method, setting the deposition voltage to be 1.5V and the deposition time to be 600s, starting deposition, and depositing manganese on the nickel foam;

(6) taking down the deposited foam nickel material, and drying in a drying oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foamed nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the weakly crystallized monolithic manganese oxide catalyst which is marked as Mn + SDBS.

The proportion of exfoliation in this example is 1%, see table 1.

FIG. 1 is a Raman diagram of the catalysts of this example and comparative examples 1 to 3, 651cm^-1The absorption peak is a tensile vibration absorption peak of the Mn-O bond. As can be seen from FIG. 1, Mn + SDBS is present at 651cm^-1The absorption peak intensity is very weak, which indicates that Mn + SDBS is a weakly crystallized monolithic manganese oxide catalyst.

Comparative example 1:

a weakly crystallized monolithic manganese oxide catalyst, the other steps (1), (2) and (4) - (7) are the same as the example, except that in step (3), the surfactant is SDS, and the following steps are carried out:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water to prepare a 0.2M manganese acetate solution, measuring 40ml of precursor solution in a 50ml beaker, magnetically stirring for 30 minutes, adding 0.1M SDS, stirring for 2 hours, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours again to obtain a solution A1;

(4) connecting a foamed nickel electrode, a platinum electrode and a calomel electrode to a working electrode, a counter electrode and a reference electrode of an electrochemical workstation in sequence;

(5) simultaneously immersing the connected nickel foam, the platinum electrode and the calomel electrode into a small beaker filled with the solution A1, keeping the heights of the nickel foam, the platinum electrode and the calomel electrode uniform, setting the deposition voltage to be 1.5V and the deposition time to be 600s by adopting a constant voltage electrodeposition method, starting deposition, and depositing manganese on the nickel foam;

(6) taking down the deposited foam nickel material, and drying in a drying oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foam nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the weak crystallization integral manganese oxide catalyst. It was designated as Mn + SDS.

The proportion of exfoliation of this comparative example was 10%, as shown in Table 1.

As can be seen from FIG. 1, Mn + SDS was present at 651cm^-1The absorption peak intensity is also very weak, which indicates that Mn + SDS is a weakly crystallized monolithic manganese oxide catalyst, but the shedding proportion is much larger than that of the catalyst prepared by the method.

Comparative example 2:

a crystallized monolithic manganese oxide catalyst, the other steps (1), (2) and (4) - (7) are the same as the example, except that the surfactant SDBS is replaced by urea in the step (3), and the following steps are carried out:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water to prepare a 0.2M manganese acetate solution, measuring 40ml of precursor solution in a 50ml beaker, magnetically stirring for 30 minutes, adding 0.1M urea, stirring for 2 hours, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours again to obtain a solution A1;

(4) connecting a foamed nickel electrode, a platinum electrode and a calomel electrode to a working electrode, a counter electrode and a reference electrode of an electrochemical workstation in sequence;

(5) simultaneously immersing the connected nickel foam, the platinum electrode and the calomel electrode into a small beaker filled with the solution A1, keeping the heights of the nickel foam, the platinum electrode and the calomel electrode uniform, setting the deposition voltage to be 1.5V and the deposition time to be 600s by adopting a constant voltage electrodeposition method, starting deposition, and depositing manganese on the nickel foam;

(6) taking down the deposited foam nickel material, and drying in a drying oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foamed nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the crystallized integral manganese oxide catalyst which is marked as Mn + urea.

The proportion of exfoliation of this comparative example is 4%, see table 1.

As can be seen from FIG. 1, Mn + urea is 651cm^-1The higher intensity of the absorption peak indicates higher crystallinity.

Comparative example 3:

a crystallized monolithic manganese oxide catalyst, the other steps (1), (2) and (4) - (7) are the same as the example, except that no surfactant is added in the step (3), and the following steps are carried out:

(1) cutting the foamed nickel into a rectangle of 1cm multiplied by 5 cm;

(2) mixing ammonia water and deionized water according to the volume ratio of 1:9 to prepare dilute ammonia water;

(3) dissolving manganese acetate in deionized water to prepare a 0.2M manganese acetate solution, measuring 40ml of precursor solution in a 50ml beaker, stirring for 2 hours and half an hour, dropwise adding 1ml of dilute ammonia water obtained in the step (2), and stirring for 12 hours to obtain a solution A2;

(4) connecting a foamed nickel electrode, a platinum electrode and a calomel electrode to a working electrode, a counter electrode and a reference electrode of an electrochemical workstation in sequence;

(5) simultaneously immersing the connected nickel foam, the platinum electrode and the calomel electrode into a small beaker filled with the solution A2, keeping the heights of the nickel foam, the platinum electrode and the calomel electrode uniform, setting the deposition voltage to be 1.5V and the deposition time to be 600s by adopting a constant voltage electrodeposition method, starting deposition, and depositing manganese on the nickel foam;

(6) taking down the deposited foam nickel material, and drying in a drying oven at 70 ℃ for 12 hours to obtain dried foam nickel;

(7) and (3) putting the dried foamed nickel into a muffle furnace, roasting for 4 hours at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and obtaining the crystallized integral manganese oxide catalyst which is marked as Mn.

The proportion of exfoliation of this comparative example was 9%, see table 1.

FIG. 1 is a Raman diagram of catalysts of examples and comparative examples 1 to 3, 651cm^-1The absorption peak is a tensile vibration absorption peak of the Mn-O bond. As can be seen from the figure, Mn + SDBS and Mn + SDS are present at 651cm^-1The absorption peak intensity is very weak, which indicates that Mn + SDBS is a weakly crystallized monolithic manganese oxide catalyst. And the Mn + urea and Mn have higher Mn-O bond tensile vibration absorption peak intensity, which indicates that the Mn + urea and the Mn have higher crystallinity.

Using the monolithic manganese-based catalysts of examples and comparative examples 1 to 3, 0.01g of the supported catalyst was weighed and subjected to ultrasonic treatment for 60 minutes, and then dried, and the mass of the catalyst was weighed, and the amount of exfoliation was calculated, and as a result, as shown in table 1 below, the exfoliation rate of the catalyst added to SDBS was minimal, and was only 1%:

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