阅读说明：本技术 一种通过还原性有机酸溶液刻蚀银掺杂的钙钛矿型金属氧化物提升其催化氧化性能的方法 (Method for improving catalytic oxidation performance of silver-doped perovskite metal oxide by etching silver-doped perovskite metal oxide with reductive organic acid solution ) 是由 李兵 李哲宇 代威力 张�杰 许勇 杨丽霞 罗旭彪 罗胜联 于 2021-08-11 设计创作，主要内容包括：本发明公开了一种通过还原性有机酸溶液刻蚀银掺杂的钙钛矿型金属氧化物提升其催化氧化性能的方法,首先将浓度为1％～20％的电负性大的银离子掺杂的钙钛矿型金属氧化物的催化剂混合于10～100mL浓度为0.1～3mol/L的还原性有机弱酸溶液中,所述钙钛矿型金属氧化物的催化剂具有ABO-(3)的立方体结构,再于还原性有机弱酸溶液中刻蚀,其次在10～80℃条件下搅拌0.1～3h的时间,刻蚀后溶液经充分过滤洗涤,在80℃条件下干燥24h,本发明通过电负性大的银离子掺杂使得在还原性有机弱酸溶液中刻蚀更加容易,适用于不同方法制备的银掺杂的钙钛矿型金属氧化物催化性能的改进,处理方法简便催化剂对VOCs、CH-(4)、CO等的催化燃烧性能显著提高,且耐热性好,结构稳定。(The invention discloses a method for improving the catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reductive organic acid solution, which comprises the following steps of firstly, etching 1-20% of silver-doped perovskite metal oxide with a reductive organic acid solutionMixing a silver ion doped perovskite type metal oxide catalyst with large electronegativity in 10-100 mL of reducing organic weak acid solution with the concentration of 0.1-3 mol/L, wherein the perovskite type metal oxide catalyst has ABO 3 The method comprises the following steps of etching the cubic structure in a reductive organic weak acid solution, stirring the solution at the temperature of 10-80 ℃ for 0.1-3 hours, fully filtering and washing the etched solution, and drying the solution at the temperature of 80 ℃ for 24 hours 4 And the catalytic combustion performance of CO and the like is obviously improved, and the catalyst has good heat resistance and stable structure.)

1. A method for improving the catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reductive organic acid solution is characterized by comprising the following steps of: firstly, mixing a silver ion doped perovskite type metal oxide catalyst with large electronegativity and concentration of 1-20% into 10-100 mL of reducing organic weak acid solution with concentration of 0.1-3 mol/L, wherein the perovskite type metal oxide catalyst has ABO₃Wherein the A site is a rare earth element or an alkaline earth element and is located at 8 vertices of the cubic structure, and the B site is a transition metal element and is located at the cubic structureAnd in the central position, the O element is in the central position of 6 surfaces of the cubic structure, the strong bond of the A-O bond at the terminal of the surface of the cubic structure is weakened through doping of silver ions with large electronegativity, the A-O bond is easier to break, the cubic structure is etched in a reductive organic weak acid solution, so that the B-site transition metal element with strong catalytic activity and a large amount of surface active oxygen are exposed, then the cubic structure is stirred for 0.1 to 3 hours at the temperature of 10 to 80 ℃, the etched solution is fully filtered and washed, and the cubic structure is dried for 24 hours at the temperature of 80 ℃.

2. The method for improving the catalytic oxidation performance of silver-doped perovskite-type metal oxide by etching the silver-doped perovskite-type metal oxide through a reducing organic acid solution according to claim 1, wherein the method comprises the following steps: the silver ion doped perovskite type metal oxide is synthesized by doping silver ions at the A site and a method without destroying the cubic structure of the perovskite type metal oxide.

3. The method for improving the catalytic oxidation performance of silver-doped perovskite-type metal oxide by etching the silver-doped perovskite-type metal oxide through a reducing organic acid solution according to claim 1, wherein the method comprises the following steps: the used reducing organic weak acid is one or a mixture of oxalic acid, DL-tartaric acid, L (+) -tartaric acid and D (-) -tartaric acid, and is prepared into a concentration of 0.1-3 mol/L and mixed with the silver ion-doped perovskite metal oxide.

Technical Field

The invention relates to the technical field of waste gas treatment, in particular to a method for improving catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reductive organic acid solution.

Background

For the treatment of waste gases such as VOCs, CH4, CO and the like, catalytic combustion is an economic and effective means. As a traditional organic waste gas treatment technology, a catalytic combustion method is one of the main technologies for treating VOCs in China at present, and the technology is to pass pollutant gas through a catalyst bed layer, and directionally and efficiently convert the gas into harmless substances convenient to treat at a relatively low temperature (generally 200-400 ℃). By adding the catalyst, the reaction process is changed, the activation energy of the reaction is reduced, and the problems of low concentration and easy escape of gas pollutants are effectively solved. The development of high-efficiency low-cost catalytic materials is the key for popularization and application of the technology.

Perovskite-type metal oxide catalysts are receiving attention due to their excellent heat resistance and structural stability, and the perovskite-type metal oxide catalysts reported at present generally have catalytic activity that does not satisfy the industrial application requirements under low temperature conditions. Therefore, on the premise of maintaining the excellent heat resistance and structural stability of the perovskite type metal oxide material, the improvement of the low-temperature catalytic oxidation performance of the perovskite type metal oxide material is the key point that the perovskite type catalyst can meet the requirements of industrial application.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art and provides a method for improving the catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reductive organic acid solution.

In order to achieve the purpose, the technical scheme provided by the invention is as follows: a method for improving the catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reductive organic acid solution comprises the steps of firstly mixing a 1-20% silver ion-doped perovskite metal oxide catalyst with large electronegativity in a 10-100 mL reductive organic weak acid solution with a concentration of 0.1-3 mol/L for etching, wherein the perovskite metal oxide catalyst has ABO₃The cubic structure of (1), wherein A is a rare earth element or an alkaline earth element and is positioned at 8 vertexes of the cubic structure, B is a transition metal element and is positioned at the central position of the cubic structure, and O is positioned at the central position of 6 surfaces of the cubic structure, the bond strength of a terminal A-O bond on the surface of the cubic structure is weakened through doping of silver ions with large electronegativity, so that the A-O bond is easier to break, the cubic structure is etched in a reductive organic weak acid solution, so that the B transition metal element with strong catalytic activity and a large amount of surface active oxygen are exposed, then the cubic structure is stirred for 0.1-3 h at the temperature of 10-80 ℃, the etched solution is fully filtered and washed, and dried for 24h at the temperature of 80 ℃.

Preferably, the silver ion-doped perovskite-type metal oxide is synthesized by doping silver ions at the a site without destroying the cubic structure of the perovskite-type metal oxide.

Preferably, the used reducing organic weak acid is one or a mixture of oxalic acid, DL-tartaric acid, L (+) -tartaric acid and D (-) -tartaric acid, and the reducing organic weak acid is prepared into a concentration of 0.1-3 mol/L and mixed with the silver ion-doped perovskite metal oxide.

The invention has the beneficial effects that:

the invention has simple reaction equipment, short reaction time and convenient reaction operation; the reaction raw materials are easy to obtain, the raw materials and the reaction cost are low, and the large-scale production is facilitated; in the whole reaction process, no toxic or harmful substance is used and generated, and the requirements of clean production are completely met; the silver ions with large electronegativity are doped to enable the etching to be easier in the reductive organic weak acid solution, the catalytic oxidation performance of the obtained perovskite type composite metal oxide catalyst etched by the reductive organic weak acid is remarkably improved, the heat resistance is good, and the structure is stable.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is an XRD spectrum of LaMnO3 and Ag ion doped La0.9Ag0.1MnO3 before and after L-Tartaric Acid (TA) etching in example 1 of the present invention;

FIG. 2 is a SEM image of LaMnO3 and Ag ion doped La0.9Ag0.1MnO3 before and after L-Tartaric Acid (TA) etching in example 1 of the present invention;

FIG. 3 is a graph comparing the catalytic performance of LaMnO3 and Ag ion doped La0.9Ag0.1MnO3 before and after L-Tartaric Acid (TA) etching in example 1 of the present invention;

FIG. 4 is a graph comparing the catalytic performance of Ag ion doped La0.8Ag0.2MnO3 prepared by D-Tartaric Acid (TA) etching co-precipitation in example 2 of the present invention;

FIG. 5 is a graph showing the catalytic performance of Ag ion-doped La0.9Ag0.1CoO3 prepared by a hydrothermal method through etching by using a mixed solution of D-tartaric acid and L-tartaric acid in example 3 of the present invention;

FIG. 6 is a graph showing the catalytic performance of La0.9Ag0.1FeO3 doped with Ag ions prepared by oxalic acid etching molten salt method in example 4 of the present invention;

FIG. 7 is a graph showing the catalytic performance of Ag ion-doped La0.9Ag0.1MnO3 prepared by sol-gel method and etched with phosphoric acid in comparative example 1;

FIG. 8 is a graph showing the catalytic performance of Ag ion-doped La0.9Ag0.1MnO3 prepared by a coprecipitation method according to the invention in comparative example 2, which was etched with hydrochloric acid.

Detailed Description

The following examples further illustrate the invention, but the scope of the invention is not limited to the following examples.

Referring to fig. 1 to 8, in a preferred embodiment of the present invention, a method for improving catalytic oxidation performance of silver-doped perovskite metal oxide by etching the silver-doped perovskite metal oxide with a reducing organic acid solution, first, a catalyst of silver ion-doped perovskite metal oxide with a large electronegativity and a concentration of 1% to 20% is mixed with 10 mL to 100mL of a reducing organic weak acid solution with a concentration of 0.1 mol/L to 3mol/L for etching, the catalyst of perovskite metal oxide has ABO₃The cubic structure of (1), wherein A site is rare earth element or alkaline earth element, is positioned at 8 vertexes of the cubic structure, B site is transition metal element and is positioned at the central position of the cubic structure, and O element is positioned at the central position of 6 surfaces of the cubic structure, the bond strength of the surface terminal A-O bond is weakened through doping of silver ions with large electronegativity, so that the A-O bond is easier to break, etching is carried out in reductive organic weak acid solution, so that the B site transition metal element with strong catalytic activity and a large amount of surface active oxygen are exposed, stirring is carried out at 10-80 ℃ for 0.1-3 h, the etched solution is fully filtered and washed, drying is carried out at 80 ℃ for 24h, and VOCs and CH of the perovskite metal oxide catalyst obtained through reductive organic weak acid treatment₄And the catalytic oxidation performance of CO and the like is remarkably improved, the catalytic activity of the catalyst provided by the invention is greatly improved in activity evaluation, and the T90 (the temperature of 90% of conversion rate) is reduced by nearly 100 ℃ compared with that of an untreated catalyst.

The invention has simple reaction equipment, short reaction time and convenient reaction operation; the reaction raw materials are easy to obtain, the raw materials and the reaction cost are low, and the large-scale production is facilitated; in the whole reaction process, no toxic or harmful substance is used and generated, and the requirements of clean production are completely met; the silver ions with large electronegativity are doped to enable the etching to be easier in the reductive organic weak acid solution, the catalytic oxidation performance of the obtained perovskite type composite metal oxide catalyst etched by the reductive organic weak acid is remarkably improved, the heat resistance is good, and the structure is stable.

As a preferred embodiment of the present invention, it may also have the following additional technical features:

in this embodiment, the silver ion-doped perovskite-type metal oxide is synthesized by doping silver ions at the a site without destroying the cubic structure of the perovskite-type metal oxide.

In the embodiment, the used reducing organic weak acid is one or a mixture of oxalic acid, DL-tartaric acid, L (+) -tartaric acid and D (-) -tartaric acid, and the reducing organic weak acid is prepared into a concentration of 0.1-3 mol/L and mixed with the silver ion doped perovskite type metal oxide.

The mass space velocity referred to herein is defined as the standard volumetric flow rate of reactant gas entering the reaction system per hour divided by the mass of catalyst. Expressed in WHSV, the unit is mL · g^-1·h^-1。

The toluene conversion in accordance with the present invention is defined as the volume percent of toluene entering the reactor that is converted, i.e., the difference in the volume percent of toluene in the incoming and outgoing gas relative to the volume percent of toluene in the incoming gas, in units%.

Example 1

According to the literature (Ni-substitated LaMnO)₃Perovskites for ethanol oxidation) to prepare LaMnO with perovskite structure₃And La doped with silver ion_0.9Ag_0.1MnO₃；

0.5g of LaMnO was taken₃Or La_0.9Ag_0.1MnO₃Putting the powder into a beaker, adding 50mL of 1 mol/L-tartaric acid solution, magnetically stirring at 25 ℃ for 1h, filtering and washing, and transferring the filter cake into an oven to dry at 80 ℃ for 24 h.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and then performing catalytic combustion on the tolueneAnd (3) performing evaluation, wherein the evaluation conditions are as follows: 100mg of the catalyst was charged in a reactor, and 100ml/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1The toluene catalytic combustion effect of the catalyst is shown in table 1.

Example 2

According to the literature (Improvements in electrical and dielectric properties of substitated multilevel Lamno)₃Silver ion doped La with perovskite structure prepared by coprecipitation method in based nanostructured synthesis by co-precipitation method)_0.8Ag_0.2MnO₃；

0.5g of La was taken_0.9Ag_0.2MnO₃Putting the powder into a beaker, adding 50mL of 2mol/L D-tartaric acid solution, magnetically stirring at 40 ℃ for 2h, filtering and washing, and transferring the filter cake into an oven to dry at 80 ℃ for 24 h.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and evaluating the catalytic combustion performance of toluene under the following evaluation conditions: 100mg of the catalyst was charged in a reactor, and 100ml/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1The toluene catalytic combustion effect of the catalyst is shown in table 1.

Example 3

Silver ion doped La ions with perovskite structure are prepared according to hydrothermal synthesis in the literature (Engineering high active oxygen sites in perovskite oxides for stable and efficient oxygen evolution)_0.9Ag_0.1CoO₃；

0.5g of La was taken_0.9Ag_0.1CoO₃Putting the powder into a beaker, adding 50mL of mixed solution of D-tartaric acid and L-tartaric acid with the concentration of 1mol/L, magnetically stirring for 2h at 25 ℃, filtering and washing, and transferring a filter cake into an oven to dry for 24h at 80 ℃.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and evaluating the catalytic combustion performance of toluene under the following evaluation conditions:100mg of the catalyst was charged in a reactor, and 100mL/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1. The toluene catalytic combustion effect of the catalyst is shown in table 1.

Example 4

According to the literature (Molten salt synthesis and hypercapacitior properties of oxidative gen-vaccum LaMnO)_3-δ) In the molten salt method, Ag element doped La with perovskite structure is synthesized_0.9Ag_0.1FeO₃；

0.5g of La was taken_0.9Ag_0.1FeO₃The powder is put into a beaker, 50mL of oxalic acid solution with the concentration of 1.5mol/L is added, magnetic stirring is carried out for 3 hours at the temperature of 30 ℃, then filtration and washing are carried out, and the filter cake is transferred into an oven to be dried for 24 hours at the temperature of 80 ℃.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and evaluating the catalytic combustion performance of toluene under the following evaluation conditions: 100mg of the catalyst was charged in a reactor, and 100ml/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1. The toluene catalytic combustion effect of the catalyst is shown in table 1.

Comparative example 1

Silver ion-doped La having a perovskite structure was prepared according to the method in example 1_0.9Ag_0.1MnO₃Taking 0.5g of La_0.9Ag_0.1MnO₃The powder was placed in a beaker, 50mL of 1mol/L phosphoric acid was added and magnetically stirred at 25 ℃ for 1h, then filtered and washed, and the filter cake was transferred to an oven to be dried at 80 ℃ for 24 h.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and evaluating the catalytic combustion performance of toluene under the following evaluation conditions: 100mg of the catalyst was charged in a reactor, and 100ml/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1. The toluene catalytic combustion effect of the catalyst is shown in table 1.

Comparative example 2

Silver ion-doped La having a perovskite structure was prepared according to the method in example 2_0.9Ag_0.1MnO₃Taking 0.5g of La_0.9Ag_0.1MnO₃The powder was placed in a beaker, 50mL of 1mol/L hydrochloric acid was added and the mixture was magnetically stirred at 25 ℃ for 1h, then filtered and washed, and the filter cake was transferred to an oven to be dried at 80 ℃ for 24 h.

Tabletting the powder, grinding the powder into particles of 40-60 meshes, and evaluating the catalytic combustion performance of toluene under the following evaluation conditions: 100mg of the catalyst was charged in a reactor, and 100ml/min of synthetic air having a toluene concentration of 1000ppm and 20 vol% O were introduced₂，80vol％N₂。WHSV＝60000mL·g^-1·h^-1. The toluene catalytic combustion effect of the catalyst is shown in table 1.

TABLE 1 catalytic oxidation efficiency of toluene of the catalyst

The above additional technical features can be freely combined and used in superposition by those skilled in the art without conflict.

The above description is only a preferred embodiment of the present invention, and the technical solutions that achieve the objects of the present invention by basically the same means are all within the protection scope of the present invention.