阅读说明：本技术 一种分子筛催化剂及其制备方法和应用 (Molecular sieve catalyst, and preparation method and application thereof ) 是由 贺泓 刘晓峰 陈毓敏 李要彬 秦奇 于 2021-01-12 设计创作，主要内容包括：本发明提供了一种分子筛催化剂及其制备方法和应用,所述催化剂包括USY分子筛和活性组分；其中,所述USY分子筛经酸处理。本发明将活性组分负载在酸处理的分子筛上制备分子筛催化剂,利用吸附-催化协同效应净化甲醛。所述分子筛催化剂避免了由于吸附量饱和而需要对吸附剂进行再生的麻烦,通过耦合催化技术在吸附浓缩甲醛的同时对甲醛进行原位催化净化。(The invention provides a molecular sieve catalyst and a preparation method and application thereof, wherein the catalyst comprises a USY molecular sieve and an active component; wherein the USY molecular sieve is treated by acid. The invention loads active components on the molecular sieve treated by acid to prepare the molecular sieve catalyst, and purifies formaldehyde by utilizing the adsorption-catalysis synergistic effect. The molecular sieve catalyst avoids the trouble that the adsorbent needs to be regenerated due to the saturation of the adsorption quantity, and the formaldehyde is subjected to in-situ catalytic purification while being adsorbed and concentrated by a coupling catalytic technology.)

1. A molecular sieve catalyst, characterized in that the catalyst comprises a USY molecular sieve and an active component;

wherein the USY molecular sieve is treated by acid.

2. The catalyst of claim 1, wherein the active component comprises an elemental metal;

preferably, the simple metal comprises any one or a combination of at least two of Pd, Pt or Au;

preferably, the mass fraction of the USY molecular sieve is 98-99.9% based on 100% of the mass of the catalyst;

preferably, the mass fraction of the active component is 0.1-2%.

3. The catalyst of claim 1 or 2, wherein the acid-treated acid solution comprises any one or a combination of at least two of hydrochloric acid, nitric acid, sulfuric acid, or citric acid, preferably hydrochloric acid.

4. The catalyst of any one of claims 1-3, wherein the catalyst further comprises an additive;

preferably, the additive comprises any one of an alkali metal compound, an alkaline earth metal compound or a rare earth element compound or a combination of at least two thereof;

preferably, the additive comprises any one of potassium carbonate, sodium nitrate, magnesium nitrate, cerium nitrate or lanthanum nitrate, or a combination of at least two thereof.

5. A process for the preparation of a catalyst according to any one of claims 1 to 4, characterized in that it comprises the following steps:

(1) stirring the USY molecular sieve in an acid solution, and washing and drying to obtain the acid-treated USY molecular sieve;

(2) and (2) adding the USY molecular sieve subjected to acid treatment in the step (1) into a solution of an active component metal salt, mixing, carrying out rotary evaporation and drying, and carrying out reduction treatment to obtain the molecular sieve catalyst.

6. The method according to claim 5, wherein the concentration of the acid solution in the step (1) is 0.1 to 0.3M, and more preferably 0.15 to 0.25M;

preferably, the mass of the USY molecular sieve and the mass of the acid solution are 1: 15-30;

preferably, the stirring temperature is 25-40 ℃;

preferably, the stirring time is 4-8 h;

preferably, the detergent to be washed comprises deionized water;

preferably, the drying temperature is 110-120 ℃;

preferably, the drying time is 10-15 h.

7. The method according to claim 5 or 6, wherein the mixing time in step (2) is 3-6 h;

preferably, the drying temperature is 110-120 ℃;

preferably, the drying time is 10-12 h.

8. The production method according to any one of claims 5 to 7, wherein the reducing agent of the reduction treatment of step (2) includes hydrogen gas;

preferably, the apparatus for reduction treatment comprises a tube furnace;

preferably, the introduction rate of the reducing agent is 15-30 mL/min;

preferably, the temperature of the reduction treatment is 300-400 ℃, and further preferably 320-360 ℃;

preferably, the time of the reduction treatment is 0.8-1.5 h.

9. The method of any one of claims 5 to 8, comprising the steps of:

(1) stirring the USY molecular sieve in an acid solution with the concentration of 0.1-0.3M for 4-8 h at 25-40 ℃, washing with deionized water, and drying for 10-15 h at 110-120 ℃ to obtain the acid-treated USY molecular sieve;

(2) and (2) adding the USY molecular sieve subjected to acid treatment in the step (1) into a solution of an active component metal salt, mixing, carrying out rotary evaporation and drying, and carrying out reduction treatment at the temperature of 300-400 ℃ for 0.8-1.5 h to obtain the molecular sieve catalyst.

10. Use of a molecular sieve catalyst according to any of claims 1 to 4, wherein the catalyst is used for degrading formaldehyde.

Technical Field

The invention belongs to the field of catalysts, and relates to a molecular sieve catalyst, and a preparation method and application thereof.

Background

With the rapid development of the industry, H₂S、SO₂、NO、NO₂And the pollution caused by the increasing emission of formaldehyde brings serious pollution to the life and environment of peopleInfluence. Formaldehyde is one of the most important indoor pollutants, and the long-term exposure of human bodies to the environment with high formaldehyde concentration can cause serious health hazards. The complete catalytic oxidation of formaldehyde into carbon dioxide and water by using a catalyst in an air purifier is a very promising practical technique for eliminating formaldehyde pollution.

CN107694564A discloses a catalyst for decomposing formaldehyde and a preparation method thereof. The catalyst comprises a carrier, a hydrophobic component and a hydrophobic porous material layer, wherein the carrier of the catalyst is activated carbon, the active components of the catalyst are platinum and palladium loaded on the carrier, the hydrophobic component is a hydrophobic porous material layer wrapped on the surface of the catalyst, the loading capacity of the platinum is 0.02-0.3 wt%, and the loading capacity of the palladium is 0.02-0.3 wt%. The preparation method of the catalyst is simple, the prepared catalyst has the advantages of low cost and capability of adsorbing and decomposing formaldehyde gas at room temperature, can be applied to an air purifier and an adsorption concentration tower, and can remarkably and quickly reduce the concentration of formaldehyde, but the efficiency of decomposing formaldehyde into water and carbon dioxide cannot reach 100%.

CN102247842A discloses a high-efficiency catalyst for eliminating formaldehyde at room temperature, which is a catalyst capable of efficiently decomposing low-concentration formaldehyde at normal temperature and normal humidity, wherein the catalyst is mainly prepared by loading Pt with mass fraction of 0-5% on TiO coated₂-SnO₂The catalyst is prepared by compounding a composite oxide in a cordierite honeycomb ceramic carrier, the combination degree between the composite oxide of the catalyst and honeycomb ceramic is weak, the catalyst is easy to fall off, and the problems of serious powder falling, unstable activity and the like of the catalyst exist after long-term use.

Therefore, it is necessary to develop a formaldehyde decomposition catalyst which has high catalytic efficiency, can decompose formaldehyde, and can be stabilized for a long period of time.

Disclosure of Invention

The invention aims to provide a molecular sieve catalyst, a preparation method and application thereof, wherein the catalyst comprises a super stable molecular sieve (USY molecular sieve) and an active component; wherein the USY molecular sieve is treated by acid. The invention loads active components on the molecular sieve treated by acid to prepare the molecular sieve catalyst, and purifies formaldehyde by utilizing the adsorption-catalysis synergistic effect. The molecular sieve catalyst avoids the trouble that the adsorbent needs to be regenerated due to the saturation of the adsorption quantity, and the formaldehyde is subjected to in-situ catalytic purification while being adsorbed and concentrated by a coupling catalytic technology.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a molecular sieve catalyst comprising a USY molecular sieve and an active component; wherein the USY molecular sieve is treated by acid.

The molecular sieve catalyst takes the USY molecular sieve treated by acid as a carrier, and the molecular sieve is treated by the acid, so that the aperture is increased, and the diffusion can be promoted; and the change of the acidity of the molecular sieve increases the dispersion degree of the active components on the surface of the molecular sieve, and the formaldehyde can be completely degraded into carbon dioxide and water without other toxic and harmful byproducts. The formaldehyde purification condition is mild, and other auxiliary measures such as heating or illumination are not needed.

Preferably, the active component comprises elemental metal.

Preferably, the simple metal comprises any one of Pd, Pt or Au or a combination of at least two of Pd, Pt and Au.

Preferably, the mass fraction of the USY molecular sieve is 98-99.9% based on 100% of the mass of the catalyst, such as: 98%, 98.2%, 98.4%, 98.5%, 99%, 99.3%, 99.6%, 99.9%, etc.

Preferably, the mass fraction of the active component is 0.1-2%, such as: 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.5%, 2%, or the like.

Preferably, the acid-treated acid solution comprises any one or a combination of at least two of hydrochloric acid, nitric acid, sulfuric acid or citric acid, preferably hydrochloric acid.

Preferably, the catalyst further comprises an additive.

Preferably, the additive comprises any one of an alkali metal compound, an alkaline earth metal compound, or a rare earth element compound, or a combination of at least two thereof.

Preferably, the additive comprises any one of potassium carbonate, sodium nitrate, magnesium nitrate, cerium nitrate or lanthanum nitrate, or a combination of at least two thereof.

In a second aspect, the present invention provides a method for preparing a catalyst as described in the first aspect, the method comprising the steps of:

(1) stirring the USY molecular sieve in an acid solution, and washing and drying to obtain the acid-treated USY molecular sieve;

(2) and (2) adding the USY molecular sieve subjected to acid treatment in the step (1) into a solution of an active component metal salt, mixing, carrying out rotary evaporation and drying, and carrying out reduction treatment to obtain the molecular sieve catalyst.

In the molecular sieve catalyst, after the USY molecular sieve is treated by acid, a simple impregnation method is further adopted to prepare the supported catalyst, and the catalyst preparation process is simple and is convenient for batch treatment.

Preferably, the concentration of the acid solution in the step (1) is 0.1-0.3M, for example: 0.15M, 0.16M, 0.18M, 0.2M or 0.3M, etc., and if the concentration is less than 0.1M, USY cannot be completely acidified; if the concentration is higher than 0.3M, the USY molecular sieve is excessively corroded, and the purification capacity of the catalyst is reduced. More preferably 0.15 to 0.25M.

Preferably, the mass ratio of the USY molecular sieve to the acid solution is 1: 15-30, for example: 1:15, 1:16, 1:18, 1:20, 1:25, or 1:30, etc.

Preferably, the stirring temperature is 25-40 ℃, for example: 25 deg.C, 27 deg.C, 29 deg.C, 30 deg.C, 32 deg.C, 35 deg.C or 40 deg.C.

Preferably, the stirring time is 4-8 h, such as: 4h, 5h, 6h, 7h or 8h and the like.

Preferably, the washing detergent comprises deionized water.

Preferably, the drying temperature is 110-120 ℃, for example: 110 ℃, 112 ℃, 114 ℃, 116 ℃, 118 ℃ or 120 ℃ and the like.

Preferably, the drying time is 10-15 h, for example: 10h, 11h, 12h, 13h, 14h or 15h, etc.

Preferably, the mixing time in the step (2) is 3-6 h, for example: 3h, 4h, 5h or 6h and the like.

Preferably, the drying temperature is 110-120 ℃, for example: 110 ℃, 112 ℃, 114 ℃, 116 ℃, 118 ℃ or 120 ℃ and the like.

Preferably, the drying time is 10-12 h, for example: 10h, 10.5h, 11h, 11.5h or 12h and the like.

Preferably, the reducing agent of the reduction treatment of step (2) comprises hydrogen.

Preferably, the apparatus for reduction treatment comprises a tube furnace.

Preferably, the introduction rate of the reducing agent is 15-30 mL/min, such as: 15mL/min, 18mL/min, 20mL/min, 23mL/min, 25mL/min, or 30mL/min, etc.

Preferably, the temperature of the reduction treatment is 300-400 ℃, for example: 300 ℃, 320 ℃, 340 ℃, 360 ℃, 380 ℃ or 400 ℃ and the like, wherein if the temperature is lower than 300 ℃, the active components in the catalyst cannot be completely reduced, and if the temperature is higher than 400 ℃, the catalyst may be damaged, so that the catalytic efficiency of the catalyst is influenced, and more preferably 320-360 ℃.

Preferably, the time of the reduction treatment is 0.8-1.5 h, for example: 0.8h, 0.9h, 1h, 1.2h, 1.4h or 1.5h and the like.

As a preferable scheme of the invention, the preparation method comprises the following steps:

(1) stirring the USY molecular sieve in an acid solution with the concentration of 0.1-0.3M for 4-8 h at 25-40 ℃, washing with deionized water, and drying for 10-15 h at 110-120 ℃ to obtain the acid-treated USY molecular sieve;

(2) and (2) adding the USY molecular sieve subjected to acid treatment in the step (1) into a solution of an active component metal salt, mixing, carrying out rotary evaporation and drying, and carrying out reduction treatment at the temperature of 300-400 ℃ for 0.8-1.5 h to obtain the molecular sieve catalyst.

In a third aspect, the present invention also provides the use of a molecular sieve catalyst as described in the first aspect, for degrading formaldehyde.

Compared with the prior art, the invention has the following beneficial effects:

(1) the formaldehyde removing efficiency of the molecular sieve catalyst can reach more than 70 percent, the formaldehyde removing efficiency of the prepared molecular sieve catalyst can reach 100 percent through further optimizing the temperature of reduction treatment and the concentration of an acid solution, other toxic and harmful byproducts are not generated, the formaldehyde purifying condition is mild, and other auxiliary measures such as heating or illumination are not needed.

(2) In the molecular sieve catalyst, after the USY molecular sieve is treated by acid, a simple impregnation method is further adopted to prepare the supported catalyst, and the catalyst preparation process is simple and is convenient for batch treatment.

(3) The molecular sieve catalyst has high-efficiency formaldehyde catalytic purification capability, and has long service life which can reach more than 12 h.

Drawings

FIG. 1 is a graph of the conversion of formaldehyde by the catalyst described in example 1 of the present invention.

FIG. 2 is a graph showing the change of the amount of carbon dioxide produced with time in the purification of formaldehyde by the catalyst of example 1 of the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The USY molecular sieves used in the following examples of the present invention are all commercially available products.

Example 1

This example provides a molecular sieve catalyst prepared by the following method:

(1) adding 2g of USY molecular sieve and 0.687mL of hydrochloric acid into 39.313mL of deionized water (the concentration of hydrochloric acid is 0.2M), stirring at 30 ℃ for 6h, filtering, washing with deionized water to be neutral, and drying in an oven at 110 ℃ for 12h to obtain an acid-treated USY molecular sieve;

(2) dissolving 0.025g of palladium nitrate into 20mL of deionized water, adding 1g of USY molecular sieve subjected to acid treatment in the step (1), mixing and stirring for 4H, removing excessive water by rotary evaporation, drying at 110 ℃ for 12H, and putting the obtained sample in a tubular furnace by using H₂The reduction of the carbon dioxide is carried out,H₂reducing for 1h at the temperature of 350 ℃ with the flow rate of 20mL/min to obtain the molecular sieve catalyst.

The conversion rate of the catalyst to formaldehyde is shown in figure 1, and as can be seen from figure 1, the catalyst of the invention can remove 100% of formaldehyde, shows excellent catalytic activity, and the conversion rate of the catalyst is basically maintained within 12h, and has a longer service life.

The graph of the change of the amount of carbon dioxide generated with time when the catalyst purifies formaldehyde is shown in figure 2, and the graph of figure 2 shows that the catalyst of the invention produces CO₂In an amount comparable to the initial concentration of formaldehyde, revealing a complete conversion of formaldehyde to CO from a carbon balance point of view₂The catalyst has excellent selectivity, does not produce other harmful and toxic byproducts, and is an ideal catalyst for purifying air.

Example 2

This example provides a molecular sieve catalyst prepared by the following method:

(1) adding 2g of USY molecular sieve and 0.927mL of hydrochloric acid into 35.073mL of deionized water (the concentration of hydrochloric acid is 0.25M), stirring for 5h at 32 ℃, filtering, washing with deionized water to be neutral, and drying in an oven at 120 ℃ for 13h to obtain an acid-treated USY molecular sieve;

(2) dissolving 0.056g of platinum nitrate and 0.0365g of sodium nitrate into 20mL of deionized water, adding 1g of USY molecular sieve subjected to acid treatment in the step (1), mixing and stirring for 6H, removing excessive water by rotary evaporation, drying at 110 ℃ for 10H, and putting the obtained sample in a tubular furnace by using H₂Reduction thereof, H₂The flow rate is 25mL/min, and the molecular sieve catalyst is obtained by reducing for 1.2h at the temperature of 360 ℃.

Example 3

This example is different from example 1 only in that the concentration of the acid solution in step (1) is 0.1M, and other conditions and parameters are exactly the same as those in example 1.

Example 4

This example is different from example 1 only in that the concentration of the acid solution in step (1) is 0.3M, and other conditions and parameters are exactly the same as those in example 1.

Example 5

This example is different from example 1 only in that the concentration of the acid solution in step (1) is 0.05M, and other conditions and parameters are exactly the same as those in example 1.

Example 6

This example is different from example 1 only in that the concentration of the acid solution in step (1) is 0.35M, and other conditions and parameters are exactly the same as those in example 1.

Example 7

This example differs from example 1 only in that the temperature of the reduction in step (2) is 300 ℃ and the other conditions and parameters are exactly the same as in example 1.

Example 8

This example differs from example 1 only in that the temperature of the reduction in step (2) is 400 ℃ and the other conditions and parameters are exactly the same as in example 1.

Example 9

This example differs from example 1 only in that the temperature of the reduction in step (2) is 250 ℃ and the other conditions and parameters are exactly the same as in example 1.

Example 10

This example differs from example 1 only in that the temperature of the reduction in step (2) is 450 ℃ and the other conditions and parameters are exactly the same as in example 1.

Comparative example 1

This comparative example differs from example 1 only in that the USY molecular sieve was not acid treated and the other conditions and parameters were exactly the same as in example 1.

Comparative example 2

This comparative example differs from example 1 only in that the USY molecular sieve described in step (1) was replaced with a ZSM-5 molecular sieve, and the other conditions and parameters were exactly the same as in example 1.

And (3) performance testing:

50mg of the catalysts obtained in examples 1-6 and comparative examples 1-2 are respectively prepared into particles of 40-60 meshes, and the particles are loaded on a fixed bed reactor for evaluating the catalytic oxidation performance of formaldehyde. The experimental conditions are as follows: the gas composition was 110ppm formaldehyde, 20% oxygen, relatively wet35 percent of the reaction temperature, helium as balance gas, the total flow rate of 100mL/min, the reaction temperature of 25 ℃ and the reaction space velocity of 120000 mL/g^-1·h^-1. The test results are shown in table 1:

TABLE 1

As can be seen from Table 1, the formaldehyde removal efficiency of the molecular sieve catalyst of the present invention can reach more than 70% as obtained in examples 1-10, and the formaldehyde removal efficiency of the prepared molecular sieve catalyst can reach 100% by further optimizing the reduction temperature and the concentration of the acid solution.

Comparing the embodiment 1 with the embodiments 3-6, the concentration of the acid solution in the step (1) can affect the performance of the prepared molecular sieve catalyst, the USY can be better acidified by optimizing the concentration of the acid solution to 0.15-0.25M, the reduction of the purification capacity of the catalyst caused by excessive corrosion is avoided, and further higher formaldehyde conversion rate is obtained.

Compared with the examples 7-10, the reduction temperature in the step (2) can affect the performance of the prepared molecular sieve catalyst, and the active component can be reduced better by optimizing the reduction temperature to 320-360 ℃, so that the catalytic efficiency of the catalyst is improved.

Compared with the comparative example 1, the USY molecular sieve is subjected to acid treatment, the pore diameter of the USY molecular sieve is increased after the acid treatment, the diffusion can be promoted, the catalytic activity is improved, and the dispersity of the noble metal on the surface of the USY molecular sieve is improved and the catalytic activity is also improved after the acid treatment.

As can be seen from comparison between example 1 and comparative example 2, the USY molecular sieve used in the present invention exhibits higher formaldehyde catalytic activity than the ZSM molecular sieve due to its specific pore channel structure and surface structure.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.