High-dispersion Pt-based catalyst based on nano island as well as preparation method and application of high-dispersion Pt-based catalyst

Abstract

The invention provides a high-dispersion Pt-based catalyst based on a nano island as well as a preparation method and application of the high-dispersion Pt-based catalyst, and belongs to the technical field of catalysts. The preparation method comprises the following steps: uniformly dispersing titanium dioxide in water to obtain a dispersion liquid; adding a water-soluble cobalt salt into the dispersion liquid, then adjusting the pH value to be alkaline, carrying out a stirring reaction 1, then carrying out solid-liquid separation, and sequentially carrying out drying 1 and calcining 1 on the obtained solid to obtain a carrier; and uniformly dispersing the carrier in water, adjusting the pH value to be acidic, adding soluble platinum salt, carrying out a stirring reaction 2, and then carrying out drying 2 and calcining 2 to obtain the high-dispersion Pt-based catalyst based on the nano island. The preparation method which is simple in process and relatively low in cost is used, the cobalt nano island is stably combined on the surface of the titanium dioxide carrier based on a positive and negative potential attraction strategy, and then Pt can be highly dispersed by utilizing the porous property of the nano island structure. The catalyst has excellent low-temperature chlorobenzene catalytic oxidation activity and stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a highly dispersed Pt-based catalyst based on nanoislands, its preparation method, and its application. Background Technology

[0002] Volatile organic compounds (VOCs) are a class of organic pollutants widely present in the atmosphere, mainly originating from human activities such as industrial production, transportation, solvent use, and fuel combustion. Catalytic combustion can treat almost all VOCs, especially for multi-component waste gases with no recycling value, offering unparalleled advantages with removal efficiency approaching 100%, no secondary pollution, and minimal safety hazards. Therefore, catalytic oxidation technology is currently a mainstream and widely studied technology. Compared to non-precious metals, precious metal-based catalysts generally possess excellent low-temperature catalytic activity; however, precious metal catalysts are susceptible to poisoning by Cl2 and HCl in the products and are expensive, limiting their large-scale application in the chemical industry. Therefore, developing novel catalysts to overcome these shortcomings has become a current research hotspot. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a highly dispersed Pt-based catalyst based on nano-islands, its preparation method, and its application. The catalyst provided by this invention exhibits low-temperature purification performance for p-chlorobenzene (T... 90 =340℃) and excellent stability.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is a method for preparing a highly dispersed Pt-based catalyst based on nano-islands, comprising the following steps: Titanium dioxide was uniformly dispersed in water to obtain a dispersion. Water-soluble cobalt salt was added to the dispersion, and the pH was adjusted to alkaline. The reaction was stirred for 1 step, followed by solid-liquid separation. The resulting solid was then dried for 1 step and calcined for 1 step to obtain the carrier. The carrier was uniformly dispersed in water, the pH was adjusted to acidic, a soluble platinum salt was added, the reaction was stirred for 2, then dried for 2 and calcined for 2 to obtain the nano-island-based highly dispersed Pt-based catalyst.

[0005] The second technical solution of the present invention is a highly dispersed Pt-based catalyst based on nano-islands prepared by the above preparation method.

[0006] The third technical solution of the present invention is an application of the above-mentioned highly dispersed Pt-based catalyst based on nano-islands in the catalytic oxidation of chlorobenzene.

[0007] The present invention discloses the following technical effects: This invention employs a simple and low-cost preparation method that stably binds cobalt nanoislands onto the surface of a titanium dioxide support based on a strategy of positive and negative potential attraction. The porous nature of the nanoisland structure then allows for high dispersion of Pt. This catalyst exhibits excellent low-temperature catalytic oxidation activity and stability for chlorobenzene, providing a new direction for developing efficient and low-cost Cl-VOCs treatment technologies. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 The XRD patterns are those of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0010] Figure 2 The conversion rates of chlorobenzene (CB) catalyzed by the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures are shown.

[0011] Figure 3 The yield of carbon dioxide (CO2) of the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures.

[0012] Figure 4 The stability curves are for the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention. Detailed Implementation

[0013] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0014] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0015] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0016] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0017] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0018] In this invention, room temperature is defined as 25±5℃.

[0019] Chlorinated volatile organic compounds (Cl-VOCs) are a class of typical air pollutants with high toxicity and poor degradation characteristics, and their efficient catalytic purification is a cutting-edge challenge in the field of environmental catalysis. Catalytic combustion technology is considered the mainstream technology for VOCs treatment due to its advantages of low energy consumption and high purification efficiency. However, precious metal catalysts suffer from problems such as high cost, easy agglomeration, and weak resistance to chlorine poisoning. Therefore, this invention provides a preparation process for a highly efficient functional catalyst for degrading chlorobenzene that solves the agglomeration problem.

[0020] The first aspect of this invention provides a method for preparing a highly dispersed Pt-based catalyst based on nano-islands, comprising the following steps: Titanium dioxide was uniformly dispersed in water to obtain a dispersion. Water-soluble cobalt salt was added to the dispersion, and the pH was adjusted to alkaline. The reaction was stirred for 1 step, followed by solid-liquid separation. The resulting solid was then dried for 1 step and calcined for 1 step to obtain the carrier. The carrier was uniformly dispersed in water, the pH was adjusted to acidic, a soluble platinum salt was added, the reaction was stirred for 2, then dried for 2 and calcined for 2 to obtain the nano-island-based highly dispersed Pt-based catalyst.

[0021] This invention first forms a structure where cobalt nanoislands are stably bonded to the surface of a titanium dioxide support by adjusting the cobalt content. The support is then obtained through drying and calcination. Subsequently, metal Pt is loaded onto the support through positive and negative potential attraction. This invention uses nanoislands to prevent the aggregation of metal atoms while inhibiting their migration and sintering, resulting in a catalyst with excellent catalytic oxidation ability of chlorobenzene.

[0022] In a preferred embodiment of the present invention, the water-soluble cobalt salt is cobalt nitrate hexahydrate; the mass ratio of titanium dioxide to cobalt nitrate is 1:(0.1~1).

[0023] More preferably, the mass ratio of titanium dioxide to cobalt nitrate is 1:(0.1~0.5).

[0024] In a preferred embodiment of the present invention, adjusting the pH to alkaline means making the pH = 9~11; the reagent used to adjust the pH to alkaline is sodium hydroxide.

[0025] In a preferred embodiment of the present invention, the temperature of the stirring reaction 1 is room temperature and the time is 20-40 min; the temperature of the calcination 1 is 400-600℃ and the time is 10-14 h, with a heating rate of 3-6℃ / min.

[0026] More preferably, the calcination temperature is 400℃, 500℃ or 600℃, the time is 10h, 11h, 12h, 13h or 14h, and the heating rate is 5℃ / min.

[0027] In a preferred embodiment of the present invention, the drying process 1 is carried out at room temperature for 6 to 10 hours.

[0028] In a preferred embodiment of the present invention, the soluble platinum salt is chloroplatinic acid, and the mass ratio of the carrier to chloroplatinic acid is 500:(2~3).

[0029] In a preferred embodiment of the present invention, adjusting the pH to acidic means making the pH = 2~3; the reagent used to adjust the pH to acidic is hydrochloric acid.

[0030] In a preferred embodiment of the present invention, the temperature of the stirring reaction 2 is room temperature and the time is 20-40 min; the temperature of the calcination 2 is 400-600℃ and the time is 2-4 h, with a heating rate of 3-6℃ / min.

[0031] More preferably, the calcination temperature 2 is 400℃, 500℃ or 600℃, the time is 2h, 3h or 4h, and the heating rate is 5℃ / min.

[0032] In a preferred embodiment of the present invention, the drying temperature 2 is 50~70℃ and the drying time is 6~10h.

[0033] A second aspect of the present invention provides a nano-island-based highly dispersed Pt-based catalyst prepared by the above preparation method.

[0034] A third aspect of the present invention provides the application of the above-mentioned nano-island-based highly dispersed Pt-based catalyst in the catalytic oxidation of chlorobenzene.

[0035] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0036] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0037] Example 1 (1) Disperse 1g of titanium dioxide in 100ml of deionized water by ultrasonication to obtain solution A; (2) Add 0.49g of cobalt nitrate hexahydrate to solution A and mix well. Then add NaOH solution to adjust the pH of the solution to 9. Stir at room temperature for 30 minutes to obtain solution B. (3) Filter solution B, dry the obtained solid at room temperature overnight, and then calcine it at 500℃ for 12h by raising the temperature at 5℃ / min to obtain carrier A; (4) Disperse 500 mg of carrier A in 100 ml of deionized water, add hydrochloric acid to adjust the pH of the solution to 3, then add 2.65 mg of chloroplatinic acid, stir for 30 min, dry in an oven at 60 °C for 8 h, and then calcine in a muffle furnace at 5 °C / min to 500 °C for 3 h to obtain the catalyst.

[0038] Comparative Example 1 (1) Disperse 1g of titanium dioxide in 100ml of deionized water by ultrasonication to obtain solution A; (2) Add 0.49g of cobalt nitrate hexahydrate to solution A and mix well. Then add NaOH solution to adjust the pH of the solution to 9. Stir at room temperature for 30 minutes to obtain solution B. (3) Filter solution B, dry the obtained solid at room temperature overnight, and then calcine it at 500℃ for 12h by increasing the temperature at 5℃ / min to obtain carrier A; (4) Disperse 500 mg of carrier A in 100 ml of deionized water, add hydrochloric acid to adjust the pH of the solution to 3, then add 1.33 mg of chloroplatinic acid, stir for 30 min, dry in an oven at 60 °C for 8 h, and then calcine in a muffle furnace at 5 °C / min to 500 °C for 3 h to obtain the catalyst.

[0039] Comparative Example 2 (1) Disperse 1g of titanium dioxide in 100ml of deionized water by ultrasonication to obtain solution A; (2) Add 0.49g of cobalt nitrate hexahydrate to solution A and mix well. Then add NaOH solution to adjust the pH of the solution to 9. Stir at room temperature for 30 minutes to obtain solution B. (3) Filter solution B, dry the obtained solid at room temperature overnight, and then calcine it at 500℃ for 12h by increasing the temperature at 5℃ / min to obtain carrier A; (4) Disperse 500 mg of carrier A in 100 ml of deionized water, add hydrochloric acid to adjust the pH of the solution to 3, then add 3.98 mg of chloroplatinic acid, stir for 30 min, dry in an oven at 60 °C for 8 h, and then calcine in a muffle furnace at 5 °C / min to 500 °C for 3 h to obtain the catalyst.

[0040] Performance testing The catalytic oxidation activity of the catalysts prepared in Example 1 and Comparative Examples 1-2 was tested as follows: 0.1 g of catalyst (40-60 mesh) was placed in a fixed-bed reactor. Liquid chlorobenzene was bubbled into the reaction system using compressed air to simulate gas. The concentration of chlorobenzene was controlled at 500 ± 50 ppm by air, the total gas flow rate was 50 ml / min, and the gas space velocity was 30000 mL·g. -1 ·h -1 Real-time monitoring of chlorobenzene and CO2 concentrations via online chromatography: Figure 1 The XRD patterns of the catalysts prepared in Example 1 and Comparative Examples 1-2 of this invention are shown below. Figure 1 It can be seen that the samples of Example 1 and Comparative Example 1 both contain characteristic peaks of titanium oxide, indicating that the samples were successfully prepared.

[0041] Figure 2 The conversion rates of chlorobenzene (CB) catalytic oxidation were measured at different temperatures using catalysts prepared in Examples 1 and 1-2 of this invention. Figure 2 As can be seen, the catalyst prepared in Example 1 exhibits superior chlorobenzene oxidation ability compared to Comparative Examples 1 and 2. The catalyst prepared in Example 1 achieved a chlorobenzene conversion rate of 90% at 340°C.

[0042] Figure 3 The carbon dioxide yield of the catalysts prepared in Example 1 and Comparative Examples 1-2 of this invention at different temperatures. Figure 3 As can be seen, the catalyst prepared in Example 1 exhibits superior chlorobenzene oxidation ability compared with Comparative Examples 1 and 2.

[0043] Figure 4The stability curves (test temperature 340℃) of the catalysts prepared in Example 1 and Comparative Examples 1-2 of this invention are shown. Figure 4 As can be seen, the catalyst prepared in Example 1 exhibits superior stability compared to Comparative Examples 1 and 2. Even after 6 hours of continuous operation, the chlorobenzene conversion rate still reaches 90%.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly dispersed Pt-based catalyst based on nanoislands, characterized in that, Includes the following steps: Titanium dioxide was uniformly dispersed in water to obtain a dispersion. Water-soluble cobalt salt was added to the dispersion, and the pH was adjusted to alkaline. The reaction was stirred for 1 step, followed by solid-liquid separation. The resulting solid was then dried for 1 step and calcined for 1 step to obtain the carrier. The carrier was uniformly dispersed in water, the pH was adjusted to acidic, a soluble platinum salt was added, the reaction was stirred for 2, then dried for 2 and calcined for 2 to obtain the nano-island-based highly dispersed Pt-based catalyst.

2. The preparation method according to claim 1, characterized in that, The water-soluble cobalt salt is cobalt nitrate hexahydrate; the mass ratio of titanium dioxide to cobalt nitrate is 1:(0.1~1).

3. The preparation method according to claim 1, characterized in that, To adjust the pH to alkaline, the pH should be set to 9-11. The reagent used to adjust the pH to alkaline is sodium hydroxide.

4. The preparation method according to claim 1, characterized in that, The stirring reaction 1 is carried out at room temperature for 20-40 min; the calcination 1 is carried out at 400-600℃ for 10-14 h with a heating rate of 3-6℃ / min.

5. The preparation method according to claim 1, characterized in that, The soluble platinum salt is chloroplatinic acid, and the mass ratio of the carrier to chloroplatinic acid is 500:(2~3).

6. The preparation method according to claim 1, characterized in that, To adjust the pH to acidic, the pH should be set to 2-3. The reagent used to adjust the pH to acidic is hydrochloric acid.

7. The preparation method according to claim 1, characterized in that, The stirring reaction 2 is carried out at room temperature for 20-40 minutes; the calcination 2 is carried out at 400-600℃ for 2-4 hours with a heating rate of 3-6℃ / min.

8. The nano-island-based highly dispersed Pt-based catalyst prepared by the preparation method according to any one of claims 1-7.

9. The application of the nano-island-based highly dispersed Pt-based catalyst of claim 8 in the catalytic oxidation of chlorobenzene.

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