Spherical cerium dioxide loaded copper oxide nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses a spherical cerium dioxide loaded copper oxide nano-catalyst and a preparation method and application thereof, the preparation method comprises the following steps: dispersing spherical cerium dioxide in ethanol to obtain a dispersion liquid; adding a copper nitrate solution into the dispersion liquid, and stirring for a period of time to obtain a mixed solution; and drying the mixed solution by distillation, drying and roasting to obtain the spherical cerium dioxide loaded copper oxide nano-catalyst. The active component of the spherical cerium dioxide loaded copper oxide nano-catalyst adopts the loaded copper oxide nano-particles, has good catalytic activity and improves the reaction rate, in addition, the spherical cerium dioxide is adopted as the carrier, has excellent specific surface area and good structural stability, can improve the dispersity of the active component, and can improve the catalytic activity of the catalyst. And the catalyst has high chemical stability and thermal stability, can maintain good catalytic performance at high temperature and high pressure, and prolongs the service life of the catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of carbon monoxide catalytic oxidation, and in particular to a spherical cerium dioxide-loaded copper oxide nanocatalyst and a preparation method and application thereof. Background Art

[0002] As we all know, cars have become an indispensable means of transportation for humans. With the increase in the number of cars on the road, it has caused the problem of air pollution in the world. These air pollutants are extremely harmful to all living things. The main pollutants emitted by car exhaust are nitrogen oxides (NOx), unburned hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM). Among the various toxic pollutants emitted, carbon monoxide (CO) is one of the main pollutants. It is a global disease that has caused countless irreversible harms to the earth. It also indirectly causes global warming and ozone depletion.

[0003] Incomplete combustion of fossil fuels leads to gradually increasing carbon monoxide emissions in the environment, which reduces oxygen delivery to human organs (such as the heart and brain) and tissues, causing harmful effects on health. Therefore, the development of a supported nanocatalyst with high stability and catalytic efficiency is of great significance to improve the efficiency and economy of catalytic reactions.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a spherical ceria-loaded copper oxide nanocatalyst and a preparation method and application thereof. The spherical ceria-loaded copper oxide nanocatalyst of the present invention can improve the efficiency and stability of CO catalytic oxidation reaction.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] The first aspect of the present invention provides a method for preparing a spherical ceria-supported copper oxide nanocatalyst, the preparation method comprising the following steps:

[0008] (a) dispersing spherical cerium dioxide in ethanol to obtain a dispersion;

[0009] (b) adding a copper nitrate solution to the dispersion and stirring for a period of time to obtain a mixed solution;

[0010] (c) evaporating the mixed solution to dryness, drying, and calcining to obtain the spherical ceria-supported copper oxide nanocatalyst.

[0011] Preferably, the spherical cerium dioxide is prepared by the following method:

[0012] The cerium nitrate and polyvinyl pyrrolidone are dissolved in a mixture of ethylene glycol and deionized water and stirred, and then subjected to magnetic stirring, and then subjected to hydrothermal reaction. After the reaction is completed, the mixture is cooled, centrifuged, washed, dried, and calcined to obtain the spherical cerium dioxide.

[0013] Preferably, the hydrothermal reaction temperature is 150-170° C., and the time is 6-10 h; the calcination temperature is 450-550° C., and the time is 4-5 h.

[0014] Preferably, the mass ratio of the cerium nitrate to polyvinyl pyrrolidone is 1:(0.4-0.6); and the mass ratio of ethylene glycol to deionized water in the mixed solution of ethylene glycol and deionized water is (5-8):1.

[0015] Preferably, in the step (a), the mass ratio of spherical cerium dioxide to ethanol is 1:(15-20).

[0016] Preferably, in step (b), the concentration of the copper nitrate solution is 0.5 to 2 mol / L.

[0017] Preferably, the mass ratio of the spherical ceria to the copper oxide in the copper oxide nanocatalyst is (0.05-0.25):1.

[0018] Preferably, in step (c), the calcination temperature is 380-420° C. and the calcination time is 2-4 hours.

[0019] The second aspect of the present invention provides a spherical ceria-loaded copper oxide nanocatalyst prepared by the above preparation method.

[0020] The third aspect of the present invention provides an application of the spherical ceria-loaded copper oxide nanocatalyst prepared by the above preparation method in a catalytic oxidation reaction of carbon monoxide.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] The active component of the spherical ceria-loaded copper oxide nanocatalyst of the present invention adopts loaded copper oxide nanoparticles, has good catalytic activity, and improves the reaction rate. In addition, the spherical ceria is used as a carrier, which has excellent specific surface area and good structural stability, can improve the dispersion of the active component, and has high chemical stability and thermal stability, can maintain good catalytic performance under high temperature and high pressure, and prolongs the service life of the catalyst.

[0023] In the preparation process of the spherical cerium dioxide of the present invention, ethylene glycol as a solvent can dissolve cerium nitrate, promote the reaction, and adjust the polarity and acidity and alkalinity of the solvent during the reaction. Polyvinyl pyrrolidone as a surfactant can adjust the surface properties of the reaction system and increase the reaction rate. A spherical cerium dioxide is prepared through the joint action of various raw materials, so that it has a better specific surface area and structural stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0025] Figure 1 The X-ray diffraction analysis diagram of spherical ceria and spherical ceria-loaded copper oxide nanocatalyst in the experimental example of the present invention;

[0026] Figure 2 This is a scanning electron microscope image of the spherical cerium dioxide-supported copper oxide nanocatalyst prepared in Example 3 of the experimental example of the present invention;

[0027] Figure 3 This is a transmission electron microscope image of the spherical cerium dioxide-supported copper oxide nanocatalyst prepared in Example 3 of the experimental example of the present invention;

[0028] Figure 4 It is a test curve of the catalytic activity of spherical ceria and spherical ceria-loaded copper oxide nanocatalyst in the experimental example of the present invention. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0030] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0031] Example 1

[0032] This embodiment is a method for preparing spherical cerium dioxide, and the method for preparing spherical cerium dioxide comprises the following steps:

[0033] 2.0 g of cerium nitrate (Ce(NO3)3·6H2O) and 0.8 g of polyvinyl pyrrolidone were dissolved in 56 mL of ethylene glycol and 8 mL of deionized water, and ultrasonic oscillation was used to assist the dissolution. The mixture was magnetically stirred at room temperature for 30 min and stirred thoroughly until a translucent purple suspension was formed. The mixed solution was poured into a hydrothermal reactor and hydrothermally reacted at 160°C for 8 h. After the reaction was completed and the reactor was naturally cooled to room temperature, the solution in the reactor was centrifuged and washed with deionized water and anhydrous ethanol until neutral. Finally, the product obtained by centrifugation was placed in an oven and dried at 80°C overnight. It was then calcined at 500°C in a muffle furnace for 4 h to obtain a spherical CeO2 carrier.

[0034] Example 2

[0035] This embodiment is a method for preparing a spherical ceria-loaded copper oxide nanocatalyst, the preparation method comprising the following steps:

[0036] (a) dispersing 1 g of the spherical cerium dioxide prepared in Example 1 in ethanol at a mass ratio of spherical cerium dioxide to ethanol of 1:18 to obtain a dispersion;

[0037] (b) adding 1 mol / L copper nitrate solution to the dispersion and stirring for 4 h to obtain a mixed solution;

[0038] (c) The mixed solution was evaporated to dryness in an oil bath, dried in an oven at 80° C., and then calcined in a muffle furnace at 400° C. for 3 h to obtain a spherical ceria-loaded copper oxide nanocatalyst with a copper oxide content of 5%, denoted as 5Cu / Ce.

[0039] Example 3

[0040] This embodiment is a method for preparing a spherical ceria-loaded copper oxide nanocatalyst, the preparation method comprising the following steps:

[0041] (a) dispersing 1 g of the spherical cerium dioxide prepared in Example 1 in ethanol at a mass ratio of spherical cerium dioxide to ethanol of 1:18 to obtain a dispersion;

[0042] (b) adding 1 mol / L copper nitrate solution to the dispersion and stirring for 4 h to obtain a mixed solution;

[0043] (c) The mixed solution was evaporated to dryness in an oil bath, dried in an oven at 80° C., and then calcined in a muffle furnace at 400° C. for 3 h to obtain a spherical ceria-loaded copper oxide nanocatalyst with a copper oxide mass content of 10%, denoted as 10Cu / Ce.

[0044] Example 4

[0045] This embodiment is a method for preparing a spherical ceria-loaded copper oxide nanocatalyst, the preparation method comprising the following steps:

[0046] (a) dispersing 1 g of the spherical cerium dioxide prepared in Example 1 in ethanol at a mass ratio of spherical cerium dioxide to ethanol of 1:18 to obtain a dispersion;

[0047] (b) adding 1 mol / L copper nitrate solution to the dispersion and stirring for 4 h to obtain a mixed solution;

[0048] (c) The mixed solution was evaporated to dryness in an oil bath, dried in an oven at 80° C., and then calcined in a muffle furnace at 400° C. for 3 h to obtain a spherical ceria-loaded copper oxide nanocatalyst with a copper oxide mass content of 15%, denoted as 15Cu / Ce.

[0049] Example 5

[0050] This embodiment is a method for preparing a spherical ceria-loaded copper oxide nanocatalyst, the preparation method comprising the following steps:

[0051] (a) dispersing 1 g of the spherical cerium dioxide prepared in Example 1 in ethanol at a mass ratio of spherical cerium dioxide to ethanol of 1:18 to obtain a dispersion;

[0052] (b) adding 1 mol / L copper nitrate solution to the dispersion and stirring for 4 h to obtain a mixed solution;

[0053] (c) The mixed solution was evaporated to dryness in an oil bath, dried in an oven at 80° C., and then calcined in a muffle furnace at 400° C. for 3 h to obtain a spherical ceria-loaded copper oxide nanocatalyst with a copper oxide mass content of 20%, denoted as 20Cu / Ce.

[0054] Experimental example

[0055] The spherical cerium dioxide (denoted as CeO2) of Example 1 and the spherical cerium dioxide-supported copper oxide nanocatalysts prepared in Examples 2 to 5 were obtained respectively;

[0056] X-ray diffraction analysis was performed on the spherical cerium dioxide (referred to as CeO2) of Example 1 and the spherical cerium dioxide-supported copper oxide nanocatalysts prepared in Examples 2 to 5. The analysis results are as follows: Figure 1 As shown;

[0057] Characteristic diffraction peaks appear at 28.77°, 33.20°, 47.59°, 56.45° and 59.28°, corresponding to the (111), (200), (220), (311), (222) crystal planes of the CeO2 cubic fluorite structure (PDF#34-0394). When the copper loading is less than 15%, the characteristic diffraction peaks of copper oxide do not appear in the figure, indicating that the copper oxide species are highly dispersed on the surface of the cerium oxide support or the surface active sites of Cu + It enters the cerium oxide lattice to form a Cu-O-Ce solid solution. When the loading is 20%, weak diffraction peaks of copper oxide appear at 35.5° and 38.6°, which are consistent with the positions of the (002) and (111) crystal planes in the copper oxide standard card.

[0058] The spherical cerium dioxide-supported copper oxide nanocatalyst prepared in Example 3 was observed by scanning electron microscopy and transmission electron microscopy. The observation results are as follows: Figure 2 , Figure 3 As shown;

[0059] Depend on Figure 2-3 It can be seen that the size distribution of spherical cerium oxide is relatively uniform, with a diameter of approximately 50nm-150nm; Figure 3 The spherical catalyst has two different lattice stripes, with lattice spacings of 0.312nm and 0.271nm, respectively. After comparison with the XRD standard card, exposed (111) and (200) crystal planes were found. CeO2 has three crystal planes with relatively low surface energy, namely (200), (220) and (111). The lower the surface energy, the more stable the properties. CeO2 crystals will preferentially grow during the growth process. The dense cerium oxide (111) surface is the most stable, and the less stable are the (220) and (200) surfaces.

[0060] The carbon monoxide oxidation catalytic performance of the above cerium dioxide and catalyst was tested, and the testing method was as follows:

[0061] Equal amounts of cerium dioxide and different catalysts were added to the fixed bed reactor, and N2 was used to purge for 20 minutes before the test to exclude other gases in the fixed bed reactor. Then, a reaction gas consisting of 0.8 vol% CO, 20 vol% O2 and 79.2 vol% N2 was introduced at a gas flow rate of 50 mL / min and a space velocity of 40000 mL / (g·h). The fixed bed reactor was heated by a program, and the change in CO concentration was observed. The CO conversion rate was calculated based on the change in CO concentration, and a curve of CO conversion rate versus temperature was drawn, as shown in FIG. Figure 4 As shown;

[0062] Depend on Figure 4It can be seen that the temperature for complete conversion of carbon monoxide catalyzed by 5Cu / Ce is 160°C; the temperature for complete conversion of carbon monoxide catalyzed by 10Cu / Ce is 155°C; the temperature for complete conversion of carbon monoxide catalyzed by 15Cu / Ce is 140°C; the temperature for complete conversion of carbon monoxide catalyzed by 20Cu / Ce is 150°C; when the temperature reaches 300°C when cerium dioxide catalyzes the oxidation of carbon monoxide, the conversion rate of carbon monoxide is only 60%.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a spherical ceria-supported copper oxide nanocatalyst, characterized in that: The steps include: (a) dispersing spherical cerium dioxide in ethanol to obtain a dispersion; (b) adding a copper nitrate solution to the dispersion and stirring for a period of time to obtain a mixed solution; (c) evaporating the mixed solution to dryness, drying, and calcining to obtain the spherical ceria-supported copper oxide nanocatalyst.

2. The preparation method according to claim 1, characterized in that: The spherical cerium dioxide is prepared by the following method: The cerium nitrate and polyvinyl pyrrolidone are dissolved in a mixture of ethylene glycol and deionized water and stirred, and then subjected to magnetic stirring, and then subjected to hydrothermal reaction. After the reaction is completed, the mixture is cooled, centrifuged, washed, dried, and calcined to obtain the spherical cerium dioxide.

3. The preparation method according to claim 2, characterized in that: The hydrothermal reaction temperature is 150-170° C. and the reaction time is 6-10 hours.

4. The preparation method according to claim 2, characterized in that: The mass ratio of the cerium nitrate to polyvinyl pyrrolidone is 1:(0.4-0.6); the mass ratio of ethylene glycol to deionized water in the mixed solution of ethylene glycol and deionized water is (5-8):

1.

5. The preparation method according to claim 1, characterized in that: In the step (a), the mass ratio of spherical cerium dioxide to ethanol is 1:(15-20).

6. The preparation method according to claim 1, characterized in that: In the step (b), the concentration of the copper nitrate solution is 0.5 to 2 mol / L.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the spherical cerium dioxide to the copper oxide in the copper oxide nanocatalyst is (0.05-0.25):

1.

8. The preparation method according to claim 1, characterized in that: In the step (c), the calcination temperature is 380-420° C. and the calcination time is 2-4 hours.

9. The spherical cerium dioxide-supported copper oxide nanocatalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the spherical ceria-supported copper oxide nanocatalyst prepared by the preparation method according to any one of claims 1 to 8 in a carbon monoxide catalytic oxidation reaction.

Images