Zirconium oxide, method for producing the same, and use thereof

Abstract

The application discloses zirconium oxide and a preparation method and application thereof. The zirconium oxide is pure monoclinic phase, and has an almond-like morphology. The preparation method has the advantages of simple process flow and easy operation control. The prepared zirconium oxide has a large specific surface area and is suitable for use as a catalyst carrier.

Description

Technical Field

[0001] This invention belongs to the field of zirconium oxide, specifically relating to a zirconium oxide, its preparation method, and its application. Background Technology

[0002] Zirconia (ZrO2), as a novel functional material, has been widely used in oxygen detectors, fuel cells, catalysis, and environmental protection. Due to its abundant surface defects and its weak acid, weak base, and redox properties, zirconium oxide is an excellent catalyst support material and can also be used as an additive to improve catalyst performance in catalytic reactions such as Fischer-Tropsch synthesis, CO and CO2 hydrogenation to methanol, and alkane isomerization, exhibiting good catalytic performance. Therefore, research on the preparation of high specific surface area zirconium oxide, the preparation of mesoporous zirconium oxide, and zirconium oxide doping has attracted widespread interest from researchers.

[0003] Zirconia exists in various phases, including monoclinic, tetragonal, and cubic. Different phases of zirconia exhibit varying physical and chemical properties, and thus different catalytic performances for different catalytic reactions. Currently, in industry, pure monoclinic zirconia is mainly obtained through calcination. However, calcination temperatures generally exceed 1000℃, which leads to a significant reduction in the specific surface area of ​​zirconia, typically only reaching 10 μm². 2 The concentration of zirconium oxide at approximately 1 / g greatly limits its application as a catalyst or catalyst support.

[0004] The conventional method for preparing zirconium oxide is precipitation, which uses a neutralization reaction to generate zirconium oxide precursor precipitates. However, the zirconium oxide obtained by this precipitation method is often a mixture of monoclinic and tetragonal or cubic phases, rather than pure monoclinic zirconium oxide.

[0005] Patent CN102627323A discloses a method for preparing monoclinic zirconia nanocrystalline powder. This method involves adding lithium ions to a zirconium nitrate solution and citric acid, mixing to form a dry gel, and then calcining at a high temperature of 600–1000°C to obtain monoclinic zirconia nanocrystalline powder. Because lithium ions are introduced during the preparation process, the resulting monoclinic zirconia contains lithium impurities. This impure monoclinic zirconia powder can be used in the preparation of structural ceramics, but due to limitations in specific surface area and impurity content, it is not suitable for use in catalyst applications where high specific surface area and purity are required.

[0006] The catalytic activity and selectivity of zirconium oxide are affected by the atomic arrangement and the number of unsaturated bonds on its surface. The morphology of zirconium oxide greatly affects the atomic arrangement and the number of unsaturated bonds on its surface, and the morphology of zirconium oxide also affects its catalytic performance. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a zirconium oxide, its preparation method, and its applications. This preparation method has the advantages of a simple process flow and easy operation and control. The obtained zirconium oxide is a pure monoclinic phase with an almond-shaped or flower-like morphology composed of multiple almond-shaped particles. It has a large specific surface area and is suitable for use as a catalyst support.

[0008] The first aspect of the present invention provides a zirconium oxide; the zirconium oxide is a pure monoclinic phase; the zirconium oxide has an almond-shaped morphology.

[0009] According to the present invention, the zirconium oxide does not contain tetragonal or cubic phases.

[0010] According to the present invention, the zirconium oxide has a flower-like morphology composed of multiple almond-shaped particles.

[0011] According to the present invention, the specific surface area of ​​the zirconium oxide is 50-120 m². 2 / g.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned zirconium oxide. The method includes the following steps:

[0013] Ammonia is added dropwise to a mixture containing additives and zirconium salts to form a precipitate; then hydrothermal crystallization and calcination are performed to obtain the zirconium oxide.

[0014] According to the present invention, the additive includes one or more of ammonium acetate, ammonium formate, ammonium propionate, ammonium oxalate, ammonium fluoride, and ammonium bromide, preferably at least one of ammonium fluoride and ammonium bromide.

[0015] According to the present invention, the zirconium salt includes one or both of zirconium oxychloride and zirconium nitrate.

[0016] According to the present invention, the ammonia is preferably water; more preferably, the mass concentration of the water is 5% to 28%.

[0017] According to the present invention, the mass ratio of the additive to the zirconium salt is 10 to 40:100.

[0018] According to the present invention, preferably, the mixture of additives and zirconium salt exists in the form of a liquid mixture; further, the mass concentration of zirconium salt in the liquid mixture formed by additives and zirconium salt is 10wt%-50wt%.

[0019] According to the present invention, the calcination temperature is 450-650°C and the calcination time is 2-8 hours.

[0020] According to the present invention, the additive and zirconium salt are mixed and stirred at 35-50°C for 2-4 hours.

[0021] According to the present invention, the ammonia is added at a constant rate. During the addition of ammonia, the mixture of the additive and the zirconium salt is kept under stirring. Furthermore, during the addition of ammonia, the temperature of the mixture of the additive and the zirconium salt is controlled at 35–50°C.

[0022] According to the present invention, the molar ratio of ammonia (NH3) to zirconium salt (Zr) is NH3:Zr = 2 to 4.5:1.

[0023] According to the present invention, the hydrothermal crystallization is carried out at a constant temperature. The temperature of the hydrothermal crystallization is 90°C to 120°C. The hydrothermal crystallization time is 8 to 72 hours. After crystallization, the crystallization is cooled to below 35°C, preferably 15 to 35°C.

[0024] According to the present invention, after hydrothermal crystallization, the product can be subjected to steps such as filtration, washing, and drying. The drying temperature is 110℃~120℃, and the drying time is 12~24h.

[0025] The third aspect of the present invention provides the application of the above-described zirconium oxide or the zirconium oxide prepared by the above-described preparation method as a catalyst support.

[0026] According to the present invention, preferably, the application is in a n-butane isomerization catalyst.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The zirconium oxide of this invention is a pure monoclinic phase; the zirconium oxide has an almond-shaped morphology. Further, it has a flower-like morphology composed of multiple almond-shaped particles. The zirconium oxide has a large specific surface area, making it suitable for use as a catalyst support. It is particularly suitable as a catalyst for the isomerization of n-butane.

[0029] (2) In the preparation method of the present invention, one or more of ammonium acetate, ammonium formate, ammonium propionate, ammonium oxalate, ammonium fluoride, and ammonium bromide are used as additives. The obtained zirconium oxide is a pure monoclinic phase with an almond-shaped and flower-like morphology composed of multiple almond-shaped particles. It has a large specific surface area and is suitable for use as a catalyst support.

[0030] (3) When the zirconium oxide of the present invention is used as a catalyst support for n-butane isomerization, the single-pass conversion rate of n-butane can reach 41%, and the selectivity of isobutane can reach 92%. Attached Figure Description

[0031] Figure 1 This is a scanning electron microscope (SEM) characterization image of ZrO-1 in Example 1;

[0032] Figure 2 This is a scanning electron microscope (SEM) characterization image of ZrO-1 in Example 1;

[0033] Figure 3 The image shows the scanning electron microscope (SEM) characterization of ZrO-A in Comparative Example 1.

[0034] Figure 4 The images show X-ray powder diffraction (XRD) characterization patterns of zirconium oxide in Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0035] The following examples will further illustrate the present invention. These embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0036] In this invention, SEM was performed using a scanning electron microscope (model ZEISS Merlin).

[0037] In this invention, XRD is performed using an X-ray powder diffractometer (D8 ADVANCE diffractometer).

[0038] In this invention, the specific surface area was measured using a Micrometrics Tristar 3000 specific surface area analyzer.

[0039] In this invention, the room temperature is 20°C.

[0040]

Example 1

[0041] At 40℃, 174g of zirconium nitrate pentahydrate and 45g of ammonium fluoride were added to 300g of deionized water and stirred for 4 hours to obtain zirconium solution A. At 40℃, 413g of 5wt% ammonia solution was added dropwise to solution A while stirring at 300rpm. After all the solution was added, stirring continued for 4 hours, then the mixture was transferred to a crystallization vessel, heated to 110℃, and kept at that temperature for 24 hours. After the crystallization, the mixture was cooled to room temperature, filtered, washed with water, and the resulting solid was dried in a 120℃ oven for 24 hours to obtain zirconium oxide precursor ZH-1. The precursor was then calcined at 550℃ for 3 hours to obtain zirconium oxide, designated ZrO-1. The properties of zirconium oxide are shown in Table 1, and the SEM images are shown in [Table 1]. Figure 1 and Figure 2 XRD pattern can be found Figure 4 The zirconium oxide is a pure monoclinic phase.

[0042] In this example, zirconium oxide ZrO-1 was used as a support to prepare a catalyst for the isomerization of n-butane.

[0043] Prepare 50g of zirconium oxide (ZrO-1). Place 6.3g of aluminum sulfate octadechydrate and 4.7g of copper sulfate pentahydrate in a beaker and dissolve them in an appropriate amount of water. Add the prepared aqueous solution dropwise to the zirconium oxide while stirring (initial wet impregnation method). After all the solution has been added, continue stirring until the mixture is homogeneous. Let it stand at room temperature for 24 hours, then dry it in an oven at 130℃ for 24 hours. Finally, calcine it in a muffle furnace at 650℃ for 4 hours to obtain the n-butane isomerization catalyst CAZ-1.

[0044] The performance evaluation of the n-butane isomerization catalyst was conducted in a fixed-bed reactor with a reaction tube size of 5 mm × 40 cm, a catalyst loading of 5 mL, and a particle size of 20-40 mesh. The reactor was placed in the isothermal zone of the furnace. The reaction temperature was 200 °C, the hydrogen pressure was 1 MPa, and the butane volume hourly space velocity was 1 h⁻¹. -1 The hydrogen-to-hydrogen molar ratio was 1:1. The catalyst required activation before use. Activation was performed by heating in a nitrogen stream containing 10% hydrogen by volume at 350°C for 8 hours. The catalyst performance evaluation results are shown in Table 2.

[0045]

Example 2

[0046] At 40℃, 174g of zirconium nitrate pentahydrate and 70g of ammonium bromide were added to 1490g of deionized water and stirred for 3 hours to obtain zirconium solution B. At 40℃, 184g of 15wt% ammonia solution was added dropwise to solution B while stirring at 300rpm. After all the solution was added, stirring continued for 4 hours. The mixture was then transferred to a crystallization vessel, heated to 120℃, and held at that temperature for 48 hours. After cooling to room temperature, the mixture was filtered, washed with water, and the resulting solid was dried in a 120℃ oven for 12 hours to obtain a zirconium oxide precursor. The precursor was then calcined at 550℃ for 4 hours to obtain zirconium oxide, designated ZrO-2, with properties shown in Table 1. The zirconium oxide was a pure monoclinic phase. (SEM images are similar.) Figure 1 , 2 The XRD pattern is similar. Figure 4 .

[0047] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0048] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0049]

Example 3

[0050] At 35℃, 200g of zirconium oxychloride octahydrate and 20g of ammonium formate were added to 180g of deionized water and stirred for 2 hours to obtain zirconium solution C. At 35℃, 211g of 10wt% ammonia solution was added dropwise to solution C while stirring at 300rpm. After all the solution was added, stirring continued for 4 hours, then the mixture was transferred to a crystallization vessel, heated to 100℃, and held at that temperature for 8 hours. After cooling to room temperature, the mixture was filtered, washed with water, and the resulting solid was dried in a 110℃ oven for 24 hours to obtain a zirconium oxide precursor. The precursor was then calcined at 650℃ for 3 hours to obtain zirconium oxide, designated ZrO-3, with properties shown in Table 1. The zirconium oxide was a pure monoclinic phase. (SEM images are similar.) Figure 1 , 2 The XRD pattern is similar. Figure 4 .

[0051] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0052] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0053]

Example 4

[0054] At 50℃, 174g of zirconium oxychloride octahydrate and 35g of ammonium propionate were added to 230g of deionized water and stirred for 4 hours to obtain zirconium solution D. At 50℃, 413g of 10wt% ammonia solution was added dropwise to solution D while stirring at 300rpm. After all the solution was added, stirring continued for 4 hours, then the mixture was transferred to a crystallization vessel, heated to 90℃, and held at that temperature for 72 hours. After cooling to room temperature, the mixture was filtered, washed with water, and the resulting solid was dried in a 110℃ oven for 24 hours to obtain a zirconium oxide precursor. The precursor was then calcined at 450℃ for 5 hours to obtain zirconium oxide, designated ZrO-4, the properties of which are shown in Table 1. The zirconium oxide was a pure monoclinic phase. (SEM images are similar.) Figure 1 , 2 The XRD pattern is similar. Figure 4 .

[0055] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0056] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0057]

Example 5

[0058] At 50℃, 24g of zirconium nitrate pentahydrate, 150g of zirconium oxychloride, 32g of ammonium acetate, and 20g of ammonium oxalate were added to 640g of deionized water and stirred for 4 hours to obtain zirconium solution E. At 50℃, 275g of 10wt% ammonia solution was added dropwise to solution E while stirring at 300rpm. After all the solution was added, stirring continued for 4 hours, then the mixture was transferred to a crystallization vessel, heated to 110℃, and held at that temperature for 48 hours. After cooling to room temperature, the mixture was filtered, washed with water, and the resulting solid was dried in a 120℃ oven for 24 hours to obtain a zirconium oxide precursor. The precursor was then calcined at 500℃ for 4 hours to obtain zirconium oxide, designated ZrO-5, whose properties are shown in Table 1. The zirconium oxide was a pure monoclinic phase. (SEM images are similar.) Figure 1 , 2 The XRD pattern is similar. Figure 4 .

[0059] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0060] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0061] Comparative Example 1

[0062] The preparation process was the same as in Example 1, except that ammonium fluoride was not added when preparing the zirconium solution. The final zirconium oxide obtained was designated ZrO-A, and its properties are shown in Table 1. SEM images are shown below. Figure 3 XRD pattern can be found Figure 4 .

[0063] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0064] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0065] Comparative Example 2

[0066] The preparation process was the same as in Example 1, except that ethylenediaminetetraacetic acid was used instead of ammonium fluoride when preparing the zirconium solution. The final zirconium oxide was designated ZrO-B, and its properties are shown in Table 1. SEM images are similar. Figure 3 XRD pattern can be found Figure 4 .

[0067] In this example, zirconium oxide was used as a support to prepare a catalyst for the isomerization of n-butane. The preparation method was the same as in Example 1.

[0068] The performance evaluation method for the catalyst for n-butane isomerization is the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0069] Table 1. Physical property data of zirconium oxide for each example.

[0070] serial number <![CDATA[Specific surface area (m 2 / g)]]> Is it a pure monoclinic phase? Example 1 ZrO-1 101 yes Example 2 ZrO-2 72 yes Example 3 ZrO-3 80 yes Example 4 ZrO-4 50 yes Example 5 ZrO-5 120 yes Comparative Example 1 ZrO-A 35 no Comparative Example 2 ZrO-B 60 no

[0071] Table 2. Application effects of n-butane isomerization catalyst

[0072] single-pass conversion of n-butane, mol% Isobutane selectivity, mol% Example 1 41 92 Example 2 40 90 Example 3 38 87 Example 4 37 88 Example 5 35 88 Comparative Example 1 25 86 Comparative Example 2 21 80

[0073] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A zirconium oxide, characterized in that, The zirconium oxide is a pure monoclinic phase; the zirconium oxide has a flower-like morphology composed of multiple almond-shaped grains; the specific surface area of ​​the zirconium oxide is 50~120 m². 2 / g.

2. The method for preparing zirconium oxide according to claim 1 comprises the following steps: adding ammonia dropwise to a mixture containing additives and zirconium salt to generate a precipitate; then hydrothermally crystallizing and calcining to obtain the zirconium oxide; The additives include one or more of ammonium acetate, ammonium formate, ammonium propionate, ammonium oxalate, ammonium fluoride, and ammonium bromide; the hydrothermal crystallization temperature is 90℃~120℃.

3. The preparation method according to claim 2, characterized in that, The additive is at least one of ammonium fluoride and ammonium bromide.

4. The preparation method according to claim 2, characterized in that, The zirconium salt includes one or two of zirconium oxychloride and zirconium nitrate; and / or, the ammonia is ammonia water.

5. The preparation method according to claim 4, characterized in that, The mass concentration of ammonia water is 5%~28%.

6. The preparation method according to claim 2, characterized in that, The mass ratio of additives to zirconium salt is 10~40:

100.

7. The preparation method according to claim 2, characterized in that, The molar ratio of ammonia (NH3) to zirconium salt (Zr) is NH3:Zr = 2~4.5:

1.

8. The preparation method according to claim 2, characterized in that, The hydrothermal crystallization time is 8~72 hours; And / or, the calcination temperature is 450~650℃, and the calcination time is 2~8h.

9. The use of the zirconium oxide according to claim 1 or the zirconium oxide prepared by any one of claims 2 to 8 as a catalyst support.

10. The application according to claim 9, characterized in that, The application is in the application of n-butane isomerization catalysts.

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