Zirconia, its preparation method and application

Abstract

This invention discloses a zirconium oxide, its preparation method, and its applications. The zirconium oxide is a pure tetragonal phase and possesses a spherical and / or near-spherical morphology. The zirconium oxide has a large specific surface area, making it suitable as a catalyst support, particularly for preparing n-butane isomerization catalysts.

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 acidity, weak basicity, 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] The catalytic activity and selectivity of zirconium oxide are influenced by the atomic arrangement and the number of unsaturated bonds on its surface. The morphology of zirconium oxide significantly affects this surface atomic arrangement and the number of unsaturated bonds, thus influencing its catalytic performance. Zirconia exists in various phases, including monoclinic, tetragonal, and cubic. Different phases exhibit varying physical and chemical properties and different catalytic performances for different catalytic reactions. The tetragonal phase of zirconium oxide is a metastable crystalline phase that readily transforms into the monoclinic phase at low temperatures. Most zirconium oxide sizing is predominantly monoclinic after preparation.

[0004] Conventional methods for preparing zirconia involve precipitation, which uses a neutralization reaction to generate zirconia precursor precipitates. However, the zirconia obtained by this precipitation method is often a mixture of monoclinic and tetragonal or cubic phases, not pure tetragonal zirconia. There are few reports on the preparation of high-purity tetragonal zirconia in the existing technology; most reports involve elemental doping. The added elements affect the performance of zirconia, limiting its applicability as a catalyst or catalyst support. CN110203969A discloses a microwave hydrothermal method for preparing yttrium-doped, stable, highly dispersed tetragonal zirconia. However, this method involves the addition of organic dispersants and mineralizers, multiple separation and washing cycles, generating large amounts of wastewater, and requiring freeze-drying at -57°C for 10 hours, resulting in high drying costs. Furthermore, the introduction of yttrium during the preparation process means that the final tetragonal zirconia contains yttrium, limiting its use in catalysts requiring high purity. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a zirconium oxide, its preparation method, and its applications. The preparation method has the advantages of simple process flow and easy operation and control. The zirconium oxide is a pure tetragonal phase with nanoscale particle size, exhibiting spherical and / or near-spherical morphologies, and has a large specific surface area, making it suitable as a catalyst support, particularly for the preparation of n-butane isomerization catalysts.

[0006] The first aspect of the present invention provides a zirconium oxide; the zirconium oxide is a pure tetragonal phase; the zirconium oxide has a spherical and / or near-spherical morphology.

[0007] According to the present invention, the zirconium oxide has a particle size distribution of 10–30 nm. Further, at least 85%, preferably 85%–90%, of the particle size is distributed in the range of 15–25 nm.

[0008] According to the present invention, 10% to 15% of the zirconium oxide particles are distributed in the range of ≥10 nm and <15 nm and >25 nm and ≤30 nm.

[0009] According to the present invention, the specific surface area of ​​the zirconium oxide is 81-100 m². 2 / g.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned zirconium oxide. The method includes the following steps:

[0011] Zirconium salt is added dropwise to a mixture containing a template agent and ammonia to form a precipitate; then it is hydrothermally crystallized and calcined to obtain the zirconium oxide.

[0012] According to the present invention, the template agent comprises at least one of dodecylbenzenesulfonic acid, dodecyl sulfuric acid, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, ammonium dodecylbenzenesulfonate, and ammonium dodecyl sulfate, preferably dodecylbenzenesulfonic acid.

[0013] According to the present invention, the zirconium salt comprises zirconium oxychloride and / or zirconium nitrate. The zirconium salt is present in solution form, wherein the concentration of the zirconium salt in the solution is 5 wt% to 36 wt%, preferably 5 wt% to 30 wt%.

[0014] According to the present invention, the molar ratio of the template agent to the zirconium element in the zirconium salt is 12 to 40:100. As a non-limiting example, the molar ratio of the template agent to the zirconium element in the zirconium salt can be any value among 14:100, 16:100, 18:100, 20:100, 22:100, 24:100, 26:100, 28:100, 30:100, 35:100, etc.

[0015] According to the present invention, the molar ratio of ammonia to zirconium salt is NH3:Zr = 2:1 to 4.5:1. Wherein, ammonia is calculated as NH3 and zirconium salt as Zr.

[0016] According to the present invention, the mass concentration of ammonia water is 5 wt% to 28 wt%, calculated as NH3.

[0017] According to the present invention, the zirconium salt is added at a constant rate. During the addition of the zirconium salt, the reaction mixture is kept under stirring. Further, the temperature of the reaction system is controlled at 35–60°C during the addition. Preferably, after the addition is complete, the reaction mixture is continued to be stirred for 0.5–2 hours.

[0018] According to the present invention, the conditions for hydrothermal crystallization are: a temperature of 90°C to 115°C and a time of 8 to 72 hours. The hydrothermal crystallization is carried out at a constant temperature. After crystallization, the temperature is cooled to below 35°C, preferably 15 to 35°C.

[0019] 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.

[0020] According to the present invention, the calcination temperature is 450-650°C and the calcination time is 2-8 hours.

[0021] 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.

[0022] According to the present invention, preferably, the application is in a n-butane isomerization catalyst.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The zirconium oxide of this invention is a pure tetragonal phase; the zirconium oxide has a spherical and / or near-spherical morphology. The zirconium oxide is nanoscale with 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.

[0025] (2) In the preparation method of the present invention, the template agent is first mixed with ammonia water, and then zirconium salt is added dropwise to the mixture. More preferably, the type and proportion of the template agent are controlled, and all conditions are coordinated to obtain pure tetragonal zirconium oxide. During the precipitation process, the template agent coats the surface of the newly formed precipitate particles, which on the one hand inhibits the growth and agglomeration of the particles and controls the size of the precipitate particles; on the other hand, the sulfate ions of the template agent interact with zirconium, making the calcined zirconium oxide tetragonal. The zirconium oxide is nanoscale, has a spherical and / or near-spherical morphology, and has a large specific surface area, making it suitable as a catalyst support.

[0026] (3) When the zirconium oxide of the present invention is used as a catalyst support for n-butane isomerization, the single-pass yield of isobutane can reach 42.5%. Attached Figure Description

[0027] Figure 1 This is a scanning electron microscope (SEM) characterization image of ZrO-1 in Example 1;

[0028] Figure 2 This is a transmission electron microscope (TEM) characterization image of ZrO-1 in Example 1;

[0029] Figure 3 The image shows the scanning electron microscope (SEM) characterization of ZrO-A in Comparative Example 1.

[0030] Figure 4 The image shows the scanning electron microscope (SEM) characterization of ZrO-D in Comparative Example 4.

[0031] Figure 5 The images show the X-ray powder diffraction (XRD) characterization patterns of zirconium oxide in Example 1 and Comparative Examples 2 and 3. Detailed Implementation

[0032] The following embodiments will further illustrate the present invention. These embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0033] In this invention, SEM was performed using a scanning electron microscope (model ZEISS Merlin).

[0034] In this invention, XRD is performed using an X-ray powder diffractometer (D8 ADVANCE diffractometer).

[0035] In this invention, the specific surface area was measured using a Micrometrics Tristar 3000 specific surface area analyzer.

[0036] In this invention, the zirconium oxide particle size is measured by using SigmaScan software to count the particle size in the TEM image, with the number of counted particles being greater than or equal to 500.

[0037] In this invention, the room temperature described in each example is 20°C.

[0038]

Example 1

[0039] 65.3 g of dodecylbenzenesulfonic acid was added to 363 g of 15 wt% ammonia solution (calculated as NH3) and stirred to dissolve, obtaining an alkaline solution. 322.2 g of zirconium oxychloride octahydrate was added to 500 g of deionized water and stirred to dissolve, obtaining a zirconium solution. At 50 °C, the zirconium solution was added dropwise to the prepared alkaline solution while stirring at 300 rpm. After all the solution was added, stirring continued for 1 hour. The mixture was then transferred to a crystallization vessel, heated to 105 °C, and held at that temperature for 24 hours. After cooling to room temperature, the mixture was filtered, washed with water, and the resulting solid was dried in a 120 °C oven for 24 hours. It was then calcined in a muffle furnace at 600 °C for 3 hours to obtain zirconium oxide, designated ZrO-1. (SEM image shown). Figure 1 TEM image Figure 2 The BET characterization data are shown in Table 1. The zirconium oxide is a pure tetragonal phase with spherical and / or near-spherical morphology. The particle size distribution of the zirconium oxide is 10–30 nm. Among them, 90% is distributed in the range of 15–25 nm, and the remaining 10% is distributed in the range of ≥10 nm and <15 nm and >25 nm and ≤30 nm.

[0040] In this example, zirconium oxide ZrO-1 was used as a support to prepare a catalyst for the isomerization of n-butane.

[0041] Prepare 50g of zirconium oxide (ZrO-1). Place 6.3g of aluminum sulfate octadecylhydrate 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 a 130℃ oven for 24 hours. Finally, calcine it in a muffle furnace at 600℃ for 4 hours to obtain the n-butane isomerization catalyst CAZ-1.

[0042] 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.

[0043]

Example 2

[0044] 113.4 g of ammonium dodecyl sulfate was added to 680 g of 5 wt% ammonia solution (calculated as NH3) and stirred to dissolve, obtaining an alkaline solution. 322.2 g of zirconium oxychloride octahydrate was added to 3243 g of deionized water and stirred to dissolve, obtaining a zirconium solution. At 35°C, the zirconium solution was added dropwise to the prepared alkaline solution while stirring at 300 rpm. After all the solution was added, stirring continued for 2 hours. The mixture was then transferred to a crystallization vessel, heated to 90°C, 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°C oven for 24 hours. It was then calcined in a muffle furnace at 450°C for 8 hours, finally yielding zirconium oxide, designated ZrO-2. SEM and TEM characterization results were similar to those of ZH-1, and BET characterization data are shown in Table 1. The zirconium oxide was a pure tetragonal phase with spherical and / or near-spherical morphology. The particle size distribution of the zirconium oxide was 10–30 nm. Of these, 86% are distributed in the 15–25 nm range. The remaining 14% are distributed in the ≥10 nm and <15 nm range and the >25 nm and ≤30 nm range.

[0045] 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.

[0046] 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.

[0047]

Example 3

[0048] 41.8 g of sodium dodecylbenzenesulfonate was added to 273 g of 28 wt% ammonia solution (calculated as NH3) and stirred to dissolve, obtaining an alkaline solution. 322.2 g of zirconium oxychloride octahydrate was added to 173 g of deionized water and stirred to dissolve, obtaining a zirconium solution. At 60 °C, the zirconium solution was added dropwise to the prepared alkaline solution while stirring at 300 rpm. After all the solution was added, stirring continued for 0.5 h. The solution was then transferred to a crystallization vessel, heated to 115 °C, and held at that temperature for 8 hours. After cooling to room temperature, the solution was filtered, washed with water, and the resulting solid was dried in a 120 °C oven for 12 hours. It was then calcined in a muffle furnace at 650 °C for 2 hours, finally yielding zirconium oxide, designated ZrO-3. SEM and TEM characterization results were similar to those of ZH-1, and BET characterization data are shown in Table 1. The zirconium oxide was a pure tetragonal phase with spherical and / or near-spherical morphology. The particle size distribution of the zirconium oxide was 10–30 nm. Of these, 85% are distributed in the 15–25 nm range. The remaining 15% are distributed in the ranges ≥10 nm and <15 nm and >25 nm and ≤30 nm.

[0049] 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.

[0050] 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.

[0051]

Example 4

[0052] 72.1 g of sodium dodecyl sulfate was added to 850 g of 5 wt% ammonia solution (calculated as NH3) and stirred to dissolve, obtaining an alkaline solution. 429.3 g of zirconium nitrate pentahydrate was added to 1832 g of deionized water and stirred to dissolve, obtaining a zirconium solution. At 45 °C, the zirconium solution was added dropwise to the prepared alkaline solution while stirring at 300 rpm. After all the solution was added, stirring continued for 1 hour. The mixture was then transferred to a crystallization vessel, heated to 110 °C, 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 115 °C oven for 24 hours. It was then calcined in a muffle furnace at 600 °C for 3 hours, finally yielding zirconium oxide, designated ZrO-4. SEM and TEM characterization results were similar to those of ZH-1, and BET characterization data are shown in Table 1. The zirconium oxide was a pure tetragonal phase with spherical and / or near-spherical morphology. The particle size distribution of the zirconium oxide was 10–30 nm. Of these, 87% are distributed in the 15–25 nm range. The remaining 13% are distributed in the ≥10 nm and <15 nm and >25 nm and ≤30 nm ranges.

[0053] 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.

[0054] 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.

[0055] Comparative Example 1

[0056] The preparation process was the same as in Example 1, except that dodecylbenzenesulfonic acid was added to the zirconium oxychloride aqueous solution instead of ammonia water when preparing the solution. Specifically, the alkaline solution was 363g of 15wt% ammonia water (calculated as NH3). 322.2g of zirconium oxychloride and 65.3g of dodecylbenzenesulfonic acid were added to 500g of deionized water and stirred to dissolve, obtaining a zirconium solution containing the template agent. At 50°C, the zirconium solution containing the template agent was added dropwise to the prepared alkaline solution while stirring at a speed of 300 rpm. After all the solution was added, stirring continued for 1 hour, then the mixture was transferred to a crystallization vessel, heated to 105°C, and kept at a constant 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°C oven for 24 hours, then calcined in a muffle furnace at 600°C for 3 hours, finally yielding zirconium oxide, designated ZrO-A. SEM images are shown below. Figure 3 Nanoscale spherical and / or near-spherical morphologies of zirconia were not obtained. BET characterization data are shown in Table 1.

[0057] 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.

[0058] 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.

[0059] Comparative Example 2

[0060] The preparation process was the same as in Example 1, except that the prepared alkaline solution was added dropwise to the zirconium solution during precipitation, instead of adding the non-zirconium solution dropwise to the alkaline solution. Specifically, 65.3 g of dodecylbenzenesulfonic acid was added to 363 g of 15 wt% ammonia water (calculated as NH3), and stirred to dissolve, obtaining an alkaline solution containing the template agent. 322.2 g of zirconium oxychloride was added to 500 g of deionized water, and stirred to dissolve, obtaining a zirconium solution. At 50°C, the alkaline solution containing the template agent was added dropwise to the zirconium solution while stirring at a speed of 300 rpm. After all the solution was added, stirring continued for 1 hour, then the mixture was transferred to a crystallization vessel, heated to 105°C, and kept at a constant 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°C oven for 24 hours, then calcined in a muffle furnace at 600°C for 3 hours, finally obtaining zirconium oxide designated ZrO-B. The obtained zirconium oxide was a mixed phase. XRD pattern is shown below. Figure 5 The BET characterization data are shown in Table 1.

[0061] 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.

[0062] 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.

[0063] Comparative Example 3

[0064] The preparation process was the same as in Example 1, except that the amount of dodecylbenzenesulfonic acid was 16.3 g. The final zirconium oxide obtained was designated ZrO-C. The resulting zirconium oxide was a mixed phase. The XRD pattern is shown below. Figure 5 The BET characterization data are shown in Table 1.

[0065] 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.

[0066] 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.

[0067] Comparative Example 4

[0068] The preparation process was the same as in Example 1, except that dodecylbenzenesulfonic acid template agent was not added when preparing the alkaline solution. The final zirconium oxide obtained was designated ZrO-D, and the SEM image is shown below. Figure 4No spherical or / or near-spherical morphology of zirconia was obtained. BET characterization data are shown in Table 1.

[0069] 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.

[0070] 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.

[0071] Table 1. Physical property data of zirconium oxide for each example.

[0072] serial number <![CDATA[Specific surface area (m 2 / g)]]> Is it a pure tetragonal phase? Example 1 ZrO-1 100 yes Example 2 ZrO-2 100 yes Example 3 ZrO-3 81 yes Example 4 ZrO-4 95 yes Comparative Example 1 ZrO-A 35 no Comparative Example 2 ZrO-B 60 no Comparative Example 3 ZrO-C 44 no Comparative Example 4 ZrO-D 35 no

[0073] Table 2. Application effects of n-butane isomerization catalyst

[0074] single-pass conversion of n-butane, mol% Isobutane selectivity, mol% Example 1 50 85 Example 2 39 92 Example 3 40 89 Example 4 38 88 Comparative Example 1 12 85 Comparative Example 2 19 81 Comparative Example 3 3 90 Comparative Example 4 10 82

[0075] 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 method for preparing zirconium oxide, wherein, The zirconium oxide is a pure tetragonal phase; the zirconium oxide has a spherical and / or near-spherical morphology; the method for preparing the zirconium oxide includes the following steps: Zirconium salt was added dropwise to a mixture containing a template agent and ammonia to form a precipitate; then hydrothermal crystallization and calcination were performed to obtain the zirconium oxide. The molar ratio of the template agent to zirconium in the zirconium salt is 12~40:100; the template agent includes at least one of dodecylbenzenesulfonic acid, dodecyl sulfuric acid, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, ammonium dodecylbenzenesulfonate, and ammonium dodecyl sulfate; the molar ratio of ammonia to zirconium salt is NH3:Zr=2:1~4.5:1; wherein ammonia is calculated as NH3 and zirconium salt is calculated as Zr; the hydrothermal crystallization conditions are: temperature of 90℃~115℃, time of 8~72 hours; during dropwise addition, the temperature of the reaction system is controlled at 35~60℃.

2. The preparation method according to claim 1, characterized in that, The zirconium oxide has a particle size distribution of 10~30 nm.

3. The preparation method according to claim 2, characterized in that, In the zirconium oxide particle size distribution, at least 85% have a particle size distribution of 15~25nm.

4. The preparation method according to claim 1, characterized in that, The specific surface area of ​​the zirconium oxide is 81~100 m². 2 / g.

5. The preparation method according to claim 1, characterized in that, The calcination temperature is 450~650℃, and / or the calcination time is 2~8h.

6. Zirconia prepared by the method according to any one of claims 1 to 5.

7. The use of the zirconium oxide as a catalyst support as described in claim 6.

8. The application according to claim 7, characterized in that, The application is in the application of n-butane isomerization catalysts.

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