Porous zinc-aluminum spinel nanoparticles, methods of making and uses thereof

Abstract

This invention provides porous zinc-aluminum spinel nanoparticles with an average particle size of 2–10 nm and a particle size of 190–380 nm. 2 The specific surface area is [value missing]. This invention also provides a method for preparing the porous zinc-aluminum spinel nanoparticles and their applications. The porous zinc-aluminum spinel nanoparticles provided by this invention possess suitable microscopic particle size, a large specific surface area, and a porous structure of "micropores" + "mesopores," exhibiting excellent performance and making them highly suitable for use as catalyst supports. The preparation method provided by this invention requires no additional additives, operates under mild conditions, is highly operable, has good reproducibility, and is low in cost, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of inorganic materials, specifically to a porous zinc-aluminum spinel nanoparticle, its preparation method, and its uses. Background Technology

[0002] Zinc-aluminum spinel is an important inorganic material widely used in catalysis as a catalyst or catalyst support due to its high thermal stability, low surface acidity, and good mechanical properties. Furthermore, its semiconductor characteristics also lead to applications in electronic devices. Currently, the main methods for preparing this type of spinel structure include hydrothermal synthesis, precipitation, melt solid-state reaction, and mechanochemical synthesis.

[0003] Chinese patent CN 103449503A discloses a method for preparing nano-zinc-aluminum spinel. The method mainly involves dissolving zinc salt in water, adding an aluminum source, stirring for 10-30 minutes, adding a pore-expanding agent, stirring again, aging at 20-100℃ for 30-60 minutes, drying, and then calcining at 500-1200℃. The amount of pore-expanding agent added is 0.5-30%, and the pore-expanding agent can be one or more of sucrose, glycerol, ammonium carbonate, ammonium bicarbonate, polystyrene emulsion, and polyethylene glycol. This preparation method involves a high calcination temperature, introduces organic matter as a pore-expanding agent, resulting in high costs, and produces zinc-aluminum spinel with excessively large sizes, which is not conducive to its use as a carrier in catalytic materials.

[0004] Chinese patent CN 106622204A discloses a zinc oxide material involving zinc-aluminum spinel, wherein the ZnO content, calculated as oxide, is 55-90%, and the specific surface area is 150-220 m² / g. 2 / g. A zinc-aluminum layered double hydroxide (LDH) structure material was prepared by alternating titration with aluminum-containing sodium carbonate solution and zinc-containing solution at a non-constant pH. After low-temperature calcination, it was transformed into uniformly dispersed zinc oxide containing zinc-aluminum spinel, with a high specific surface area. This material can be used as a sulfur adsorption / desorption material, a sulfur reduction aid for FCC catalysts, and a hydrodesulfurization support. The material obtained by this patent contains 55-90% ZnO, and when titrated under alkaline conditions with a pH of 8.5-9.5, the highest specific surface area can reach 220 m². 2 / g.

[0005] Chinese patent CN 102583467A discloses a method for preparing nano-ZnAl2O4 spinel. The method involves using divalent zinc salt, trivalent aluminum salt, and urea, adding deionized water to obtain a mixed salt. The mixture is heated, stirred, allowed to stand, and cooled at 70-110℃. The resulting filter cake is ground to obtain a zinc-aluminum hydrotalcite precursor, which is then calcined at 700-1000℃ for 1-5 hours and cooled to room temperature to obtain ZnAl2O4 spinel. Treatment with a 5-15 mol / L alkaline solution can remove highly dispersed Al2O3 or ZnO. This patented method requires urea and involves high calcination temperatures, resulting in relatively large spinel particles (10-40 nm), making it unsuitable for use as a catalyst support.

[0006] Chinese patent CN 106315639A discloses an ultrasonic preparation method for high-purity ZnAl2O4 nanoparticles. The method involves first grinding aluminum powder and zinc powder separately, and then ultrasonically hydrolyzing them to obtain aluminum hydroxide colloidal solutions and zinc hydroxide colloidal solutions, respectively. After drying, these solutions are ground to obtain aluminum hydroxide and zinc oxide powders. The aluminum hydroxide powder is then calcined and ground to obtain γ-Al2O3. The γ-Al2O3 powder and zinc oxide powder are then mixed and ultrasonically activated to obtain a mixed sol. After drying, grinding, and calcination, ZnAl2O4 nanoparticles are obtained. The ultrasonic preparation method of this patent yields nanoparticles with a size of up to 100 nm, which is not ideal for use as a catalyst carrier.

[0007] Existing methods or processes for preparing zinc-aluminum spinel are relatively complex, resulting in nanostructures with large microparticle sizes (typically 10-100 nm). This hinders the generation of active sites or the attachment of the active phase, thus limiting its application in catalysis, particularly in small-molecule catalysis using CO, CO2, and H2 as raw materials. Therefore, developing porous spinel structures with smaller microparticle sizes and larger specific surface areas is of great significance for expanding its applications in catalysis. Summary of the Invention

[0008] To overcome the shortcomings of the existing technology, one object of the present invention is to provide a porous zinc-aluminum spinel nanoparticle with a suitable micro-particle size and a larger specific surface area, which is very suitable for use in the field of catalysis, especially in the field of small molecule catalysis using raw materials such as CO, CO2, and H2.

[0009] Another object of the present invention is to provide a method for preparing the porous zinc-aluminum spinel nanoparticles and their uses.

[0010] The porous zinc-aluminum spinel nanoparticles provided by this invention have an average particle size of 2–10 nm and a particle size of 190–380 nm. 2 Specific surface area per g.

[0011] The porous zinc-aluminum spinel nanoparticles provided by this invention have an average particle size of about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, about 10 nm, or any combination thereof. In some preferred embodiments, the porous zinc-aluminum spinel nanoparticles have an average particle size of 3 to 6 nm.

[0012] The porous zinc-aluminum spinel nanoparticles provided by this invention have a specific surface area of ​​approximately 190 m². 2 / g, approximately 200m 2 / g, approximately 230m 2 / g, approximately 250m 2 / g, approximately 280m 2 / g, approximately 300m 2 / g, approximately 320m 2 / g, approximately 350m 2 / g, approximately 380m 2 / g can be any combination of specific surface area ranges. In some preferred embodiments, the specific surface area of ​​the porous zinc-aluminum spinel nanoparticles can be 230–350 m². 2 / g.

[0013] The porous zinc-aluminum spinel nanoparticles provided by this invention have a porous structure characterized by "micropores" + "mesopores," comprising, by volume percentage: 5-13% micropores (i.e., pore size < 2 nm) and 87-95% mesopores (i.e., pore size 2-50 nm). In some preferred embodiments, the porous zinc-aluminum spinel nanoparticles comprise: 5-13% micropores, 75-85% mesopores of 2-10 nm, and 7-12% mesopores larger than 10 nm.

[0014] The porous zinc-aluminum spinel nanoparticles provided by this invention have a pore volume of 0.3–1.2 cm³. 3 / g.

[0015] XRD and transmission electron microscopy (TEM) analyses revealed that the porous zinc-aluminum spinel nanoparticles provided by this invention contain almost no dispersed ZnO nanoparticles (preferably no dispersed zinc oxide ZnO), thus exhibiting a more rigid structure, improved hydrothermal resistance, and better thermal stability. This invention also provides a method for preparing the porous zinc-aluminum spinel nanoparticles described in any of the above technical solutions, comprising the following steps:

[0016] S1: Prepare Zn-containing solutions with a volume of V. 2+ And Al 3+ Salt solutions and precipitant solutions;

[0017] S2: Add an alkaline solution with a pH of 9-10 to the reaction vessel, then add the salt solution and the precipitant solution dropwise into the reaction vessel at the same rate for co-precipitation. By volume, control the pH to 7-9 during the first 20-50% of the addition of V, and control the pH decrease to 1-20% during the remaining addition.

[0018] S3: After the co-precipitation is completed, aging is performed, and the resulting solid is dried and then calcined at 300-400°C to obtain the porous zinc-aluminum spinel nanoparticles.

[0019] The preparation method provided by this invention adopts a co-precipitation process. Under the combined effect of a series of process conditions such as temperature, solution flow rate, and pH value, the raw materials are co-precipitated to form a precursor. After aging, the microstructure of the precursor is further stabilized. Subsequently, after drying and low-temperature calcination, the porous spinel material described in this invention is formed, which has a suitable size as a catalyst carrier and a larger specific surface area.

[0020] In the preparation method provided by this invention, the Zn-containing... 2+ And Al 3+ In salt solutions, Zn 2+ With Al 3+ The molar ratio can be 0.5 to 1.5:2, for example, about 0.5:2, about 0.8:2, about 1:2, about 1.2:2, about 1.5:2, or any combination of molar ratios within this range. The metal ions used to form the salt solution can be their respective soluble salts or hydrates, for example, nitrates, carbonates, chlorides, sulfates, or their respective hydrates.

[0021] In the preparation method provided by this invention, the precipitant solution may contain one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate, with a concentration of 0.1–0.5 g / mL. In some preferred embodiments, the precipitant may be sodium carbonate.

[0022] In the preparation method provided by this invention, the alkaline solution can be an aqueous solution formed from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate, with a concentration of 0.05–2 mol / L. The type of alkaline solution can be the same as or different from the precipitant solution.

[0023] In the preparation method provided by this invention, the volume of the added alkali solution is 40-60% (volume ratio) of V, for example, it can be about 40%, about 45%, about 50%, about 55%, about 60%, or any combination of volume ratios within this range. In some preferred embodiments, the volume of the added alkali solution is 50% of V.

[0024] In the preparation method provided by the present invention, the coprecipitation temperature can be 60-80°C, for example, about 60°C, about 65°C, about 70°C, about 75°C, about 80°C, or any combination of temperature ranges.

[0025] In the preparation method provided by this invention, the dripping rate of the salt solution and the precipitant solution is 0.75 to 1.5% of the volume V per minute. Too fast or too slow a dripping rate will affect the microstructure of the target product, thus failing to obtain the desired product.

[0026] In the preparation method provided by this invention, due to the pre-added alkaline solution, the coprecipitation system exhibits a strong alkalinity overall. As the salt solution and precipitant solution are added dropwise in parallel, the pH value of the coprecipitation system gradually decreases. The decrease in pH value is controlled within a certain range to avoid significant changes affecting the microstructure of the target product. In some preferred embodiments, the pH value is controlled to be 7-9 when the first 20-50% of the solution (V) is added, and the decrease in pH value is controlled to be 2-20% when the remaining solution is added. For example, this could be about 2%, about 5%, about 10%, about 12%, about 15%, about 18%, about 20%, or any combination thereof.

[0027] In the preparation method provided by this invention, the aging process can be at the same temperature as the coprecipitation or at a slightly higher temperature, which can be adjusted accordingly by those skilled in the art. In some preferred embodiments, the aging process can be at the same temperature as the coprecipitation, and the aging time can be 0.5–24 h.

[0028] In the preparation method provided by the present invention, after aging, the obtained solid is separated and washed, for example, with water. The degree of washing is preferably such that the conductivity of the washing liquid is less than 50 μS / cm.

[0029] In the preparation method provided by this invention, the purpose of drying is to remove residual free water after washing. The drying temperature can be 80–120°C, and the drying time can be 10–16 hours. In some preferred embodiments, the degree of drying is such that the moisture content of the material is less than 1 wt%.

[0030] In the preparation method provided by the present invention, the calcination can be low-temperature calcination, which is beneficial for controlling the grain size. The calcination temperature can be 300-350℃ and the calcination time can be 3-6h.

[0031] In the preparation method provided by the present invention, the desired material can be obtained through a separation step, such as separating solid matter after aging. The separation method can be a common method in the art, including but not limited to natural sedimentation, (atmospheric pressure or vacuum) filtration, centrifugation, etc.

[0032] This invention also provides the use of porous zinc-aluminum spinel nanoparticles as described in any of the above-described technical solutions, or porous zinc-aluminum spinel nanoparticles prepared by any of the above-described technical solutions, as catalyst supports. For example, the catalyst can be a catalyst for the hydrogenation of CO2 to methanol.

[0033] The technical solution provided by this invention has the following advantages:

[0034] The porous zinc-aluminum spinel nanoparticles provided by this invention have suitable micro-particle size, large specific surface area, and a porous structure of "micropores" + "mesopores". They have excellent performance and are very suitable as catalyst supports. The catalytic active components can be attached to the pores, thereby achieving uniform dispersion of the active components. This can significantly improve the catalytic performance of the obtained catalyst and has very important economic and industrial value.

[0035] The preparation method provided by this invention achieves the preparation of porous zinc-aluminum spinel nanoparticles by controlling a series of process conditions. It does not require the use of more additives (such as pore expanders, sodium aluminate, etc.), the conditions are mild, the operation is highly operable, the repeatability is good, the cost is low, and it is suitable for large-scale industrial production. Attached Figure Description

[0036] Figure 1 The images shown are TEM images of the zinc-aluminum spinel nanoparticles prepared in Example 1. Image A is a TEM image of the zinc-aluminum spinel nanoparticles, image B is a magnified partial image of image A, and image C is a schematic diagram of the standard structure of zinc-aluminum spinel.

[0037] Figure 2 The nitrogen physisorption-desorption curves are shown for the zinc-aluminum spinel nanoparticles prepared in Examples 1-4.

[0038] Figure 3 The pore structure curves are for the zinc-aluminum spinel nanoparticles prepared in Examples 1-4. Detailed Implementation

[0039] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0040] Unless otherwise specified, all raw materials or reagents used in the embodiments and comparative examples of this invention are commercially available products.

[0041] Unless otherwise specified, all percentages used in the embodiments and comparative examples of this invention are mass percentages.

[0042] In the embodiments and comparative examples of the present invention, the specific surface area and pore structure of the obtained products were tested using a nitrogen physical adsorption instrument, and the pore volume of the products was calculated. Figure 2 and Figure 3 As shown.

[0043] Example 1: Preparation of Zinc Aluminum Spinel Nanoparticles

[0044] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, add water to prepare a 4L aqueous solution for later use, designated as precipitant A; weigh 1200g of sodium carbonate, add water to prepare a 4L aqueous solution for later use, designated as precipitant B. In a 10L reactor, first add 2L of 0.1mol / L potassium bicarbonate solution to the bottom of the reactor, then begin adding precipitant A and precipitant B dropwise in parallel, maintaining a uniform precipitation rate of 40mL / min. Control the reactor temperature at 70℃. During the precipitation process, control the pH value to 8 when adding the first 30% (volume ratio) of solution, and control the pH value to 7 when adding the last 70% (volume ratio). After precipitation, continue stirring at the same temperature for 0.5h, then cool. Filter, repeatedly wash the filter cake until the conductivity of the wash liquid is less than 50μS / cm, dry at 110℃ for 15h to remove free water from the filter cake, forming a precursor with a water content of less than 1%. The precursor was transferred to a muffle furnace for calcination at a controlled temperature of 350°C for 5 hours, after which it was removed to obtain zinc-aluminum spinel nanoparticles.

[0045] like Figure 1 As shown in Figure B and Figure C, it can be seen that the obtained nanoparticles have a zinc aluminum spinel (ZnAl2O4) structure and do not contain dispersed ZnO nanoparticles.

[0046] The spinel nanoparticles have an average size of 3.8 nm. Among the spinel nanoparticles, micropores smaller than 2 nm account for 9%, pores between 2 and 10 nm account for 84%, and pores between 10 and 50 nm account for 7%. The specific surface area is 258.7 m². 2 / g, pore volume is 0.38cm 3 / g.

[0047] Example 2: Preparation of Zinc Aluminum Spinel Nanoparticles

[0048] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, add water to prepare a 4L aqueous solution for later use, designated as precipitant A; weigh 1000g of sodium carbonate, add water to prepare a 4L aqueous solution for later use, designated as precipitant B. In a 10L reactor, first add 2L of 0.05mol / L sodium bicarbonate solution to the bottom of the reactor, then begin adding precipitant A and precipitant B dropwise in parallel, maintaining a uniform precipitation rate of 50mL / min. Control the reactor temperature at 80℃. During the precipitation process, control the pH value to 8 when adding the first 20% (volume ratio) of solution, and control the pH value to 6.5 when adding the last 80% (volume ratio). After precipitation, continue stirring at the same temperature for 1 hour, then cool. Filter, repeatedly wash the filter cake until the conductivity of the wash liquid is less than 50μS / cm, and dry at 110℃ for 10 hours to remove free water from the filter cake, forming a precursor with a water content of less than 1%. The precursor was transferred to a muffle furnace for calcination at a controlled temperature of 300°C for 3 hours, and then removed to obtain zinc-aluminum spinel nanoparticles.

[0049] The spinel nanoparticles have an average size of 4.8 nm. Micropores smaller than 2 nm account for 9%, pores between 2 and 10 nm account for 82%, and pores between 10 and 50 nm account for 9%. The specific surface area is 264.1 m². 2 / g, pore volume is 0.48cm 3 / g.

[0050] Example 3: Preparation of Zinc Aluminum Spinel Nanoparticles

[0051] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, add water to prepare a 4L aqueous solution for later use, designated as precipitant A; weigh 1300g of sodium carbonate, add water to prepare a 4L aqueous solution for later use, designated as precipitant B. In a 10L reactor, first add 2L of 1.5mol / L ammonium bicarbonate to the bottom of the reactor, then begin adding precipitant A and precipitant B dropwise in parallel, maintaining a uniform precipitation rate of 60mL / min. Control the reactor temperature at 75℃. During the precipitation process, control the pH value to 9 when adding the first 50% (volume ratio) of the solution, and control the pH value to 8 when adding the last 50% (volume ratio). After precipitation, continue stirring at the same temperature for 1 hour, then cool. Filter, repeatedly wash the filter cake until the conductivity of the wash liquid is less than 50μS / cm, dry at 110℃ for 16 hours to remove free water from the filter cake, forming a precursor with a water content of less than 1%. The precursor was transferred to a muffle furnace for calcination at a controlled temperature of 320°C for 5 hours, and then removed to obtain zinc-aluminum spinel nanoparticles.

[0052] The spinel nanoparticles have an average size of 5.1 nm, with micropores smaller than 2 nm accounting for 6%, pores between 2 and 10 nm accounting for 82%, and pores between 10 and 50 nm accounting for 12%. The specific surface area is 233.5 m². 2 / g, pore volume 0.35cm 3 / g.

[0053] Example 4: Preparation of Zinc Aluminum Spinel Nanoparticles

[0054] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, and dissolve them in water to prepare a 4L aqueous solution, designated as precipitant A. Weigh 1200g of sodium carbonate and dissolve it in water to prepare a 4L aqueous solution, designated as precipitant B. In a 10L reactor, first add 2L of a 0.01mol / L alkaline solution (a mixture of sodium bicarbonate and potassium bicarbonate in a 1:1 mass ratio) to the bottom of the reactor. Then, begin adding precipitant A and precipitant B dropwise in parallel, maintaining a uniform precipitation rate of 30mL / min. Control the reactor temperature at 60℃. During the precipitation process, control the pH to 7 when adding the first 30% (volume ratio) of the solution, and control the pH to 6.8 when adding the remaining 70% (volume ratio). After precipitation, continue stirring at the same temperature for 1 hour, then cool down. The filter cake was filtered and repeatedly washed until the conductivity of the wash liquid was less than 50 μS / cm. It was then dried at 110℃ for 14 h to remove free water from the filter cake, forming a precursor with a water content of less than 3%. The precursor was transferred to a muffle furnace for calcination at 320℃ for 5 h to obtain zinc-aluminum spinel nanoparticles.

[0055] The spinel nanoparticles have an average size of 3.4 nm. Among the spinel nanoparticles, micropores smaller than 2 nm account for 12%, pores between 2 and 10 nm account for 76%, and pores between 10 and 50 nm account for 12%. The specific surface area is 348.2 m². 2 / g, pore volume 1.01cm 3 / g.

[0056] Comparative Example 1

[0057] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, add water to prepare a 4L aqueous solution for later use, designated as precipitant A; weigh 1200g of sodium carbonate, add water to prepare a 4L aqueous solution for later use, designated as precipitant B. Add precipitant A and precipitant B dropwise in a 10L reactor in a parallel flow, maintaining a uniform precipitation rate. Control the reactor temperature at 80℃, the pH of the solution in the reactor at 8, and the flow rate of precipitant A and precipitant B at 100mL / min. After precipitation, continue stirring at the same temperature for 2-3 hours, then cool. Filter, wash and dry the filter cake to ensure a water content of <1%. Transfer to a muffle furnace for calcination, control the calcination temperature at 700℃, calcinate for 5 hours, then remove to obtain zinc-aluminum spinel particles.

[0058] The zinc-aluminum spinel particles have an average size of 36 nm, are monopore materials with a size greater than 50 nm, and have a specific surface area of ​​60 m². 2 / g, pore volume 0.14cm3 / g.

[0059] Comparative Example 2

[0060] Weigh 828g of zinc nitrate hexahydrate and 2087g of aluminum nitrate nonahydrate, add water to prepare a 4L aqueous solution for later use, designated as precipitant A; weigh 1200g of sodium carbonate, add water to prepare a 4L aqueous solution for later use, designated as precipitant B. Add precipitant A and precipitant B dropwise in a 10L reactor in a parallel flow, maintaining a uniform precipitation rate. Control the reactor temperature at 70℃, the pH of the solution in the reactor at 7, and the flow rate of precipitant A and precipitant B at 100mL / min. After precipitation, continue stirring at the same temperature for 2-3 hours, then cool. Filter, wash and dry the filter cake to ensure a moisture content of <1%. Transfer to a muffle furnace for calcination, control the calcination temperature at 600℃, calcinate for 5 hours, and then remove to obtain zinc-aluminum spinel particles.

[0061] The zinc-aluminum spinel particles have an average size of 25 nm, are monoporous materials with a size greater than 40 nm, and have a specific surface area of ​​72 m². 2 / g, pore volume is 0.18cm 3 / g.

[0062] Application examples

[0063] Weigh 15g of zinc-aluminum spinel nanoparticles prepared in Examples 1-4 and Comparative Examples 1-2, disperse them in 100mL of 0.05mol / L potassium bicarbonate solution to obtain a suspension, stir for 1h, raise the temperature to 70℃, then add 100mL of a mixed solution containing copper nitrate and zinc nitrate (copper-zinc molar ratio of 2:1, total ion concentration of 1mol / L) and 100mL of 1.5mol / L potassium carbonate solution to the above suspension in a co-current flow. Control the pH of the precipitation to 8, and the temperature to 70℃. After precipitation, wash, dry at 120℃ for 8h, and then calcine in a muffle furnace at 350℃ for 4h to obtain the catalyst supported on zinc-aluminum spinel nanoparticles. Its specific surface area and average particle size are listed in Table 1.

[0064] The obtained supported catalyst was subjected to a CO2 hydrogenation reaction to produce methanol under the following conditions:

[0065] After the catalyst is compressed into tablets, crushed, and sieved to 20-40 mesh, 2g is taken and loaded into a microreactor. A reaction gas with a H2:CO2 ratio of 3:1 (volume ratio) is introduced, and the space velocity is 10000h. -1 The reaction was carried out at 5 MPa and 250 °C for 24 h. The CO2 single-pass conversion rate was obtained by gas chromatography and the results are shown in Table 1.

[0066] Table 1

[0067]

[0068] As shown in Table 1, compared to the large-pore, large-particle-size zinc-aluminum spinel particles of Comparative Examples 1-2, the spinel nanoparticles prepared in this invention can load more catalytically active components when used as a catalyst support, thus resulting in a significantly higher single-pass CO2 conversion rate under the same reaction conditions. Table 1 also shows that when the supported catalyst is formed from zinc-aluminum spinel particles, the calcination temperature is relatively low, so the loading process essentially does not alter the original zinc-aluminum spinel structure, and the resulting supported catalyst maintains a smaller average particle size and a larger specific surface area.

[0069] Examples 1-4 also show that as the specific surface area increases, the catalytic effect is also improved accordingly. This indicates that an increased specific surface area can load more catalytically active components, resulting in a better catalytic effect.

[0070] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0071] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A porous zinc-aluminum spinel nanoparticle, characterized in that, The porous zinc-aluminum spinel nanoparticles have an average particle size of 2–10 nm and a particle size of 220–380 μm. 2 The porous zinc-aluminum spinel nanoparticles, with a specific surface area of ​​ / g, comprise: 5–13% micropores, 75–85% mesopores of 2–10 nm, and 7–12% mesopores larger than 10 nm, and the pore volume of the porous zinc-aluminum spinel nanoparticles is 0.3–1.2 cm³. 3 / g.

2. The porous zinc-aluminum spinel nanoparticles according to claim 1, characterized in that, The porous zinc-aluminum spinel nanoparticles have a specific surface area of ​​230–350 m². 2 / g.

3. The method for preparing porous zinc-aluminum spinel nanoparticles according to claim 1 or 2, characterized in that, Includes the following steps: S1: Prepare Zn-containing solutions with a volume of V. 2+ And Al 3+ Salt solutions and precipitant solutions; S2: Add an alkaline solution with a pH of 9-10 to the reaction vessel, and then add the salt solution and the precipitant solution dropwise into the reaction vessel at the same rate for co-precipitation. By volume, control the pH to 7-9 when adding the first 20-50% of V, and control the pH to decrease by 1-20% when adding the remaining solution. The dropwise rate of the salt solution and the precipitant solution is 0.75-1.5% of V per minute. as well as S3: After the co-precipitation is completed, aging is performed. The resulting solid is dried and then calcined at 300-400℃ to obtain the porous zinc-aluminum spinel nanoparticles. Among them, the Zn-containing 2+ And Al 3+ In salt solutions, Zn 2+ With Al 3+ The molar ratio is 0.5–1.5 :

2.

4. The preparation method according to claim 3, characterized in that, The precipitant solution contains one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate, with a concentration of 0.1–0.5 g / mL.

5. The preparation method according to claim 3 or 4, characterized in that, The alkaline solution is an aqueous solution formed from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate, with a concentration of 0.05–2 mol / L; and / or The volume of the alkaline solution added is 40-60% of V.

6. The preparation method according to claim 3 or 4, characterized in that, In step S2, the temperature of the co-precipitation is 60–80°C.

7. The preparation method according to claim 3 or 4, characterized in that, In step S3, the aging and co-precipitation are carried out at the same temperature, and the aging time is 0.5–24 h; and / or The drying process is performed at 80–120°C for 10–16 hours; and / or The roasting is carried out at 300-350℃ for 3-6 hours.

8. The use of the porous zinc-aluminum spinel nanoparticles according to claim 1 or 2 or the porous zinc-aluminum spinel nanoparticles prepared by the preparation method according to any one of claims 3-7 as a catalyst support.

9. The use according to claim 8, wherein, The catalyst is a catalyst for the hydrogenation of CO2 to methanol.

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