Forming technology of high-pore-volume alumina material

Abstract

The invention discloses a forming technology of a high-pore-volume aluminum oxide material, which comprises the following steps: firstly, adding aluminum oxide powder into rotary granulation equipment, slowly adding a compound A while stirring, introducing hot air for a period of time for pretreatment, adding an acid solution while stirring for treatment, and preparing into a spherical shape, a rhombus shape, a strip shape or a clover shape and the like according to requirements. And adsorbing and removing the compound A from the formed material through hot air, and then roasting or performing metal impregnation. According to the invention, the organic matter is used for protecting alumina pores, so that the concentration of the acid solution can be improved, the local acidification degree is enhanced, and the strength of the formed material is improved.

Description

Technical Field

[0001] This invention belongs to the field of inorganic material preparation and relates to a method for forming alumina, specifically to a forming technology for high-porosity alumina materials. Background Technology

[0002] Due to its excellent surface properties, such as large specific surface area, strong surface adsorption performance, and surface acidic centers, alumina materials are widely used as catalyst carriers and drying adsorbents in various industries.

[0003] For example, in hydrorefining, alumina supports have a significant impact on the activity, selectivity, and stability of catalysts. They can increase the effective surface area of ​​the catalyst and provide a suitable pore structure for specific reactions.

[0004] In automotive exhaust catalytic converters, large-pore alumina is extensively used as a catalyst support.

[0005] Current research focuses on how to synthesize highly porous alumina.

[0006] Patent CN102515229A discloses a method for preparing activated alumina: Sodium aluminate solution is added to 1-3 mol / L nitric acid to form a sol with pH 6-10 at 20-50 °C. After aging at 50-90 °C for 2-10 hours, the alumina is washed by vacuum filtration and then azeotropically distilled with n-butanol (1:3-8 volume ratio) to obtain a precursor. Calcination yields activated alumina with large pore volume and high specific surface area. This method is simple, and the n-butanol can be recycled.

[0007] Patent CN105060323A uses an inorganic aluminum salt solution reacted with an acid-base mixture to prepare a slurry. After aging, washing, and supercritical drying, a gibbsite precursor is obtained, which is then calcined to obtain porous γ-alumina. The optimal product has a pore volume of 5.4 cm³ / g and a specific surface area of ​​423.7 m² / g. Another sample with a pore volume of 4.7 cm³ / g and a specific surface area of ​​388.4 m² / g was also prepared.

[0008] Alumina requires shaping during application, and acidic substances are often added during this process. However, the pore structure of alumina is very prone to collapse during acidification, losing its original structure. Therefore, in addition to synthesizing high-porosity alumina, shaping technology is crucial for preserving more of the original structure. Summary of the Invention

[0009] To address the shortcomings of current technologies, this invention provides a forming technology for high-porosity alumina materials.

[0010] A forming technology for a high-porosity alumina material includes the following steps:

[0011] (1) Pretreatment: A certain amount of alumina powder is added to the rotary granulator while stirring and slowly added (PV•m 氧化铝 Compound A is passed through hot air at a certain temperature for a period of time, then cooled down for later use.

[0012] (2) Shaping: A certain proportion of acidic liquid can be added while stirring. The rotation speed and processing time can be adjusted according to the required particle size, or the mixture can be transferred to other equipment and made into strips, clover shapes or rhombuses as needed.

[0013] (3) Post-processing: After molding, the material is first desorbed by hot air, and then roasted or metal impregnated as needed.

[0014] In step (1) of this invention, alumina powder S A ≥ 300 m 2 / g, PV ≥ 0.65 mL / g, compound A is: n-heptane or isooctane.

[0015] In step (1) of this invention, the temperature of the hot air is 95-100 ℃ and the introduction time is 10-40 min.

[0016] In step (2) of the present invention, the acidic liquid is nitric acid, formic acid, acetic acid or a mixture thereof.

[0017] In step (3) of the present invention, hot air at 100-120°C should adsorb compound A through an adsorption material and reuse it.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The original pores of alumina are filled with organic matter. During acidification, the acid mostly contacts only the outer surface of the alumina, thus controlling the degree of acidification. Moreover, the concentration of the acid solution can be much higher than conventional methods, further enhancing the localized acidification and improving the strength of the granulated material. In addition, compound A can be recovered after granulation, preventing waste and environmental pollution. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for a better understanding of the technical solutions of the present invention and are not intended to limit the present invention. For those skilled in the art, several improvements and substitutions can be made without departing from the principles of the present invention, and all such improvements and substitutions fall within the scope of protection of the present invention.

[0021] Example 1:

[0022] (1) Pretreatment: Add 1200 g of alumina powder to a rotary granulator, while stirring, slowly add 840 mL of n-heptane, and pass hot air at 95 °C for 20 min, then cool down for later use.

[0023] (2) Molding: Continue stirring while adding 360 g of 20% nitric acid. Set the rotation speed to 3000 r / min and process for 15 min.

[0024] (3) Post-processing: After molding, the material is first desorbed by hot air at 110°C and then roasted.

[0025] Example 2:

[0026] (1) Pretreatment: Add 1200 g of alumina powder to a rotary granulator, while stirring, slowly add 840 mL of n-heptane, and pass hot air at 100°C for 20 min, then cool down for later use.

[0027] (2) Molding: Continue to add 360 g of 20% nitric acid while stirring. Set the rotation speed to 3000 r / min and process for 15 min.

[0028] (3) Post-processing: After molding, the material is first desorbed by hot air at 110°C and then roasted.

[0029] Example 3:

[0030] (1) Pretreatment: Add 1200 g of alumina powder to a rotary granulator, while stirring, slowly add 840 mL of n-heptane, pass hot air at 95°C for 20 min, and cool down for later use.

[0031] (2) Molding: Continue stirring while adding 360 g of 20% formic acid. Set the rotation speed to 3000 r / min and process for 15 min.

[0032] (3) Post-processing: After molding, the material is first desorbed by hot air at 110°C and then roasted.

[0033] Example 4:

[0034] (1) Pretreatment: Add 1200 g of alumina powder to a rotary granulator, while stirring, slowly add 840 mL of n-heptane, pass hot air at 95°C for 20 min, and cool down for later use.

[0035] (2) Molding: Continue stirring while adding 360 g of 20% acetic acid. Set the rotation speed to 3000 r / min and process for 15 min.

[0036] (3) Post-processing: After molding, the material is first desorbed by hot air at 110°C and then roasted.

[0037] Example 5:

[0038] (1) Pretreatment: Add 1200 g of alumina powder to a rotary granulator, while stirring, slowly add 840 mL of isooctane, pass hot air at 95°C for 20 min, and cool down for later use.

[0039] (2) Molding: Continue stirring while adding 360 g of 20% nitric acid. Set the rotation speed to 3000 r / min and process for 15 min.

[0040] (3) Post-processing: The shaped material is first desorbed by hot air at 110°C and then roasted.

[0041] Comparative Example 1:

[0042] 1200 g of alumina powder was added to a rotary granulator, and 360 g of 20% nitric acid was added while stirring. The rotation speed was set to 3000 r / min, and the process was carried out for 15 min. After forming, the powder was calcined.

[0043] Comparative Example 2:

[0044] 1200 g of alumina powder was added to a rotary granulator, and 360 g of 20% formic acid was added while stirring. The rotation speed was set to 3000 r / min, and the treatment time was 15 min. After forming, the granulated powder was calcined.

[0045] The table below shows the performance test data of the materials prepared in the examples and comparative examples.

[0046] Table 1. Properties of Alumina Materials

[0047] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 serial number A1 A2 A3 A4 A5 B1 B2 <![CDATA[Specific surface area m 2 / g]]> 373 369 371 375 368 251 295 Pore ​​volume mL / g 0.9 0.87 0.89 0.85 0.88 0.59 0.63 Crushing strength N 73 78 75 71 77 81 77

[0048] As can be seen from Table 1, the alumina spherical material prepared by the method described in this patent can retain the specific surface area and pore volume of the raw material to a greater extent compared with the comparative example. At the same time, the shaped material exhibits excellent mechanical strength, which fully meets the strength requirements of the catalyst support in practical applications.

Claims

1. A forming technology method for a high-porosity alumina material, comprising pretreatment, forming, and post-treatment processes, as detailed below: (1) Pretreatment: A certain amount of alumina powder is added to the rotary granulator while stirring and slowly added (PV•m 氧化铝 Compound A is passed through hot air at a certain temperature for a period of time, then cooled down for later use. (2) Shaping: A certain proportion of acidic liquid can be added while stirring. The rotation speed and processing time can be adjusted according to the required particle size, or the mixture can be transferred to other equipment and made into strips, clover shapes or rhombuses as needed. (3) Post-processing: After molding, the material is first desorbed by hot air, and then roasted or metal impregnated as needed.

2. The preparation method according to claim 1, characterized in that, In step (1), alumina powder S A ≥ 300m 2 / g, PV ≥ 0.65 mL / g, compound A is: n-heptane or isooctane.

3. The preparation method according to claim 1, characterized in that, In step (1), the hot air temperature is 95-100 ℃ and the air passage time is 10-40 min.

4. The preparation method according to claim 1, characterized in that, In step (2), the acidic liquid is nitric acid, formic acid, acetic acid, or a mixture thereof.

5. The preparation method according to claim 1, characterized in that, In step (3), the temperature of the hot air is 100-120 ℃, and it should adsorb compound A through the adsorption material for reuse.