Process for the preparation of alumina pellets from oil-ammonia column

Abstract

The application discloses a method for preparing alumina small balls by using an oil-ammonia column. The method comprises the following steps: dropping prepared aluminum sol into the column formed by an upper oil phase and a lower organic amine aqueous solution phase, solidifying the aluminum sol into balls by using the organic amine aqueous solution, and finally forming high-strength alumina small balls through aging, drying and calcination. The alumina small balls prepared by the method have uniform particle size distribution, large pore volume and specific surface area, high mechanical strength and good sphericity, and are suitable for being used as a carrier of a catalyst.

Description

Technical Field

[0001] This invention belongs to the field of solid catalysts, and specifically relates to a method for preparing a spherical catalyst support, particularly a method for preparing a catalyst support for a moving bed. Background Technology

[0002] As is well known, alumina possesses excellent thermal stability, strong adsorption capacity, high surface activity, and adjustable specific surface area and pore structure, making it widely used in various industrial fields such as catalyst supports and adsorbents. In industrial applications, to avoid increased bed resistance caused by the catalyst, the catalyst support needs to be shaped to achieve a specific regular shape. Commonly used catalyst support shapes in industrial applications include spherical, circular, strip-shaped, and clover-shaped, among which spherical alumina supports are the most widely used due to their uniform filling, uniform fluid distribution, and high wear resistance. Currently, commonly used methods for preparing spherical alumina include hot oil column forming, oil-ammonia column forming, spray drying, and spherical forming, among others.

[0003] Among various molding methods, the oil-ammonia column molding method is the most mature method for preparing spherical alumina. This method involves dropping the prepared alumina sol into a column composed of an upper oil phase and a lower ammonia water phase, then solidifying it to obtain alumina gel microspheres. After drying and calcination, high-strength alumina microspheres are finally formed. The oil-ammonia column molding method has advantages such as low energy consumption, high strength of alumina microspheres, and uniform pore structure. Furthermore, its mild operating conditions (room temperature and atmospheric pressure) make it an advantageous molding method for synthesizing catalyst supports.

[0004] USP4542113 discloses a method for preparing spherical alumina. This method uses hydrated alumina powder as raw material, adds dilute nitric acid solution to prepare an aluminum sol through gelation, adds urea as a sol stabilizer, and then obtains spherical alumina through an oil-ammonia column molding process. The alumina spheres prepared by this method have a large surface area, but the pore volume of the spheres is only 0.45 cm³. 3 / g, and this method has problems such as additive residue and poor sphericity.

[0005] Patent CN104891538A discloses a method for preparing spherical γ-Al₂O₃. This method uses boehmite as a raw material, which is acidified and soluble, then a boehmite suspension is added to form a mixed sol. Finally, spherical alumina is obtained through an oil-ammonia column molding method. The alumina spheres prepared by this method can achieve a specific surface area of ​​240-300 m². 2 / g, but the prepared alumina sol has poor stability and the alumina microspheres have low strength.

[0006] In current patents, most oil-ammonia column forming processes use ammonia water as the ammonia water phase in the oil-ammonia column. Ammonia water is volatile and consumed in large quantities. Moreover, the highest mass fraction of ammonia in industrial ammonia water is only 28%. The curing effect of the spheres in ammonia water is low, resulting in spheres with low strength and poor sphericity. Summary of the Invention

[0007] Currently, most ammonia solutions use ammonia water as the ammonia phase in oil-ammonia columns. This invention uses an organic amine aqueous solution instead of the ammonia water phase. The organic amine effectively prevents ammonia volatilization and provides better curing results. Simultaneously, the organic amine reacts with the alumina sol during curing, resulting in a certain pore-expanding effect. The alumina microspheres prepared by this invention have high sphericity, uniform particle size distribution, large pore volume and specific surface area, and high mechanical strength, making them suitable for use as catalyst supports.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing alumina microspheres using an oil-ammonia column molding process includes the following steps:

[0010] (1) Preparation of aluminum sol: Boehmite and deionized water are mixed and stirred evenly. Then, an acid solution is added to dissolve the mixture. The mixture is stirred continuously until it is evenly mixed to obtain aluminum oxide sol.

[0011] (2) Preparation of alumina microspheres by oil-ammonia column molding: The upper layer of the oil-ammonia column is an oil phase and the lower layer is an organic amine aqueous solution phase. A nonionic surfactant solution is added to the phase interface. Aluminum sol is dropped into the oil-ammonia column to form spherical gel particles. After aging, drying and calcination, alumina microspheres are obtained.

[0012] Further, the acid solution mentioned in step (1) is a 5-35 wt% nitric acid solution or hydrochloric acid solution, and the amount added is adjusted according to the H+ content. + The molar ratio of Al2O3 to Al2O3 is 0.02-0.30.

[0013] Furthermore, the alumina content in the alumina sol obtained in step (1) is 10-30 wt%.

[0014] Further, the oil phase in step (2) is one or more of kerosene, cyclohexane, n-octane, n-decane and dodecane.

[0015] Further, the organic amine mentioned in step (2) is any one of cyclopropylamine, formamide, n-propylamine, isobutylamine, dimethylformamide, dimethylacetamide and diethylenetriamine, and the mass fraction of the organic amine phase aqueous solution is 5-35 wt%.

[0016] Further, in step (2), the height of the oil phase is 2-50 cm, and the height of the organic amine solution phase is 10-100 cm.

[0017] Further, the nonionic surfactant mentioned in step (2) is one or more of the following: sorbitan monooleate polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkyl glucoside, nonylphenol polyoxyethylene ether, and octylphenyl polyoxyethylene ether.

[0018] Furthermore, the aging time described in step (2) is 1-24 h.

[0019] Furthermore, the drying temperature in step (2) is 50-150 °C, and the time is 6-24 h.

[0020] Furthermore, the roasting temperature in step (2) is 450-1150 °C and the time is 4-12 h.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) This invention provides a new method for preparing alumina microspheres using an oil-ammonia column. It uses an organic amine aqueous solution as the ammonia phase in the oil-ammonia column to replace ammonia. The organic amine can effectively prevent ammonia volatilization, and the curing speed is fast, the sphere formation efficiency is higher, and the resulting alumina microspheres have high sphericity and high mechanical strength.

[0023] (2) In this invention, an organic amine aqueous solution is used as the ammonia phase in the oil-ammonia column. After the sol particles are solidified in the ammonia phase, they react with the ammonium ions generated by the thermal decomposition of organic amine during the aging process, which plays a further solidification role. In the subsequent calcination process, the gas generated by the decomposition of organic amine moves in the small ball and also plays a certain role in expanding the pores. The resulting alumina small balls have large pore volume and high specific surface area. Attached Figure Description

[0024] Figure 1 This is a photograph of the alumina support synthesized in Example 1. As can be seen from the figure, it has good sphericity and uniform particle size distribution. Detailed Implementation

[0025] A method for preparing alumina microspheres using an oil-ammonia column molding process includes the following steps:

[0026] (1) Preparation of aluminum sol: Boehmite and deionized water are mixed and stirred evenly. Then, an acid solution is added to dissolve the mixture. The mixture is stirred continuously until it is evenly mixed to obtain aluminum oxide sol.

[0027] (2) Preparation of alumina microspheres by oil-ammonia column molding: The upper layer of the oil-ammonia column is an oil phase and the lower layer is an organic amine aqueous solution phase. A nonionic surfactant solution is added to the phase interface. Aluminum sol is dropped into the oil-ammonia column to form spherical gel particles. After aging, drying and calcination, alumina microspheres are obtained.

[0028] The acid solution is a 5-35 wt% nitric acid solution or hydrochloric acid solution, and the amount added is adjusted according to the H+ content. + The molar ratio of Al2O3 to Al2O3 is 0.02-0.30.

[0029] The oil phase is one or a mixture of kerosene, cyclohexane, n-octane, n-decane, and dodecane.

[0030] The organic amine is any one of cyclopropylamine, formamide, n-propylamine, isobutylamine, dimethylformamide, dimethylacetamide, and diethylenetriamine, and the mass fraction of the organic amine phase aqueous solution is 5-35 wt%.

[0031] The nonionic surfactant is one or more of the following: sorbitan monooleate polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkyl glucoside, nonylphenol polyoxyethylene ether, and octylphenyl polyoxyethylene ether.

[0032] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0033] Example 1

[0034] (1) Preparation of aluminum sol:

[0035] Take 50 g of boehmite and 102.0 g of deionized water, stir to form a suspension with an alumina content of 25 wt%, stir for 30 min, and then add 35 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.02, and alumina sol is formed after stirring for 60 min.

[0036] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0037] The upper layer of the oil-ammonia column is a cyclohexane oil phase with a height of 2 cm, and the lower layer is a 5 wt% cyclopropylamine aqueous solution phase with a height of 10 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 1 h, filtered, dried at 50 ℃ for 6 h, and calcined at 450 ℃ for 4 h to obtain γ-Al2O3 microspheres.

[0038] Example 2

[0039] (1) Preparation of aluminum sol:

[0040] Take 50 g of boehmite and 115.2 g of deionized water, stir to form a suspension with an alumina content of 23 wt%, stir for 30 min, and then add 30 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.06, and alumina sol is formed after stirring for 60 min.

[0041] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0042] The upper layer of the oil-ammonia column is an octane oil phase with a height of 5 cm, and the lower layer is a 10 wt% formamide aqueous solution phase with a height of 15 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 2 h, filtered, dried at 60 ℃ for 20 h, and calcined at 450 ℃ for 6 h to obtain γ-Al2O3 microspheres.

[0043] Example 3

[0044] (1) Preparation of aluminum sol:

[0045] Take 50 g of boehmite and 130.1 g of deionized water, stir to form a suspension with an alumina content of 21 wt%, stir for 30 min, and then add 25 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.09, and alumina sol is formed after stirring for 60 min.

[0046] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0047] The upper layer of the oil-ammonia column is an octane oil phase with a height of 10 cm, and the lower layer is a 15 wt% n-propylamine aqueous solution phase with a height of 20 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 3 h, filtered, dried at 70 ℃ for 18 h, and calcined at 500 ℃ for 7 h to obtain γ-Al2O3 microspheres.

[0048] Example 4

[0049] (1) Preparation of aluminum sol:

[0050] Take 50 g of boehmite and 150.0 g of deionized water, stir to form a suspension with an alumina content of 19 wt%, stir for 30 min, and then add 20 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). +The molar ratio of Al2O3 to Al2O3 is 0.12, and alumina sol is formed after stirring for 60 min.

[0051] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0052] The upper layer of the oil-ammonia column is a kerosene oil phase with a height of 15 cm, and the lower layer is a 20 wt% isobutylamine aqueous solution phase with a height of 25 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 4 h, filtered, dried at 80 ℃ for 14 h, and calcined at 550 ℃ for 8 h to obtain γ-Al2O3 microspheres.

[0053] Example 5

[0054] (1) Preparation of aluminum sol:

[0055] Take 50 g of boehmite and 173.5 g of deionized water, stir to form a suspension with an alumina content of 17 wt%, stir for 30 min, and then add 15 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.15, and alumina sol is formed after stirring for 60 min.

[0056] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0057] The upper layer of the oil-ammonia column is a n-decane oil phase with a height of 20 cm, and the lower layer is a 25 wt% dimethylformamide aqueous solution phase with a height of 30 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 5 h, filtered, dried at 90 ℃ for 12 h, and calcined at 550 ℃ for 8 h to obtain γ-Al2O3 microspheres.

[0058] Example 6

[0059] (1) Preparation of aluminum sol:

[0060] Take 50 g of boehmite and 203.3 g of deionized water, stir to form a suspension with an alumina content of 15 wt%, stir for 30 min, and then add 10 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.18, and alumina sol is formed after stirring for 60 min.

[0061] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0062] The upper layer of the oil-ammonia column is a dodecane oil phase with a height of 25 cm, and the lower layer is a 30 wt% dimethylacetamide aqueous solution phase with a height of 40 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 8 h, filtered, dried at 130 ℃ for 8 h, and calcined at 1050 ℃ for 8 h to obtain θ-Al2O3 microspheres.

[0063] Example 7

[0064] (1) Preparation of aluminum sol:

[0065] Take 50 g of boehmite and 330.0 g of deionized water, stir to form a suspension with an alumina content of 10 wt%, stir for 30 min, and then add 5 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.21, and alumina sol is formed after stirring for 60 min.

[0066] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0067] The upper layer of the oil-ammonia column is a dodecane oil phase with a height of 35 cm, and the lower layer is a 35 wt% diethylenetriamine aqueous solution phase with a height of 55 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. The molded wet gel spheres are aged in an organic amine solution for 12 h, filtered, dried at 150 ℃ for 6 h, and calcined at 1050 ℃ for 10 h to obtain θ-Al2O3 microspheres.

[0068] Example 8

[0069] (1) Preparation of aluminum sol:

[0070] Take 50 g of boehmite and 102.0 g of deionized water, stir to form a suspension with an alumina content of 25 wt%, stir for 30 min, and then add 35 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.24, and an alumina sol is formed after stirring for 60 min.

[0071] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0072] The upper layer of the oil-ammonia column is a cyclohexane oil phase with a height of 40 cm, and the lower layer is a 25 wt% cyclopropylamine aqueous solution phase with a height of 75 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by fatty alcohol polyoxyethylene ether, water and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 16 h, filtered and then dried at 80 ℃ for 24 h and calcined at 1100 ℃ for 12 h to obtain θ-Al2O3 microspheres.

[0073] Example 9

[0074] (1) Preparation of aluminum sol:

[0075] Take 50 g of boehmite and 102.0 g of deionized water, stir to form a suspension with an alumina content of 25 wt%, stir for 30 min, and then add 25 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.27, and an alumina sol is formed after stirring for 60 min.

[0076] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0077] The upper layer of the oil-ammonia column is a cyclohexane oil phase with a height of 45 cm, and the lower layer is a 25 wt% cyclopropylamine aqueous solution phase with a height of 90 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by nonylphenol polyoxyethylene ether, water and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 20 h, filtered and then dried at 50 ℃ for 24 h and calcined at 1150 ℃ for 8 h to obtain θ-Al2O3 microspheres.

[0078] Example 10

[0079] (1) Preparation of aluminum sol:

[0080] Take 50 g of boehmite and 102.0 g of deionized water, stir to form a suspension with an alumina content of 30 wt%, stir for 30 min, and then add 15 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.30, and alumina sol is formed by stirring for 60 min.

[0081] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0082] The upper layer of the oil-ammonia column is a cyclohexane oil phase with a height of 50 cm, and the lower layer is a 25 wt% cyclopropylamine aqueous solution phase with a height of 100 cm. A surfactant solution is added to the phase interface. The surfactant solution is prepared by mixing octylphenyl polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres are aged in an organic amine solution for 24 h, filtered, dried at 150 °C for 14 h, and calcined at 1150 °C for 4 h to obtain θ-Al2O3 microspheres.

[0083] Comparative Example 1

[0084] (1) Preparation of aluminum sol:

[0085] Take 50 g of boehmite and 140.0 g of deionized water, stir to form a suspension with an alumina content of 20 wt%, stir for 30 min, and then add 20 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.06, and alumina sol is formed after stirring for 60 min.

[0086] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0087] The upper layer of the oil-ammonia column was a cyclohexane oil phase with a height of 5 cm, and the lower layer was 25 wt% ammonia water with a height of 55 cm. A surfactant solution was added to the phase interface. The surfactant solution was prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres were aged in ammonia water for 16 h, filtered, dried at 60 ℃ for 24 h, and calcined at 500 ℃ for 4 h to obtain γ-Al2O3 microspheres.

[0088] Comparative Example 2

[0089] (1) Preparation of aluminum sol:

[0090] Take 50 g of boehmite and 140.0 g of deionized water, stir to form a suspension with an alumina content of 20 wt%, stir for 30 min, and then add 20 wt% nitric acid solution dropwise to achieve an alumina ratio (Ha). + The molar ratio of Al2O3 to Al2O3 is 0.08, and alumina sol is formed after stirring for 60 min.

[0091] (2) Preparation of alumina microspheres by oil-ammonia column molding:

[0092] The upper layer of the oil-ammonia column was a cyclohexane oil phase with a height of 5 cm, and the lower layer was 15 wt% ammonia water with a height of 55 cm. A surfactant solution was added to the phase interface. The surfactant solution was prepared by using sorbitan monooleate polyoxyethylene ether, water, and ethanol in a volume ratio of 0.2:15:10. After molding, the wet gel spheres were aged in ammonia water for 16 h, filtered, dried at 60 ℃ for 24 h, and calcined at 1100 ℃ for 4 h to obtain θ-Al2O3 microspheres.

[0093] Table 1 Performance data of the obtained alumina microspheres

[0094]

[0095] Table 1 shows that the pore volume of the samples obtained using organic amines is above 0.70 mL / g, the sphericity is above 0.979, and the strength is above 70 N. The pore volume, sphericity, and strength are significantly better than those of Comparative Examples 1 and 2, which use ammonia water as the ammonia water phase. This proves that using organic amines as the ammonia water phase in an oil-ammonia column can yield alumina microspheres with high strength, high sphericity, and high pore volume.

[0096] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing alumina microspheres using an oil-ammonia column, characterized in that, Includes the following steps: (1) Preparation of aluminum sol: Boehmite and deionized water are mixed and stirred evenly. Then, an acid solution is added to dissolve the mixture. The mixture is stirred continuously until it is evenly mixed to obtain aluminum oxide sol. (2) Preparation of alumina microspheres by oil-ammonia column molding: The upper layer of the oil-ammonia column is an oil phase and the lower layer is an organic amine aqueous solution phase. A nonionic surfactant solution is added to the phase interface. Aluminum sol is dropped into the oil-ammonia column to form spherical gel particles. After aging, drying and calcination, alumina microspheres are obtained. The organic amine mentioned in step (2) is any one of cyclopropylamine, formamide, n-propylamine, isobutylamine, dimethylformamide, dimethylacetamide and diethylenetriamine, and the mass fraction of the organic amine phase aqueous solution is 5-35 wt%.

2. The method for preparing alumina microspheres according to claim 1, characterized in that, The acid solution mentioned in step (1) is a 5-35 wt% nitric acid solution or hydrochloric acid solution, and the amount added is according to H + The molar ratio of Al2O3 to Al2O3 is 0.02-0.

30.

3. The method for preparing alumina microspheres according to claim 1, characterized in that, The alumina content in the alumina sol obtained in step (1) is 10-30 wt%.

4. The method for preparing alumina microspheres according to claim 1, characterized in that, The oil phase mentioned in step (2) is one or more of kerosene, cyclohexane, n-octane, n-decane and dodecane.

5. The method for preparing alumina microspheres according to claim 1, characterized in that, The height of the oil phase in step (2) is 2-50 cm, and the height of the organic amine aqueous solution phase is 10-100 cm.

6. The method for preparing alumina microspheres according to claim 1, characterized in that, The nonionic surfactant mentioned in step (2) is one or more of the following: sorbitan monooleate polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkyl glucoside, nonylphenol polyoxyethylene ether, and octylphenyl polyoxyethylene ether.

7. The method for preparing alumina microspheres according to claim 1, characterized in that, In step (2), the aging time of alumina sol particles in the organic amine aqueous solution phase is 1-24 h.

8. The method for preparing alumina microspheres according to claim 1, characterized in that, The drying temperature in step (2) is 50-150 °C and the time is 6-24 h.

9. The method for preparing alumina microspheres according to claim 1, characterized in that, The roasting temperature in step (2) is 450-1150 ℃ and the time is 4-12 h.

Images