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Alumina in high hydrothermal stability, and preparation method

A technology of spherical alumina and thermal stability, applied in the preparation of alumina/hydroxide, alumina/aluminum hydroxide, etc. The effect of thermal stability

Inactive Publication Date: 2007-05-09
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, excessive Si is not conducive to the structural stability of alumina at high temperatures.

Method used

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  • Alumina in high hydrothermal stability, and preparation method
  • Alumina in high hydrothermal stability, and preparation method
  • Alumina in high hydrothermal stability, and preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] A. Preparation of spherical alumina

[0027] Dissolve 30g of aluminum powder with a particle size of 50μm in 250g of 10% hydrochloric acid to prepare aluminum sol, and dissolve 20g of hexamethylenetetramine in 55g of deionized water to prepare a coagulant solution. Drop into molding oil at 70°C for molding, separate the shaped pellets from the oil, age at 130°C for 5 hours, wash the obtained product, dry at 120°C for 10 hours, and roast at 600°C for 6 hours to obtain spherical alumina . After measurement, the specific surface area of ​​the obtained spherical alumina is 199.77m 2 / g, the pore volume is 0.85ml / g, the particle diameter is 1.5mm, and the bulk density is 0.5g / cm 3 .

[0028] B. Surface modification

[0029] 0.0541g (NH 4 ) 3 PO 4 ·3H 2 O was dissolved in 5ml of deionized water to form a solution, and 3 g of spherical alumina obtained in step A was immersed in the solution for 4 hours, and the solution was poured out; the spherical alumina was dried a...

Embodiment 2

[0032] 0.1073g (NH 4 ) 3 PO 4 ·3H 2 O was dissolved in 5ml of deionized water to form a solution, 3 g of the spherical alumina obtained in step A of Example 1 was immersed in the solution for 4 hours, and the solution was poured out; the spherical alumina was dried at 100 ° C for 8 hours, 550 ℃ for 4 hours to obtain modified spherical alumina. where P 2 o 5 The mass percent content is 1.25%. After 24h hydrothermal treatment, the specific surface area of ​​the sample is 178.57m 2 / g.

Embodiment 3

[0034] 0.2147g (NH 4 ) 3 PO 4 ·3H 2 O was dissolved in 6ml of deionized water to form a solution, and 3 g of the spherical alumina obtained in step A of Example 1 was immersed in the solution for 5 hours, and the solution was poured out; the spherical alumina was dried at 110° C. for 10 hours, and then dried at 600 ℃ roasting for 5 hours to obtain modified spherical alumina, where P 2 o 5 The mass percent content is 2.5%. After 24h hydrothermal treatment, the specific surface area of ​​the sample is 173.9m 2 / g.

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Abstract

This invention provides a method for preparing spherical Al2O3 with high hydrothermal stability. Based on the mechanisms of Al2O3 sintering and phase change, the method introduces phosphate ions, which can react with OH groups on the pore walls to reduce the quantity of OH groups and change the surface acidity of Al2O3. The method can prevent the sintering and phase change of Al2O3 pore channels, thus can improve the hydrothermal stability of spherical Al2O3 carrier. The hydrothermal stability of modified spherical Al2O3 is much higher than that of unmodified spherical Al2O3. The specific surface area of modified spherical Al2O3 is 190-200 m2 / g, the pore volume is 0.85-1.25 mL / g, the particle diameters are 0.5-5 mm, the packing density is 0.3-0.55 g / cm3, and the weight content of P2O5 is 0.5-5%. The spherical Al2O3 can be used as catalyst or catalyst carrier for petrochemicals and fine chemicals.

Description

Technical field: [0001] The invention relates to a spherical alumina with high hydrothermal stability and a preparation method thereof. The spherical alumina is mainly used as a catalyst or a catalyst carrier in petrochemical and fine chemical industries. technical background: [0002] The spherical alumina prepared by the oil column molding method has excellent pore structure and high strength, and has been widely used as a catalyst or catalyst carrier in the petrochemical and fine chemical fields. However, due to the preparation method, the hydrothermal stability of the spherical alumina prepared by the oil column molding method is poor, and its specific surface area gradually decreases under the conditions of higher temperature and the presence of water vapor, resulting in a continuous decrease in its catalytic performance. Similar to alumina prepared by other methods, there are hydroxyl groups on the surface of spherical alumina prepared by oil column molding method, and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01F7/30
Inventor 李殿卿段雪王媛徐向宇
Owner BEIJING UNIV OF CHEM TECH
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