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Method for preparing alumina in fire resistant and high specific surface

A high specific surface, alumina technology, used in the preparation of alkali metal aluminate/alumina/aluminum hydroxide, chemical instruments and methods, chemical/physical processes, etc., can solve the problem that heat resistance stability is difficult to meet its requirements and other problems, to achieve the effect of low cost, low production cost and easy reaction process

Inactive Publication Date: 2005-01-12
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above-mentioned modified alumina material should be used as a carrier material for high-performance automobile exhaust purification catalysts or natural gas catalytic combustion catalysts. Since the catalysts are in a high-temperature environment above 1000 °C for a long time, their heat resistance stability is still difficult. meet its requirements

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Al according to the proportion of alumina wet gel 2 o 3 : SiO 2 :H 2 O=1: 0.017~0.17: 40~80 (molar ratio),

[0015] Dissolve sodium metaaluminate in water, add water glass (SiO 2 20~30wt%, Na 2 (05-10%wt%), stir evenly, add dilute nitric acid dropwise to adjust the pH value to 8.5-9.5, continue stirring for 0.5-2 hours, and leave to age for 5-24 hours to obtain alumina wet gel. The alumina wet gel is washed with distilled water for 5 to 8 times, then the water in the gel is exchanged with absolute ethanol, then placed in an autoclave, and a supercritical medium (such as ethanol, methanol, ethanol-methanol or ethanol - nitric acid (pH is a solvent of 3 to 4), carry out supercritical drying, the heating rate is 1.5K / min, after reaching a temperature of 280°C and a pressure of 8.5MPa, keep it for 1 to 4 hours, and then slowly emit gas at a constant temperature, Alumina xerogels are obtained; treated in an air atmosphere at 300-600° C. to prepare alumina with high te...

Embodiment 2

[0017] First, dissolve 3.5g of sodium metaaluminate in 40g of water, and add 0.68g of water glass (SiO 2 25.9wt%, Na 2 O 8.0%wt%), after stirring evenly, add 0.1M dilute nitric acid dropwise until the pH is 9, continue stirring for half an hour, and leave to age for ten hours to obtain alumina wet gel. Wash and filter the aluminum oxide wet gel six times with distilled water, then exchange the water in the gel with 50ml of absolute ethanol for 2 times and filter with suction, then place it in an autoclave, add 50ml of absolute ethanol (for supercritical medium) , for supercritical drying. The heating rate is 1.5K / min, and the temperature reaches 280°C and the pressure is 8.5MPa, and then it is kept for 2 hours, and then the gas is slowly released at a constant temperature to obtain an alumina xerogel. The alumina xerogel was treated in an air atmosphere at 500°C for 4 hours, and the specific surface area of ​​alumina was 436m 2 / g, treated in 1100°C air atmosphere for 4h, i...

Embodiment 3

[0019] With the same operation as in Example 1, the difference is that the supercritical medium is changed to 50ml methanol, and the supercritical temperature and pressure are changed to 270°C and 10MPa respectively. The obtained alumina xerogel was treated in an air atmosphere at 500°C for 4 hours, and the specific surface area of ​​alumina was 395m 2 / g, treated in 1100°C air atmosphere for 4h, its specific surface area is 168m 2 / g.

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Abstract

In the invention, meta-aluminate and soluble glass are used as raw materials to preparate aluminum oxide with high-temp. resistant and high specific surface by techonlogy that using sol-gel process to prepare aluminium oxide humidity gel and using supercritical fluid drying method to prepare aluminum oxide xerogel. The aluminum oxide contains silicon oxide (wt% is 0.1-10), the aluminum oxide xerogel is processed for 4h on 500 deg.c temp., its specific superficial area is more than 365 m2 / g, then it is processed for 4h, its specific superfical area is more than 165 m2 / g.

Description

technical field [0001] The invention relates to the chemical preparation of inorganic and solid materials, in particular to a method for preparing high-temperature-resistant and high-specific-surface alumina. Background technique [0002] For many catalysts, alumina is a very good and economical catalyst carrier. Many crystalline aluminas have a large specific surface area, but they are used as catalyst carriers for catalytic purification of automobile exhaust and catalytic combustion of natural gas. It is said that there are serious disadvantages, that is, when the temperature is about 1000-1200 ° C, it will transform into the α phase, resulting in a sharp decrease in the specific surface area, causing the aggregation of active components loaded on the surface, thereby significantly reducing the catalyst activity. Therefore, stabilizing the structure of alumina to maintain a large specific surface at high temperatures and preventing conversion to α-type alumina with a small...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J21/04B01J21/12C01F7/14
Inventor 周仁贤岳宝华郑小明
Owner ZHEJIANG UNIV
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