Process for preparing active aluminium oxide

Abstract

The present invention relates to the preparation process of active gamma-Al2O3. The mixed water solution of materials including aluminum chloride, ammonia water, pore expander ammonium oxalate or ammonium citrate, etc. is heated and concentrated to produce aluminum hydroxide precipitate; the precipitate is dried and heated to obtain solid powder and to decompose its NH4Cl, which is recovered from hot gas flow through cooling and crystallization; and the solid powder is roasted at 400-800 deg.c for 3-6 hr to convert into gamma-Al2O3. The present invention produces aluminum hydroxide through evaporation and concentration, rather than neutralization, and aluminium hydroxide is precipitated and separated in a stable and balanced solid-liquid state, and this is favorable to producing aluminium hydroxide grains with homogeneous size.

Description

(1) Technical field [0001] The present invention relates to a kind of activated alumina, especially γ-Al 2 o 3 method of preparation. (2) Background technology [0002] γ-Al 2 o 3 It is the most widely used industrial catalyst carrier. The preparation method usually adopts acid-base neutralization to generate solid precipitation. There are three main types: the first is the acid method, that is, the neutralization reaction of aluminum salt and alkali. The raw materials used include aluminum trichloride and ammonia water, etc. Patent ZL94107295 .9 A method for preparing a hydrogenation catalyst carrier disclosed, which uses an acidic aqueous solution containing aluminum ions and an alkaline aqueous solution containing or not containing aluminum ions for neutralization to prepare activated alumina, and the method used is the acid method. The second is the alkaline method, that is, the neutralization reaction of aluminate and acid. The aluminates used are mainly sodium met...

AI Technical Summary

Problems solved by technology

The above preparation of γ-Al 2 o 3 There are following three disadvantages in the conventional method: first, there are many preparation steps, which usually include: acid-base neutralization (precipitation)-aging-filtering-washing-drying-crushing-molding-roasting

Second, the filtrate and washing filtrate contain a large amount of soluble ions. If this type of liquid is discharged directly, it will pollute the environment. If it is treated, the production cost will be greatly increased.

Third, in industrial production, the volume of the neutralization reactor is large, and the acid-base liquid flow is added while contacting the reaction. There is inevitably a concentration gradient and a temperature gradient, which makes the size of the generated solid particles uneven, and eventually leads to a dispersed pore distribution.