Behavior of Sodium in the Silica Alumina Gels Prepared by the Instantaneous Mixing Cogelation -Influence of Sodium on Surface Area, Solid Acid and Catalytic Properties-

HIRANO Hiroto, HIRANUMA Mitsuyasu, MUKAIDA Ken-ichi

doi:10.1246/nikkashi.1998.737

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Other Title

瞬時混合共ゲル化法により調製したシリカアルミナゲル中のナトリウムの挙動 -比表面積, 固体酸, 触媒特性への残存ナトリウムの影響-
シュンジコンゴウキョウゲルカホウニヨリチョウセイシタシリカアル
Acidity and Catalytic Activity of Silica Alumina Gels Prepared by Cogelation Using Instantaneous Mixing Method. Part 3. Behavior of Sodium in the Silica Alumina Gels Prepared by the Instantaneous Mixing Cogelation. Influence of Sodium on Surface Area, Solid Acid and Catalytic Properties.

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Abstract

Hydrogels of silica, alumina, and five silica-aluminas were prepared with aqueous solutions of sodium silicate and aluminium nitrate using the instantaneous mixing method. For purification the hydrogels were dispersed with a fixed volume of de-ionized water against a gel using high speed mixer (150 rps) and then filtrated. Such operations with water repeated up to fifth, and finally the same operation with ammonia water was added. The seven hydrogels were calcined, ground and sieved to be these xerogels with the size under 100 mesh. Resulting from the decrease of sodium remained with repetition of filtration for all the hydrogels, a mechanism how the sodium was removed from the gels through washing process, was considered. Moreover, it was considered how the sodium remained has influences on solid acid amount, catalytic activity for isomerization of 1-butene and specific surface area.<BR>In silica-rich gels, a large amount of sodium is caught into the bulk phase, and that sodium can not be removed, consequently the sodium remained became high. Because sodium acts as base to neutralize acid sites, removal of the sodium results to bring about recovery of latent acid sites, followed by increasing amount of solid acid sites and catalytic activity. Generation of strong acid sites results in increase in the surface area, because sintering is depressed by repulsion of surface charge between the primary particles. Increasing of the specific surface area agreed with increasing of the acid amount of strong acid region.

Journal

NIPPON KAGAKU KAISHI

NIPPON KAGAKU KAISHI 1998 (11), 737-744, 1998-11-10

The Chemical Society of Japan

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