Studies on the mechanism of zeolite X crystallization. II. Effect of silica sources of starting materials on the gas-phase adsorption at solid phases.

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概要

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• The mechanism of zeolite X crystallization was studied by using two kinds of silica sources, tetraethyl orthosilicate and silica sol. The adsorption of benzene and cyclohexane was subjected to a measurement to clarify the distribution of cation Na<SUP>+</SUP> and the change in the pore structure and surface of solid phases with reaction progress. The relation between specific surface area and reaction time has been revealed by means of adsorption of nitrogen gas, benzene, and cyclohexane as follows: 1) In the early stage of reaction or in the amorphous solid state, N<SUB>2</SUB>≈C<SUB>6</SUB>H<SUB>6</SUB>≈C<SUB>6</SUB>H<SUB>12</SUB> for tetraethyl orthosilicate and N<SUB>2</SUB>≈C<SUB>6</SUB>H<SUB>6</SUB>>C<SUB>6</SUB>H<SUB>12</SUB> for silica sol; 2) for crystals in the early stage, N<SUB>2</SUB>>C<SUB>6</SUB>H<SUB>12</SUB>>C<SUB>6</SUB>H<SUB>6</SUB> for tetraethyl orthosilicate and N<SUB>2</SUB>>C<SUB>6</SUB>H<SUB>12</SUB>≈C<SUB>6</SUB>H<SUB>6</SUB> for silica sol; 3) for crystals in a sufficiently developed stage, N<SUB>2</SUB>>>C<SUB>6</SUB>H<SUB>12</SUB>>C<SUB>6</SUB>H<SUB>6</SUB> for tetraethyl orthosilicate and N<SUB>2</SUB>≈C<SUB>6</SUB>H<SUB>6</SUB>>C<SUB>6</SUB>H<SUB>12</SUB> for silica sol. In the case of silica sol, the crystallization mechanism is based on inhomogeneous nucleation; a number of critical nuclei may be generated but their dimension is small. In the case of tetraethyl orthosilicate critical nuclei are fewer in number and larger in size than in the case of silica sol; the mechanism of crystallization is based on homogeneous nucleation.

• 公益社団法人 日本化学会の論文

著者

• Hino Ryozi

  Department Of Material Science Faculty Of Science And Engineering Shimane University

• Toki Kenzi

  Department of Chemistry, Faculty of Science, Shimane University

• Aoi Hiroyasu

  Department of Chemistry, Faculty of Science, Shimane University

• Hino Ryozi

  Department of Chemistry, Faculty of Science, Shimane University

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• Studies on the mechanism of zeolite X crystallization. II. Effect of silica sources of starting materials on the gas-phase adsorption at solid phases.

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