TPAイオンを含む非晶質シリカのアルカリ溶液からのシリカライト及び石英の結晶成長

概要

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Silicalite, considered to be a polymorph of SiO_2, was prepared hydrothermally using amorphous silica, tetrapropylammonium bromide (TPA-Br) and NaOH. Silicalite was synthesized in a quartz glass ampoule under the following conditions, [NaOH]/[SiO_2] = 0.2 and [TPA-Br]/[SiO_2] = 0.1. With an increase of [NaOH]/[SiO_2] ratio quartz precipitated gradually instead of silicalite; thus, at 0.9 of [NaOH]/[SiO_2] ratio, the main product was quartz irrespective of the presence of TPA^+ ion. Several ppms of aluminium and boron ions were always detected in the crystals. The extra addition of either of the two ions in the starting materials facilitated the formation of silicalite. Silicalite (or ZSM-5 of extra high silica content) is formed in a Pyrex glass ampoule or under the presence of Pyrex glass rods in a silica ampoule, though serious contamination (50-200 ppm) by both ions is unavoidable.
社団法人日本セラミックス協会の論文
1990-04-01