日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

ZK-4 zeolite has an LTA framework structure with Si/Al=1-3. It can be synthesized by using an organic structure directing agent (SDA), tetramethylammonium ion (Me₄N⁺). Its role, however, has been not made clear up to now. Analytical results of powder X-ray diffraction patterns of as synthesized ZK-4s suspect us a Me₄N⁺ in a sodalite cage plays a role to support and stabilize the structure of the sodalite cage from its inside. With the Raman spectroscopy method, the Raman peak positions at ca. 490 cm⁻¹, which is related to average T-O-T (T=Si or Al) angles of zeolite frameworks, were invariant to the Si/Al ratios of as synthesized ZK-4s. However, those of SDA removed ZK-4s depend on their Si/Al ratios. The optimized average T-O-T angle realized by the existence of Me₄N⁺ enables us to synthesize ZK-4 zeolites. Roles of Me₄N⁺ as an SDA are also discussed considering the previous results, e.g. crystal structure of SOD synthesized by using Me₄N⁺.