メカノケミカル法を用いた Fe 置換 MWW 型ゼオライトの合成

Fe-substituted MWW-type zeolites ([Fe]-MWWMC) were successfully synthesized by a mechanochemically assisted hydrothermal synthesis, termed the mechanochemical method, for the first time and compared with samples prepared by the conventional hydrothermal method ([Fe]-MWWHT). A mechanochemical reaction between SiO₂ and α-FeOOH, which is the first step of the mechanochemical method, yielded an amorphous Si_Fe composite oxide that consisted of tetrahedrally coordinated Fe species in a SiO₂ network, as confirmed by X-ray diffraction, UV-vis and Fourier transform infrared spectroscopies. A hydrothermal treatment for crystallization of the zeolite using a thus-prepared amorphous Si_Fe composite as a precursor as the second step led to the formation of [Fe]-MWWMC zeolites with well-introduced and dispersed Fe species in their framework. The improved homogeneity of the Fe species in [Fe]-MWWMC resulted in less extra-framework Fe species compared with [Fe]MWWHT. The mechanochemical method was thus confirmed as an efficient route for the synthesis of metallosilicates with well-introduced and dispersed heteroatoms in their framework.