Development of Synthetic Route for Fe-substituted MWW-type Zeolites Using Mechanochemical Method

Zeolite-based catalysts for oxidative upgrading of methane: design and control of active sites

“…This could arise from the difference in the nature of the Ga species in [Ga]-MFI MC and [Ga]-MFI HT . Our related studies on zeolites synthesized via the mechanochemical method 25,26 suggest that the Ga species in [Ga]-MFI MC are distributed in the particles more uniformly than those in [Ga]-MFI HT , and these well-distributed Ga species result in the unique catalytic activity. For the aromatization of propane, Giannetto et al demonstrated that extra-framework Ga species and Brønsted acid sites in steam-treated [Al,Ga]-MFI zeolites cooperatively functioned as active sites by altering the ratio of extra-framework Ga species to acid sites.…”

“…Trivalent cations consisting of Al 3+ and Ga 3+ are known to be introduced into zeolite frameworks relatively easily, while the complete incorporation of other metal cations into frameworks is quite challenging even in the case of widely investigated Fe 3+ regardless of the same valence as the trivalent cations described above (typically, intra- and extra-framework Fe species are generated). 26 The limited element scope makes the freedom of catalyst design narrower, compared to the other two preparation methods. Besides, one-pot hydrothermal synthesis of heteroatom-incorporated zeolites is sometimes impossible depending on heteroatoms, framework topologies, and molar ratios of Si to heteroatoms.…”

Environmentally Friendly Green Synthesis of Fine Particles by Dry Mechanical Processes Toward SDGs: A Review

“…Copyright: (2022) Elsevier. et al, 2021) and hydrothermal treatment (Kanie et al, 2018;Nada et al, 2019;Osuga et al, 2022;Zhang et al, 2020), have often been employed in the synthesis of various functional nanoparticles for weakening the thermal treatment conditions.…”

Improvement of Catalytic Activity of Ce-MFI-Supported Pd Catalysts for Low-Temperature Methane Oxidation by Creation of Concerted Active Sites

“…31−34 In the case of Pd/Ce-MFI, the zeolite support, Ce-MFI, was synthesized using a mechanochemical method, which was also applied to various metal-containing zeolites, including Ti-MFI, 35,36 Ti-BEA, 37 Sn-MFI, 38 Al,Fe-MFI, 39 Ga-MFI, 40 and Fe-MWW. 41 This method consists of two processes: (1) a mechanochemical reaction between SiO 2 and a metal oxide or hydroxide induced by planetary ball milling to prepare an amorphous Si−metal composite oxide and (2) successive hydrothermal treatment of the thus-prepared precursor to crystallize the metal-containing zeolites. For Ce-MFI, this synthesis method yielded small and highly dispersed Ce species in zeolite crystals, which did not occur on the zeolite surface during typical impregnation or conventional one-step hydrothermal synthesis.…”

“…Recently, our group found that when Pd species were impregnated onto the surface of Ce-containing MFI-type zeolite (Ce-MFI) the resultant catalyst (Pd/Ce-MFI) produced ethane in the OCM reaction even at temperatures as low as 100–300 °C . Zeolites, which are porous crystalline materials, are known to provide specific catalytically active sites associated with intra- and/or extra-framework metal species and unique pore structures. − In the case of Pd/Ce-MFI, the zeolite support, Ce-MFI, was synthesized using a mechanochemical method, which was also applied to various metal-containing zeolites, including Ti-MFI, , Ti-BEA, Sn-MFI, Al,Fe-MFI, Ga-MFI, and Fe-MWW . This method consists of two processes: (1) a mechanochemical reaction between SiO 2 and a metal oxide or hydroxide induced by planetary ball milling to prepare an amorphous Si–metal composite oxide and (2) successive hydrothermal treatment of the thus-prepared precursor to crystallize the metal-containing zeolites.…”