Recent strategies for synthesis of metallosilicate zeolites

Incorporation of catalytically active metallic sites into the framework of silica-based zeolites is highly efficient for design of active, selective, and stable heterogeneous catalysts, but there are still many challenges for this kind of preparation such as the presence of aggregated metallic sites due to the alkaline media in the synthesis, relatively low concentration of these metallic sites in the zeolite frameworks, and difficulty for morphological control of metallosilicate zeolites. To overcome these issues, it has been developed new strategies for synthesis of metallosilicate zeolites such as introduction of additives to adjust crystallization rate, addition of chelating agents to form heteroatom complexes, growth of zeolite crystals along with targeted directions, zeolite transformation, and heteroatom replacements. In this review, the recent progresses for syntheses of metallosilicate zeolites are concisely summarized. In addition, the fundamental principles are briefly discussed for the formation of the metallosilicate zeolites. This review should be helpful for design and preparation of the heteroatom-substituted silica-based zeolites as highly efficient heterogeneous catalysts.