Controllable synthesis of Si-DD3R molecular sieves nanocrystalline by microwave assisting dry-gel conversion method

All-silica Deca-Dodecasil 3 Rhombohedral (Si-DD3R) type zeolite with a two-dimensional pore system is a very attractive size selective adsorbent which enables only small molecules to adsorb. It is a great potential candidate in the fields of separation and catalysis. In this work, nanocrystalline Si-DD3R molecular sieves with the particle size of about 30 nm were synthesized by microwave assisting dry-gel conversion (MADGC) method. The advantages of microwave radiation, HF and dry-gel conversion (DGC) were well combined and effectively decrease the size andin situsynthesis time. At 433 K, highly uniform nancrystalline Si-DD3R was obtained in 7 h without seeding. When the partial pressure was 1.0 bar, the CO(2)adsorbed amount reached about 0.83 mmol g(-1). The zeolites are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM).