Hydrothermal conversion of kenyaite into zeolite omega in tetramethylammonium cations system

Zeolite omega has been synthesized through recrystallization of kenyaite. The X-ray diffraction, scanning electron micrograph, vibrational spectroscopy, 27Al magic angle spinning nuclear magnetic resonance (MAS NMR), and 13C cross-polarization (CP)/MAS NMR are used to explore the changes of medium-range structure and other crystallization behaviors. Parts of the 5 membered rings and 6 membered rings are remained as secondary building units (SBUs) of zeolite omega and the 4 membered rings are formed during the reaction period from 10 h to 48 h. Zeolite omega with high purity and crystallinity could be prepared from the substrates with molar composition: 3.6 Na2O: Al2O3: x SiO2: y H2O: 0.96 TMABr (x = 15–20, y = 120–220) by heating at 90 °C for 72 h, 100 °C for 48 h and 110 °C for 44 h.