Effect of Al content on phase transitions of zeolite MEL

The effect of the Si/Al ratio on the synthesis of zeolite MEL and their influence in the phase transitions that results has been studied. Depending on the Al content tetragonal (I-4m2) or MFI intergrowth have been observed. In samples with high Al content the formation of a new orthorhombic (Imm2) phase is proposed. Comparison of the experimentally determined powder X-ray data and the theoretically predicted powder X-ray data generated by using the models obtained by density functional theory (DFT) in the tetragonal and orthorhombic crystal systems of the zeolite with MEL structure has been carried out.