Effect of the aluminium content on the ZSM—5 zeolite crystallization in the presence of alkanolamine

Abstract The alkanolamines have been found to favour the crystallization of MFI structures only in the presence of Al (ZSM—5 zeolite), but not in its absence (silicalites) as the tetralkylammonium salts do. When the starting SiO 2 Al 2 O 3 molar ratios ( R 0 ) > 100 a mixture of ZSM—5 and a crystalline silicate (magadiite) is formed. The magadiite percentage increases with R 0 , until it becomes the single phase present when Al is practically absent in the sample. The structural Al content in the ZSM—5 phase, as determined for the various samples by three independent methods, never goes below two atoms per unit cell of 96 tetrahedral (T) atoms (Si + Al).