Effect of aluminium source and content on the synthesis of zeolite ZSM-5 from kanemite via solid-state transformation

The effect of the incorporation of aluminium during the synthesis of zeolit e ZSM-5 from kanemite via solid-state transformation was studied using X-ra y powder diffraction, Si-29 and Al-27 NMR spectroscopy, thermal analysis an d elemental analysis. During cation exchange, which takes place in highly b asic media, silicate layers of kanemite give rise to the formation of silic a colloids and shorter silicate layers. For Si/Al ratios greater than or eq ual to 19, some aluminium is incorporated into the short silicate layers, h owever, most of the aluminium is incorporated into the Si-O-Si network duri ng the condensation of the silica colloids in silica polymers when the pH i s lowered to 8.5, independent of the aluminium source used (NaAlO2, Al-2(SO 4)(3) or Al(NO3)(3). 9H(2)O). Mesoporous materials are synthesized from Al- containing kanemite, that is, aluminium is added during the synthesis of ka nemite. The formation of silica colloids during cation exchange is the reas on why, unlike the synthesis of mesoporous materials, aluminium could be ad ded to the kanemite-template mixture during cation exchange. The highest am ount of incorporated aluminium was obtained using NaAlO2 because it is the aluminium source for which the pH is highest during cation exchange and con sequently it is the aluminium source which yields the highest amount of sil ica colloid precipitates during the adjustment of the pH to 8.5.