Regulation of Al distribution in ITR zeolite for methanol to propylene

Abstract

ITR zeolite could be potentially used as catalysts in methanol to propylene (MTP), where their performance is strongly related to its Al distribution. However, the control of Al distribution in ITR zeolite poses a significant synthetic challenge. Herein, we demonstrate the possibility to control the Al distribution in ITR zeolites using zeolite A as an aluminum source (A-ITR). The A-ITR exhibited similar crystallinity, nanosheet morphology, textual parameters, and acidic concentration with those of conventional ITR made zeolites using aluminum isopropoxide as an aluminum source (C-ITR). Characterizations of the zeolite product with ²⁷Al MQ MAS NMR spectra, ²⁷Al MAS NMR spectra, and 1-hexene cracking reveal that the A-ITR zeolites have more Al species distributed in T6 and T8 sites located in relatively smaller micropores of the framework than C-ITR. As a result, the A-ITR gave enhanced catalyst lifetime and propylene selectivity due to the suppression of the aromatic cycle in the MTP reaction, compared with the C-ITR. This work provides an alternative approach to prepare efficient ITR zeolites for MTP reaction.