Mesoporogen‐Free Synthesis of Hierarchical SAPO‐34 with Low Template Consumption and Excellent Methanol‐to‐Olefin Conversion

Significant interest has emerged in the development of nanometer‐sized and hierarchical silicoaluminophosphate zeolites (SAPO‐34) because of their enhanced accessibility and improved catalytic activity for methanol‐to‐olefin (MTO) conversion. A series of nanometer‐sized SAPO‐34 catalysts with tunable hierarchical structures was synthesized in a Al 2 O 3 /H 3 PO 4 /SiO 2 /triethylamine(TEA)/H 2 O system by using a mesoporogen‐free nanoseed‐assisted method. The nanometer‐sized hierarchical S H ‐3.0 catalyst (TEA/Al 2 O 3 =3.0) possessed the highest crystallinity, highest abundance of intracrystalline meso‐/macropores, and the most suitable acidity among all obtained catalysts, showing the highest ethylene and propylene selectivity of 85.4 %. This is the highest reported selectivity for MTO reactions under similar conditions. Detailed analysis of the coke produced during the reaction revealed that the small‐sized methyl‐substituted benzene and bulky methyl‐substituted pyrene were mainly located inside the crystals instead of on the surface of the crystals, which provided further insight into understanding the deactivation of the SAPO‐34 catalyst during MTO reaction. Significantly, the simple and cost‐effective synthetic process and superb catalytic performance of the nanometer‐sized hierarchical SAPO‐34 is promising for their practical large‐scale application for MTO conversion.