Accelerated, impurity-free crystallization of aluminum-rich beta zeolite with aluminophosphate as the aluminum carrier

Zeolite Beta, discovered in 1967, features a unique three-dimensional (3D) 12-ring channel system and a highly tunable Si/Al ratio (SAR), granting exceptional stability and acidity crucial for catalysis. While conventional hydrothermal synthesis normally yields zeolite Beta with the SAR range of 10–30 using tetraethylammonium hydroxide (TEAOH) as the organic structure-directing agent (OSDA), the discovery of Al-rich natural mineral (Tschernichite) with the ∗BEA topology (SAR∼3.3) spurred efforts to synthesize low-SAR Beta zeolite for enhanced acid site density, hydrophilicity and ion-exchange capacity, enabling applications like dehydration, separation and shape-selective catalysis. However, achieving low SARs for the hydrothermal crystallization of zeolite Beta is still challenging, requiring excess Na + which promotes impurity phases (e.g., GIS , ANA , MOR ), prolongs crystallization period and reduces yield. Inspired by our recent work on the kinetic-control synthesis of high-silica NaY zeolite using aluminophosphate as the aluminum carrier, this study presents an accelerated, impurity-free synthetic route to achieve Al-rich zeolite Beta. Using the pre-synthesized aluminophosphate (e.g., AlPO-5) as a partial Al source favors the formation of a silica-rich Beta zeolite nucleus, thus effectively suppresses impurities (eliminating GIS phase in Na + -containing system) and amorphous phase (in Na + -free system), ultimately accelerating crystallization process. Based on this synthetic control, this study successfully synthesized the phase-pure Beta zeolite at SAR of 7.55 (Na + -free) and 6.58 (Na + -containing), while this strategy was extended to the Beta zeolite synthesis with other aluminophosphate, including SSZ-51 ( SFO) and AlPO-18 ( AEI) .