Influence of Al3+ on polymorph A enrichment in the crystallization of beta zeolite

An anion-promoted increase of the SiO2/Al2O3 ratio of zeolites

“…S14† is a resonance at ca . 56 ppm related to the tetrahedral Al species regardless of the absence/presence of NaI, 47 indicating that NaI has no influence on the evolution of the Al species during the crystallization. Fig.…”

Synthesis of polymorph A-enriched beta zeolites in a HF-concentrated system

“…19 Very recently, Yan's group has made great achievements in synthesizing A-enriched beta zeolites containing 65% polymorph A. They demonstrated that the ultra-concentrated synthesis conditions 13,[20][21][22][23] (H 2 O/Si ≤ 1.12) and the partial decomposition of tetraethylammonium hydro-xide (TEAOH) are crucial to the enrichment of polymorph A in beta zeolites. In these studies, the polymorphic composition was determined by either the PXRD refinement or PXRD simulation method which is suitable when no more than two polymorphs are present in the zeolite.…”

An elaborate structure investigation of the chiral polymorph A-enriched zeolite beta

“…17,[19][20][21] Until now, only pure polymorph C 13,14 and nearly 85% enriched polymorph B [22][23][24] have been synthesized in limited chemical composition with specially designed organic structure-directing agents. However, zeolite beta with a percentage of polymorph A exceeding 50% is rare, though many strategies 17,[19][20][21][25][26][27][28] have been used to selectively synthesize the polymorph A of zeolite beta.…”