A study of the formation of microporous material SAPO-37

•Formation of SAPO-37 was studied under HTS and DGC conditions.•SAPO-37 crystallization pathways are proposed. SAPO-37 crystallizes from a precursor containing large pores and sodalite cages.•Si is incorporated into the framework via forming aluminosilicates.

The crystallization of microporous material SAPO-37 was studied under hydrothermal synthesis (HTS) and dry gel conversion (DGC) conditions. The evolution of the intermediate phases as a function of crystallization time was followed by several techniques including PXRD, SEM, AFM, and solid-state NMR. For DGC, SAPO-37 crystallizes from a semi-crystalline layered precursor containing large pores and sodalite cages, whose structure is held by weak nonbonding interactions. Si atoms are only incorporated in the later stage of the crystallization via the formation of aluminosilicate species. Under HTS conditions, the crystallization pathway of SAPO-37 is somewhat similar to that for DGC. The AFM data suggest that the crystal growth mechanism is “birth and spread”, and the final SAPO-37 crystals have rough (1 1 1) surfaces terminated by different structural building units. The findings of the present work provide new physical insights into the formation of SAPO-37.

Graphical abstractFormation of microporous material SAPO-37 was studied under hydrothermal synthesis (HTS) and dry gel conversion (DGC) conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide