Synthesis and properties of SAPO-37

Abstract

The synthesis of silicoaluminophosphate SAPO-37 which has the faujasite structure type is described. The SAPO-37 product is extensively characterized by X-ray powder diffraction (XRD), chemical analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TG) and Guinier–Lenné photographs. Direct comparison between SAPO-37 and zeolite Y is drawn from Fourier-transform infrared spectroscopy of both the frame-work and of sorbed pyridine, and also from oxygen adsorption studies. Aging of the synthesis gel appears to aid the crystallization of pure materials, whilst long synthesis times lead to co-crystallization with SAPO-5 and/or SAPO-40. The incorporation of silicon into the framework of SAPO-37 is demonstrated by ²⁷Al, ³¹P and ²⁹Si magic-angle spinning magnetic resonance (MAS NMR). Preliminary results for a comparison of H-SAPO-37 and H-Y in o-xylene isomerization are discussed.