Influence of Additives and Growth Inhibitors in Improving the Physicochemical Properties of Silicoaluminophosphate Molecular Sieve, SAPO-11.

Silicoalumiophosphates (SAPOs) are microporous crystalline materials extensively utilized as adsorbents and catalysts. The present work utilized two strategies to synthesize nanocrystalline SAPO-11. The first strategy involves a surfactant as a mesoporogen to reduce the crystallite size and increase the surface area for the materials synthesized at 200 °C in 2 days. In the second strategy, the synthesis temperature and time were significantly reduced to 160 °C and 3 h using propylene oxide as a pH accelerator. The reduction in the particle size and the improvement in the surface area were achieved using propyltriethoxysilane, which inhibited the growth of SAPO-11 particles. The materials were thoroughly characterized using XRD, N2 -sorption, FTIR, pyridine-adsorbed FTIR, electron microscopy, XPS, and NMR. The surfactant-assisted synthesis formed a nanorod morphology with a large external and BET surface area. The low-temperature synthesis involving silane as a growth inhibitor and propylene oxide as a pH modulator demonstrated a rectangular nanoplatelet morphology with a large surface area. The synthesis was scaled up to 10 g with no change in the experimental parameters. A synthesis strategy facilitating nuclei formation and retarding the growth of particle size will attract academia and industrial researchers to utilize these strategies for the manufacturing of zeolites of different frameworks on a large scale.