Synthesis, characterization and catalytic activity of SnAPO-5 in hydrogenation reaction

Abstract

Tin containing aluminophosphate molecular sieve with AFI structure (SnAPO-5) has been synthesized hydrothermally by using Sn(II) and Sn(IV) salts as precursors. The SnAPO-5 materials have been thoroughly characterized by powder X-ray diffraction, FTIR, UV-vis spectroscopy, scanning electron microscopy, thermal analysis, N₂ sorption and surface area measurements, and elemental analysis using ICP. FTIR and UV-vis spectral data of calcined SnAPO-5 reveal that Sn can be substituted for the phosphorous sites up to 2 mole% in the framework lattices. Substitution of Sn preferably occurs at the phosphorous sites rather than for Al at lower metal concentration [Sn(II) or Sn(IV) ≤ 2 mole% SnO₂] but higher loading leads to octahedral tin species. The calcined SnAPO-5 material exhibits good hydrogenation activity for the reduction of cyclohexanone to cyclohexanol using 2-butanol as hydrogen donor molecule under the liquid-phase reaction conditions. Other metallophosphates such as CoAPO-5, MnAPO-5 and FeAPO-5 fail to undergo this hydrogenation reaction under similar experimental conditions.