Phase-Selective Synthesis of a Silicoaluminophosphate Molecular Sieve with 3-Aminopropyltriethoxysilane as the Silica Source

Silicoaluminophosphate (SAPO) molecular sieves with CHA and AFI structures have been synthesized under hydrothermal conditions from similar reaction mixtures using 3-Aminopropyl-triethoxysilane as silicon source. The XRD analysis indicated that the phase selectivity could follow the sequence of SAPO-34→SAPO-34+ SAPO-5→SAPO-5 →amorphous phase with increasing the amount of the silicon source. The phase selectivity can be explained by the increasing alkalinity of the medium with the 3-Aminopropyltriethoxysilane concentration.