AUTOCLAVE SYNTHESIS AND THERMAL TRANSFORMATIONS OF THE ALUMINOPHOSPHATE MOLECULAR-SIEVE VPI-5 - AN INSITU X-RAY-DIFFRACTION STUDY

The synthesis of DPA-VPI-5 and TBA-VPI-5 and their phase transformation to AlPO4-8 have been studied by X-ray diffraction in situ. The synchrotron radiation-energy dispersive diffraction is shown to be able to monitor these two fast reactions in real time. The results indicate that nucleation may occur already during the aging of the synthesis gel. The different rates of transformtion of DPA-VPI-5 and TBA-VPI-5 show that the microstructure of the two materials is different.