Growth of SAPO-34 in polymer hydrogels through vapor-phase transport

Cross-linked polyacrylamide (C-PAM) hydrogels were employed to reduce the crystal size of SAPO-34 molecular sieves in a vapor-phase transport process. A wide size distribution of SAPO-34 crystals, ranging from a few nanometers to 3-5 μm, was produced when the synthesis precursor gels contained the appropriate amount of C-polyacrylamide (C-PAM) hydrogels. Specifically, these dispersions of SAPO-34 crystallites were formed when the molar ratio of polyacrylamide to Al2O3 was between 0.29 and 043. These crystals exhibited a BET surface area of 342-325 m2/g, micropore volume of 0.15-0.12 cm3/g, and TEA entrapment of 9.3-8.0%. Microanalysis using EDXS revealed the presence of residual precursor materials, such as phosphorus, supporting the fact that our samples possessed a lower BET surface area and micropore volume as compared with the SAPO-34 prepared by hydrothermal method in the literature.