Characterization of intermediate TPA-ZSM-5 type structures during crystallization.
A wide range of anal. techniques (x-ray diffraction (XRD), DTA/TGA, IR, texture, SEM/TEM, and 13C, 27Al, 29Si MAS NMR) were used to characterize intermediates formed during crystn. of Pr4N ZSM-5 (TPA-ZSM-5) catalysts. Initial crystn. products are XRD-amorphous and consist of an Al-rich phase next to an increasing amt. of TPA-ZSM-5 entities with dimensions of the order of the unit cell of ZSM-5. In the final crystn. stage (.ltorsim.8 days) the TPA-ZSM-5 entities recombine to a cryst. ZSM-5 framework. A large amt. of framework defects are then still present in the XRD-cryst. TPA-ZSM-5 framework as evidenced by 29Si MAS NMR. These defects disappear upon calcination.
Dieser Eintrag ist freigegeben.