APPLICATION OF THE INDIRECT FOURIER-TRANSFORM METHOD TO A STUDY OF ZEOLITE NUCLEATION

The nucleation events of synthesis reactions of ZSM5 and Na-A zeolites were studied, with particular emphasis on the role of organic template, TPA+ (tetrapropylammonium), in the ZSM5 synthesis. Qualitative evaluation of the structural units was obtained by Small-Angle X-ray Scattering (SAXS) measurements which were analyzed using an indirect Fourier transform method. In the presence of organic cation TPA+ in the ZSM5 synthesis we found globular structural units, 5 nm in diameter, which aggregate to elongated bodies 44 nm long. These results suggest that the zeolite ZSM5 building blocks are globular structural units, 5 nm in diameter, containing silica, alumina, organic cation and water, which fuse together to produce elongated aggregates that may compose the final unit cell. We found that the Na-A zeolite follows nucleation via 1 nm globular particles, which suggests that the existence of globular structural units in the nucleation of zeolites is a general phenomenon.