CHARACTERIZATION OF THE EXTRA-LARGE-PORE ZEOLITE UTD-1

The molecular sieve UTD-1 is investigated using scanning and transmiss ion electron microscopies (TEM), solid-stale NMR spectroscopy, electro n (ED) and X-ray diffraction (XRD), adsorption studies, and catalytic test reactions. The results confirm that UTD-1 is the first high-silic a zeolite to contain a one-dimensional. extra-large 14-ring pore syste m. TEM and ED shaw that UTD-1 is faulted along the (002) planes. Simul ations of XRD patterns of faulted structures using DIFFaX indicate tha t the XRD pattern of a framework containing the so-called double crank shaft chains is in better agreement with the experimental pattern than a framework with the narsarsukite chains previously reported. Thermal /hydrothermal stability studies show that UTD-1 has similar stability to other medium- and large-pore, high-silica zeolites. The ratio of is omerization to disproportionation, and the distribution of trimethylbe nzene isomers in the m-xylene isomerization test reaction from UTD-1 a re similar to those obtained from other large-pore zeolites (zeolites Y or L). However, UTD-1 shows a p-lo-xylene ratio of products below on e.