Most Complex Zeolite Structure Solved

By combining high-resolution transmission electron microscopy images with X-ray powder diffraction data for the first time, researchers have solved the structure of TNU-9, an aluminosilicate zeolite that, they say, is "by far the most complex zeolite framework known to date" (Nature 2006, 444, 79).

The silica-rich material boasts 24 crystallographically distinct silicon atoms. This translates into 72 degrees of freedom (24 silicon atoms x 3 atomic coordinates). The structure elucidation—carried out by Christian Baerlocher and Lynne B. McCusker of the Swiss Federal Institute of Technology, Zurich, and their colleagues—required 16 days of computing time.

TNU-9's three-dimensional 10-ring channel system is reminiscent of the one in the important industrial zeolite ZSM-5, the researchers note, but it does have some unique features. "Catalytic testing indicates that TNU-9's activity is distinctly different from that of ZSM-5," McCusker points out.