Volume 87 Issue 18 | p. 44 | Concentrates
Issue Date: May 4, 2009

Chiral Zeolite With Really Big Pores

A germanosilicate with 20-Å pores might be able to trap or catalyze chiral molecules and larger molecules than previously possible
Department: Science & Technology
A 3-D representation depicts the 30 TO4 units (T = Si or Ge) that define ITQ-37's largest pore, which is roughly 20 Å in diameter.
Credit: Avelino Corma
8718scon_ITQ37cxd_opt
 
A 3-D representation depicts the 30 TO4 units (T = Si or Ge) that define ITQ-37's largest pore, which is roughly 20 Å in diameter.
Credit: Avelino Corma

A multinational team of chemists has synthesized a chiral porous germanosilicate zeolite with unusually large pores of roughly 20 Å diameter (Nature 2009, 458, 1154). Porous crystalline materials are widely used in purification processes, gas separation, and catalysis. The exceptional openness of the new material, dubbed ITQ-37, may enable those processes to be selectively applied to chiral molecules and to larger molecules than was previously possible. Junliang Sun and Avelino Corma of Polytechnic University of Valencia, in Spain, and Xiaodong Zou of Stockholm University and coworkers used a large dicationic organic structure-directing agent—a bulky diquaternary ammonium compound—to mediate the synthesis of ITQ-37. The team employed a combination of high-resolution electron microscopy, X-ray diffraction, and novel computational methods to determine its crystal structure. Tests show that ITQ-37-based catalysts are three times more effective at mediating formation of acetals from bulky aldehydes than catalysts based on a common zeolite of similar crystal size but with smaller pores.

 
Chemical & Engineering News
ISSN 0009-2347
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