A friendlier route to zeolites
Context: Minerals called zeolites are essential to industrial chemistry because they help convert crude petroleum into useful chemicals, including the materials used in plastics. By dramatically reducing the cost of petrochemicals, zeolites make everything from pills to pocket protectors more aff ordable. Now researchers at the University of St. Andrews in Scotland have discovered a way to make these nanostructured minerals that is not only cheaper but also faster, safer, and less toxic.
Methods and Results: Zeolites are typically made in hot water at dangerously high pressures. The minerals are riddled with nanometer-wide pores; molecules tucked inside these pores react quickly and cleanly. Chemists create the zeolites through a “condensation reaction,” during which mineral precursors encapsulate molecules added as templates, forming a porous solid. Instead of making zeolites in water, Emily Cooper, a chemistry postdoc at St. Andrews, and her colleagues used liquid salts at a relatively low temperature. These liquids are made of charged molecules, or ions, so mineral precursors condense around them directly, eliminating the need for templates. Afterward, the salt ions are removed, leaving a structure with nanometer-sized holes. The recipe yielded five new nanoporous materials; two represented classes that had never been seen before.
Why it matters: The standard process for making zeolites is expensive and dangerous, and it requires specialized equipment. With the new technique, even a high-school laboratory should be able to make them. The millions of possible salt compositions produced through this process could result in the creation of families of zeolites with entirely new functions, leading to better and cheaper everyday products.
Source: Cooper, E. R. et al. (2004) Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues. Nature 430:1012-6.