image: Hierarchically nanoporous aluminosilicate frameworks can be hydrothermally synthesized by using a multi-ammonium surfactant as the zeolite structure-directing agent. The structure-directing surfactant is composed of two hydrophobic long alkyl chains and a zeolite structure-directing hydrophilic head group. During the zeolite formation, the hydrophilic head groups of the surfactant assemble with aluminosilicate anions that are polymerized to the crystalline zeolite framework. The hydrophobic interactions between surfactant tails causes a micellar assembly that further aggregates into hexagonally ordered arrangement. After surfactant was removed through calcination in air, the hierarchically nanoporous (0.55 nm due to the zeolite structure-directing group, and 3.5 nm due to the aggregates of surfactant tails) zeolite architecture is obtained. The hierarchically nanoporous crystalline molecular sieve can be applied to adsorption, separation and catalysis of bulky molecular species. This image relates to an article that appeared in the July 15, 2011, issue of Science, published by AAAS. The study, by K. Na of KAIST in Daejeon, Korea, and colleagues was titled, "Directing Zeolite Structures into Hierarchically Nanoporous Architectures." view more
Credit: Image © <i>Science</i>AAAS