Hierarchical nano-manufacturing of multiscale, porous

2010 Spring Symposium

Mark A. Snyder
P.C. Rossin Assistant Professor
Department of Chemical Engineering
Lehigh University
Bethlehem, PA 18015

Abstract – Despite the promise for deriving liquid hydrocarbon fuels and high-value chemicals from renewable cellulosic feedstocks, various technological challenges have stifled the rapid commercialization of the integrated biorefinery. The efficient and selective downstream processing of cellulose derivatives (e.g., hexose, fructose, glucose, etc.) exists as a formidable processing bottleneck. Owing to properties such as breadth of operating conditions, designable chemical selectivity, and recyclability, heterogeneous catalytic routes serve as an attractive means, in lieu of biological, thermochemical, and homogeneous ones, for efficient hydrothermal processing of sugary cellulose derivatives. Yet, hydrothermal instability of current catalytic supports opens exciting opportunities for the development of next-generation catalysts capable of meeting selectivity, efficiency, and stability needs of the future biorefinery.

This talk will highlight efforts to realize hydrothermally stable inorganic materials bearing multiscale, three-dimensionally ordered pore topology and tunable surface functionality. Specifically, it will focus on a hierarchical nanotemplating approach in which pre-formed inorganic nanoparticles are assembled into ordered colloidal crystal structures and employed as hard, sacrificial templates for both direct and indirect replica formation of various hydrothermally stable porous materials (e.g., carbon, titania, zeolite). The work is predicated upon the hypothesis that hard inorganic templates help resist pore collapse during structural coarsening or confined growth of inorganic replica materials, and that decoupling template formation and replication allows for precise and versatile engineering of the template, and thus the replica pore topology.

This talk will focus on various stages of hierarchical materials assembly, beginning with techniques for controlled synthesis of primary inorganic nanoparticle building units with nanometer resolution, and encompassing descriptions of their assembly into ordered porous structures, templating of higher-order porous materials, and realization of multiscale (e.g., micro-/mesoporous) porous substrates. Examples of materials that will be discussed include mono- and multi-layer colloidal crystal films, three-dimensionally ordered mesoporous (3DOm) carbon and titania replica particles and thin films, size-tunable, uniformly shaped zeolitic (i.e., silicalilte-1) nanocrystals, and 3DOm-imprinted single crystal zeolite particles. The resulting tunable porous materials hold exciting implications for applications ranging from catalysis to molecular separations, and simultaneous reaction-separations technologies.

Speaker’s Biography – Mark A. Snyder obtained his B.S in Chemical Engineering with highest honors from Lehigh University in 2000, and his Ph.D. in Chemical Engineering from the University of Delaware in 2006. His doctoral research on multiscale modeling of molecular transport in polycrystalline zeolite membranes was recognized with an American Institute of Chemical Engineers (AIChE) Graduate Research Award in 2005. During his doctoral work, he was also awarded the T.W. Fraser and Shirley Russell Teaching Fellowship (2004), the Robert L. Pigford Teaching Assistant Award (2003), and the Robert L. Pigford Graduate Fellowship (2000). Snyder carried out post-doctoral research in the Department of Chemical Engineering and Materials Science at the University of Minnesota from 2006-2008, investigating the benign synthesis of metal oxide nanoparticles and their assembly into mono- to multi-layer porous thin films, permselective encapsulation of living cells towards novel therapeutics, and formation of replica porous structures. Snyder joined Lehigh University’s Department of Chemical Engineering in August 2008 as an Assistant Professor, and was awarded a P.C. Rossin Assistant Professorship in June 2009, a position that he will hold through 2011. At Lehigh, Snyder’s Porous and Functionalized Nanomaterials Lab focuses on the rational design and engineering of functionalized inorganic nanoparticles and porous materials primarily for catalysis, membrane-based separations, and integrated reaction-separation technologies spanning applications in biofuels, renewable chemicals, dye-sensitized solar cells, and carbon capture.