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Page RESEARCH DIRECTOR:
Enrique Iglesia, Professor of Chemical Engineering, University of California at Berkeley and Faculty Scientist, Lawrence Berkeley Laboratory
SUMMARY:
This project addresses the development and use of frequency modulation techniques in order to measure individual rates of gas and surface diffusion and of adsorption processes within mesoporous solids. These methods allow the accurate measurement of effective diffusivities at realistic conditions of catalysis and separations, even when several pathways contribute to transport by diffusion. Experimental efforts focus on measurements of surface and gas phase diffusion rates in two types of porous solids: mesoporous solids consisting of random aggregates of quasi-spheres and ordered mesoporous solids formed by liquid template synthesis methods and consisting of cylindrical pores of uniform cross-section (MCM materials). This effort is complemented by rigorous simulations of the structure of these porous solids, including their surface electronic properties and adsorption characteristics, and of surface and gas phase diffusion. These simulations combine the use of molecular dynamics methods to describe the structure of the solids and their surfaces and the hopping frequency of adsorbed molecules with the use of Monte Carlo simulations of surface diffusion based on transition state theory. These effective diffusivity and structural measurements and simulations are used to guide the synthesis of inorganic porous membranes and solids and the design of pressure-swing schemes that can be used to couple diffusive separations with catalytic reactions. This project is a collaboration with Dr. Sebastian C. Reyes (Exxon Research and Engineering Co.)
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Last Updated 10/29/98.