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March 3, 2015

Developing Descriptors to Understand and Predict Catalytic Performance

The development of descriptors that relate the physico-chemical properties of catalytically active materials to their activity, selectivity, or stability is a primary objective of catalysis research. Good descriptors should provide fundamental insight into catalytic performance, be simple to measure or calculate, be amenable to systematic variation or tuning, and provide guidance to the rational design of new materials with superior catalytic properties. In this talk, I will discuss the development and application of such descriptors to the design of catalysts for two classes of industrially important reactions: the selective oxidation of propylene to acrolein, and the dehydrogenation of propane to propylene. In the first system, the band gap of a mixed metal oxide catalyst is identified as an insightful descriptor its catalytic activity for propylene oxidation. Through theoretical and experimental investigation, the basis for band gap as a descriptor for activity is identified, and the power of this descriptor to guide formulation of more active catalysts is examined. In the second system, it is discovered that multiple descriptors are required to account for the catalytic performance of a series of supported single site catalysts toward propane dehydrogenation. By identifying and applying these descriptors to catalytic design, it becomes possible to rationally control not only the activity of a catalyst, but also the mechanism by which it operates. These examples demonstrate the power of a descriptor-based approach to catalysis research to provide both deeper fundamental understanding and practical guidance for the design of novel catalytic materials with improved performance.

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March 16, 2015

Break it Down: Discovering the Secrets of Cellulosic Decomposition Reactions for Renewable Chemicals and Fuels

Determining how to efficiently convert cellulose into smaller molecules is vital for harnessing this abundant biopolymer as a renewable source of chemicals and fuels. Understanding the molecular-level chemistry can aid the rational design of improved processes. This knowledge had remained elusive, despite decades of research into the chemical mechanisms governing its conversion. To solve these mysteries, we have created multiscale models of thermochemical and enzymatic conversions of cellulose that allow us to investigate complex reaction networks, determine elementary steps, calculate kinetic parameters, and compare model results with experimental data. Our thermochemical investigations focused on revealing key mechanisms in the cellulose pyrolysis reaction network. The results of these studies have been used in the first mechanistic model of cellulose pyrolysis, providing a valuable tool for process design and optimization. The enzymatic investigation revealed the previously elusive detailed mechanism of an industrially important cellulase, revealing targets for protein engineering. Together, this work highlights how advanced computational tools can uncover notoriously complex carbohydrate chemistry that we can use to advance renewable chemicals and fuels.

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March 31, 2015

Reilly Lecture: Advances in siRNA and Protein Delivery Through Smart Polymers

Engineering the molecular design of intelligent biomaterials by controlling structure, recognition and specificity is the first step in coordinating and duplicating complex biological and physiological processes. Recent developments in siRNA and protein delivery have been directed towards the preparation of targeted formulations for protein delivery to specific sites, use of environmentally-responsive polymers to achieve pH- or temperature-triggered delivery, usually in modulated mode, and improvement of the behavior of their mucoadhesive behavior and cell recognition. We address design and synthesis characteristics of novel crosslinked networks capable of protein release as well as artificial molecular structures capable of specific molecular recognition of biological molecules. Molecular imprinting and microimprinting techniques, which create stereo-specific three-dimensional binding cavities based on a biological compound of interest can lead to preparation of biomimetic materials for intelligent drug delivery, drug targeting, and tissue engineering. We have been successful in synthesizing novel glucose- and protein-binding molecules based on non-covalent directed interactions formed via molecular imprinting techniques within aqueous media. We have also developed structurally superior materials to serve as effective carriers for siRNA delivery to combat Crohn disease and ulcerative colitis.

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April 1, 2015

Reilly Lecture: Nanotechnology and Bioengineering in an Evolving Chemical Engineering World

Nanotechnology and Bioengineering, have evolved out of chemical engineering because of the need to address important societal problems. Emphasis in such areas has led to the solution of complex chemical engineering problems that required non-newtonian flows, non-ideal thermodynamics, multicomponent systems, macromolecular analysis and diagnostic/intelligent responsive systems. The introduction of these fields brought up also an emphasis on translational research, product engineering, development of devices/systems and processes and an associated emphasis on applications and commercialization. An unfortunate result of these changes was a shift of Chemical Engineering from fundamentals to applied sciences. I examine the underlying reasons for this shift, with emphasis on changes in societal needs in the 1970s to translational research that started in the late 1980s. I examine the impact of these changes on ChE education, including the academic shift towards applied sciences and the de-emphasis of fundamentals. We address new educational and research directions that will provide a corrective path towards convergence in chemical engineering.

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