JUSTIN NOTESTEIN
Northwestern University

UNDERSTANDING AND IMPLEMENTING NEW OXIDE CATALYSTS

Abstract

Supported oxide catalysts are used in selective oxidation (oxidative dehydrogenation, oxidative coupling, synthesis of oxygenates), emissions control (VOC catalytic oxidation, NO SCR), metathesis and isomerization, ammonia synthesis, CO hydrogenations, photocatalysis, and many other critical reactions. Modified oxides are also enhanced supports for metal nanoparticle catalysis. This has led to substantial, sustained interest in these materials within academia and the chemical industry. However, two critical issues cloud work in supported oxides: 1) limited molecular-level knowledge of structure, including the number and specific reactivity of active sites vs. inert spectators, and 2) limited ability to rationally tune supported oxides to give a desired structure. This talk will thus focus on two areas of research: 1) improved understanding and implementation of ‘typical’ supported oxides and synthetic routes to break out of historical trends in materials synthesis, and 2) the development of ‘nanocavity’ oxides that introduce new avenues of control in supported oxides.
The first part will show how materials syntheses control the speciation of supported metal oxides, and therefore their reactivity. Recent examples will be drawn from our work in alkane oxidation, epoxidation, dehydrogenation, and deNOx, time permitting. Understanding catalyst surface structure is backed by an array of spectroscopic probes (X-ray absorption, UV-visible, FTIR, etc.), and a novel titration by phosphonic acids, which is shown to be a new method able to distinguish total, surface-accessible, and catalytically-relevant supported oxide sites. Combining these methods with quantitative temperature-programmed reduction can unify many independent observations of oxide catalyst reactivity.
The second part will describe methods to control 1-2 nm-sized structures on mixed oxide surfaces, with the goal of mimicking the steric and environmental control of zeolites or many enzymes. Templated atomic layer deposition and related sol-gel techniques are described which create nanoscale cavities (or islands, depending on one’s perspective) of one oxide on top of another. Novel applications of these materials will be described, including unprecedented shape-selective photooxidations, emergent selectivity in acid catalysis, and the ability to stabilize the size-selected deposition of metal nanoparticles. Combining new synthesis for classic supported oxides and these sub-nm oxide films is introducing new tools for design and use of selective oxide catalysts.

JUSTIN NOTESTINE is currently an associate professor at Northwestern University. He received his BSE at Princeton University in 2001 and his PhD at the University of California Berkeley in 2006, both in Chemical Engineering. Since 2007, he has been a member of the department of Chemical and Biological Engineering and the Center for Catalysis and Surface Science. He is an affiliate of several consortia on sustainability, materials, and nanotechnology. Research in Prof. Notestein’s group focuses on the development of new hybrid, oxide, and nanostructured catalysts and adsorbents for a number of transformations relevant to sustainable energy, selective oxidation, and improving industrial chemical processes. Special attention is on developing full synthesis-structure-function relationships for improving the process of new catalyst development. This work is supported by the US DOE, NSF, Toyota, and Dow Chemical. Among other recognition, Prof. Notestein has been awarded a Dreyfus Foundation New Faculty Award, a DuPont Young Professor Award, and several teaching and academic advising awards.

For more info: www.chem-eng.utoronto.ca/news.htm

Websites of Interest

• University of Toronto
• Faculty of Applied Science & Engineering
• Department of Chemical Engineering & Applied Chemistry