Texas Distinguished Faculty Lectureship Series
Seminar Abstract:
“If only we knew more about _____, we could do a better job of _____”
Every researcher has probably written a variation of the above sentence many times, from the first draft of their dissertation proposition to their latest paper or proposal! However, the continuing arrival of exciting new tools and the accelerating expansion of knowledge they make possible often keep our focus on the first half of the sentence, at the expense of the second half.
In catalysis the challenge has been to design better catalysts from a molecular-level understanding of surface reaction mechanisms and site requirements. This has been a dream for decades. To specify the composition and structure of matter to effect a desired catalytic transformation with desired and predicted rate and selectivity remains a monumental challenge. Surface science alone has not proven to be sufficient for this purpose. Over the past decade the rise of powerful, computationally efficient theoretical methods has shown promise, not just for identifying catalytic intermediates and reaction pathways accessible to experiments, but of providing quantitative predictions of energetics for elementary reaction processes not easily accessed experimentally.
We have focused on the first principles design of catalysts for reactions where selectivity is the overriding consideration. This is more challenging than designing for higher activity, since one must consider reaction processes that compete with the desired channel. After initial successes in the creation of new oxide catalysts from surface science discoveries alone, we have progressed to the design of olefin epoxidation catalysts based on the integration of surface science, computational chemistry, and catalytic reactor studies. These have led to the prediction and validation of new bimetallic catalysts for the synthesis of ethylene oxide.
Prediction without demonstrating performance is of limited value, but there are also critical steps in between. One must be able not only to construct the design, but to demonstrate its survival, if not its detailed function, under operating conditions, in order to claim successful “design.” We have carried out extensive high throughput reactor experiments and characterization studies to try to make such connections. These studies provide critical insights into both successes and failures in first principles catalyst design.