Unraveling Catalytic Mechanisms and Kinetics: Lessons from Electrical Networks

Meeting Program – November 2016

Ravindra Datta
Professor Ravindra Datta
Professor in the Department of Chemical Engineering,
Fuel Cell Center,
Worchester Polytechnic Institute

 

Abstract – Catalytic reaction networks, in general, comprise of multiple steps and pathways. While one can now readily predict kinetics of these molecular steps from first principles, there is not yet available a comprehensive framework for: 1) visualizing and analyzing these reaction networks in their full complexity; and 2) unequivocally identifying the germane steps and pathways.

Thus, we have developed an approach called the “Reaction Route (RR) Graph” approach, which allows: 1) direct enumeration of all the pathways as walks on the RR Graph; 2) thermodynamic consistence of step kinetics; 3) elucidation of dominant pathways that contribute materially to the overall flux; 4) identification of bottleneck steps in each of these pathways; and 5) development of explicit rate laws based on the electrical analogy.

The electrical network analogy is based on two aspects of RR Graphs, namely: 1) quasi-steady state (QSS) mass balance of intermediate species, the equivalent of the Kirchhoff’s Current Law (KCL) of electrical circuits; and 2) Hess’s law, or thermodynamic consistence, the equivalent of the Kirchhoff’s Potential Law (KPL), which makes RR Graphs precisely equivalent to electrical networks. Further, we define the step resistance in terms of step kinetics to make the analogy complete. The approach is described with the help of the water-gas shift example.

Biography – Ravi Datta is Professor of Chemical Engineering and Director of WPI Fuel Cell Center. He obtained his Ph.D. degree from the University of California, Santa Barbara, in 1981. From then until 1998, he was a Professor of Chemical Engineering at the University of Iowa, when he moved to WPI, and served as Chemical Engineering Department Head until 2005. Ravi’s research is focused on catalytic and electrocatalytic reaction engineering of Clean Energy, including, fuel cells, hydrogen, renewable fuels, novel catalysts, and catalytic reaction networks. He is a coauthor of 150 papers and 8 patents, and has been a mentor to 25 doctoral students.