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.