Identifying Active Sites of the Water-Gas Shift Reaction over Titania Supported Platinum Catalysts under Uncertainty

摘要

A comprehensive uncertainty quantification framework has been developed forintegrating computational and experimental kinetic data and to identify activesites and reaction mechanisms in catalysis. Three hypotheses regarding theactive site for the water-gas shift reaction on Pt/TiO2 catalysts are tested -Pt(111), an edge interface site, and a corner interface site. Uncertaintiesassociated with DFT calculations and model errors of microkinetic models of theactive sites are informed and verified using Bayesian inference and predictivevalidation. Significant evidence is found for the role of the oxide support inthe mechanism. Positive evidence is found in support of the edge interfaceactive site over the corner interface site. For the edge interface site, theCO-promoted redox mechanism is found to be the dominant pathway and only attemperatures above 573 K does the classical redox mechanism contributesignificantly to the overall rate. At all reaction conditions, water andsurface O-H bond dissociation steps at the Pt/TiO2 interface are the main ratecontrolling steps.