Identifying the role of oxide supports in transition metal catalysis is critical toward our understanding of heterogeneous catalysis. The water-gas shift (WGS) reaction is a prototypical example where oxide support dictates catalytic activity, yet the cause for this remains uncertain. Herein, we show that a single descriptor—the equilibrium constant for hydroxyl formation—relates the WGS turnover frequency across disparate oxide supports. The dissimilar equilibrium constant, or oxophilicity, between early and late transition metals exemplify the utility of metal-support interfacial sites to circumvent adsorption-energy scaling restrictions, thereby providing bifunctional gains for the WGS reaction class. In relation, the equilibrium constant for hydroxyl formation is equivalent to the equilibrium constant for the formal heterolytic dissociation of hydrogen, and therefore, reflects the ability of the metal-support interface to participate in hydrogen heterolysis. The ubiquitous coexistence, yet divergent chemical behavior of homo- and heterolytically activated hydrogen renders oxide support identity central toward our understanding of hydrogenation catalysis.
This work was supported by the US Department of Energy
(DOE), Office of Science, Office of Basic Energy Sciences,
Division of Chemical Sciences, Geosciences, and Biosciences
and performed at the Environmental Molecular Sciences
Laboratory in (EMSL), which is a DOE Office of Science
User Facility located at the Pacific Northwest National
Laboratory (PNNL). PNNL is a multiprogram national
laboratory operated for DOE by Battelle. Computational
resources were provided by a user proposal at the National
Energy Research Scientific Computing Center (NERSC), a
DOE Office of Science User Facility. N.N. would like to thank
Oliver Y. Gutierrez for critical feedback during the final stage
of manuscript preparation.
Revised: August 31, 2020 |
Published: May 15, 2020
Citation
Nelson N.C., and J. Szanyi. 2020.Heterolytic hydrogen activation: Understanding support effects in water-gas shift, hydrodeoxygenation, and CO oxidation catalysis.ACS Catalysis 10, no. 10:5663-5671.PNNL-SA-148219.doi:10.1021/acscatal.0c01059