Steam-created grain boundaries for methane C-H activation in palladium catalysts.

Autor:	Huang W; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA., Johnston-Peck AC; Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA., Wolter T; Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA., Yang WD; Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA., Xu L; Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA., Oh J; Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA., Reeves BA; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA., Zhou C; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA., Holtz ME; Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA., Herzing AA; Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA., Lindenberg AM; Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA., Mavrikakis M; Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA., Cargnello M; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.; SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
Jazyk:	angličtina
Zdroj:	Science (New York, N.Y.) [Science] 2021 Sep 24; Vol. 373 (6562), pp. 1518-1523. Date of Electronic Publication: 2021 Sep 23.
DOI:	10.1126/science.abj5291
Abstrakt:	Defects may display high reactivity because the specific arrangement of atoms differs from crystalline surfaces. We demonstrate that high-temperature steam pretreatment of palladium catalysts provides a 12-fold increase in the mass-specific reaction rate for carbon-hydrogen (C–H) activation in methane oxidation compared with conventional pretreatments. Through a combination of experimental and theoretical methods, we demonstrate that an increase in the grain boundary density through crystal twinning is achieved during the steam pretreatment and oxidation and is responsible for the increased reactivity. The grain boundaries are highly stable during reaction and show specific rates at least two orders of magnitude higher than other sites on the palladium on alumina (Pd/Al 2 O 3 ) catalysts. Theoretical calculations show that strain introduced by the defective structure can enhance C–H bond activation. Introduction of grain boundaries through laser ablation led to further rate increases.
Databáze:	MEDLINE
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