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Spatial profiling of a Pd/Al2O3 catalyst during selective ammonia oxidation

DOI: 10.1021/acscatal.0c05356 DOI Help

Authors: Donato Decarolis (Cardiff Catalysis Institute, Cardiff University, Cardiff; UK Catalysis Hub, Research Complex at Harwell) , Adam H. Clark (Paul Scherrer Institute) , Tommaso Pellegrinelli (Queen's University of Belfast) , Maarten Nachtegaal (Paul Scherrer Institute) , Evan Lynch (UK Catalysis Hub, Research Complex at Harwell; University of Southampton) , C. Richard A. Catlow (Cardiff Catalysis Institute, Cardiff University, Cardiff; UK Catalysis Hub, Research Complex at Harwell; University College London) , Emma K. Gibson (University of Glasgow; UK Catalysis Hub, Research Complex at Harwell) , Alexandre Goguet (Queen's University Belfast; Catalysis Hub, Research Complex at Harwell) , Peter P. Wells (UK Catalysis Hub, Research Complex at Harwell; University of Southampton; Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Catalysis , VOL 50 , PAGES 2141 - 2149

State: Published (Approved)
Published: February 2021

Open Access Open Access

Abstract: The utilization of operando spectroscopy has allowed us to watch the dynamic nature of supported metal nanoparticles. However, the realization that subtle changes to environmental conditions affect the form of the catalyst necessitates that we assess the structure of the catalyst across the reactant/product gradient that exists across a fixed bed reactor. In this study, we have performed spatial profiling of a Pd/Al2O3 catalyst during NH3 oxidation, simultaneously collecting mass spectrometry and X-ray absorption spectroscopy data at discrete axial positions along the length of the catalyst bed. The spatial analysis has provided unique insights into the structure–activity relationships that govern selective NH3 oxidation—(i) our data is consistent with the presence of PdNx after the spectroscopic signatures for bulk PdNx disappear and that there is a direct correlation to the presence of this structure and the selectivity toward N2; (ii) at high temperatures, ≥400 °C, we propose that there are two simultaneous reaction pathways—the oxidation of NH3 to NOx by PdO and the subsequent catalytic reduction of NOx by NH3 to produce N2. The results in this study confirm the structural and catalytic diversity that exists during catalysis and the need for such an understanding if improvements to important emission control technologies, such as the selective catalytic oxidation of NH3, are to be made.

Journal Keywords: ammonia oxidation; operando spectroscopy; Pd nanoparticles; SPACI-FB; heterogeneous catalysis

Subject Areas: Chemistry

Facility: SuperXAS at Swiss Light Source

Added On: 08/02/2021 09:20

Documents:
acscatal.0c05356.pdf

Discipline Tags:

Catalysis Inorganic Chemistry Physical Chemistry Chemistry

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