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Chemical imaging of Fischer-Tropsch catalysts under operating conditions

DOI: 10.1126/sciadv.1602838 DOI Help

Authors: Stephen W. T. Price (Diamond Light Source) , David Martin (University College London; Research Complex at Harwell) , Aaron Parsons (Diamond Light Source) , Wojciech A. Sławiński (ISIS Facility) , Antonios Vamvakeros (University College London; Research Complex at Harwell) , Stephen J. Keylock (Diamond Light Source) , Andrew Beale (University College London; Research Complex at Harwell; Finden Limited) , J. Frederick W. Mosselmans (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Science Advances , VOL 3

State: Published (Approved)
Published: March 2017
Diamond Proposal Number(s): 10242 , 12064 , 12499 , 12601 , 14440

Open Access Open Access

Abstract: Although we often understand empirically what constitutes an active catalyst, there is still much to be understood fundamentally about how catalytic performance is influenced by formulation. Catalysts are often designed to have a microstructure and nanostructure that can influence performance but that is rarely considered when correlating structure with function. Fischer-Tropsch synthesis (FTS) is a well-known and potentially sustainable technology for converting synthetic natural gas (“syngas”: CO + H2) into functional hydrocarbons, such as sulfur- and aromatic-free fuel and high-value wax products. FTS catalysts typically contain Co or Fe nanoparticles, which are often optimized in terms of size/composition for a particular catalytic performance. We use a novel, “multimodal” tomographic approach to studying active Co-based catalysts under operando conditions, revealing how a simple parameter, such as the order of addition of metal precursors and promoters, affects the spatial distribution of the elements as well as their physicochemical properties, that is, crystalline phase and crystallite size during catalyst activation and operation. We show in particular how the order of addition affects the crystallinity of the TiO2 anatase phase, which in turn leads to the formation of highly intergrown cubic close-packed/hexagonal close-packed Co nanoparticles that are very reactive, exhibiting high CO conversion. This work highlights the importance of operando microtomography to understand the evolution of chemical species and their spatial distribution before any concrete understanding of impact on catalytic performance can be realized.

Journal Keywords: Operandomultimodal tomographyXRD-CTXRF-CTFischer-TropschCobaltintergrowth

Subject Areas: Chemistry, Materials, Technique Development


Instruments: I18-Microfocus Spectroscopy