title: Chemical imaging of Fischer-Tropsch catalysts under operating conditions.
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 TiO2anatase 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.
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
authors.forename: Stephen W T
authors.initials: SW
authors.lastname: Price
authors.affiliation: Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, U.K.; Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: David J
authors.initials: DJ
authors.lastname: Martin
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
authors.forename: Aaron D
authors.identifier: 0000-0001-5601-6296
authors.initials: AD
authors.lastname: Parsons
authors.affiliation: ISIS Facility, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K.
authors.forename: Wojciech A
authors.identifier: 0000-0002-9578-0374
authors.initials: WA
authors.lastname: Sławiński
authors.affiliation: Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, U.K.; Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
authors.forename: Antonios
authors.initials: A
authors.lastname: Vamvakeros
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Keylock
authors.affiliation: Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, U.K.; Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.; Finden Limited, The Workstation Merchant House, 5 East St. Helen Street, Abingdon, Oxfordshire OX14 5EG, U.K.
authors.forename: Andrew M
authors.identifier: 0000-0002-0923-1433
authors.initials: AM
authors.lastname: Beale
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.; School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, U.K.
authors.forename: J Frederick W
authors.identifier: 0000-0001-6473-2743
authors.initials: JF
authors.lastname: Mosselmans
keywords: Cobalt; Fischer-Tropsch; Operando; XRD-CT; XRF-CT; intergrowth; multimodal tomography