Chemical imaging of single catalyst particles with scanning μ-XANES-CT and μ-XRF-CT

DOI: 10.1039/C4CP04488F
PMID: 25407850

Authors: Stephen Price (Diamond Light Source) , Konstantin Ignatyev (Diamond Light Source) , Tina Geraki (Diamond Light Source) , Mark Basham (Diamond Light Source) , Jacob Filik (Diamond Light Source) , Nghia T. Vo (Diamond Light Source) , Peter Witte (BASF Nederland B.V.) , Andrew Beale (University College London) , Fred Mosselmans (Diamond Light Source)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics

State: Published (Approved)
Published: November 2014
Diamond Proposal Number(s): 4939

Abstract: The physicochemical state of a catalyst is a key factor in determining both activity and selectivity; however these materials are often not structurally or compositionally homogeneous. Here we report on the 3-dimensional imaging of an industrial catalyst, Mo- promoted colloidal Pt supported on carbon. The distribution of both the active Pt species and Mo promoter have been mapped over a single particle of catalyst using microfocus X-ray Fluorescence computed tomography. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure revealed a mixed local coordination environment, including the presence of both metallic Pt clusters and Pt chloride species, but also no direct interaction between the catalyst and Mo promoter. We also report on the benefits of scanning μ-XANES computed tomography for chemical imaging, allowing for 2- and 3-dimensional mapping of the local electronic and geometric environment, in this instance for both the Pt catalyst and Mo promoter throughout the catalyst particle.

Subject Areas: Chemistry, Materials, Technique Development


Instruments: B18-Core EXAFS , I18-Microfocus Spectroscopy