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Our latest work on X-ray tomographic diffraction imaging of operating dense ceramic hollow-fibre catalytic membrane reactors (CMRs)

You can see our latest work on X-ray tomographic diffraction imaging of operating dense ceramic hollow-fibre catalytic membrane reactors (CMRs) – “Real-time tomographic diffraction imaging of catalytic membrane reactors for the oxidative coupling of methane” in Catalysis Today. The paper is a result of a collaboration between scientists at UCL Chemistry, Finden, ESRF,  VITO and ISIS Neutron and Muon Source.

Real time tomographic diffraction figHighlights include:
  • Synchrotron X-ray diffraction computed tomography applied to three packed bed catalytic membrane reactors.
  • The solid-state evolution of catalysts and membranes is tracked under operating conditions.
  • A new crystal structure model of BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) is suggested and used for the diffraction data analysis

 

 

Catalytic membrane reactors have the potential to render the process of oxidative coupling of methane economically viable. Here, the results from operando XRD-CT studies of three different catalytic membrane reactors, employing BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite membranes with Mn-Na-W/SiO2 and La-promoted Mn-Na-W/SiO2 catalysts, are presented. It is shown that synchrotron X-ray tomographic diffraction imaging allows the extraction of spatially-resolved diffraction information from the interior of these working catalytic membrane reactors and makes it possible to capture the evolving solid-state chemistry of their components under various operating conditions (i.e. temperature and chemical environment).

Read the paper at https://doi.org/10.1016/j.cattod.2020.05.045

Operando and Postreaction Diffraction Imaging of the La–Sr/CaO Catalyst in the Oxidative Coupling of Methane Reaction

Operando and Postreaction Diffraction Imaging figureOur paper on Operando and Postreaction Diffraction Imaging of the La–Sr/CaO Catalyst in the Oxidative Coupling of Methane Reaction has been published online by The Journal of Physical Chemistry.

A La–Sr/CaO catalyst was studied operando during the oxidative coupling of methane (OCM) reaction using the X-ray diffraction computed tomography technique. Full-pattern Rietveld analysis was performed in order to track the evolving solid-state chemistry during the temperature ramp, OCM reaction, as well as after cooling to room temperature. We observed a uniform distribution of the catalyst main components: La2O3, CaO–SrO mixed oxide, and the high-temperature rhombohedral polymorph of SrCO3. These were stable initially in the reaction; however, doubling the gas hourly space velocity resulted in the decomposition of SrCO3 to SrO, which subsequently led to the formation of a second CaO–SrO mixed oxide. These two mixed CaO–SrO oxides differed in terms of the extent of Sr incorporation into their unit cell. By applying Vegard’s law during the Rietveld refinement, it was possible to create maps showing the spatial variation of Sr occupancy in the mixed CaO–SrO oxides. The formation of the Sr-doped CaO species is expected to have an important role in this system through the enhancement of the lattice oxygen diffusion as well as increased catalyst basicity.

Read the full article at https://pubs.acs.org/doi/10.1021/acs.jpcc.8b09018