Dynamic catalysts for the production of clean energy – DYCAT

The scientific approach is based on the coupling between advanced in-situ/operando characterization techniques, kinetics/catalytic performance and theoretical modelling.

DYCAT has prepared highly dispersed catalysts of Pt/CeO2 and Pd/CeO2 at the atomic scale.
The reducing Water Gas Shift atmosphere rapidly agglomerates Pt single atoms to form nanoparticles with a size of around 1.5 nm. H2 production only occurs after Pt nanoparticles are formed demonstrating that single atoms are not active towards water-gas shift. Nevertheless, the dynamic construction of Pt NPs seems to pass through an active intermediate state linked with an optimal H2 production for few min which depends on the Pt loading (greatest optimum for 0.52 wt% Pt). However, O2 pulses (5 min at 235°C) can regenerate the catalyst. In addition, an oxidizing treatment at 500°C for 1 h also re-activate and even slightly promotes the activity.

In-situ/operando characterizations (CO-DRIFT, Environmental Transmission Electron Microscopy (E-TEM), TPR/TPO, Raman spectroscopy, Time resolved Photoelectron Spectroscopy) and additional catalytic experiments to unravel the impact of O2 pulses on WGS activity of Pt/CeO2 catalysts.
In-situ/operando characterizations (operando XAS, DRIFT, E-TEM) and additional catalytic experiments to unravel the impact of rich pulses on CH4 oxidation of Pd/CeO2 catalysts.
Study of the stability, morphology of Pt and Pd atoms and nanoparticles on CeO2 (111) by DFT computational investigations

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The DYCAT research project aims to investigate the interaction between a catalytically active metal (Pt and Pd) and CeO2, used as a support. We have recently found that the structure and electronic properties of platinum can be optimized by applying a suitable catalyst pretreatment based on short-term alternating reducing/oxidizing sequences at mild temperatures. This concept of “dynamic catalysts” can tailor and stabilize efficient nanoparticles for catalysis. The DYCAT project objective is to unravel and transfer this innovative concept to further key catalytic reactions in energy production, such as the water-gas shift reaction for H2 production and the clean catalytic combustion of CH4. For developing highly active catalysts, mainly the CeO2 surface properties and its interaction with Pt and Pd will be considered. The scientific approach is based on the coupling between advanced in-situ/operando characterization techniques, kinetics/catalytic performance and theoretical modelling. Synchrotron based techniques with high time and spatial resolutions like X-ray absorption / emission spectroscopy (XAS, ME-XAS, HERFD-XANES or V2C-XES) will be used to access information on the electronic state, local coordination environment, interaction with reactants and noble metal particle size variation under applied reaction conditions. Complementary information on the dynamic variations of active sites at the nanoscale will be obtained on a new generation of Environmental Transmission Electron Microscope (aberration-corrected) with a high temporal resolution. The synergy between these two families of characterization methods is essential, very innovative, and a clear added value to the Franco-German collaboration. Furthermore, the coupling of these cutting-edge methods with systematic catalytic tests and theoretical calculations is expected to significantly improve the fundamental understanding of the noble metal/ceria interface dynamic behaviour, which is the prerequisite for operando shaping efficient catalysts for WGS and CH4 oxidation reactions.