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SUMMARY:Watching catalysts at work: time-resolved spectroscopy under dynam
 ic conditions
DTSTART:20170503T110000
DTEND:20170503T120000
DTSTAMP:20260501T113318Z
UID:c23d016892be7b9f91d0f03e87022fcfee0e477efe0f204620a3df7f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Davide Ferri\nPaul Scherrer Institute\nPhysico-chemical analyt
 ical methods are invaluable tools for materials characterization. A number
  of these methods have become indispensable to obtain key structural infor
 mation on heterogeneous catalytic materials under operando conditions. How
 ever\, spectroscopic experiments are typically performed at steady state u
 nder static reaction conditions thus in principle precluding our access to
  information on relevant species\, e.g. intermediates. Structural changes 
 associated to near surface variations involved in reaction mechanisms are 
 often subtle or obscured by bulk structural changes or contributions\, e.g
 . a significant portion of the support but also of a metal particle that a
 re extraneous to the reaction. In pulsed experiments\, the catalyst is sti
 mulated to perform a specific event and to exhibit the structural changes 
 associated with it. Because of the nature of such experiments\, second to 
 sub-second time resolution is required\, while pulse repetition (modulatio
 n) improves the signal-to-noise ratio of any spectroscopic/diffraction met
 hod. Further enhancement of the structural change can be achieved by filte
 ring the static signals\, e.g. the unresponsive bulk or dominant adsorbed 
 species\, by phase sensitive analysis. From a catalytic view point\, pulse
  experiments simulate well the operation of automotive catalysts. Hence\, 
 the potential of pulse experiments is demonstrated in selected cases using
  infrared\, UV-vis spectroscopy and X-ray based methods to characterize ca
 talysts involved in NOx selective catalytic reduction and three-way cataly
 sis. It is demonstrated how subtle structural changes can be captured and 
 their temporal response assessed precisely by this approach. This provides
  access to a detailed\, often unprecedented\, structural dynamics of catal
 ytic systems.
LOCATION:Emosson
STATUS:CONFIRMED
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