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Thermal ageing of a commercial LNT catalyst: effects on the structure and functionalities

DOI: 10.1016/j.cattod.2021.04.006 DOI Help

Authors: Tommaso Pellegrinelli (Queen’s University Belfast) , Geoffrey Mccullough (Queen’s University Belfast) , Roberto Caporali (Ford Motor Company) , Iain Murray (Ford Motor Company) , Veronica Celorrio (Diamond Light Source) , Emma K. Gibson (University of Glasgow) , Christopher Hardacre (University of Manchester) , Alexandre Goguet (Queen's University of Belfast)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Catalysis Today , VOL 27

State: Published (Approved)
Published: April 2021
Diamond Proposal Number(s): 15151

Abstract: Hydrothermal degreening and ageing procedures were applied to a tri-metal (Pt-Pd-Rh) fully formulated lean NOX Trap catalyst to evaluate the effects of thermal stress on the performances and structural properties. X-ray absorption fine structure (XAFS) analysis revealed that the average size of the platinum particles was the same after degreening and ageing treatments. The formation of a new phase of alloyed Pt-Pd was observed to increase with the thermal load. The size of the ceria particles also increased after the ageing treatment. NOX storage capacity experiments revealed a substantial decrease of the concentration of active NOX storage sites which correlated with both ageing and degreening protocols. The performances of the treated catalyst were evaluated through spatially resolved (SpaciMS) lean-rich cycles. During the lean phase, the impact of the decrease in storage sites was significant on the aged sample, where an enlargement of the area required to achieve full storage was observed. On the other hand, the regeneration functionalities did not appear to be particularly affected by ageing. Rather, the aged sample showed a decrease of oxygen storage capacity (OSC), which promoted a lower reductant consumption and therefore a quicker and more efficient reduction process. On the other hand, the different distributions of adsorbed species by the end of the lean phase produced greater spread presence of NH3 and NOX slip along the channels of the aged sample during the reduction.

Journal Keywords: Lean NOx trap; ageing; Spaci-MS; Characterisation

Subject Areas: Chemistry

Instruments: B18-Core EXAFS

Other Facilities: HarwellXPS

Added On: 20/04/2021 08:23

Discipline Tags:

Catalysis Physical Chemistry Engineering & Technology Automotive Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)