Mono- and bimetallic Rh and Pt NSR-catalysts prepared by controlled deposition of noble metals on support or storage component

Abstract

Mono- and bimetallic Rh and Pt based NO storage-reduction (NSR) catalysts, where the noble metals were deposited on the AlO support or BaCO storage component, have been prepared using a twin flame spray pyrolysis setup. The catalysts were characterized by nitrogen adsorption, CO chemisorption combined with diffuse reflectance infrared Fourier transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy. The NSR performance of the catalysts was investigated by fuel lean/rich cycling in the absence and presence of SO (25 ppm) as well as after H desulfation at 750 °C. The performance increased when Rh was located on BaCO enabling good catalyst regeneration during the fuel rich phase. Best performance was observed for bimetallic catalysts where the noble metals were separated, with Pt on AlO and Rh on BaCO. The Rh-containing catalysts generally showed much higher tolerance to SO during fuel rich conditions and lost only little activity during thermal aging at 750 °C.

A Review on the Impact of SO2 on the Oxidation of NO, Hydrocarbons, and CO in Diesel Emission Control Catalysis

“…No effect is shown for propane because of the lack of activity at the test temperature of 200 °C. This inhibition impact is more pronounced with a high SO 2 dose. ,,,,,,− Compared with HCs and NO, the negative impact of sulfur is less significant for CO in the practical application of DOCs.…”

Mechanistic Investigation of the Reduction of NOx over Pt- and Rh-Based LNT Catalysts

“…Typical catalyst formulations include different platinum group metals (PGM) such as Pt, Pd, or Rh, but the debate concerning the precise role of each constituent is still open. In particular, it has been reported that Pd or Rh are more reactive than Pt in the reduction of adsorbed NO x , more selective to N 2 , and with higher sulfur resistance [16][17][18][19].…”

First principles investigation of NO2 and SO2 adsorption on γ-Al2O3 supported mono- and diatomic metal clusters

“…One of the main deactivation mechanisms of NSR catalysts is sulfur poisoning, 21 which reduces the performance of both the precious metal and the storage component. 17,[22][23][24] Oxides of sulfur (SO x ) exist in small but noticable quantities in fuel. Due to their higher affinity towards the storage and reduction components, SO x species compete with NO x for the same adsorption sites, binding much more strongly and blocking further NO x adsorption.…”