Comparison of precious metal doped and impregnated perovskite oxides for TWC application

Smart Pd Catalyst with Improved Thermal Stability Supported on High-Surface-Area LaFeO3 Prepared by Atomic Layer Deposition

“…This value of CO adsorption may not be an accurate representation of available Pd sites on the surface since metal−support interaction has been shown to affect the state of Pd. 36 Rates on the 1 wt% Pd/MgAl 2 O 4 sample, reported in Figure 6b, were initially high and similar to those on the reduced LaFeO 3 deposited on 1 wt% Pd/MgAl 2 O 4 on a rate per Pd basis. The rates on Pd/MgAl 2 O 4 sample decreased significantly following calcination at 800 °C probably due to sintering of the Pd particles; however, unlike the case for the perovskite-containing catalyst, activity was not restored by hightemperature reduction.…”

Understanding the Impact of Defects on Catalytic CO Oxidation of LaFeO3-Supported Rh, Pd, and Pt Single-Atom Catalysts

“…30−32 Previous studies demonstrated that the physical and chemical and, accordingly, catalytic properties of perovskites can be tuned by partial substitution of the A and B sites with transition-metal ions. 32−36 For example, Pd doping of LFO can strongly improve the CO oxidation activity. 37 Another recent experiment highlighted that the catalytic activity of CO oxidation on LFO-supported Rh and Cu catalysts was enhanced by the presence of La defects.…”

Platinum incorporation into titanate perovskites to deliver emergent active and stable platinum nanoparticles

“…Previously, a regenerative concept whereby platinum group metal atoms can interchange between metallic nanoparticles and the bulk perovskite matrix to reactivate catalytic activity has been demonstrated by a stoichiometric perovskite system through combustion method at relatively low temperature (8)(9)(10). However, the low structural phase purity, time frame, movement, support interaction and sporadic dispersion of nanoparticles rendered this ineffective for rapid redox fluctuations common in vehicle engines, resulting in controversy over the mechanism and claims made have raised questions about this approach (11)(12)(13). Our findings certainly suggest that it is very difficult to homogeneously dissolve Pt into a perovskite structure due to the very limited stability range of Pt oxides, although an overall regenerative process to/from the perovskite matrix clearly occurs with some exchange between Pt and sublattice.…”

“…Instead stable, anchored oxide nanoparticles are formed (15). Previous attempts at incorporating Pt into a crystalline perovskite structure have utilised low temperature methods such as combustion synthesis, resulting in low structural clarity and unstable mobile nanoparticles that are more prone to the effects of ageing (8)(9)(10)(11)(12)(13)17). Here, we have opted for high temperature solid state synthesis to give better phase purity, which also affords wellcharacterised materials; however, Pt oxides are unstable, dissociating at low temperatures, ≥400 o C and so not compatible with solid stae synthesis that usually requires higher temperature (18).…”