Industrially Produced Fe- and Mn-Based Perovskites: Effect of Synthesis on Reactivity in Three-Way Catalysis: Part 1.

La0.6Ca0.2Fe0.8Cu0.2O3, undoped (LF) and Ca, Cu-doped (LCFC), powders, obtained by different industrial procedures, are compared to evaluate reproducibility and scale-up in different industrial synthetic approaches: flame spray pyrolysis (FSP) and coprecipitation (COP). Also the effects of varying composition (doping) and FSP process variability are considered as comparative studies on morphological, crystallographic, redox and compositional properties, and functional activity. A model reaction (CO + NO) and reactions with an automotive exhaust mixture were carried out. Unexpected results on the effectiveness of doping for catalytic activity emerged. Samples with the same compositions proved to be significantly affected by the synthesis, with variability within the same process. The activity of LCFC COP is comparable to the FSP analogue, at stoichiometric conditions, notwithstanding differences highlighted by characterization. In an oxygen-deficient mixture, LCFC-COP yields higher NO reduction and CO oxidation activity than LCFC-FSP. The absence of Ca in the lattice was unexpectedly beneficial. The doping effectiveness must be carefully checked for large-scale production.

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

Platinum functions exceptionally well as a nanoparticulate catalyst in many important fields, such as in the removal of atmospheric pollutants, but it is scarce, expensive and not always sufficiently durable. Here, we report a perovskite system in which 0.5 wt% Pt is integrated into the support and its subsequent conversion through exsolution to achieve a resilient catalyst. Owing to the instability of most Pt oxides at high temperatures, a thermally stable platinum oxide precursor, barium platinate, was used to preserve the platinum as an oxide during the solid-state synthesis in an approach akin to the Trojan horse legend. By tailoring the procedure, it is possible to produce a uniform equilibrated structure with active emergent Pt nanoparticles strongly embedded in the perovskite surface that display better CO oxidation activity and stability than those of conventionally prepared Pt catalysts. This catalyst was further evaluated for a variety of reactions under realistic test environments-CO and NO oxidation, diesel oxidation catalysis and ammonia slip reactions were investigated.