Abstract
LaCoO3 films were deposited onto MgAl2O4 powders by atomic layer deposition (ALD) and then used as catalyst supports for Pt. X-ray diffraction (XRD) showed that the 0.5 nm films exhibited a perovskite structure after redox cycling at 1073 K, and scanning transmission electron microscopy and elemental mapping via energy-dispersive X-ray spectroscopy (STEM/EDS) data demonstrated that the films covered the substrate uniformly. Catalysts prepared with 3 wt % Pt showed that the Pt remained well dispersed on the perovskite film, even after repeated oxidations and reductions at 1073 K. Despite the high Pt dispersion, CO adsorption at room temperature was negligible. Compared with conventional Pt on MgAl2O4, the reduced forms of the LaCoO3-containing catalyst were highly active for the CO oxidation and water gas shift (WGS) reactions, while the oxidized catalysts showed much lower activities. Surprisingly, the reduced catalysts were much less active than the oxidized catalysts for toluene hydrogen. Catalysts prepared from thin films of Co3O4 or La2O3 exhibited properties more similar to Pt/MgAl2O4. Possible reasons for how LaCoO3 affects properties are discussed.
Highlights
Sintering is a serious problem with supported metal catalysts in high-temperature applications, such as in automotive emissions control, because it leads to a loss of catalytically active surface area [1]
The weight changes associated with deposition of Co3 O4 films on MgAl2 O4 are shown in Figure S1a, which demonstrates that the amount Co3 O4 that was added per cycle was independent of the number of cycles and equal to 5.0
The results of this study demonstrate that thin films of LaCoO3 can be formed by atomic layer deposition (ALD) and that these films can exhibit interesting properties as supports for Pt catalysts
Summary
Sintering is a serious problem with supported metal catalysts in high-temperature applications, such as in automotive emissions control, because it leads to a loss of catalytically active surface area [1]. The idea behind intelligent catalysts is that catalytic metals can become part of the perovskite lattice for some perovskites under oxidizing conditions, return to the surface under reducing conditions. This “ingress” of large metal particles into the perovskite and “egress” of smaller metal particles out of the lattice could allow redispersion of the catalyst and restoration of activity. The perovskites that are of interest for this application typically have low surface areas, at least after high-temperature cycling
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
