Figure 4.

High thermomechanical stability of RCT catalysts. (a) In situ environmental transmission electron microscopy images depicting the intact macroporous SiO₂ RCT structure and absence of NP migration after high temperature O₂ and then H₂ treatment. (b) Preserved NP size distribution in Pd₄Au₉₆/SiO₂ RCT catalysts after 1 h of O₂ treatment at 800 °C, indicating no appreciable NP sintering. The high thermomechanical stability of RCT catalysts allows for the high levels of catalytic activity and selectivity to be maintained in the continuous hydrogenation of (c) 1-hexyne to 1-hexene (gas phase), and (d) benzaldehyde to benzyl alcohol (liquid phase). (e) When tested for propene oxidation, Pd/Al₂O₃ RCT catalysts record comparable light-off curves before (filled red squares) and after 7 h of calcination in air at 950 °C (open red squares). For comparison, two different commercial Pd/Al₂O₃ catalysts (labeled ComA and ComB) require appreciably higher temperatures to achieve their precalcination conversion levels due to severe NP aggregation and sintering postcalcination. Data of catalysts before and after calcination in (d) are shown with filled and open squares, respectively. (a) adapted with permission from ref (100). Copyright 2020 The Authors under a CC-BY 4.0 license. (b) adapted with permission from ref (47). Copyright 2021 Wiley-VCH. (c) adapted with permission from ref (98). Copyright 2019 American Chemical society. (d) adapted with permission from ref (89). Copyright 2023 American Chemical society. (e) adapted with permission from ref (91). Copyright 2020 Elsevier B.V.