Structure, Chemical Composition, And Reactivity Correlations during the In Situ Oxidation of 2-Propanol

Abstract

Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step toward gaining fundamental insight in catalysis. We report the evolution of the structure and chemical composition of size-selected micellar Pt nanoparticles (∼1 nm) supported on nanocrystalline γ-Al(2)O(3) during the catalytic oxidation of 2-propanol using X-ray absorption fine-structure spectroscopy. Platinum oxides were found to be the active species for the partial oxidation of 2-propanol (<140 °C), while the complete oxidation (>140 °C) is initially catalyzed by oxygen-covered metallic Pt nanoparticles, which were found to regrow a thin surface oxide layer above 200 °C. The intermediate reaction regime, where the partial and complete oxidation pathways coexist, is characterized by the decomposition of the Pt oxide species due to the production of reducing intermediates and the blocking of O(2) adsorption sites on the nanoparticle surface. The high catalytic activity and low onset reaction temperature displayed by our small Pt particles for the oxidation of 2-propanol is attributed to the large amount of edge and corner sites available, which facilitate the formation of reactive surface oxides. Our findings highlight the decisive role of the nanoparticle structure and chemical state in oxidation catalytic reactions.

Catalytic hydrodeoxygenation of guaiacol over platinum supported on metal oxides and zeolites

“…[57]). This value corresponded well to the results of the STEM measurements where particles between 0.5 and 3 nm were observed; some sintering may have occurred (Table 2) which may be due to oxygen incorporation into the metallic Pt lattice [58][59][60]. For Pt/SG-SiO 2 the local structure of the calcined sample was similar to bulk metallic Pt particles with 12 Pt neighbours in accordance with the rather large particle size observed by other characterization methods (for details see ESI, Figure S6).…”

Nanocatalysis: size- and shape-dependent chemisorption and catalytic reactivity

“…[114]. Although the size of the NPs in different sample similar (~1 nm), the shape of the NPs w was observed that the onset temperature increases with incre atoms, namely, the reaction barrier is higher on low understood based on the higher stability of platinum detrimental for this chemical process, since occur more readily on metallic Pt [373].…”

In situ coarsening study of inverse micelle-prepared Pt nanoparticles supported on γ-Al2O3: pretreatment and environmental effects

“…58, the annealing of similar inverse micelle prepared Pt NPs up to 500 1C in H 2 , did not lead to the complete removal of the encapsulating polymeric ligands, while an absence of carbon is observed on the same sample when annealed at/above 375 1C in O 2 . 20,58,60 Therefore, the starting state of NPs in S1 before the H 2 annealing at/above 400 1C is characterized by ligand-free NPs, while residual polymeric ligands are still expected on S2 NPs at the same stage.…”

“…[8][9][10][11][12][13][14][15] Furthermore, the NP size was also shown to influence the binding of adsorbates 16,17 and selectivity of NP catalysts. [18][19][20][21][22] Sintering is a major factor contributing to the decrease in the reactivity of NPs used in catalytic converters 23 and fuel cells. 24 Therefore, designing NP-support systems that ensure the stability of the NPs under reaction conditions, e.g., under a given chemical environment and at high temperature, is essential in order to maintain their catalytic performance and lifetime in an industrial setting.…”