Rationalization of Interactions in Precious Metal/Ceria Catalysts Using the d‐Band Center Model

Abstract

A correlation between ceria reducibility and the precious-metal d-band center is reported for ceria-supported precious-metal catalysts. The results could provide the missing link to fully explain the occurrence of strong metal-support interaction (SMSI) and hydrogen spillover in catalysts that consist of dispersed metals in contact with reducible metal oxides.

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

“…Overall, the presence of oxygen vacancies is apparent in TPR results, leading to a significant decrease in the reduction temperature of the neighboring PdO. Noteworthy, a decrease in the reduction temperature of the metal oxide supported on redox-active oxide such as ZnO is a reliable sign of the established strong metal support interaction (SMSI) [26]. It is clear that the calcination atmosphere of ZnO influences the reduction profile of the PdZn/ZnO catalysts.…”

“…Furthermore, it was shown previously that the exposure of ZnO to atmospheric pressure of H2, can change the concentration of the Schottky defects mainly that of oxygen vacancies [25]. In addition, the creation of defects through reduction modifies the d-band states of a reducible metal oxide (such as ZnO) which changes the interaction with the adsorbates [26]. As a result, it can be expected that the increased concentration of oxygen vacancies in ZnO support might improve the performance of the PdZn/ZnO catalyst at low temperature MSR.…”

Role of Metal–Support Interactions, Particle Size, and Metal–Metal Synergy in CuNi Nanocatalysts for H2 Generation

“…[6][7][8][9][10][11] In addition to intrinsic changes in the bimetallic nanocatalysts brought about by composition and geometric features (e.g., particle size and shape), the electronic perturbation of the catalytic sites due to electronic metalsupport interactions also has a strong influence on the inherent reactivity. [12][13][14][15][16][17][18][19][20][21][22][23] Therefore, the use of supported bimetallic nanomaterials is an interesting and important strategy for developing new catalysts with enhanced activity and selectivity. Because catalysis occurs on the surface, there are economic and fundamental incentives to produce catalysts in the form of highly dispersed supported metal nanoparticles.…”

Promotion of Pt Nanoparticles by Lattice Oxygen in SmFeO3 Perovskite Group for Carbon Monoxide and Ethylene Oxidation

“…The variation in catalytic activity when A-site is partially substituted with another cation can be related to several factors [15,[64][65][66][67]: (i) as x increases, the amount of active oxygen increases, while its specific reactivity decreases. The catalytic activity as determined by balancing these two factors becomes maximum eventually at an intermediate value of x; (ii) an increase in x causes an increase in reducibility or oxidizing power but a decrease in reoxidation ability of perovskite; (iii) an increase in oxide ion mobility with increasing x facilitates the supply of oxygen from the bulk to the surface catalytic sites, thus increasing the availability of oxygen for the catalytic oxidation of hydrocarbons as well as the number of promoter species; (iv) the electronic metasupport interaction (EMSI) [65][66][67] between Pt NPs and the redox-active metal oxide, Ce-doped perovskites in the present case. EMSI is based on the d-band center theory that correlates the chemisorption energies to the electronic properties of a metal catalyst [67].…”

“…The catalytic activity as determined by balancing these two factors becomes maximum eventually at an intermediate value of x; (ii) an increase in x causes an increase in reducibility or oxidizing power but a decrease in reoxidation ability of perovskite; (iii) an increase in oxide ion mobility with increasing x facilitates the supply of oxygen from the bulk to the surface catalytic sites, thus increasing the availability of oxygen for the catalytic oxidation of hydrocarbons as well as the number of promoter species; (iv) the electronic metasupport interaction (EMSI) [65][66][67] between Pt NPs and the redox-active metal oxide, Ce-doped perovskites in the present case. EMSI is based on the d-band center theory that correlates the chemisorption energies to the electronic properties of a metal catalyst [67]. By depositing Pt on Cedoped perovskite the d-band center in platinum shifts in such a way that optimizes adsorption of reactants and enhances oxidation reactions at lower temperatures.…”