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Reduction behavior of PdO-NiO/SiO2: how Pd location affects cinnamaldehyde hydrogenation
Rim C J van de Poll1, Heiner Friedrich2, Emiel J M Hensen1
1Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology Eindhoven The Netherlands e.j.m.hensen@tue.nl.
Catalysis Science & Technology
|January 6, 2025
Summary
Palladium oxide (PdO) on nickel oxide (NiO) catalysts show enhanced activity in cinnamaldehyde hydrogenation due to improved palladium dispersion at lower reduction temperatures compared to PdO on silica (SiO2).
Area of Science:
- Catalysis
- Materials Science
- Surface Chemistry
Background:
- Investigating the reducibility and catalytic performance of palladium-based catalysts is crucial for various chemical transformations.
- Nickel oxide (NiO) and silica (SiO2) are common supports for metal catalysts, influencing their properties and reactivity.
- Strong electrostatic adsorption and incipient wetness impregnation are methods used to prepare supported metal catalysts.
Purpose of the Study:
- To compare the reducibility and catalytic activity of palladium oxide (PdO) precursors supported on NiO versus SiO2.
- To understand the effect of support material (NiO vs. SiO2) and reduction temperature on palladium dispersion and hydrogenation performance.
- To evaluate the catalysts in the hydrogenation of cinnamaldehyde.
Main Methods:
- Preparation of NiO/SiO2 catalysts using incipient wetness impregnation.
- Strong electrostatic adsorption of PdO precursor onto NiO and SiO2 supports.
- Characterization using High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM), quasi-in situ X-ray Photoelectron Spectroscopy (XPS), CO Infrared (IR) spectroscopy, and H2 chemisorption.
- Evaluation of catalytic performance in cinnamaldehyde hydrogenation at varying reduction temperatures.
Main Results:
- PdO supported on SiO2 required higher reduction temperatures to achieve significant cinnamaldehyde hydrogenation rates.
- PdO supported on NiO particles dispersed on SiO2 could be reduced at room temperature.
- The NiO-supported palladium catalyst exhibited higher activity in cinnamaldehyde hydrogenation, attributed to better palladium dispersion at lower reduction temperatures.
Conclusions:
- The presence of NiO as a support enhances the reducibility of PdO precursors at lower temperatures.
- Lower reduction temperatures lead to higher palladium dispersion on NiO/SiO2 catalysts, boosting catalytic activity.
- This study highlights the importance of support-metal interactions in designing efficient hydrogenation catalysts.
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