Supported metal nanoparticle catalysts have become increasingly crucial for many catalytic applications. However, long‐term catalyst stability remains a problem due to catalyst deactivation caused by coke formation and sintering. The deposition of a thin overcoating via atomic layer deposition (ALD) onto metal‐supported nanoparticles has shown to greatly inhibit catalyst deactivation. This work utilizes a model catalyst system comprised of Pt nanoparticles supported on Al2O3to demonstrate the effect of an atomically thin overcoating on supported metal nanoparticles. Continuous operando small‐angle X‐ray scattering (SAXS) and X‐ray absorption near edge spectroscopy (XANES) monitor structural and electronic changes to the catalyst and overcoating during calcination. SAXS data fitting reveals the formation of nanopores in the overcoating at high temperatures, while XANES monitors the oxidation state of the Pt catalyst. Herein, the usefulness of combined X‐ray techniques is demonstrated to characterize supported metal catalysts to further understanding of the synergistic effects of the ALD overcoating to aid in the design of new catalyst materials.
An ultra-thin overcoating of zirconium oxide (ZrO2) film on CuO-ZnO-Al2O3(CZA) catalysts by atomic layer deposition (ALD) was proved to enhance the catalytic performance of CZA/HZSM-5 (H form of Zeolite Socony Mobil-5) bifunctional catalysts for hydrogenation of CO2to dimethyl ether (DME). Under optimal reaction conditions (i.e. 240 °C and 2.8 MPa), the yield of product DME increased from 17.22% for the bare CZA/HZSM-5 catalysts, to 18.40% for the CZA catalyst after 5 cycles of ZrO2ALD with HZSM-5 catalyst. All the catalysts modified by ZrO2ALD displayed significantly improved catalytic stability of hydrogenation of CO2to DME reaction, compared to that of CZA/HZSM-5 bifunctional catalysts. The loss of DME yield in 100 h of reaction was greatly mitigated from 6.20% (loss of absolute value) to 3.01% for the CZA catalyst with 20 cycles of ZrO2ALD overcoating. Characterizations including hydrogen temperature programmed reduction, x-ray powder diffraction, and x-ray photoelectron spectroscopy revealed that there was strong interaction between Cu active centers and ZrO2.
more » « less- Award ID(s):
- 2306177
- PAR ID:
- 10402412
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Nanotechnology
- Volume:
- 34
- Issue:
- 23
- ISSN:
- 0957-4484
- Page Range / eLocation ID:
- Article No. 235401
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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