Improved Thermal Stability and Methane-Oxidation Activity of Pd/Al2O3 Catalysts by Atomic Layer Deposition of ZrO2

Onn, Tzia Ming; Zhang, Shuyi; Arroyo‐Ramírez, Lisandra; Chung, Yu-Chieh; Graham, George W.; Pan, Xiaoqing; Gorte, Raymond J.

doi:10.1021/acscatal.5b01348

Cited by 127 publications

(92 citation statements)

References 28 publications

(63 reference statements)

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“…The deposition of 20 ALD cycles of either CeO 2 or ZrO 2 , with calcination at 773 K, did not change the patterns. While peaks associated with crystalline CeO 2 would be difficult to distinguish from the mixture of tetragonal and monoclinic ZrO 2 , previous work has shown that ALD films this thin (the film on the 20 CeO 2 /ZrO 2 sample is only 0.33 nm thick) are invisible to XRD [20]. The effects of calcining the same three samples to 1073 K is shown in Figure 2b.…”

Section: Resultsmentioning

confidence: 90%

Stabilization of ZrO2 Powders via ALD of CeO2 and ZrO2

et al. 2017

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ZrO 2 powders were modified by atomic layer deposition (ALD) with CeO 2 and ZrO 2 , using Ce(TMHD) 4 and Zr(TMHD) 4 as the precursors, in order to determine the effect of ALD films on the structure, surface area, and catalytic properties of the ZrO 2 . Growth rates were measured gravimetrically and found to be 0.017 nm/cycle for CeO 2 and 0.031 nm/cycle for ZrO 2 . The addition of 20 ALD cycles of either CeO 2 or ZrO 2 was found to stabilize the surface area of the ZrO 2 powder following calcination to 1073 K and to suppress the tetragonal-to-monoclinic transition. Shrinkage of ZrO 2 wafers was also suppressed by the ALD films. When used as a support for Pd in CO oxidation, the CeO 2 -modified materials significantly enhanced rates due to interactions between the Pd and the CeO 2 . Potential applications for modifying catalyst supports using ALD are discussed.

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Section: Resultsmentioning

confidence: 90%

Stabilization of ZrO2 Powders via ALD of CeO2 and ZrO2

et al. 2017

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“…The term "static" is used here to refer to the sample inside the reactor being exposed to non-flowing (i.e., static) precursors. The reactor itself can be rotating, or the particles inside the reactor can be agitated in various other ways [44,66,67], although simple static reactors without any moving parts have successfully been used to coat catalysts and SOFC electrodes [68][69][70][71][72][73][74][75]. In a static reactor, the sample is held in a sealed vessel that can be evacuated.…”

Section: Ald Reactor Designs For Catalysts and Sofc Electrodesmentioning

confidence: 99%

“…However, since only a few ALD cycles are required to reach substantial weight loadings (see Section 1.4), long exposure and purge times (on the order of 10's of minutes or perhaps even hours) may be acceptable, as demonstrated by the fixed bed static reactor design developed by researchers at BASF [56]. It should be noted that exposure times can be shortened by using agitated or rotating bed reactors [44,66,67], using thin pelletized samples (Figure 3) [70][71][72][73], and increasing precursor partial pressures [56,57].…”

Section: Ald Reactor Designs For Catalysts and Sofc Electrodesmentioning

confidence: 99%

“…Large pores may imply only a partial coverage of the metal particles. This fact is particularly important when the material is subjected to calcination treatments [70], which are therefore a useful tool to further modify the overcoat textural properties, allowing a fine-tuning of the catalytic features. Indeed, it has been reported that calcination is fruitful for producing an increase of activity of the catalyst in some cases, with the metal being accessible, while still protected [91].…”

Section: Coated Surfaces For Enhanced Stabilitymentioning

confidence: 99%

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Atomic Layer Deposition on Porous Materials: Problems with Conventional Approaches to Catalyst and Fuel Cell Electrode Preparation

et al. 2018

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Atomic layer deposition (ALD) offers exciting possibilities for controlling the structure and composition of surfaces on the atomic scale in heterogeneous catalysts and solid oxide fuel cell (SOFC) electrodes. However, while ALD procedures and equipment are well developed for applications involving flat surfaces, the conditions required for ALD in porous materials with a large surface area need to be very different. The materials (e.g., rare earths and other functional oxides) that are of interest for catalytic applications will also be different. For flat surfaces, rapid cycling, enabled by high carrier-gas flow rates, is necessary in order to rapidly grow thicker films. By contrast, ALD films in porous materials rarely need to be more than 1 nm thick. The elimination of diffusion gradients, efficient use of precursors, and ligand removal with less reactive precursors are the major factors that need to be controlled. In this review, criteria will be outlined for the successful use of ALD in porous materials. Examples of opportunities for using ALD to modify heterogeneous catalysts and SOFC electrodes will be given.

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“…However, the catalytic activity is not stable when directly used in the reactions. Therefore, impregnation and embedding of the Pd-based catalysts in metal oxide support are required to increase the activity and stability of the active Pd-based catalysts [10,27]. Herein, an attempt to investigate the influences of different precursors used for preparation of ceria materials by thermal decomposition of metal complexes on the function as the catalytic support materials has been accomplished.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

Wattanathana

Wannapaiboon

Veranitisagul

et al. 2017

Advances in Materials Science and Engineering

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Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO 2 ) powders were synthesized by thermal decomposition of cerium(III) complexes prepared by using cerium(III) nitrate or cerium(III) chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II) nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H 2 in He stream at 700 ∘ C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III)-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pd + ( > 2) species than the materials prepared from cerium(III)-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

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Improved Thermal Stability and Methane-Oxidation Activity of Pd/Al₂O₃ Catalysts by Atomic Layer Deposition of ZrO₂

Cited by 127 publications

References 28 publications

Stabilization of ZrO2 Powders via ALD of CeO2 and ZrO2

Stabilization of ZrO2 Powders via ALD of CeO2 and ZrO2

Atomic Layer Deposition on Porous Materials: Problems with Conventional Approaches to Catalyst and Fuel Cell Electrode Preparation

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

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