Promotion of yttrium (Y) on the water resistance and hydrothermal stability of Pd/ZrO2 catalyst coated on the monolith for complete methane oxidation

Wu, Yang; Chen, Jianjun; Qu, Pengfei; Hu, Wei; Shen, Puqing; Zhang, Guochen; Jiao, Yi; Zhong, Lin; Chen, Yaoqiang

doi:10.1016/j.jtice.2019.07.002

Cited by 14 publications

(3 citation statements)

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“…Pd-based catalysts are still the most effective solution to remove CH 4 from NGVs exhaust up to now, and even pure palladium TWCs are the direction of future efforts. Al 2 O 3 is the most commonly used support for supported Pd catalysts; however, they are prone to severe deactivation in the presence of water vapor. , In order to overcome H 2 O-induced deactivation and make up other defects, metal oxide support materials with high oxygen mobility, such as CeO 2 and ZrO 2 , have been widely studied and gradually become one of the main components of automotive catalysts. − In addition, based on the consideration of making full use of the synergistic effect of various elements to design the high-performance catalysts, the CeO 2 –ZrO 2 –Al 2 O 3 (CZA) composite with excellent oxygen storage capacity, marvelous thermal stability, and surprising low-temperature light-off activity is gradually replacing Al 2 O 3 , CeO 2 or ZrO 2 and playing an important role in commercial stoichiometric NGVs catalysts. − Nevertheless, the three-way catalytic performance of the Pd/CeO 2 –ZrO 2 –Al 2 O 3 (Pd/CZA) catalyst still has room for further improvement.…”

Section: Introductionmentioning

confidence: 99%

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Guo,

Li,

Zhang

et al. 2024

J. Phys. Chem. C

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The combined route of stoichiometric combustion + three-way catalysis (TWC) is an era choice for natural gas vehicles (NGVs) to actively respond to the environmental protection requirements of gradual pressurization. However, synergistic and efficient purification of exhaust gas in a humid atmosphere is still one of the key challenges. The catalytic performance of phosphorus-doped and phosphorus-free CeO2–ZrO2–Al2O3 (CZA)-supported Pd-based model catalysts for CH4, NO, and CO was evaluated in a practical operating environment close to stoichiometric combustion. Phosphorus doping induces the formation of abundant surface lattice oxygen, promotes the active migration of interface charges, and improves the catalytic activity of the Pd/CeO2–ZrO2–P2O5–Al2O3 (Pd/CZPA) catalyst for CH4 and NO conversion. However, the catalytic oxidation of CO strongly depends on the dispersion of Pd nanoparticles, regardless of whether phosphorus is added or not. This research provides a useful guidance for the development of new pure palladium TWC for NGVs, regional environmental governance, as well as re-examining the value of phosphorus.

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Section: Introductionmentioning

confidence: 99%

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Guo,

Li,

Zhang

et al. 2024

J. Phys. Chem. C

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“…Pd/ZrO 2 catalyst has higher catalytic activity and stability than Pd/Al 2 O 3 and Pd/CeO 2 catalysts under wet conditions. − The stability of Pd/ZrO 2 catalyst was further enhanced by using yttria-stabilized zirconia (Y 2 O 3 –ZrO 2 ) to replace ZrO 2 support. − Y 2 O 3 –ZrO 2 as the support of noble metal catalysts has been widely used due to rich oxygen vacancies. , Metal–support interaction relates to Y 2 O 3 –ZrO 2 oxygen vacancies. − Oxygen vacancies can also adsorb and dissociate water molecules to form hydroxyls. , Pd/Y 2 O 3 –ZrO 2 catalysts cannot efficiently convert methane at about 400 °C in the presence of about 10 vol % water vapor. Pd/Y 2 O 3 –ZrO 2 catalyst activity under wet conditions is hopefully improved by inert species partially covering the Y 2 O 3 –ZrO 2 surface to tune palladium-support interaction and decrease water dissociation sites.…”

Section: Introductionmentioning

confidence: 99%

Boosting Methane Combustion over Pd/Y₂O₃–ZrO₂ Catalyst by Inert Silicate Patches Tuning Both Palladium Chemistry and Support Hydrophobicity

Wu,

Yang,

Zhang

et al. 2023

ACS Appl. Mater. Interfaces

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Supported palladium (Pd) catalysts are widely utilized to reduce the emission of exhaust CH 4 from lean-burn engines by catalytic combustion. A large amount of water vapor in the exhaust makes hydroxyls accumulate on the catalyst surface at temperatures below 450 °C, leading to severe catalyst deactivation. Tuning palladium chemistry and inhibiting water adsorption are critical to developing active catalysts. Modifying the support surface with inert silicates would both change the palladium−support interaction and decrease water adsorption sites. This study reports an improved Pd/Y 2 O 3 −ZrO 2 catalyst by constructing silicate patches on yttria-stabilized zirconia (Y 2 O 3 −ZrO 2 ) support. The silicates hindered electron transfer from Y 2 O 3 −ZrO 2 oxygen vacancies to palladium, which optimized palladium chemistry, especially the reducibility of active PdO species, and thereby boosted CH 4 conversion under dry conditions. The temperature of 90% methane conversion (T 90 ) over the catalyst decreased from 386 to 309 °C. Moreover, the inert silicates decreased surface oxygen vacancies of Y 2 O 3 −ZrO 2 to improve support hydrophobicity, thereby inhibiting hydroxyl accumulation. The poisoning effect of water on the active sites located on the palladium-silicate interface was alleviated. When reaction gases contained 10 vol % water, the silicate-modified catalyst still showed higher activity with T 90 of 404 °C, which is lower than T 90 of 452 °C for unmodified catalyst. This work represents a step forward in preparing high-performance palladium catalysts for low-temperature wet methane combustion.

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“…For example, Pt sintering could be suppressed by loading Pt particles onto CeO 2 [2] or MgO [3]. Pd sintering was suppressed by loading Pd onto CeO 2 [4] or YSZ (Y-doped ZrO 2 ) [5]. Rh sintering was also suppressed by loading Rh onto Nd-doped La-ZrO 2 [6].…”

Section: Introductionmentioning

confidence: 99%

In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures

Nakayama

Nagata²,

Abe

et al. 2020

Catalysts

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One of the main factors in the deterioration of automobile three-way catalysts is the sintering of platinum group metals (PGMs). In this study, we used in situ tunneling electron microscopy (TEM) to examine the sintering of Rh particles as the temperature increases. Two types of environmental conditions were tested, namely, vacuum atmosphere with heating up to 1050 °C, and N2 with/without 1% O2 at 1 atm and up to 1000 °C. Under vacuum, Rh particles appeared to be immersed in ZrO2. In contrast, at 1 atm N2 with or without 1% O2, the sintered Rh particles appeared spherical and not immersed in ZrO2. The latter trend of Rh sintering resembles the actual engine-aged catalyst observed ex situ in this study. In the N2 atmosphere, the sintering of support material (ZrO2 or Y-ZrO2) was first observed by in situ TEM, followed by Rh particle sintering. The Rh particle size was slightly smaller on Y-ZrO2 compared to that on ZrO2. To better understand these experimental results, density functional theory was used to calculate the systems’ junction energies, assuming three layers of Rh(111) 4 × 4 structures joined to the support material (ZrO2 and Y-ZrO2). The calculated energies were consistent with the in situ TEM observations in the N2 atmosphere.

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Promotion of yttrium (Y) on the water resistance and hydrothermal stability of Pd/ZrO2 catalyst coated on the monolith for complete methane oxidation

Cited by 14 publications

References 55 publications

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Boosting Methane Combustion over Pd/Y₂O₃–ZrO₂ Catalyst by Inert Silicate Patches Tuning Both Palladium Chemistry and Support Hydrophobicity

In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures

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Promotion of yttrium (Y) on the water resistance and hydrothermal stability of Pd/ZrO2 catalyst coated on the monolith for complete methane oxidation

Cited by 14 publications

References 55 publications

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Comparative Investigation of Three-Way Conversion over Palladium-Based Catalysts Supported on Phosphorus-Doped and Phosphorus-Free Ceria–Zirconia–Alumina

Boosting Methane Combustion over Pd/Y2O3–ZrO2 Catalyst by Inert Silicate Patches Tuning Both Palladium Chemistry and Support Hydrophobicity

In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures

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Boosting Methane Combustion over Pd/Y₂O₃–ZrO₂ Catalyst by Inert Silicate Patches Tuning Both Palladium Chemistry and Support Hydrophobicity