Application progress of small-pore zeolites in purifying NOx from motor vehicle exhaust

Cheng, Haodan; Tang, Xiaolong; Yi, Honghong; Pan, Rouxing; Zhang, Jie; Gao, Feifei; Yu, Qingjun

doi:10.1016/j.cej.2022.137795

Cited by 26 publications

(5 citation statements)

References 58 publications

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“…The treatment of NO x at low exhaust temperatures is challenging due to the limited effectiveness and poor denitrification efficiency of selective catalytic reduction (SCR) catalysts under these conditions. − Passive NO x adsorption, efficiently adsorbing and desorbing NO x at low and high temperatures, respectively, is increasingly viewed as a promising approach to tackle NO x emissions during low-temperature cold start-ups. Currently, PNA materials are considered to be the most promising technology for addressing NO x emissions during low-temperature cold start-ups. ,− Pd-modified zeolite PNA materials are attracting increasing attention because of their excellent NO x storage capacity, resistance to poisoning, and hydrothermal stability and have become some of the most promising PNA candidates. ,, Despite many advantages of Pd/zeolite PNA materials, their NO x adsorption capacity still cannot meet practical needs; therefore, further improvement of catalyst adsorption performance is required. Zheng and Konstantin et al demonstrated that atomically dispersed Pd primarily acts as the active adsorption site at the cation sites of zeolites, while PdO 2 and PdO particles are distributed on the zeolite’s outer surface.…”

Section: Introductionmentioning

confidence: 99%

“… 6 , 13 − 15 Pd-modified zeolite PNA materials are attracting increasing attention because of their excellent NO x storage capacity, resistance to poisoning, and hydrothermal stability and have become some of the most promising PNA candidates. 14 , 16 , 17 Despite many advantages of Pd/zeolite PNA materials, their NO x adsorption capacity still cannot meet practical needs; therefore, further improvement of catalyst adsorption performance is required. Zheng 18 and Konstantin et al 19 demonstrated that atomically dispersed Pd primarily acts as the active adsorption site at the cation sites of zeolites, while PdO 2 and PdO particles are distributed on the zeolite’s outer surface.…”

Section: Introductionmentioning

confidence: 99%

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Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Liu,

Li,

Shao

et al. 2024

ACS Omega

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Passive NO x adsorber (PNA) materials are primarily considered for reducing nitrogen oxide emissions during the low-temperature cold start of a motor vehicle. Pd/SSZ-13 has attracted considerable attention because of its outstanding hydrothermal stability and sulfur resistance. Optimizing the dispersion of precious metal Pd in Pd/SSZ-13 is crucial for enhancing PNA performance and nitrogen oxide adsorption capability. In this study, we prepared Pd/SSZ-13 using different methods and evaluated their influence on the NO x adsorption capability. The characterization results show that the dispersion of precious metal Pd in the Pd/SSZ-13 catalyst prepared by the quantitative ionexchange method is as high as 92.13%, and the loading amount is as high as 98.93%. Pd predominantly exists as Pd 2+ , achieving near-total loading and further improving the catalyst's NO x adsorption capacity. This study offers innovative approaches and methods for applying Pd/SSZ-13 as a PNA material, serving as a reference for its further optimization and performance enhancement. Continued research into the preparation and adsorption performance of Pd/SSZ-13 materials could offer solutions to reduce motor vehicle nitrogen oxide emissions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Liu,

Li,

Shao

et al. 2024

ACS Omega

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“…It should be mentioned that the temperature necessary for thermal treatment is usually very high [12]. For instance, loading the Pd onto SSZ-13 requires hydrothermal treatment at 750 • C to increase the dispersion of the Pd 2+ for the NO capture [13,14]. After H 2 purging at 300 • C, the Pt can be dispersed in zeolite in the form of the Pt 0 active species for the catalytic oxidation of the VOCs [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Application of Unconventional External-Field Treatments in Air Pollutants Removal over Zeolite-Based Adsorbents/Catalysts

Cheng,

Ren,

Yao

et al. 2023

Catalysts

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Zeolite-based materials are widely used as adsorbents and catalysts for purifying air pollutants like NOx and VOCs due to abundant pore structure, regular pore distribution, and numerous ion exchange sites. Thermal treatment is a necessary procedure for both removing impurities in pores and promoting the metal active dispersed evenly before the zeolite-based adsorbents/catalysts were applied for purifying the NOx/VOCs. Nevertheless, the conventional thermal field treatment (i.e., high-temperature calcination, high-temperature purging, etc.) takes large energy consumption. In contrast, unconventional external-field treatments such as non-thermal plasma and microwave show significant advantages of high efficiency, low energy consumption as well and low pollution, which were used to substitute the traditional thermal treatment in many fields. In this paper, the roles of non-thermal plasma or microwave in the adsorption/catalysis of the NOx/VOCs are reviewed from three aspects assisting activation of materials, cooperative catalysis process, and assisting zeolites synthesis. The reasons for unconventional treatments in improving textural properties, active sites, performance, etc. of zeolite-based materials were illuminated in detail. Moreover, the influences of various parameters (i.e., power, time, temperature, etc.) on the above aspects are elaborated. It is hoped that this review could provide some advanced guidance for the researchers to develop highly efficient materials.

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“…The increasingly stringent regulations on diesel vehicles pose higher requests for after-treatment systems. , In recent decades, many efforts have been devoted to alleviating nitrogen oxides (NO x ) emitted from lean-burn engines. , The selective catalytic reduction with ammonia (NH 3 -SCR) has been proven to be efficient for reducing the NO x emissions from diesel vehicles at temperatures above 200 °C. , As for the NO x emissions during the cold start (<200 °C), passive NO x adsorber (PNA) is proposed as a promising technology for the abatement of NO x at temperatures below 200 °C. − …”

Section: Introductionmentioning

confidence: 99%

Na Cocations and Hydrothermal Aging Cooperatively Boost the Regeneration of Phosphorus-Poisoned Pd/SSZ-13 for Passive NO_x Adsorption

Li,

Ding,

Hao

et al. 2023

Environ. Sci. Technol.

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Pd/SSZ-13 has been proposed as a passive NO x adsorber (PNA) for low-temperature NO x adsorption. However, it remains challenging for Pd/SSZ-13 to work efficiently when suffering from phosphorus poisoning. Herein, we report a simple and efficient strategy to regenerate the phosphorus-poisoned Pd/SSZ-13 based on the cooperation between hydrothermal aging treatment and Na cocations. It was found that hydrothermal aging treatment enabled the redispersion of Pd and P-containing species in phosphorus-poisoned Pd/SSZ-13. Meanwhile, the presence of Na cocations significantly reduced the formation of AlPO4 and retained more paired Al sites for highly dispersed Pd2+ ions, which was of great importance for the recovery of adsorption performance. To our satisfaction, the restoration ratio of the adsorption capacity of poisoned Pd/SSZ-13 was >90% after regeneration. Strikingly, the NO x adsorption activities of phosphorus-poisoned Pd/SSZ-13 with phosphorus loadings of 0.2 and 0.4 mmol g–1 almost completely recovered upon regeneration. This study demonstrates the promoting effect of Na cocations on the regeneration of phosphorus-poisoned Pd/SSZ-13 by hydrothermal aging treatment, which provides useful guidance for the design of PNA materials with excellent durability for cold-start application.

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Application progress of small-pore zeolites in purifying NOx from motor vehicle exhaust

Cited by 26 publications

References 58 publications

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Application of Unconventional External-Field Treatments in Air Pollutants Removal over Zeolite-Based Adsorbents/Catalysts

Na Cocations and Hydrothermal Aging Cooperatively Boost the Regeneration of Phosphorus-Poisoned Pd/SSZ-13 for Passive NO_x Adsorption

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Application progress of small-pore zeolites in purifying NOx from motor vehicle exhaust

Cited by 26 publications

References 58 publications

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber

Application of Unconventional External-Field Treatments in Air Pollutants Removal over Zeolite-Based Adsorbents/Catalysts

Na Cocations and Hydrothermal Aging Cooperatively Boost the Regeneration of Phosphorus-Poisoned Pd/SSZ-13 for Passive NOx Adsorption

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Na Cocations and Hydrothermal Aging Cooperatively Boost the Regeneration of Phosphorus-Poisoned Pd/SSZ-13 for Passive NO_x Adsorption