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The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts

The majority of NO(x) is exhausted during the cold-start period for the low temperature of vehicle emissions, which can be solved by using Pd/zeolite catalysts to trap NO(x) at low temperature and release NO(x) at a high temperature that must be higher than the operating temperature of selective cat...

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Autores principales: Jiang, Ming, Wang, Jun, Wang, Jianqiang, Shen, Meiqing
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479726/
https://www.ncbi.nlm.nih.gov/pubmed/30934944
http://dx.doi.org/10.3390/ma12071045
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author Jiang, Ming
Wang, Jun
Wang, Jianqiang
Shen, Meiqing
author_facet Jiang, Ming
Wang, Jun
Wang, Jianqiang
Shen, Meiqing
author_sort Jiang, Ming
collection PubMed
description The majority of NO(x) is exhausted during the cold-start period for the low temperature of vehicle emissions, which can be solved by using Pd/zeolite catalysts to trap NO(x) at low temperature and release NO(x) at a high temperature that must be higher than the operating temperature of selective catalytic reduction catalysts (SCR). In this work, several Pd/Beta catalysts were prepared to identify the influence of Si/Al ratios on NO and C(3)H(6) adsorption and desorption characterizations. The physicochemical properties were identified using N(2) physical adsorption, Fourier Transform Infrared Spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS), and Na(+) titration, while the adsorption and desorption characterizations were investigated by catalyst evaluation. The results indicated that the amount of dispersed Pd ions, the main active sites for NO and C(3)H(6) adsorption, decreased with the increase of Si/Al ratios. Besides this, the intensity of Brønsted and Lewis acid decreased with the increase of Si/Al ratios, which also led to the decrease of NO and C(3)H(6) adsorption amounts. Therefore, Pd dispersion and the acidic properties of Pd/Beta together determined the adsorption ability of NO and C(3)H(6). Moreover, lower Si/Al ratios resulted in the formation of an additional dispersed Pd cationic species, Pd(OH)(+), from which adsorbed NO released at a much lower temperature. Finally, an optimum Si/Al ratio of Pd/Beta was found at around 55 due to the balanced performance between the adsorption amounts and desorption temperature.
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spelling pubmed-64797262019-04-29 The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts Jiang, Ming Wang, Jun Wang, Jianqiang Shen, Meiqing Materials (Basel) Article The majority of NO(x) is exhausted during the cold-start period for the low temperature of vehicle emissions, which can be solved by using Pd/zeolite catalysts to trap NO(x) at low temperature and release NO(x) at a high temperature that must be higher than the operating temperature of selective catalytic reduction catalysts (SCR). In this work, several Pd/Beta catalysts were prepared to identify the influence of Si/Al ratios on NO and C(3)H(6) adsorption and desorption characterizations. The physicochemical properties were identified using N(2) physical adsorption, Fourier Transform Infrared Spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS), and Na(+) titration, while the adsorption and desorption characterizations were investigated by catalyst evaluation. The results indicated that the amount of dispersed Pd ions, the main active sites for NO and C(3)H(6) adsorption, decreased with the increase of Si/Al ratios. Besides this, the intensity of Brønsted and Lewis acid decreased with the increase of Si/Al ratios, which also led to the decrease of NO and C(3)H(6) adsorption amounts. Therefore, Pd dispersion and the acidic properties of Pd/Beta together determined the adsorption ability of NO and C(3)H(6). Moreover, lower Si/Al ratios resulted in the formation of an additional dispersed Pd cationic species, Pd(OH)(+), from which adsorbed NO released at a much lower temperature. Finally, an optimum Si/Al ratio of Pd/Beta was found at around 55 due to the balanced performance between the adsorption amounts and desorption temperature. MDPI 2019-03-29 /pmc/articles/PMC6479726/ /pubmed/30934944 http://dx.doi.org/10.3390/ma12071045 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Jiang, Ming
Wang, Jun
Wang, Jianqiang
Shen, Meiqing
The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title_full The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title_fullStr The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title_full_unstemmed The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title_short The Influence of Si/Al Ratios on Adsorption and Desorption Characterizations of Pd/Beta Served as Cold-Start Catalysts
title_sort influence of si/al ratios on adsorption and desorption characterizations of pd/beta served as cold-start catalysts
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479726/
https://www.ncbi.nlm.nih.gov/pubmed/30934944
http://dx.doi.org/10.3390/ma12071045
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