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Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation

Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron...

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Autores principales: Liu, Zhen, Zhang, Zhongdong, Xing, Wei, Komarneni, Sridhar, Yan, Zifeng, Gao, Xionghou, Zhou, Xiaoping
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4199779/
https://www.ncbi.nlm.nih.gov/pubmed/25328502
http://dx.doi.org/10.1186/1556-276X-9-550
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author Liu, Zhen
Zhang, Zhongdong
Xing, Wei
Komarneni, Sridhar
Yan, Zifeng
Gao, Xionghou
Zhou, Xiaoping
author_facet Liu, Zhen
Zhang, Zhongdong
Xing, Wei
Komarneni, Sridhar
Yan, Zifeng
Gao, Xionghou
Zhou, Xiaoping
author_sort Liu, Zhen
collection PubMed
description Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH(3)-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)(+) or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400 h on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Brønsted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage.
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spelling pubmed-41997792014-10-17 Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation Liu, Zhen Zhang, Zhongdong Xing, Wei Komarneni, Sridhar Yan, Zifeng Gao, Xionghou Zhou, Xiaoping Nanoscale Res Lett Nano Express Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH(3)-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)(+) or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400 h on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Brønsted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage. Springer 2014-10-03 /pmc/articles/PMC4199779/ /pubmed/25328502 http://dx.doi.org/10.1186/1556-276X-9-550 Text en Copyright © 2014 Liu et al.; licensee Springer. http://creativecommons.org/licenses/by/4.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
spellingShingle Nano Express
Liu, Zhen
Zhang, Zhongdong
Xing, Wei
Komarneni, Sridhar
Yan, Zifeng
Gao, Xionghou
Zhou, Xiaoping
Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title_full Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title_fullStr Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title_full_unstemmed Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title_short Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation
title_sort tailoring acidity of hzsm-5 nanoparticles for methyl bromide dehydrobromination by al and mg incorporation
topic Nano Express
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4199779/
https://www.ncbi.nlm.nih.gov/pubmed/25328502
http://dx.doi.org/10.1186/1556-276X-9-550
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