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Title: Silver‐Promoted Dehydroaromatization of Ethylene over ZSM‐5 Catalysts

Abstract

The shape selectivity of ZSM‐5 (MFI type) catalysts is ideal for the production of C6–C8 aromatics. Developing high‐performance zeolite catalysts with improved selectivity to aromatics, particularly from diversified (non‐petroleum) feedstocks, has broad commercial appeal. Non‐oxidative coupling (NOC) of ethylene was examined over Ag‐ZSM‐5 catalysts at 400 °C and shows that Ag+ sites promote dehydroaromatization with enhanced selectivity to toluene and xylenes. Metal exchange of H‐ZSM‐5 results in Ag zoning wherein Ag+ site density is higher on the exterior of ZSM‐5 particles. Catalyst performance was characterized with varying Ag loading as well as the use of methane co‐feed. Aromatic selectivity is about 60 % on Ag‐ZSM‐5 compared to 20 % on H‐ZSM‐5, which is qualitatively consistent with density functional theory (DFT) showing that ethylene forms strong complexes with Ag+ (Lewis acid) sites. DFT calculations also reveal that ethylene activation on H+ (Brønsted acid) sites is more energetically favorable, and likely constitutes the first mechanistic step in ethylene‐to‐liquids (ETL) reactions. Ag‐ZSM‐5 is thus identified as an effective catalyst for low‐temperature ETL reactions that has the potential to outperform conventional metal‐exchanged zeolites.

Authors:
 [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Department of Chemical and Biomolecular EngineeringUniversity of Houston Houston TX 77204 USA
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1543477
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
ChemCatChem
Additional Journal Information:
Journal Volume: 9; Journal Issue: 9; Journal ID: ISSN 1867-3880
Publisher:
ChemPubSoc Europe
Country of Publication:
United States
Language:
English
Subject:
Chemistry

Citation Formats

Hsieh, Ming‐Feng, Zhou, Yunwen, Thirumalai, Hari, Grabow, Lars C., and Rimer, Jeffrey D. Silver‐Promoted Dehydroaromatization of Ethylene over ZSM‐5 Catalysts. United States: N. p., 2017. Web. doi:10.1002/cctc.201700192.
Hsieh, Ming‐Feng, Zhou, Yunwen, Thirumalai, Hari, Grabow, Lars C., & Rimer, Jeffrey D. Silver‐Promoted Dehydroaromatization of Ethylene over ZSM‐5 Catalysts. United States. doi:10.1002/cctc.201700192.
Hsieh, Ming‐Feng, Zhou, Yunwen, Thirumalai, Hari, Grabow, Lars C., and Rimer, Jeffrey D. Fri . "Silver‐Promoted Dehydroaromatization of Ethylene over ZSM‐5 Catalysts". United States. doi:10.1002/cctc.201700192.
@article{osti_1543477,
title = {Silver‐Promoted Dehydroaromatization of Ethylene over ZSM‐5 Catalysts},
author = {Hsieh, Ming‐Feng and Zhou, Yunwen and Thirumalai, Hari and Grabow, Lars C. and Rimer, Jeffrey D.},
abstractNote = {The shape selectivity of ZSM‐5 (MFI type) catalysts is ideal for the production of C6–C8 aromatics. Developing high‐performance zeolite catalysts with improved selectivity to aromatics, particularly from diversified (non‐petroleum) feedstocks, has broad commercial appeal. Non‐oxidative coupling (NOC) of ethylene was examined over Ag‐ZSM‐5 catalysts at 400 °C and shows that Ag+ sites promote dehydroaromatization with enhanced selectivity to toluene and xylenes. Metal exchange of H‐ZSM‐5 results in Ag zoning wherein Ag+ site density is higher on the exterior of ZSM‐5 particles. Catalyst performance was characterized with varying Ag loading as well as the use of methane co‐feed. Aromatic selectivity is about 60 % on Ag‐ZSM‐5 compared to 20 % on H‐ZSM‐5, which is qualitatively consistent with density functional theory (DFT) showing that ethylene forms strong complexes with Ag+ (Lewis acid) sites. DFT calculations also reveal that ethylene activation on H+ (Brønsted acid) sites is more energetically favorable, and likely constitutes the first mechanistic step in ethylene‐to‐liquids (ETL) reactions. Ag‐ZSM‐5 is thus identified as an effective catalyst for low‐temperature ETL reactions that has the potential to outperform conventional metal‐exchanged zeolites.},
doi = {10.1002/cctc.201700192},
journal = {ChemCatChem},
issn = {1867-3880},
number = 9,
volume = 9,
place = {United States},
year = {2017},
month = {3}
}

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