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Title: Microwave-Assisted Conversion of Low Rank Coal under Methane Environment

Abstract

Addition of methane during microwave coal pyrolysis could greatly affect the product distribution to valuable products including the formation of char. Here in this work, low rank coal was exposed to microwave energy in the presence of different methane concentrations (0, 25, 50, and 90%) at 980 °C for 2 h. Increasing methane concentration was found to increase both the char and tar yields mainly due to carbon deposition during methane decomposition and hydrogenation of trapped carbon into tars. Analysis of the gas composition suggested that some of the methane was activated in the presence of the coal minerals, which could act as a catalyst, forming light hydrocarbons C 2–C 7 which account for up to 5% of the gaseous products at a methane concentration of 90%; they accounted for less than 0.5% in the absence of methane. Methyl groups may also have been substituted into aromatic compounds as observed in the tar analysis where the number of methyl substitutions in the detected parent phenol and naphthalene increased with methane concentration. Tar yield could also increase indirectly with methane addition through hydrogenation reactions with unsaturated coal compounds. The formation of char under different methane concentrations was examined by many characterizationmore » tools including Raman, dielectric properties, XRD, BET, SEM, and EDS. The results suggest that the addition of methane did not help in forming ordered carbon chars, not only due to amorphous carbon deposition on the char surface but also due to hydrogenation or alkylation reactions with char. The presence of methane enhanced the formation of C 2s and benzene; a possible correlation between the formation rate of benzene and hydrogen during pyrolysis is proposed.« less

Authors:
ORCiD logo [1];  [2];  [2];  [1]
  1. National Energy Technology Lab. (NETL), Morgantown, WV (United States); AECOM, Morgantown, WV (United States)
  2. National Energy Technology Lab. (NETL), Morgantown, WV (United States)
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1532658
Grant/Contract Number:  
FE0004000
Resource Type:
Accepted Manuscript
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Volume: 33; Journal Issue: 2; Journal ID: ISSN 0887-0624
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; Microwave pyrolysis; Methane addition; Dehydroaromatization; Tar yield; Char properties; Low rank coal

Citation Formats

Abdelsayed, Victor, Shekhawat, Dushyant, Smith, Mark, and Hammache, Sonia. Microwave-Assisted Conversion of Low Rank Coal under Methane Environment. United States: N. p., 2019. Web. doi:10.1021/acs.energyfuels.8b03805.
Abdelsayed, Victor, Shekhawat, Dushyant, Smith, Mark, & Hammache, Sonia. Microwave-Assisted Conversion of Low Rank Coal under Methane Environment. United States. doi:10.1021/acs.energyfuels.8b03805.
Abdelsayed, Victor, Shekhawat, Dushyant, Smith, Mark, and Hammache, Sonia. Wed . "Microwave-Assisted Conversion of Low Rank Coal under Methane Environment". United States. doi:10.1021/acs.energyfuels.8b03805.
@article{osti_1532658,
title = {Microwave-Assisted Conversion of Low Rank Coal under Methane Environment},
author = {Abdelsayed, Victor and Shekhawat, Dushyant and Smith, Mark and Hammache, Sonia},
abstractNote = {Addition of methane during microwave coal pyrolysis could greatly affect the product distribution to valuable products including the formation of char. Here in this work, low rank coal was exposed to microwave energy in the presence of different methane concentrations (0, 25, 50, and 90%) at 980 °C for 2 h. Increasing methane concentration was found to increase both the char and tar yields mainly due to carbon deposition during methane decomposition and hydrogenation of trapped carbon into tars. Analysis of the gas composition suggested that some of the methane was activated in the presence of the coal minerals, which could act as a catalyst, forming light hydrocarbons C2–C7 which account for up to 5% of the gaseous products at a methane concentration of 90%; they accounted for less than 0.5% in the absence of methane. Methyl groups may also have been substituted into aromatic compounds as observed in the tar analysis where the number of methyl substitutions in the detected parent phenol and naphthalene increased with methane concentration. Tar yield could also increase indirectly with methane addition through hydrogenation reactions with unsaturated coal compounds. The formation of char under different methane concentrations was examined by many characterization tools including Raman, dielectric properties, XRD, BET, SEM, and EDS. The results suggest that the addition of methane did not help in forming ordered carbon chars, not only due to amorphous carbon deposition on the char surface but also due to hydrogenation or alkylation reactions with char. The presence of methane enhanced the formation of C2s and benzene; a possible correlation between the formation rate of benzene and hydrogen during pyrolysis is proposed.},
doi = {10.1021/acs.energyfuels.8b03805},
journal = {Energy and Fuels},
number = 2,
volume = 33,
place = {United States},
year = {2019},
month = {1}
}

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This content will become publicly available on January 9, 2020
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