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Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst

The direct conversion of methane to aromatics, mainly benzene without using oxygen, was studied. In prior, a comparison was conducted for the catalytic properties of W/USY, W/Al2O3, W/H , and W/HZSM-5. Among all the support used, the W/HZSM-5 catalyst showed the best activity and stability with high...

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Main Authors: Kusmiyati, Kusmiyati, Saidina Amin, Nor Aishah
Format: Conference or Workshop Item
Language:English
Published: 2005
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T Technology (General)
Online Access:http://eprints.utm.my/id/eprint/6318/1/Kusmiyati2005_DehydroaromatizationOfMethaneInTheAbsenceOfOxygenOver.pdf
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spelling my.utm.63182017-08-29T01:26:36Z http://eprints.utm.my/id/eprint/6318/ Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst Kusmiyati, Kusmiyati Saidina Amin, Nor Aishah T Technology (General) The direct conversion of methane to aromatics, mainly benzene without using oxygen, was studied. In prior, a comparison was conducted for the catalytic properties of W/USY, W/Al2O3, W/H , and W/HZSM-5. Among all the support used, the W/HZSM-5 catalyst showed the best activity and stability with highest methane conversion of 8.4%, corresponding to aromatics selectivity of 97.54% at 973 K and 1 atm. Meanwhile, almost 7% of methane was converted on the other W-supported catalysts, which were drastically deactivated. Further study was performed to investigate the role of acidity of the W/HZSM-5 catalyst. The acidic properties of the catalysts have undergone changes due to the introduction of Li ion. The catalytic properties for those catalysts with Li contents, including 3W/HZSM-5, 3W/Li-HZSM-5(10), 3W/Li-HZSM-5(12), 3W/Li-HZSM-5(46), and 3WLiZSM-5 catalysts were tested at 1073 K and 1 atm. The results demonstrated that the introduction of a certain amount of Li into the ZSM-5 catalyst influences the catalytic performance of dehydroaromatization of methane under the non-oxidative condition. Over W/HZSM-5, a maximum methane conversion achieved was 16%, but decreased considerably to 8% over 320 min. of time on stream. Furthermore, the corresponding aromatic selectivity dropped rapidly from 93% to 56%. While, over the 3W/Li-HZSM-5(10) catalyst which contains 74% of strong acid sites of the parent HZSM-5 resulted in a slight decrease in methane conversion from 18% to 12%, with corresponding to aromatics from 91% to 85%, that was observed after 320 min. of time on stream. However, in the case of more Li content was added, the activity of the catalyst decreased as shown those on the 3W/Li-HZSM-5(12), 3W/Li-HZSM-5(46), and 3W/Li-ZSM-5 catalysts. Also it was found that the catalyst performance could be improved by reducing the amount of the strong acid sites, but considerable reduction in the amount of acidic sites, particularly the Brönsted acid sites, is unfavorable for the non-oxidative methane dehydroaromatization. The 3W/Li-HZSM-5(10) catalyst is found to be suitable catalyst as it has the optimum Brönsted acid sites and consequently, gives the maximum methane conversion and selectivity to aromatics. These results suggest that Li modified W/HZSM-5 catalysts is bifunctional catalyst in which both W active sites and Brönsted acid sites of HZSM-5 support are crucial factors for good catalytic performance. 2005 Conference or Workshop Item PeerReviewed application/pdf en http://eprints.utm.my/id/eprint/6318/1/Kusmiyati2005_DehydroaromatizationOfMethaneInTheAbsenceOfOxygenOver.pdf Kusmiyati, Kusmiyati and Saidina Amin, Nor Aishah (2005) Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst. In: Annual Fundamental Science Seminar 2005, July 4-5, 2005, Ibnu Sina Institute for Fundamental Science Studies, UTM.
institution Universiti Teknologi Malaysia
building UTM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
url_provider http://eprints.utm.my/
language English
topic T Technology (General)
spellingShingle T Technology (General)
Kusmiyati, Kusmiyati
Saidina Amin, Nor Aishah
Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
description The direct conversion of methane to aromatics, mainly benzene without using oxygen, was studied. In prior, a comparison was conducted for the catalytic properties of W/USY, W/Al2O3, W/H , and W/HZSM-5. Among all the support used, the W/HZSM-5 catalyst showed the best activity and stability with highest methane conversion of 8.4%, corresponding to aromatics selectivity of 97.54% at 973 K and 1 atm. Meanwhile, almost 7% of methane was converted on the other W-supported catalysts, which were drastically deactivated. Further study was performed to investigate the role of acidity of the W/HZSM-5 catalyst. The acidic properties of the catalysts have undergone changes due to the introduction of Li ion. The catalytic properties for those catalysts with Li contents, including 3W/HZSM-5, 3W/Li-HZSM-5(10), 3W/Li-HZSM-5(12), 3W/Li-HZSM-5(46), and 3WLiZSM-5 catalysts were tested at 1073 K and 1 atm. The results demonstrated that the introduction of a certain amount of Li into the ZSM-5 catalyst influences the catalytic performance of dehydroaromatization of methane under the non-oxidative condition. Over W/HZSM-5, a maximum methane conversion achieved was 16%, but decreased considerably to 8% over 320 min. of time on stream. Furthermore, the corresponding aromatic selectivity dropped rapidly from 93% to 56%. While, over the 3W/Li-HZSM-5(10) catalyst which contains 74% of strong acid sites of the parent HZSM-5 resulted in a slight decrease in methane conversion from 18% to 12%, with corresponding to aromatics from 91% to 85%, that was observed after 320 min. of time on stream. However, in the case of more Li content was added, the activity of the catalyst decreased as shown those on the 3W/Li-HZSM-5(12), 3W/Li-HZSM-5(46), and 3W/Li-ZSM-5 catalysts. Also it was found that the catalyst performance could be improved by reducing the amount of the strong acid sites, but considerable reduction in the amount of acidic sites, particularly the Brönsted acid sites, is unfavorable for the non-oxidative methane dehydroaromatization. The 3W/Li-HZSM-5(10) catalyst is found to be suitable catalyst as it has the optimum Brönsted acid sites and consequently, gives the maximum methane conversion and selectivity to aromatics. These results suggest that Li modified W/HZSM-5 catalysts is bifunctional catalyst in which both W active sites and Brönsted acid sites of HZSM-5 support are crucial factors for good catalytic performance.
format Conference or Workshop Item
author Kusmiyati, Kusmiyati
Saidina Amin, Nor Aishah
author_facet Kusmiyati, Kusmiyati
Saidina Amin, Nor Aishah
author_sort Kusmiyati, Kusmiyati
title Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
title_short Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
title_full Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
title_fullStr Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
title_full_unstemmed Dehydroaromatization of methane in the absence of oxygen over modified W/HZSM-5 catalyst
title_sort dehydroaromatization of methane in the absence of oxygen over modified w/hzsm-5 catalyst
publishDate 2005
url http://eprints.utm.my/id/eprint/6318/1/Kusmiyati2005_DehydroaromatizationOfMethaneInTheAbsenceOfOxygenOver.pdf
http://eprints.utm.my/id/eprint/6318/
_version_ 1643644527486959616
score 13.211869

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