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Title: Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites

Abstract

The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 degrees C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, which might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ringmore » formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1437562
Report Number(s):
NREL/JA-5100-71537
Journal ID: ISSN 0926-3373
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis. B, Environmental; Journal Volume: 234; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; methane co-aromatization; pore size; selectivity; isotope labelling; post-synthetic treatment

Citation Formats

He, Peng, Jarvis, Jack, Meng, Shijun, Wang, Aiguo, Kou, Shiyu, Gatip, Richard, Yung, Matthew, Liu, Lijia, and Song, Hua. Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites. United States: N. p., 2018. Web. doi:10.1016/j.apcatb.2018.04.034.
He, Peng, Jarvis, Jack, Meng, Shijun, Wang, Aiguo, Kou, Shiyu, Gatip, Richard, Yung, Matthew, Liu, Lijia, & Song, Hua. Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites. United States. doi:10.1016/j.apcatb.2018.04.034.
He, Peng, Jarvis, Jack, Meng, Shijun, Wang, Aiguo, Kou, Shiyu, Gatip, Richard, Yung, Matthew, Liu, Lijia, and Song, Hua. Mon . "Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites". United States. doi:10.1016/j.apcatb.2018.04.034.
@article{osti_1437562,
title = {Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites},
author = {He, Peng and Jarvis, Jack and Meng, Shijun and Wang, Aiguo and Kou, Shiyu and Gatip, Richard and Yung, Matthew and Liu, Lijia and Song, Hua},
abstractNote = {The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 degrees C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, which might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ring formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.},
doi = {10.1016/j.apcatb.2018.04.034},
journal = {Applied Catalysis. B, Environmental},
number = C,
volume = 234,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 2018},
month = {Mon Oct 01 00:00:00 EDT 2018}
}