Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes: A comparative study with Ga/HZSM-5

N. Al-Yassir; M. N. Akhtar; S. Al-Khattaf

doi:10.1007/s10934-011-9552-z

Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes: A comparative study with Ga/HZSM-5

N. Al-Yassir, M. N. Akhtar, S. Al-Khattaf^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

66 Scopus citations

Abstract

A series of gallium-containing HZSM-5 zeolites with different Ga contents (Ga/(Al+Ga) = 0.1-0.6) were prepared by hydrothermal in situ synthesis and post synthesis. Their catalytic performance were compared in the aromatization of propane, butane and propane/butane mixture (1:1 molar). Galloaluminosilicate obtained via hydrothermal in situ synthesis exhibited high fraction of acidic framework Ga³⁺ with few dispersed extracrystalline Ga ₂O₃. Ga/HZSM-5 obtained by post synthesis showed the presence of extracrystalline Ga₂O₃ and/or extra framework gallyl ions. The aromatization performance of Ga-containing HZSM-5 followed the following sequence; galloaluminosilicate>Ga/HZSM-5 (ion-exchange)>Ga/ HZSM-5 (impregnation) ≫ HZSM-5. Optimum aromatization performance over galloaluminosilicate was achieved with Ga/(Al+Ga) ratio of 0.3. Propane conversion reached 50.9 wt% over galloaluminosilicate with Ga/(Al+Ga) of 0.3, as compared to 31.8 and 40.7 wt% for the corresponding Ga/HZSM-5 obtained by impregnation and ionexchange, respectively, at gas hourly space velocity of 1,600 h^-1, and 540 °C. Comparison of aromatic selectivity at the same conversion level (∼10.0 wt%) revealed that galloaluminosilicate is more selective than Ga/HZSM-5. The superior performance of galloaluminosilicate was attributed to the presence of highly dispersed-reducible extra-framework Ga ₂O₃ (Lewis-dehydrogenating sites) formed by degalliation in close proximity to zeolitic Brönsted sites. Thus, hydrothermal in situ approach can thus be considered as an effective method for improving the aromatization performance of HZSM-5.

Original language	English
Pages (from-to)	943-960
Number of pages	18
Journal	Journal of Porous Materials
Volume	19
Issue number	6
DOIs	https://doi.org/10.1007/s10934-011-9552-z
State	Published - Dec 2012

Bibliographical note

Funding Information:
Acknowledgments The authors would like to express their appreciations to King Abdulaziz City for Science and Technology for their financial support under project No.12-3MT. The authors would like also to extend their appreciation to the support from the Ministry of Higher Education, Saudi Arabia in establishing the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals. The authors are grateful for Prof. Sachio Asaoka (University of Kitakyushu) for his

Keywords

Ga extra framework species
Ga/H-ZSM-5
Galloaluminosilicate
H-TPR
Lower alkane aromatization

ASJC Scopus subject areas

General Materials Science
Mechanics of Materials
Mechanical Engineering

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10.1007/s10934-011-9552-z

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title = "Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes: A comparative study with Ga/HZSM-5",

abstract = "A series of gallium-containing HZSM-5 zeolites with different Ga contents (Ga/(Al+Ga) = 0.1-0.6) were prepared by hydrothermal in situ synthesis and post synthesis. Their catalytic performance were compared in the aromatization of propane, butane and propane/butane mixture (1:1 molar). Galloaluminosilicate obtained via hydrothermal in situ synthesis exhibited high fraction of acidic framework Ga3+ with few dispersed extracrystalline Ga 2O3. Ga/HZSM-5 obtained by post synthesis showed the presence of extracrystalline Ga2O3 and/or extra framework gallyl ions. The aromatization performance of Ga-containing HZSM-5 followed the following sequence; galloaluminosilicate>Ga/HZSM-5 (ion-exchange)>Ga/ HZSM-5 (impregnation) ≫ HZSM-5. Optimum aromatization performance over galloaluminosilicate was achieved with Ga/(Al+Ga) ratio of 0.3. Propane conversion reached 50.9 wt\% over galloaluminosilicate with Ga/(Al+Ga) of 0.3, as compared to 31.8 and 40.7 wt\% for the corresponding Ga/HZSM-5 obtained by impregnation and ionexchange, respectively, at gas hourly space velocity of 1,600 h-1, and 540 °C. Comparison of aromatic selectivity at the same conversion level (∼10.0 wt\%) revealed that galloaluminosilicate is more selective than Ga/HZSM-5. The superior performance of galloaluminosilicate was attributed to the presence of highly dispersed-reducible extra-framework Ga 2O3 (Lewis-dehydrogenating sites) formed by degalliation in close proximity to zeolitic Br{\"o}nsted sites. Thus, hydrothermal in situ approach can thus be considered as an effective method for improving the aromatization performance of HZSM-5.",

keywords = "Ga extra framework species, Ga/H-ZSM-5, Galloaluminosilicate, H-TPR, Lower alkane aromatization",

author = "N. Al-Yassir and Akhtar, \{M. N.\} and S. Al-Khattaf",

note = "Funding Information: Acknowledgments The authors would like to express their appreciations to King Abdulaziz City for Science and Technology for their financial support under project No.12-3MT. The authors would like also to extend their appreciation to the support from the Ministry of Higher Education, Saudi Arabia in establishing the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals. The authors are grateful for Prof. Sachio Asaoka (University of Kitakyushu) for his",

year = "2012",

month = dec,

doi = "10.1007/s10934-011-9552-z",

language = "English",

volume = "19",

pages = "943--960",

journal = "Journal of Porous Materials",

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T1 - Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes

T2 - A comparative study with Ga/HZSM-5

AU - Al-Yassir, N.

AU - Akhtar, M. N.

AU - Al-Khattaf, S.

N1 - Funding Information: Acknowledgments The authors would like to express their appreciations to King Abdulaziz City for Science and Technology for their financial support under project No.12-3MT. The authors would like also to extend their appreciation to the support from the Ministry of Higher Education, Saudi Arabia in establishing the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals. The authors are grateful for Prof. Sachio Asaoka (University of Kitakyushu) for his

PY - 2012/12

Y1 - 2012/12

N2 - A series of gallium-containing HZSM-5 zeolites with different Ga contents (Ga/(Al+Ga) = 0.1-0.6) were prepared by hydrothermal in situ synthesis and post synthesis. Their catalytic performance were compared in the aromatization of propane, butane and propane/butane mixture (1:1 molar). Galloaluminosilicate obtained via hydrothermal in situ synthesis exhibited high fraction of acidic framework Ga3+ with few dispersed extracrystalline Ga 2O3. Ga/HZSM-5 obtained by post synthesis showed the presence of extracrystalline Ga2O3 and/or extra framework gallyl ions. The aromatization performance of Ga-containing HZSM-5 followed the following sequence; galloaluminosilicate>Ga/HZSM-5 (ion-exchange)>Ga/ HZSM-5 (impregnation) ≫ HZSM-5. Optimum aromatization performance over galloaluminosilicate was achieved with Ga/(Al+Ga) ratio of 0.3. Propane conversion reached 50.9 wt% over galloaluminosilicate with Ga/(Al+Ga) of 0.3, as compared to 31.8 and 40.7 wt% for the corresponding Ga/HZSM-5 obtained by impregnation and ionexchange, respectively, at gas hourly space velocity of 1,600 h-1, and 540 °C. Comparison of aromatic selectivity at the same conversion level (∼10.0 wt%) revealed that galloaluminosilicate is more selective than Ga/HZSM-5. The superior performance of galloaluminosilicate was attributed to the presence of highly dispersed-reducible extra-framework Ga 2O3 (Lewis-dehydrogenating sites) formed by degalliation in close proximity to zeolitic Brönsted sites. Thus, hydrothermal in situ approach can thus be considered as an effective method for improving the aromatization performance of HZSM-5.

AB - A series of gallium-containing HZSM-5 zeolites with different Ga contents (Ga/(Al+Ga) = 0.1-0.6) were prepared by hydrothermal in situ synthesis and post synthesis. Their catalytic performance were compared in the aromatization of propane, butane and propane/butane mixture (1:1 molar). Galloaluminosilicate obtained via hydrothermal in situ synthesis exhibited high fraction of acidic framework Ga3+ with few dispersed extracrystalline Ga 2O3. Ga/HZSM-5 obtained by post synthesis showed the presence of extracrystalline Ga2O3 and/or extra framework gallyl ions. The aromatization performance of Ga-containing HZSM-5 followed the following sequence; galloaluminosilicate>Ga/HZSM-5 (ion-exchange)>Ga/ HZSM-5 (impregnation) ≫ HZSM-5. Optimum aromatization performance over galloaluminosilicate was achieved with Ga/(Al+Ga) ratio of 0.3. Propane conversion reached 50.9 wt% over galloaluminosilicate with Ga/(Al+Ga) of 0.3, as compared to 31.8 and 40.7 wt% for the corresponding Ga/HZSM-5 obtained by impregnation and ionexchange, respectively, at gas hourly space velocity of 1,600 h-1, and 540 °C. Comparison of aromatic selectivity at the same conversion level (∼10.0 wt%) revealed that galloaluminosilicate is more selective than Ga/HZSM-5. The superior performance of galloaluminosilicate was attributed to the presence of highly dispersed-reducible extra-framework Ga 2O3 (Lewis-dehydrogenating sites) formed by degalliation in close proximity to zeolitic Brönsted sites. Thus, hydrothermal in situ approach can thus be considered as an effective method for improving the aromatization performance of HZSM-5.

KW - Ga extra framework species

KW - Ga/H-ZSM-5

KW - Galloaluminosilicate

KW - H-TPR

KW - Lower alkane aromatization

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SN - 1380-2224

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JO - Journal of Porous Materials

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ER -

Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes: A comparative study with Ga/HZSM-5

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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