Interaction of Zn 2+ with extraframework aluminum in HBEA zeolite and its role in enhancing n-pentane isomerization

Kamarudin Nur Hidayatul Nazirah, Aishah Abdul Jalil, Sugeng Triwahyono, Rino R. Mukti, Muhammad Arif Ab Aziz, Herma Dina Setiabudi, Mohd Nazlan Mohd Muhid, Halimaton Hamdan

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The electrodeposition method was used to produce Zn 2+ cation precursors, followed by the introduction of Zn 2+ cation precursors to HBEA by the ion exchange technique. The introduction of Zn 2+ cations slightly changed the specific surface area and crystallinity of HBEA. IR, XPS and solid state MAS NMR results showed that Zn 2+ cations interacted with (AlO) + extraframework aluminum to form Zn(OAl) 2 and simultaneously induced the formation of bridging hydroxyl groups, Si(OH)Al. The pyridine adsorbed IR study revealed that the presence of Zn 2+ cations fully eliminated weak and partially eliminated strong Bronsted acid sites. As a result, strong and relatively weak Lewis acid sites were formed in which the pyridine probe molecule desorbed at 623 K and below. The presence of Zn 2+ cations enhanced the catalytic activity of HBEA in n-pentane isomerization due to the presence of strong Lewis acid sites; the sites may facilitate the formation and maintenance of active protonic acid sites through a hydrogen spillover mechanism. At 598 K, the yield of isopentane for Zn-HBEA was 25.7% higher than that of HBEA. Within a reaction temperature range of 373-648 K, the apparent activation energy for isomerization of n-pentane over HBEA and Zn-HBEA was 118.76 and 90.79 kJ/mol, respectively.

Original languageEnglish
Pages (from-to)104-112
Number of pages9
JournalApplied Catalysis A: General
Volume431-432
DOIs
Publication statusPublished - 26 Jul 2012
Externally publishedYes

Fingerprint

Zeolites
Isomerization
Aluminum
Cations
Positive ions
Lewis Acids
Acids
Pyridine
Electrodeposition
Specific surface area
Hydroxyl Radical
pentane
Hydrogen
Catalyst activity
Ion exchange
X ray photoelectron spectroscopy
Activation energy
Nuclear magnetic resonance
Molecules

Keywords

  • Bridging hydroxyl groups
  • Extraframework aluminum
  • n-Pentane isomerization
  • Protonic acid sites
  • Zn-HBEA

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

Interaction of Zn 2+ with extraframework aluminum in HBEA zeolite and its role in enhancing n-pentane isomerization. / Nur Hidayatul Nazirah, Kamarudin; Jalil, Aishah Abdul; Triwahyono, Sugeng; Mukti, Rino R.; Aziz, Muhammad Arif Ab; Setiabudi, Herma Dina; Muhid, Mohd Nazlan Mohd; Hamdan, Halimaton.

In: Applied Catalysis A: General, Vol. 431-432, 26.07.2012, p. 104-112.

Research output: Contribution to journalArticle

Nur Hidayatul Nazirah, Kamarudin ; Jalil, Aishah Abdul ; Triwahyono, Sugeng ; Mukti, Rino R. ; Aziz, Muhammad Arif Ab ; Setiabudi, Herma Dina ; Muhid, Mohd Nazlan Mohd ; Hamdan, Halimaton. / Interaction of Zn 2+ with extraframework aluminum in HBEA zeolite and its role in enhancing n-pentane isomerization. In: Applied Catalysis A: General. 2012 ; Vol. 431-432. pp. 104-112.
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AU - Triwahyono, Sugeng

AU - Mukti, Rino R.

AU - Aziz, Muhammad Arif Ab

AU - Setiabudi, Herma Dina

AU - Muhid, Mohd Nazlan Mohd

AU - Hamdan, Halimaton

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AB - The electrodeposition method was used to produce Zn 2+ cation precursors, followed by the introduction of Zn 2+ cation precursors to HBEA by the ion exchange technique. The introduction of Zn 2+ cations slightly changed the specific surface area and crystallinity of HBEA. IR, XPS and solid state MAS NMR results showed that Zn 2+ cations interacted with (AlO) + extraframework aluminum to form Zn(OAl) 2 and simultaneously induced the formation of bridging hydroxyl groups, Si(OH)Al. The pyridine adsorbed IR study revealed that the presence of Zn 2+ cations fully eliminated weak and partially eliminated strong Bronsted acid sites. As a result, strong and relatively weak Lewis acid sites were formed in which the pyridine probe molecule desorbed at 623 K and below. The presence of Zn 2+ cations enhanced the catalytic activity of HBEA in n-pentane isomerization due to the presence of strong Lewis acid sites; the sites may facilitate the formation and maintenance of active protonic acid sites through a hydrogen spillover mechanism. At 598 K, the yield of isopentane for Zn-HBEA was 25.7% higher than that of HBEA. Within a reaction temperature range of 373-648 K, the apparent activation energy for isomerization of n-pentane over HBEA and Zn-HBEA was 118.76 and 90.79 kJ/mol, respectively.

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