Iron-catalyzed propylene epoxidation by nitrous oxide: Toward understanding the nature of active iron sites with modified Fe-MFI and Fe-MCM-41 catalysts

Qinghong Zhang, Qian Guo, Xiaoxing Wang, Tetsuya Shishido, Ye Wang

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

Alkali metal salt (KCl)-modified Fe-MFI and Fe-MCM-41 containing iron species in different locations have been studied for the epoxidation of propylene with nitrous oxide. In the allylic oxidation of propylene without modification, the samples with iron species in the framework positions showed slightly higher activity for the formation of acrolein and allyl alcohol. After modification with KCl, propylene oxide (PO) became the main product. Significant differences in PO formation activity were observed between the samples containing iron in different locations. For the Fe-MFI and the Fe-MCM-41 prepared by the direct hydrothermal (DHT) method, in which iron was located mainly in the framework position, much lower activity was obtained after KCl modification. In contrast, the Fe-MFI after steam treatment and the Fe-MCM-41 prepared by template ion-exchange (TIE) and conventional impregnation methods, which contained extra-framework iron species (e.g., FeOx clusters), exhibited higher PO formation activity after modification. A PO selectivity of 80% could be achieved at a propylene conversion of 3.3% over the KCl-modified Fe-MCM-41 prepared by the TIE or the impregnation method at 598 K (time on stream, 70 min). The modification with KCl increased the dispersion of the extra-framework iron species. Consequently, highly dispersed extra-framework iron species, probably in tetrahedral coordination, are proposed for the epoxidation of propylene with nitrous oxide.

Original languageEnglish (US)
Pages (from-to)105-116
Number of pages12
JournalJournal of Catalysis
Volume239
Issue number1
DOIs
StatePublished - Apr 1 2006

Fingerprint

epoxidation
Epoxidation
nitrous oxides
Nitrous Oxide
Multicarrier modulation
propylene
Propylene
Iron
propylene oxide
iron
catalysts
Catalysts
Oxides
Impregnation
Ion exchange
templates
Alkali Metals
Acrolein
Steam
MCM-41

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Physical and Theoretical Chemistry

Cite this

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title = "Iron-catalyzed propylene epoxidation by nitrous oxide: Toward understanding the nature of active iron sites with modified Fe-MFI and Fe-MCM-41 catalysts",
abstract = "Alkali metal salt (KCl)-modified Fe-MFI and Fe-MCM-41 containing iron species in different locations have been studied for the epoxidation of propylene with nitrous oxide. In the allylic oxidation of propylene without modification, the samples with iron species in the framework positions showed slightly higher activity for the formation of acrolein and allyl alcohol. After modification with KCl, propylene oxide (PO) became the main product. Significant differences in PO formation activity were observed between the samples containing iron in different locations. For the Fe-MFI and the Fe-MCM-41 prepared by the direct hydrothermal (DHT) method, in which iron was located mainly in the framework position, much lower activity was obtained after KCl modification. In contrast, the Fe-MFI after steam treatment and the Fe-MCM-41 prepared by template ion-exchange (TIE) and conventional impregnation methods, which contained extra-framework iron species (e.g., FeOx clusters), exhibited higher PO formation activity after modification. A PO selectivity of 80{\%} could be achieved at a propylene conversion of 3.3{\%} over the KCl-modified Fe-MCM-41 prepared by the TIE or the impregnation method at 598 K (time on stream, 70 min). The modification with KCl increased the dispersion of the extra-framework iron species. Consequently, highly dispersed extra-framework iron species, probably in tetrahedral coordination, are proposed for the epoxidation of propylene with nitrous oxide.",
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Iron-catalyzed propylene epoxidation by nitrous oxide : Toward understanding the nature of active iron sites with modified Fe-MFI and Fe-MCM-41 catalysts. / Zhang, Qinghong; Guo, Qian; Wang, Xiaoxing; Shishido, Tetsuya; Wang, Ye.

In: Journal of Catalysis, Vol. 239, No. 1, 01.04.2006, p. 105-116.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Iron-catalyzed propylene epoxidation by nitrous oxide

T2 - Toward understanding the nature of active iron sites with modified Fe-MFI and Fe-MCM-41 catalysts

AU - Zhang, Qinghong

AU - Guo, Qian

AU - Wang, Xiaoxing

AU - Shishido, Tetsuya

AU - Wang, Ye

PY - 2006/4/1

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AB - Alkali metal salt (KCl)-modified Fe-MFI and Fe-MCM-41 containing iron species in different locations have been studied for the epoxidation of propylene with nitrous oxide. In the allylic oxidation of propylene without modification, the samples with iron species in the framework positions showed slightly higher activity for the formation of acrolein and allyl alcohol. After modification with KCl, propylene oxide (PO) became the main product. Significant differences in PO formation activity were observed between the samples containing iron in different locations. For the Fe-MFI and the Fe-MCM-41 prepared by the direct hydrothermal (DHT) method, in which iron was located mainly in the framework position, much lower activity was obtained after KCl modification. In contrast, the Fe-MFI after steam treatment and the Fe-MCM-41 prepared by template ion-exchange (TIE) and conventional impregnation methods, which contained extra-framework iron species (e.g., FeOx clusters), exhibited higher PO formation activity after modification. A PO selectivity of 80% could be achieved at a propylene conversion of 3.3% over the KCl-modified Fe-MCM-41 prepared by the TIE or the impregnation method at 598 K (time on stream, 70 min). The modification with KCl increased the dispersion of the extra-framework iron species. Consequently, highly dispersed extra-framework iron species, probably in tetrahedral coordination, are proposed for the epoxidation of propylene with nitrous oxide.

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