Direct synthesis of well-ordered and unusually reactive MnSBA-15 mesoporous molecular sieves with high manganese content

M. Selvaraj, Tai Gyu Lee

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

The mesoporous MnSBA-15 materials with different nsi/n Mn ratios of 4, 8, 20, and SO have been synthesized, for the first time, using manganese nitrate tetrahydrate and Pluronic 123 triblock polymer [(EO)20(PO)70-(EO)20] by simply adjusting the molar ratio of water to hydrochloric acid (nH2o/nHCl) under direct hydrothermal conditions. For the effect of structural and textural properties with incorporation of manganese, the MnSBA-15 has been synthesized with different synthesis temperatures at the fixed molar ratios of n Si/nMn = 4 and nH2o/nHCl = 295 in the synthesis gel. The hydrothermal and thermal stabilities of MnSBA-15 have also been investigated. The calcined MnSBA-15 materials prepared have been characterized by ICP-AES, XRD, N2 adsorption, ESR, FE-SEM, and TEM. The ICP-AES studies show a higher amount of manganese incorporation on the silica pore walls, as MnSBA-15 with a nSi/nMn ratio up to 2.2 can be successfully prepared at a fixed nH2o/nHCl molar ratio of 295 by adjusting the ratios of nSi/nMn in the synthesis gel. The structural and textural properties of calcined MnSBA-15 prepared can be found by the results of XRD and N2 adsorption. The investigation of ESR results clearly describe the effect of structure and Mn species coordination on the SB A-15 silica pore walls while the uniform pore diameter and rope-like hexagonal mesoporous structure of MnSBA-15 can be identified by TEM and FE-SEM images. With increasing synthesis temperature, an increase the unit cell parameter, pore size, and pore volume and a decrease the specific surface area and pore wall thickness of MnSBA-15 can be obviously noted by the results of XRD and N2 adsorption. The hexagonal MnSBA-15 materials prepared could be tested as catalysts in epoxidation of trans-stilbene to produce trans-stilbene oxide under various optimal conditions while their catalytic properties could also be compared to the results of MnMCM-41 and ZrMnMCM-41.

Original languageEnglish
Pages (from-to)21793-21802
Number of pages10
JournalJournal of Physical Chemistry B
Volume110
Issue number43
DOIs
Publication statusPublished - 2006 Nov 2

Fingerprint

Molecular sieves
absorbents
Manganese
manganese
porosity
synthesis
Adsorption
Silicon Dioxide
Paramagnetic resonance
Gels
stilbene
Silica
Transmission electron microscopy
Poloxamer
Stilbenes
Scanning electron microscopy
adsorption
Epoxidation
Hydrochloric Acid
Hydrochloric acid

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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title = "Direct synthesis of well-ordered and unusually reactive MnSBA-15 mesoporous molecular sieves with high manganese content",
abstract = "The mesoporous MnSBA-15 materials with different nsi/n Mn ratios of 4, 8, 20, and SO have been synthesized, for the first time, using manganese nitrate tetrahydrate and Pluronic 123 triblock polymer [(EO)20(PO)70-(EO)20] by simply adjusting the molar ratio of water to hydrochloric acid (nH2o/nHCl) under direct hydrothermal conditions. For the effect of structural and textural properties with incorporation of manganese, the MnSBA-15 has been synthesized with different synthesis temperatures at the fixed molar ratios of n Si/nMn = 4 and nH2o/nHCl = 295 in the synthesis gel. The hydrothermal and thermal stabilities of MnSBA-15 have also been investigated. The calcined MnSBA-15 materials prepared have been characterized by ICP-AES, XRD, N2 adsorption, ESR, FE-SEM, and TEM. The ICP-AES studies show a higher amount of manganese incorporation on the silica pore walls, as MnSBA-15 with a nSi/nMn ratio up to 2.2 can be successfully prepared at a fixed nH2o/nHCl molar ratio of 295 by adjusting the ratios of nSi/nMn in the synthesis gel. The structural and textural properties of calcined MnSBA-15 prepared can be found by the results of XRD and N2 adsorption. The investigation of ESR results clearly describe the effect of structure and Mn species coordination on the SB A-15 silica pore walls while the uniform pore diameter and rope-like hexagonal mesoporous structure of MnSBA-15 can be identified by TEM and FE-SEM images. With increasing synthesis temperature, an increase the unit cell parameter, pore size, and pore volume and a decrease the specific surface area and pore wall thickness of MnSBA-15 can be obviously noted by the results of XRD and N2 adsorption. The hexagonal MnSBA-15 materials prepared could be tested as catalysts in epoxidation of trans-stilbene to produce trans-stilbene oxide under various optimal conditions while their catalytic properties could also be compared to the results of MnMCM-41 and ZrMnMCM-41.",
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Direct synthesis of well-ordered and unusually reactive MnSBA-15 mesoporous molecular sieves with high manganese content. / Selvaraj, M.; Lee, Tai Gyu.

In: Journal of Physical Chemistry B, Vol. 110, No. 43, 02.11.2006, p. 21793-21802.

Research output: Contribution to journalArticle

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N2 - The mesoporous MnSBA-15 materials with different nsi/n Mn ratios of 4, 8, 20, and SO have been synthesized, for the first time, using manganese nitrate tetrahydrate and Pluronic 123 triblock polymer [(EO)20(PO)70-(EO)20] by simply adjusting the molar ratio of water to hydrochloric acid (nH2o/nHCl) under direct hydrothermal conditions. For the effect of structural and textural properties with incorporation of manganese, the MnSBA-15 has been synthesized with different synthesis temperatures at the fixed molar ratios of n Si/nMn = 4 and nH2o/nHCl = 295 in the synthesis gel. The hydrothermal and thermal stabilities of MnSBA-15 have also been investigated. The calcined MnSBA-15 materials prepared have been characterized by ICP-AES, XRD, N2 adsorption, ESR, FE-SEM, and TEM. The ICP-AES studies show a higher amount of manganese incorporation on the silica pore walls, as MnSBA-15 with a nSi/nMn ratio up to 2.2 can be successfully prepared at a fixed nH2o/nHCl molar ratio of 295 by adjusting the ratios of nSi/nMn in the synthesis gel. The structural and textural properties of calcined MnSBA-15 prepared can be found by the results of XRD and N2 adsorption. The investigation of ESR results clearly describe the effect of structure and Mn species coordination on the SB A-15 silica pore walls while the uniform pore diameter and rope-like hexagonal mesoporous structure of MnSBA-15 can be identified by TEM and FE-SEM images. With increasing synthesis temperature, an increase the unit cell parameter, pore size, and pore volume and a decrease the specific surface area and pore wall thickness of MnSBA-15 can be obviously noted by the results of XRD and N2 adsorption. The hexagonal MnSBA-15 materials prepared could be tested as catalysts in epoxidation of trans-stilbene to produce trans-stilbene oxide under various optimal conditions while their catalytic properties could also be compared to the results of MnMCM-41 and ZrMnMCM-41.

AB - The mesoporous MnSBA-15 materials with different nsi/n Mn ratios of 4, 8, 20, and SO have been synthesized, for the first time, using manganese nitrate tetrahydrate and Pluronic 123 triblock polymer [(EO)20(PO)70-(EO)20] by simply adjusting the molar ratio of water to hydrochloric acid (nH2o/nHCl) under direct hydrothermal conditions. For the effect of structural and textural properties with incorporation of manganese, the MnSBA-15 has been synthesized with different synthesis temperatures at the fixed molar ratios of n Si/nMn = 4 and nH2o/nHCl = 295 in the synthesis gel. The hydrothermal and thermal stabilities of MnSBA-15 have also been investigated. The calcined MnSBA-15 materials prepared have been characterized by ICP-AES, XRD, N2 adsorption, ESR, FE-SEM, and TEM. The ICP-AES studies show a higher amount of manganese incorporation on the silica pore walls, as MnSBA-15 with a nSi/nMn ratio up to 2.2 can be successfully prepared at a fixed nH2o/nHCl molar ratio of 295 by adjusting the ratios of nSi/nMn in the synthesis gel. The structural and textural properties of calcined MnSBA-15 prepared can be found by the results of XRD and N2 adsorption. The investigation of ESR results clearly describe the effect of structure and Mn species coordination on the SB A-15 silica pore walls while the uniform pore diameter and rope-like hexagonal mesoporous structure of MnSBA-15 can be identified by TEM and FE-SEM images. With increasing synthesis temperature, an increase the unit cell parameter, pore size, and pore volume and a decrease the specific surface area and pore wall thickness of MnSBA-15 can be obviously noted by the results of XRD and N2 adsorption. The hexagonal MnSBA-15 materials prepared could be tested as catalysts in epoxidation of trans-stilbene to produce trans-stilbene oxide under various optimal conditions while their catalytic properties could also be compared to the results of MnMCM-41 and ZrMnMCM-41.

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