Microspectroscopic studies of template interactions in AlPO4-5 and SAPO-5 crystals

S. C. Popescu, S. Thomson, Russell Francis Howe

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Individual crystals of the aluminophosphate AlPO4-5 and the silicon-substituted aluminophosphate SAPO-5 synthesized with a triethylamine template have been studied by FTIR and Raman microspectroscopy. Both materials as synthesized contain the template in the protonated form. In AlPO4-5, the protonated template is charge balanced by hydroxide ions. Dehydration causes elimination of water leaving the template in the free amine form, but this process is reversible. Measurements with polarized infrared radiation reveal that both the protonated and free template molecules are oriented with the C-3 axes perpendicular to the channel direction. In SAPO-5, deprotonation of the template also occurs on dehydration but to a lesser extent, and protonated template is still present after heating in vacuo to 500 K. The balance between protonated and free template depends on the extent of hydration of the sample and the presence or absence of negative charge on the framework. After thermal calcination to remove the template completely, the single crystals of AlPO4-5 are devoid of hydroxy groups, whereas SAPO-5 shows two types of hydroxy groups oriented perpendicular to the channel axes.

Original languageEnglish
Pages (from-to)111-118
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume3
DOIs
Publication statusPublished - Jan 2001

Keywords

  • MOLECULAR-SIEVES
  • INORGANIC SOLIDS
  • SINGLE-CRYSTALS
  • IR
  • DECOMPOSITION
  • SPECTROSCOPY
  • MICROSCOPY
  • SILICON
  • SPECTRA
  • NMR

Cite this

Microspectroscopic studies of template interactions in AlPO4-5 and SAPO-5 crystals. / Popescu, S. C.; Thomson, S.; Howe, Russell Francis.

In: Physical Chemistry Chemical Physics, Vol. 3, 01.2001, p. 111-118.

Research output: Contribution to journalArticle

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abstract = "Individual crystals of the aluminophosphate AlPO4-5 and the silicon-substituted aluminophosphate SAPO-5 synthesized with a triethylamine template have been studied by FTIR and Raman microspectroscopy. Both materials as synthesized contain the template in the protonated form. In AlPO4-5, the protonated template is charge balanced by hydroxide ions. Dehydration causes elimination of water leaving the template in the free amine form, but this process is reversible. Measurements with polarized infrared radiation reveal that both the protonated and free template molecules are oriented with the C-3 axes perpendicular to the channel direction. In SAPO-5, deprotonation of the template also occurs on dehydration but to a lesser extent, and protonated template is still present after heating in vacuo to 500 K. The balance between protonated and free template depends on the extent of hydration of the sample and the presence or absence of negative charge on the framework. After thermal calcination to remove the template completely, the single crystals of AlPO4-5 are devoid of hydroxy groups, whereas SAPO-5 shows two types of hydroxy groups oriented perpendicular to the channel axes.",
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N2 - Individual crystals of the aluminophosphate AlPO4-5 and the silicon-substituted aluminophosphate SAPO-5 synthesized with a triethylamine template have been studied by FTIR and Raman microspectroscopy. Both materials as synthesized contain the template in the protonated form. In AlPO4-5, the protonated template is charge balanced by hydroxide ions. Dehydration causes elimination of water leaving the template in the free amine form, but this process is reversible. Measurements with polarized infrared radiation reveal that both the protonated and free template molecules are oriented with the C-3 axes perpendicular to the channel direction. In SAPO-5, deprotonation of the template also occurs on dehydration but to a lesser extent, and protonated template is still present after heating in vacuo to 500 K. The balance between protonated and free template depends on the extent of hydration of the sample and the presence or absence of negative charge on the framework. After thermal calcination to remove the template completely, the single crystals of AlPO4-5 are devoid of hydroxy groups, whereas SAPO-5 shows two types of hydroxy groups oriented perpendicular to the channel axes.

AB - Individual crystals of the aluminophosphate AlPO4-5 and the silicon-substituted aluminophosphate SAPO-5 synthesized with a triethylamine template have been studied by FTIR and Raman microspectroscopy. Both materials as synthesized contain the template in the protonated form. In AlPO4-5, the protonated template is charge balanced by hydroxide ions. Dehydration causes elimination of water leaving the template in the free amine form, but this process is reversible. Measurements with polarized infrared radiation reveal that both the protonated and free template molecules are oriented with the C-3 axes perpendicular to the channel direction. In SAPO-5, deprotonation of the template also occurs on dehydration but to a lesser extent, and protonated template is still present after heating in vacuo to 500 K. The balance between protonated and free template depends on the extent of hydration of the sample and the presence or absence of negative charge on the framework. After thermal calcination to remove the template completely, the single crystals of AlPO4-5 are devoid of hydroxy groups, whereas SAPO-5 shows two types of hydroxy groups oriented perpendicular to the channel axes.

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