Evolved gas analysis of amorphous precursors for S-doped TiO2 by TG-FTIR and TG/DTA-MS: Part 3. Candidate from thiourea and Ti(IV)-ethoxide

J. Madarász, Ana Brǎileanu, Maria Crişan, Malina Rǎileanu, G. Pokol

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Thermal decomposition of an amorphous precursor for S-doped titania (TiO2) nanopowders, prepared by controlled sol-gel hydrolysis-condensation of titanium(IV) tetraethoxide and thiourea in aqueous ethanol, has been studied up to 800 °C in flowing air. Simultaneous thermogravimetric and differential thermal analysis coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR) have been applied for analysis of released gases (EGA) and their evolution dynamics in order to explore and simulate thermal annealing processes of fabrication techniques of the aimed S:TiO2 photocatalysts with photocatalytic activities under visible light. The precursor sample prepared with thiourea, released first water endothermically from room temperature to 190 °C, carbonyl sulfide (COS) from 120 to 240 °C in two stages, ammonia (NH3) from 170 to 350 °C in three steps, and organic mater (probably ether and ethylene) between 140 and 230 °C. The evolution of CO2, H2O and SO2, as oxidation products, occurs between 180 and 240 °C, accompanied by exothermic DTA peaks at 190 and 235 °C. Some small mass gain occurs before the following exothermic heat effect at 500 °C, which is probably due to the simultaneous burning out of residual carbonaceous and sulphureous species, and transformation of amorphous titania into anatase. The oxidative process is accompanied by evolution of CO 2 and SO2. Anatase, which formed also in the exothermic peak at 500 °C, mainly keeps its structure, since only 10% of rutile formation is detected below or at 800 °C by XRD. Meanwhile, from 500 °C, a final burning off organics is also indicated by continuous CO2 evolution and small exothermic effects.

Original languageEnglish
Pages (from-to)265-271
Number of pages7
JournalJournal of Thermal Analysis and Calorimetry
Volume97
Issue number1
DOIs
Publication statusPublished - Jul 2009

Fingerprint

Thiourea
Gas fuel analysis
gas analysis
thioureas
Differential thermal analysis
thermal analysis
titanium
anatase
Gases
gases
rutile
mass spectrometers
thermal decomposition
temperature effects
hydrolysis
sulfides
ammonia
Mass spectrometers
ethers
Carbon Monoxide

Keywords

  • Anatase
  • Evolved gas analysis
  • FTIR-spectroscopic gas cell
  • Mass spectrometry
  • Simultaneous thermogravimetry and differential thermal analysis
  • Thiourea
  • Titania precursor
  • Titanium(IV)-ethoxide

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics

Cite this

Evolved gas analysis of amorphous precursors for S-doped TiO2 by TG-FTIR and TG/DTA-MS : Part 3. Candidate from thiourea and Ti(IV)-ethoxide. / Madarász, J.; Brǎileanu, Ana; Crişan, Maria; Rǎileanu, Malina; Pokol, G.

In: Journal of Thermal Analysis and Calorimetry, Vol. 97, No. 1, 07.2009, p. 265-271.

Research output: Contribution to journalArticle

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abstract = "Thermal decomposition of an amorphous precursor for S-doped titania (TiO2) nanopowders, prepared by controlled sol-gel hydrolysis-condensation of titanium(IV) tetraethoxide and thiourea in aqueous ethanol, has been studied up to 800 °C in flowing air. Simultaneous thermogravimetric and differential thermal analysis coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR) have been applied for analysis of released gases (EGA) and their evolution dynamics in order to explore and simulate thermal annealing processes of fabrication techniques of the aimed S:TiO2 photocatalysts with photocatalytic activities under visible light. The precursor sample prepared with thiourea, released first water endothermically from room temperature to 190 °C, carbonyl sulfide (COS) from 120 to 240 °C in two stages, ammonia (NH3) from 170 to 350 °C in three steps, and organic mater (probably ether and ethylene) between 140 and 230 °C. The evolution of CO2, H2O and SO2, as oxidation products, occurs between 180 and 240 °C, accompanied by exothermic DTA peaks at 190 and 235 °C. Some small mass gain occurs before the following exothermic heat effect at 500 °C, which is probably due to the simultaneous burning out of residual carbonaceous and sulphureous species, and transformation of amorphous titania into anatase. The oxidative process is accompanied by evolution of CO 2 and SO2. Anatase, which formed also in the exothermic peak at 500 °C, mainly keeps its structure, since only 10{\%} of rutile formation is detected below or at 800 °C by XRD. Meanwhile, from 500 °C, a final burning off organics is also indicated by continuous CO2 evolution and small exothermic effects.",
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AB - Thermal decomposition of an amorphous precursor for S-doped titania (TiO2) nanopowders, prepared by controlled sol-gel hydrolysis-condensation of titanium(IV) tetraethoxide and thiourea in aqueous ethanol, has been studied up to 800 °C in flowing air. Simultaneous thermogravimetric and differential thermal analysis coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR) have been applied for analysis of released gases (EGA) and their evolution dynamics in order to explore and simulate thermal annealing processes of fabrication techniques of the aimed S:TiO2 photocatalysts with photocatalytic activities under visible light. The precursor sample prepared with thiourea, released first water endothermically from room temperature to 190 °C, carbonyl sulfide (COS) from 120 to 240 °C in two stages, ammonia (NH3) from 170 to 350 °C in three steps, and organic mater (probably ether and ethylene) between 140 and 230 °C. The evolution of CO2, H2O and SO2, as oxidation products, occurs between 180 and 240 °C, accompanied by exothermic DTA peaks at 190 and 235 °C. Some small mass gain occurs before the following exothermic heat effect at 500 °C, which is probably due to the simultaneous burning out of residual carbonaceous and sulphureous species, and transformation of amorphous titania into anatase. The oxidative process is accompanied by evolution of CO 2 and SO2. Anatase, which formed also in the exothermic peak at 500 °C, mainly keeps its structure, since only 10% of rutile formation is detected below or at 800 °C by XRD. Meanwhile, from 500 °C, a final burning off organics is also indicated by continuous CO2 evolution and small exothermic effects.

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