Evolution of reactivity of highly porous chars from Raman microscopy

Tsachi Livneh, Ezra Bar-Ziv, Osvalda Senneca, Piero Salatino

Research output: Contribution to journalConference articlepeer-review

53 Scopus citations

Abstract

The effect of heat treatment on the evolution of reactivity of a highly porous pure synthetic char was studied with the aid of Raman scattering measurements. Two sets of experiments were carried out: A) Samples were oxidized in air at 600°C without heat treatment and Raman spectra were measured as a function of conversion. B) Samples were heat-treated in the range 900-1400°C, in nitrogen, then characterized by micro-Raman spectroscopy, in the range 800-1800 cm-1, and then oxidized by air at 500°C and by CO2 at 900°C in a thermogravimetric balance. In all Raman scattering measurements the G and D bands were dominant and a weak '1180 cm-1' band was apparent. The following conclusions can be drawn from results of experiments A and B respectively: A) Throughout reaction with oxygen the most significant changes in reactivity and Raman features occur in the conversion range 0-30%. This is consistent with previous measurements of thermal resistivity and intrinsic reaction rate. B) Heat treatment up to 900°C at time duration up to 300 minutes did not show any effect on reactivity. Decrease in reactivity was apparent at and beyond 1200°C. The characteristics of each of the three Raman bands showed clear correlation with reactivity changes both in air and CO2. These were attributed to morphological (dimensions and ordering) changes in the rearrangement of the carbon network structure, as previously suggested. Interpretation of these changes and their effect on reactivity is proposed.

Original languageEnglish
Pages (from-to)65-82
Number of pages18
JournalCombustion Science and Technology
Volume153
Issue number1
DOIs
StatePublished - 1 Jan 2000
EventMCS-99: 1st Mediterranean Combustion Symposium - Antalya, Turkey
Duration: 20 Jun 199925 Jun 1999

ASJC Scopus subject areas

  • Chemistry (all)
  • Chemical Engineering (all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy (all)

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