Using Solid-State 13C NMR to Study Pyrolysis Final Temperature Effects on Biochar Stability

  • C. F. B. V. Alho
  • R. Auccaise
  • C. M. B. F. Maia
  • E. H. Novotny
  • R. C. C. Lelis
Conference paper

Abstract

Recent results in biochar research show that it is not only composed of stable carbon, since a portion of these materials is degraded relatively easily once applied to soil, and this condition is most dependent on pyrolysis conditions, especially the final temperature. Thus, the aim of this study was to evaluate pyrolysis final temperature effects on the stability of biochar produced from forest residues using solid-state 13C NMR. Pyrolysis was performed at a heating rate of 10°C·min−1 up to the final temperature of interest (350, 450 and 550°C), maintaining this temperature for 60 min. Solid-state 13C NMR spectra were obtained on a Varian 500-MHz spectrometer for fresh wood and biochars produced at 350, 450 and 550°C for Eucalyptus dunnii (DUN) and Pinus caribaea (CAR). Comparing fresh samples with their respective biochars, regardless of the botanical group, after pyrolysis, carbohydrates are degraded, and there is a change in the structure of the materials, with a predominance of aromatic structures, which are more resistant to degradation, therefore reflecting in the increased stability of these materials. For 350°C, it is still possible to observe signals related to lignin indicating that up to this temperature it has not been completely degraded. The spectra of biochars produced at 450 and 550°C are very similar, indicating that there is no need to produce biochars at very high final temperatures, since the structure of these materials obtained at 550°C slightly altered as of 450°C, keeping the predominance of aromatic structures.

Keywords

Biochar Pyrogenic carbon Forest residues Organic matter stability NMR 

References

  1. Atalla, R.H., and D.L. VanderHart. 1999. The role of solid state 13C NMR spectroscopy in studies of the nature of native celluloses. Solid State Nuclear Magnetic Resonance 15: 1–19.CrossRefGoogle Scholar
  2. Haw, J.F., G.E. Maciel, and C.J. Biermann. 1984. Carbon-13 nuclear magnetic resonance study of rapid steam hydrolysis of red Oak. Holzforschung 38: 327–331.CrossRefGoogle Scholar
  3. Leary, G.J., R.H. Newman, and K.R. Morgan. 1986. A carbon-13 nuclear magnetic resonance study of chemical processes involved in the isolation of Klason lignin. Holzforschung 40: 267–272.CrossRefGoogle Scholar
  4. Pereira, R.C., J. Kaal, M.C. Arbestain, R.P. Lorenzo, W. Aitkenhead, M. Hedley, F. Macías, J. Hindmarsh, and J.A. Maciá-Agulló. 2011. Contribution to characterisation of biochar to estimate the labile fraction of carbon. Organic Geochemistry 42: 1331–1342.CrossRefGoogle Scholar
  5. VanderHart, D.L., and R.H. Atalla. 1984. Studies of microstructures in native celluloses using solid-state 13C NMR. Macromolecules 17: 1465–1472.CrossRefGoogle Scholar
  6. Wikberg, H., and S.L. Maunu. 2004. Characterisation of thermally modified hard- and softwoods by 13C CPMAS NMR. Carbohydrates Polymers 58: 461–466.CrossRefGoogle Scholar

Copyright information

© Zhejiang University Press and Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • C. F. B. V. Alho
    • 1
  • R. Auccaise
    • 2
  • C. M. B. F. Maia
    • 3
  • E. H. Novotny
    • 2
  • R. C. C. Lelis
    • 1
  1. 1.Forest Products DepartmentFederal Rural University of Rio de JaneiroSeropédicaBrazil
  2. 2.Embrapa SoilsRio de JaneiroBrazil
  3. 3.Empraba ForestsColomboBrazil

Personalised recommendations