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Communication Dans Un Congrès Année : 2014

Mechanism of lignin pyrolysis investigated by in-situ rheology and ex-situ spectroscopic methods

Binod Shrestha
  • Fonction : Auteur
Sandrine Hoppe
GP2
Thierry Ghislain
  • Fonction : Auteur
  • PersonId : 771533
  • IdRef : 159060508
Philippe Marchal
Anthony Dufour

Résumé

The thermochemical conversion of lignin has received an increasing interest in the frame of different biorefinery concepts for the production of chemicals or energy. It is needed to better understand the physical and chemical conversion of lignin for feeder and reactor designs. In-situ rheology reveals the viscoelastic behaviour of lignin upon thermal conversion. The softening, re-solidification (char formation), swelling and shrinking behaviours are quantified during pyrolysis in real-time [1]. The in-situ rheology of an alkali lignin (Protobind 1000) was conducted in high torque controlled strain rheometer from 35°C to 400°C with a heating rate of 5°C.min-1. The swelling, through glass phase transition overlapped with depolymerization, and solidification (crosslinking and "char" formation) are two main phenomena observed during lignin pyrolysis. The onset of temperatures for softening and solidification for this lignin has been found to be 141°C and 248°C respectively. An ex-situ characterization of lignin/char residues obtained at different temperatures after quenching in the rheometer gives a clear understanding of the pathway of lignin degradation. The lignin residues were sampled from the mid-point temperatures of the softening range and solidification range to study the chemical transformations undergoing. Elemental analysis, FTIR and solid state NMR were conducted after quenching on the solid residues (lignin/char). The quenched solid was also extracted by suitable solvent and followed by acetylation and GPC-UV analysis. The combination of 13C NMR and GPC-UV reveals the depolymerization followed by crosslinking of lignin/char. NMR and FTIR provide the evolution of functional moieties upon temperature. Physical and chemical mechanisms occurring during lignin pyrolysis are accounted for in this study thanks to all these complementary methods. 1. Dufour A, Castro-Diaz M, Marchal P, Brosse N, Olcese R, Bouroukba M, Snape C. "In Situ Analysis of Biomass Pyrolysis by High Temperature Rheology in Relations with 1H NMR". Energy Fuels 2012, 26, 6432-6441.
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Dates et versions

hal-00992453 , version 1 (18-05-2014)

Identifiants

  • HAL Id : hal-00992453 , version 1
  • PRODINRA : 314318

Citer

Binod Shrestha, Sandrine Hoppe, Thierry Ghislain, Philippe Marchal, Nicolas Brosse, et al.. Mechanism of lignin pyrolysis investigated by in-situ rheology and ex-situ spectroscopic methods. PYRO 2014 (20th International Symposium on Analytical and Applied Pyrolysis), May 2014, Birmingham, United Kingdom. ⟨hal-00992453⟩
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