International Scientific Journal

Thermal Science - Online First

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Combined organic acid leaching and torrefaction as pine wood pretreatment before fast pyrolysis

Reducing pine wood particle size is beneficial for acid leaching (shorter leaching time, smaller equipment size) and also for pyrolysis (low pyrolysis time, high oil and sugar yields). Torrefaction helps to improve the energy efficiency of grinding. However, it is not well established whether Alkali and Alkaline Earth Metals (AAEM's) can still be removed effectively, after torrefaction, by leaching with an acetic acid solution, while keeping high oil and sugar yields. To investigate this, an experimental study was carried out combining torrefaction (290°C, 20 minutes) and subsequently acid leaching of pine wood as pretreatment step before fast pyrolysis of the feedstock at 530°C. The oil, char, gas, water, pyrolytic lignin, light oxygenates and levoglucosan yields were compared with the results obtained from fast pyrolysis of untreated pine wood and acid leached pine wood at 530°C. In addition, pyrolysis vapors were condensed step-wise into two distinguished fractions (condensation T=80oC) to increase the levoglucosan concentration up to 45 wt% with or without applying torrefaction as pretreatment. Intra-particle reactions during torrefaction are more profound in the presence of AAEM's. Cellulose and Lignin derived products (e.g. levolucosan (~0.2 kg/kg pine wood) and pyrolytic lignin (~0.11 kg/kg pine wood) were not affected by the torrefaction pre-treatment of acid leached pine wood. In general, torrefaction of acid leached pine wood followed by fast pyrolysis showed similar total organics, char, gas, light oxygenates and produced water yields compared to fast pyrolysis of acid leached pine wood. Contrary, when acid leaching is applied after torrefaction the organics (dry bio-oil) and light oxygenates yields are quite comparable to the results of untreated pine wood fast pyrolysis.
PAPER REVISED: 2019-01-06
PAPER ACCEPTED: 2019-06-06
  1. Bridgwater, A. V., Review of fast pyrolysis of biomass and product upgrading. Biomass and Bioenergy, 38 (2012), 0, pp. 68-94.
  2. Oudenhoven, S.R.G., et al., Using pyrolytic acid leaching as a pretreatment step in a biomass fast pyrolysis plant: Process design and economic evaluation. Biomass and Bioenergy, 95 (2016), pp. 388-404.
  3. Lappas, A.A., et al., Catalytic pyrolysis of pine wood for transportation fuels, Energy and Environ. 1 (2012), 3, pp. 285-297
  4. Westerhof, R.J.M., et al., Stepwise fast pyrolysis of pine wood, Energy and Fuels. 26 (2012), 12, 7263-7273
  5. Westerhof, R. J. M., et al., Effect of Temperature in Fluidized Bed Fast Pyrolysis of Biomass: Oil Quality Assessment in Test Units, Ind. Eng. Chem. Res.49 (2009), 3, 1160-1168.
  6. Oasmaa A., et al., Fast Pyrolysis Bio-Oils from Wood and Agricultural Residues, Energy and Fuels 24 (2009), 2, pp. 1380-1388
  7. P. Basu, Pine wood Gasification, Pyrolysis and Torrefaction: Practical Design and Theory, 2013, doi:10.1016/C2011-0-07564-6.
  8. Bridgeman, T.G., et al., An investigation of the grindability of two torrefied energy crops, Fuel 89 (2010), pp. 3911-3918
  9. Gil, M.V., et al., Grindability and combustion behavior of coal and torrefied pine wood blends, Bioresource Technology 191 (2015), pp. 205-212
  10. van der Stelt, M.J.C., et al., Pine wood upgrading by torrefaction for the production of biofuels: A review, Biomass and Bioenergy 35 (2011), pp. 3748-3762.
  11. Proskurina, S., et al., Pine wood for industrial applications: The role of torrefaction, Renewable Energy. 111 (2017), pp. 265-274
  12. Gao, P., et al., Effects of alkali and alkaline earth metals on N-containing species release during rice straw pyrolysis, Energies 8 (2015), 11, pp. 13021-13032
  13. S. Hu, S., et al., Effects of inherent alkali and alkaline earth metallic species on pine wood pyrolysis at different temperatures, Bioresource Technology 192 (2015), pp. 23-30
  14. Barker, A.V, D.J. Pilbeam, Handbook of plant nutrition, Environment. 49 (2007) pp. 632.
  15. Piskorz, J., et al., Pretreatment of wood and cellulose for production of sugars by fast pyrolysis, Journal of Analytical and Applied Pyrolysis 16 (1989), pp. 127-142
  16. Vassilev, S.V., et al., An overview of the organic and inorganic phase composition of pine wood, Fuel. 94 (2012), pp. 1-33.
  17. Westerhof, R.J.M., et al., Biofuel and Methyl Levulinate from biomass-derived fractional condensed pyrolysis oil and alcohol. Energy Technology, 5 (2017), pp. 205-215
  18. Luque, L., et al., Pyrolysis based bio-refinery for the production of bioethanol from demineralized lignocellulosic biomass. Bioresource Technology 161 (2014), pp. 20-28
  19. Persson, H., et al., Wood-derived acid leaching of pine wood for enhanced production of sugars and sugar derivatives during pyrolysis: Influence of acidity and treatment time, Journal of Analytical and Applied Pyrolysis 127 (2017), pp. 329-334
  20. Oudenhoven, S.R.G., et al., Effect of temperature on the fast pyrolysis of organic-acid leached pinewood; the potential of low temperature pyrolysis, Biomass and Bioenergy 89 (2015), pp. 78-90
  21. Oudenhoven, S.R.G., et al., Demineralization of wood using wood-derived acid: Towards a selective pyrolysis process for fuel and chemicals production, Journal of Analytical and Applied Pyrolysis 103 (2013), pp. 112-118
  22. Oudenhoven, S.R.G., et al., Fast pyrolysis of organic acid leached wood, straw, hay and bagasse: Improved oil and sugar yields, Journal of Analytical and Applied Pyrolysis 116 (2015), pp. 253-262
  23. Piskorz, J., et al., Pretreatment of wood and cellulose for production of sugars by fast pyrolysis. Journal of Analytical and Applied Pyrolysis 16 (1989), 2, pp. 127-142
  24. Westerhof, R.J.M., et al., Controlling the water content of pine wood fast pyrolysis oil, Industrial Engineering Chemistry Research 46 (2007), pp. 9238-9247