Slow pyrolysis of cork granules under nitrogen atmosphere: by-products characterization and their potential valorization

Document Type : Research Paper


LNEG - Laboratório Nacional de Energia e Geologia I.P., LEN - Laboratório de Energia, Estrada do Paço do Lumiar 22, 1649-038 Lisboa, Portugal.


Cork granules (Quercus suber L.) were slowly pyrolyzed at temperatures between 400-700 °C and under N2 flow. While preserving its structure, some cells of the cork biochar became interconnected, allowing such carbon residue to be used as templates for manufacturing ceria redox materials. The pyrolytic char morphology was similar to that of the natural precursor. The produced cork biochar belonged to Class 1 (C > 60%) and possessed a high heating value of 32 MJ kg1. Other pyrolysis-derived compounds were identified and quantified through GC-FID and GC-MS analyses. The yield of gases released during cork pyrolysis was strongly dependent on the temperature used due to the thermal decomposition reactions involved in the degradation of cork. In particular, rising pyrolysis temperature from 500 to 700 ºC resulted in reducing the total hydrocarbon gases from 74 to 24 vol%. On the other hand, the yield of H2 increased from 0 to 58% by increasing the pyrolysis temperature from 400 to 700 ºC. Due to the presence of suberin in cork, the composition and yield of bio-oil could be regulated by the pyrolysis temperature. Cork bio-oil was found to consist of long-chain hydrocarbons (from C11 to C24). The bio-oil resulting from the slow pyrolysis of cork residues is suitable as an appropriate feedstock for producing aliphatic-rich pyrolytic biofuels or as a source of olefins. Overall, the findings of this study suggest that Quercus suber L. could be a promising feedstock for biochar and biofuel production through the pyrolytic route and could contribute to the environmental and economic sustainability of the cork production industry.

Graphical Abstract

Slow pyrolysis of cork granules under nitrogen atmosphere: by-products characterization and their potential valorization


  • Quercus Suber L pyrolysis by-products including biochar and bio-oil were investigated.
  • Cork biochar belonged to class 1 (C>60%) with HHV of 32 MJ kg-1.
  • Cork bio-oil consisted of long-chain hydrocarbons (from C11 to C24).
  • H2 yield increased from 0 to 58% by increasing temperature from 400 and 700ºC, respectively.
  • Total hydrocarbon gases dropped from 74 to 24% by raising T from 500 to 700ºC.


  1. Al-Kassir, A., Gañán-Gómez, J., Mohamad, A.A., Cuerda-Correa, E.M., 2010. A study of energy production from cork residues: sawdust, sandpaper dust, and triturated wood. Energy. 35(1), 382-386.
  2. APCOR's Cork Yearbook 2020.
  3. APCOR's Information Bureau: Cork Sector in Numbers 2019.
  4. Aroso, M.I., Araújo, A.R., Pires, R.A., Reis, R.L., 2017. Cork: current technological developments and future perspectives for this natural, renewable, and sustainable material. ACS Sustainable Chem. Eng. 5(12), 11130-11146.
  5. Basu, P., 2018. Chapter 5-Pyrolysis, in biomass gasification, pyrolysis and torrefaction-practical design and theory, 3rd Academic Press, London, UK. pp. 155-187.
  6. Bento, M.F., Cunha, M.A., Moutinho, A.M.C., Pereira, H., Fortes, M.A., 1992. A mass spectrometry study of thermal dissociation of cork. Int. J. Mass Spectrom. Ion Processes. 112(2-3), 191-204.
  7. Bhatia, S.K., Gurav, R., Choi, T.R., Kim, H.J., Yang, S.Y., Song, H.S., Park, J.Y., Park, Y.L., Han, Y.H., Choi, Y.K., Kim, S.H., Yoon, J.J., Yang, Y.H., 2020. Conversion of waste cooking oil into biodiesel using heterogeneous catalyst derived from cork biochar. Bioresour. Technol. 302, 122872.
  8. Blázquez, G., Pérez, A., Iáñez-Rodríguez, I., Martínez-García, C., Calero, M., 2019. Study of the kinetic parameters of thermal and oxidative degradation of various residual materials. Biomass Bioenergy .124, 13-24.
  9. Cardoso, B., Mestre, A.S., Carvalho, A.P., Pires, J., 2008. Activated carbon derived from cork powder waste by KOH activation: preparation, characterization, and VOCs adsorption. Ind. Eng. Chem. Res. 47(16), 5841-5846.
  10. Carriço, C., Ribeiro, H.M., Marto, J., 2018. Converting cork by-products to ecofriendly cork bioactive ingredients: novel pharmaceutical and cosmetics applications. Ind. Crops. Prod. 125, 72-84.
  11. Castola, V., Marongiu, B., Bighelli, A., Floris, C., Laï, A., Casanova, J., 2005. Extractives of cork (Quercus suber ): chemical composition of dichloromethane and supercritical CO2 extracts. Ind. Crops Prod. 21(1), 65-69.
  12. Chen, H., 2015. Lignocellulose biorefinery engineering: principles and applications, Woodhead Publishing Series in Energy: Number 74. Woodhead Publishing Ltd., Cambridge, UK.
  13. Costa, R., Lourenço, A., Oliveira, V., Pereira, H., 2019. Chemical characterization of cork, phloem, and wood from different Quercus suber provenances and trees. Heliyon. 5(12), e02910.
  14. Dhyani, V., Bhaskar, T.A., 2018. A comprehensive review on the pyrolysis of lignocellulosic biomass. Renewable Energy. 129, 695-716.
  15. Encinar, J.M., Gonzalez, J.F., Gonzalez, J., 2000. Fixed-bed pyrolysis of Cynara cardunculus L. product yields and compositions. Fuel Proc. Technol. 68(3), 209-222.
  16. EPA - United States Environmental Protection Agency, Air Emission Measurement Center (EMC), EMC Promulgated test methods, 2017. Method 11 - Determination of hydrogen sulfide content of fuel gas streams in petroleum refineries.
  17. FAO - State of the World's Forests Report, 2020. The food and agriculture organization (FAO) of the United Nations, Rome, Italy.
  18. Fernandes, E.M., Correlo, V.M., Chagas, J.A.M., Mano, J.F., Reis, R.L., 2011. Properties of new cork-polymer composites: advantages and drawbacks as compared with commercially available fibreboard materials. Compos. Struct. 93(12), 3120-3129.
  19. Fernandes, E.M., Correlo, V.M., Mano, J.F., Reis, R.L., 2015. Cork-polymer biocomposites: mechanical, structural and thermal properties. Mater. Design. 82, 282-289.
  20. Ferreira, R., Garcia, H., Sousa, A.F., Petkovic, M., Lamosa, P., Freire, C.S., Silvestre, A.J., Rebelo, L.P.N., Pereira, C.S., 2012. Suberin isolation process from cork using ionic liquids: characterisation of ensuing products. New J. Chem. 36(10), 2014-2024.
  21. Fukuyama, T., Maetani, S., Ryu I., 2014. 3.22 Carbonylation and Decarbonylation Reactions, in Comprehensive Organic Synthesis: Second Edition. Elsevier Ltd. 3, 1073-1100.
  22. Gil, L., 1997. Powder cork waste: an overview. Biomass Bioenergy. 13, 59-61.
  23. Gil, L., 2009. Cork composites: a review. Materials. 2(3), 776-789.
  24. Guedes, R.E., Luna, A.S., Rodrigues Torres, A.R., 2018. Operating parameters for bio-oil production in biomass pyrolysis: a review. J. Anal. Appl. Pyrolysis. 129, 134-149.
  25. Haq, I., Qaisar, K., Nawaz, A., Akram, F., Mukhtar, H., Zohu, X., Xu, Y., Mumtaz, M.W., Rashid, U., Ghani, W.A.W.A.K., Choong, T.S.Y., 2021. Advances in valorization of lignocellulosic biomass towards energy generation. Catalysts. 11(3), 309.
  26. Houben, D., Evrard, L., Sonnet, P., 2013. Beneficial effects of biochar application to contaminated soils on the bioavailability of Cd, Pb, and Zn and the biomass production of rapeseed (Brassica napus L.). Biomass Bioenergy. 57, 196-204.
  27. Hu, X., Gholizadeh, M., 2019. Biomass pyrolysis: a review of the process development and challenges from initial researches up to the commercialization stage. J. Energy Chem. 39, 109-143.
  28. Iliopoulou, E.F., Triantafyllidis, K.S., Lappas, A.A., 2019. Overview of catalytic upgrading of biomass pyrolysis vapors toward the production of fuels and high-value chemicals. Willey Interdiscip. Rev.: Energy Environ. 8(1), e322.
  29. Irfan, M., Chen, Q., Yue, Y., Pang, R., Lin, Q., Zhao, X., Chen, H., 2016. Co-production of biochar, bio-oil, and syngas from halophyte grass (Achnatherum splendens) under three different pyrolysis temperatures. Bioresour. Technol. 211, 457-463.
  30. Kan, T., Strezov, V., Evans, T.J., 2016. Lignocellulosic biomass pyrolysis: a review of product properties and effects of pyrolysis parameters. Renew. Sust. Energy Rev. 57, 1126-1140.
  31. Lagorce-Tachon, A., Mairesse, F., Karbowiak, T., Gougeon, R.D., Bellat, J.P., Sliwa, T., Simon, J.M., 2018. Contribution of image processing for analyzing the cellular structure of cork. J. Chemom. 32(1), e2988.
  32. Le Barbenchon, L., Girardot, J., Kopp, J.B., Viot, P., 2018. Strain rate effect on the compressive behaviour of reinforced cork agglomerates. EPJ Web Conf. 183, 03018.
  33. Leite, C., Pereira, H., 2017. Cork-containing barks-a review. Front. Mater. 3, 63.
  34. Lu, Q., Yang, X.L., Zhu, X.F., 2008. Analysis on chemical and physical properties of bio-oil pyrolyzed from rice husk. J. Anal. Appl. Pyrolysis. 82(2), 191-198.
  35. Marques, A.V., Pereira, H., 2014. Aliphatic bio-oils from corks: a Py-GC/MS study. J. Anal. Appl. Pyrolysis. 109, 29-40.
  36. Martins, C.I., Gil, V., 2020. Processing-structure-properties of cork polymer composites. Front. Mater. 7, 297.
  37. Mateus, M.M., Bordado, J.C., Santos, R.G., 2016. Potential biofuel from liquefied cork-Higher heating value comparison. Fuel. 174, 114-117.
  38. Mohan, D., Pittman Jr, C.U., Steele, P.H., 2006. Pyrolysis of wood/biomass for bio-oil: a critical review. Energy Fuels. 20(3), 848-889.
  39. Nunes, L.J.R., Matias, J.C.O., Catalão, J.P.S., 2013. Energy recovery from cork industrial waste: production and characterisation of cork pellets. Fuel. 113, 24-30.
  40. Oliveira, F.A.C., Barreiros, M.A., Haeussler, A., Caetano, A.P., Mouquinho, A.I., Oliveira e Silva, P.M.O., Novais, R.M., Pullar, R.C., Abanades, S., 2020. High-performance cork-templated ceria for solar thermochemical hydrogen production via two-step water-splitting cycles. Sustainable Energy Fuels. 4(6), 3077-3089.
  41. Oliveira, F.R., Patel, A.K., Jaisi, D.P., Adhikari, S., Lu, H., Khanal, S.K., 2017. Environmental application of biochar: current status and perspectives. Bioresour. Technol. 246, 110-122.
  42. Órfão, J.J., Antunes, F.J., Figueiredo, J.L., 1999. Pyrolysis kinetics of lignocellulosic materials-three independent reactions model. Fuel. 78(3), 349-358.
  43. Pan, S., Pu, Y., Foston, M., Ragauskas, A.J., 2013. Compositional characterization and pyrolysis of Loblolly pine and Douglas-fir bark. Bioenergy Res. 6(1), 24-34.
  44. Pereira, C.C., Pinho, C., 2013. Determination of fluidized bed combustion kinetic and diffusive data of four wood chars from the central region of Portugal. Energy Fuels. 27(12), 7521-7530.
  45. Pereira, H., 1988. Chemical composition and variability of cork from Quercus suber Wood Sci. Technol. 22(3), 211-218.
  46. Pereira, H., 1992. The thermochemical degradation of cork. Wood Sci. Technol. 26(4), 259-269.
  47. Pereira, H., 2013. Variability of the chemical composition of cork. BioResources. 8(2), 2246-2256.
  48. Pereira, H., 2015. The rationale behind cork properties: a review of structure and chemistry. BioResour. 10(3), 6207-6229.
  49. Pinto, F., Paradela, F., Carvalheiro, F., Duarte, L.C., Costa, P., André, R., 2018. Co-pyrolysis of pre-treated biomass and wastes to produce added value liquid compounds. Chem. Eng. Trans. 65, 211-216.
  50. Ronsse, F., Nachenius, R.W., Prins, W., 2015. Carbonization of biomass, in Pandey, A., Bhaskar, T., Stocker, M., Sukumaran, R. (Eds.) Recent Advances in Thermochemical Conversion of Biomass, 1st; Elsevier, Amsterdam, pp. 293-324.
  51. Ronsse, F., van Hecke, S., Dickinson, D., Prins, W., 2013. Production and characterization of slow pyrolysis biochar: Influence of feedstock type and pyrolysis conditions. GCB Bioenergy. 5(2), 104-115.
  52. Rosa, M.E., Fortes, M.A., 1988. Thermogravimetric analysis of cork. J. Mater. Lett. 7, 1064-1065.
  53. Şen, A., Marques A.V., Gominho J., Pereira, H., 2012. Study of thermochemical treatments of cork in the 150-400 ºC range using colour analysis and FTIR spectroscopy. Ind. Crops Prod. 38, 132-138.
  54. Şen, A., Van den Bulcke, J., Defoirdt, N., Van Acker, J., Pereira, H., 2014. Thermal behaviour of cork and cork components. Thermochim. Acta. 582, 94-100.
  55. Silva, S.P., Sabino, M.A., Fernandes, E.M., Correlo, V.M., Boesel, L.F., Reis, R.L., 2005. Cork: properties, capabilities and applications. Int. Mater. Rev. 50(6), 345-365.
  56. Sousa, A.F., Pinto, P.C., Silvestre, A.J., Neto, C.P., 2006. Triterpenic and other lipophilic components from industrial cork byproducts. J. Agric. Food Chem. 54(18), 6888-6893.
  57. Tan, X.F., Liu, S.B., Liu, Y.G., Gu, Y.L., Zeng, G.M., Hu, X., Wang, X.J., Liu, S.H., Jiang, L.H., 2017. Biochar as potential sustainable precursors for activated carbon production: multiple applications in environmental protection and energy storage. Bioresour. Technol. 227, 359-372.
  58. Teixeira, J., Almeida, A., Freitas, M., Pilão, R., Neto, P., Pereira, I., Ribeiro, A., Ribeiro, A., 2017. Pyrolysis of cork granules: influence of operating variables on char yield. Int. J. Chem. Eng. 9, 16-22.
  59. Uçar, S., Karagöz, S., 2009. The slow pyrolysis of pomegranate seeds: the effect of temperature on the product yields and bio-oil properties. J. Anal. Appl. Pyrolysis. 84(2), 151-156.
  60. Wang, C., Du, Z., Pan, J., Li, J., Yang, Z., 2007. Direct conversion of biomass to bio-petroleum at low temperature. J. Anal. Appl. Pyrolysis. 78(2), 438-444.
  61. Wang, G., Dai, Y., Yang, H., Xiong, Q., Wang, K., Zhou, J., Li, Y., Wang, S., 2020. A review of recent advances in biomass pyrolysis. Energy Fuels. 34(12), 15557-15578.
  62. Wen, J.L., Xue, B.L., Sun, S.L., Sun, R.C., 2013. Quantitative structural characterization and thermal properties of birch lignins after auto-catalyzed organosolv pre-treatment and enzymatic hydrolysis. J. Chem. Technol. Biotechnol. 88(9), 1663-1671.
  63. Xia, C., Cai, L., Zhang, H., Zuo, L., Shi, S., Lam, S., 2021. A review on the modeling and validation of biomass pyrolysis with a focus on product yield and composition. Biofuel Res. J. 8(1), 1296-1315.
  64. Yang, H., Yan, R., Chin, T., Liang, D.T., Chen, H., Zheng, C., 2004. Thermogravimetric analysis-fourier transform infrared analysis of palm oil waste pyrolysis. Energy Fuel. 18(6), 1814-1821.
  65. Yao, F., Wu, Q., Lei, Y., Guo, W., Xu, Y., 2008. Thermal decomposition kinetics of natural fibers: activation energy with dynamic thermogravimetric analysis. Polym. Degrad. Stab. 93(1), 90-98.
  66. Yona, A.M.C., Budija, F., Kričej, B., Kutnar, A., Pavlič, M., Pori, P., Tavzes, C., Petrič, M., 2014. Production of biomaterials from cork: liquefaction in polyhydric alcohols at moderate temperatures. Ind. Crops Prod. 54, 296-301.
  67. Zanzi, R., 2001. Pyrolysis of biomass.PhD. dissertation, Royal Institute of Technology, Stockholm, Sweden.
  68. Zhang, S., Yang, X., Zhang, H., Chu, C., Zheng, K., Ju, M., Liu, L., 2019. Liquefaction of biomass and upgrading of bio-oil: a review. Molecules. 24(12), 2250.