Pyrolysis behavior of alternative cork species

Abstract

Pyrolysis is a useful technique in the characterization of the thermal behavior, kinetics and chemical composition of new materials. Alternative cork feedstocks are obtained from tree species possessing cork-enriched outer barks that are currently unused and could be used in thermal applications such as pyrolysis or gasification. An understanding of their thermal reactions is required, and this study is set to explore the pyrolysis behavior of alternative cork feedstocks from Quercus cerris, Beaucarnea recurvata and Betula pendula. Thermogravimetric analyses were carried out, and kinetics of the pyrolysis reaction were evaluated with isoconversional Vyazovkin method. The application of pyrolysis for estimation of the chemical composition of the corks of these species was also evaluated using Lorentzian multi-peak fitting. Wet chemical and FT-IR analyses were performed to determine the chemical composition of the corks and to compare the Lorentzian multi-peak fitting estimations. The results show that corks from different species have different pyrolytic degradation patterns. Pyrolysis of cork takes place in three major steps and two complementary steps. Lignin as well as suberin contents determine the thermal reactivity of cork. Desuberinised cork shows higher heat resistance at high temperatures than raw cork. Activation energy of cork varies between different species. Lorentzian multi-peak fitting could be used to estimate the chemical composition of cork as an alternative method to wet-chemical methods.