Wood and non-wood differ with respect to their anatomical, physical, and
chemical properties, even among their species, resulting in different behaviors
during thermal conversion. Hence, understanding the degradation of these
feedstocks by pyrolysis is attractive to establish biorefinery possibilities for
renewable resources. Additionally, biomass pretreatment technology plays an
important role in many biorefinery processes. Therefore, an approach that
integrates such pretreatment with pyrolysis offers an attractive, novel method
for improving the end-product spectrum (e.g., enriched either with aliphatic or
aromatic constituents). Furthermore, a rapid analytical method for biomass
feedstocks characterization was preliminarily developed through their
pyrolysis product profiles for detecting chemical changes that were taking place
in these feedstocks during different chemical treatments.
In the primary stage of this research, the effect of pyrolysis conditio
ns on
the pyrolysis products of differently-treated feedstocks, from hot-water
extraction (“autohydrolysis”) and soda-anthraquinone (AQ) delignification was
investigated. The further aim was to clarify the difference in the pyrolysis
products of wood materials, including hardwood and softwood, with non-wood materials as well as the pretreatment impact on these feedstocks. Hence,
the thermochemical behavior of woody silver birch (Betula pendula) and
Norway spruce (Picea abies) sawdust, and non-woody okra (Abelmoschus
esculentus) and miscanthus (Miscanthus x giganteus) stalks, both untreated and
after various chemical treatments (hot-water extraction, delignification, and
hot-water extraction followed by delignification), was investigated by
pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The formation
of the pyrolysis products from feedstock samples with varying mass portions of
the structural constituents (cellulose, hemicelluloses, and lignin) were
determined at 500 oC and 700 oC at hold times of 5 s and 20 s. In all cases, major
GC-amenable condensable products were measured semi-quantitatively and
classified into several product groups. Additionally, the formation of pyrolysis
products was found to be characteristically dependent on feedstock
composition and pyrolysis conditions.
In the final stage of research, the main aim was to achieve a better
understanding of the studies on lignocellulosic with respect to their main carbohydrate constituents (cellulose and hemicelluloses, including
glucomannan and xylan) by the same instrument under the same pyrolysis
conditions. Among the product groups, the primary ones, including lactone,
furan, and cyclopentenone derivatives, accounted for 72-85 % (from cellulose),
86-90 % (from glucomannan), and 76-81 % (from xylan) of the total amount of
pyrolysis products determined.
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