June 19-24, 2016
Lignin is the third-most abundant natural polymer after cellulose and hemicellulose and the only renewable source of aromatics in nature. Moreover lignin is the most relevant waste from industry of paper and bioethanol. Nowadays the common way to dispose it is combustion but the possibility to recovery aromatic moiety from thermochemical conversion of lignin has been received a grown attention. In this field the most promising approach is pyrolysis and particularly interesting is use of microwave (MW) like heating source. Microwave assisted pyrolysis (MAP) was successfully applied in the treatment of plastic materials[5, 6] and biomasses. In this work MAP kraft lignin at reduced pressure was studied to magnify functionalized aromatic moieties recovery. For this reason, MAP processes were performed at different pressure (1 bar, 0.13 bar, 0.013 bar) with and without a fractionating system in a multimode MW batch reactor using carbon like MW absorber. Particularly this study was devoted to correlate quantity and composition of Bio-oils recovered with residence time into reactor. Bio-oils obtained were dark brown liquids and showed a low viscosity and density (close to 1cP and 1 g/mL respectively). The most relevant achievements were gained at residual pressure of 0.013 kPa whit a 37 wt% of Bio-oil collected without fractionating and at residual pressure of 0.013 kPa with fractionating when process was carried out in 9 min. Compositions of Bio-oils were evaluated through 1H-NMR, FT-IR ATR and A quatitative GC-MS method that allowed to evaluation concentration of Bio-oils compounds[8, 9]. Analysis showed high concentration of multisubstituted aromatic ring and few light hydrocarbons/organic acids (C1-C4) from advanced thermal degradation of lignin structure.Data collected showed that MAP at reduced pressure of kraft lignin was a reliable way to process it to recovery high quantity of complex mixture of aromatic compounds.
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Mattia Bartoli, Marco Frediani, Luca Rosi, and Piero Frediani, "Microwave assisted pyrolysis of kraft lignin at reduce pressure in a multimode oven" in "5th International Congress on Green Process Engineering (GPE 2016)", Franco Berruti, Western University, Canada Cedric Briens, Western University, Canada Eds, ECI Symposium Series, (2016). https://dc.engconfintl.org/gpe2016/40