Analytical pyrolysis study of different lignin biomass

Lignin represents about 20–30 wt% of the wood content and it is an aromatic polymer composed of phenyl propane units that are connected through ether and condensed (C-C) linkages. It is the major by-product of second-generation bioethanol production. Lignin is a main impurity in the separation of cellulose from wood for pulp and paper. Four different lignins have been selected for this study including Alcell lignin, Kraft lignin and two milled wood lignins (MWL) derived from coniferous trees (softwoods) and deciduous trees (hardwood). Pyrolysis gas chromatography (Py-GC-MS) tests were performed on each sample using CDS 5200 pyrolyser connected to a gas chromatograph with mass spectra Shimadzu GCMS. The pyrolysis products with a phenolic nature obtained by pyrolysis of all four types of lignin has reflected the nature of different lignin origins. The results have shown that more components identified by pyrolysis of MWL (hardwood and softwood) in comparison with commercial lignins (Alcell and Kraft). Components that have been observed via Py-GC-MS analysis indicating that degradation of all four bonds and lead to formation of three main structural units of lignin. The structural analysis of the commercial lignins revealed the partial similarity to the commercially available lignin that means raw materials contains the sufficient aromatics to be used for bio-oil production