The transformation of lignocellulosic biomass into bio‐based commodity chemicals is technically possible. Among thermochemical processes, fast pyrolysis, a relatively mature technology that has now reached a commercial level, produces a high yield of an organic‐rich liquid stream. Despite recent efforts to elucidate the degradation paths of biomass during pyrolysis, the selectivity and recovery rates of bio‐compounds remain low. In an attempt to clarify the general degradation scheme of biomass fast pyrolysis and provide a quantitative insight, the use of fast pyrolysis microreactors is combined with spectroscopic techniques (i.e., mass spectrometry and NMR spectroscopy) and mixtures of unlabeled and 13C‐enriched materials. The first stage of the work aimed to select the type of reactor to use to ensure control of the pyrolysis regime. A comparison of the chemical fragmentation patterns of “primary” fast pyrolysis volatiles detected by using GC‐MS between two small‐scale microreactors showed the inevitable occurrence of secondary reactions. In the second stage, liquid fractions that are also made of primary fast pyrolysis condensates were analyzed by using quantitative liquid‐state 13C NMR spectroscopy to provide a quantitative distribution of functional groups. The compilation of these results into a map that displays the distribution of functional groups according to the individual and main constituents of biomass (i.e., hemicelluloses, cellulose and lignin) confirmed the origin of individual chemicals within the fast pyrolysis liquids.

PEGylated or oxyethylated lignins (OEL) have recently become a hot topic as precursors for novel lignin-based and sustainable materials or active substances such as hydrogels, aerogels, carbogels, dispersants, and surfactants. Since functional properties of OEL and the resulting materials are strongly affected by the degree of oxyethylation (DOE) of phenolic hydroxyl groups (OHphen), analytical techniques for its determination are crucial. OELs with different levels of modification were obtained by reacting lignins from different pulping procedures with varying amounts of poly­(ethylene) glycol-α,ω-diglycidyl ether (PEGDGE). Parent lignins and OELs were characterized by means of selective aminolysis that is subsequent preacetylation and selective deacetylation of aromatic acetates of preacetylated lignin/OEL with pyrrolidine. The reaction product 1-acetyl pyrrolidine was quantified using GC/FID. The DOE of OEL, obtained by subtraction of OHphen content before and after lignin oxyethylation, was found to be in the range between 53.4% and 70.0%. Selective aminolysis has been shown to be very accurate for OEL analysis but is very time-consuming. Thus, it was the aim to investigate the extent to which FTIR features of acetylated lignin and OEL relate to OHphen contents and DOE of OEL as obtained by aminolysis. Strong linear correlations (R 2 = 0.94–0.97) were found between OHphen contents of lignin/OEL and IR vibrations related to phenolic and aliphatic acetoxy groups. The results demonstrate that, with appropriate calibration, FTIR spectroscopy combined with sample preacetylation is a promising tool for a rapid and accurate determination of the DOE of OELs.

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Fast pyrolysis of water-insoluble (W-I) tannins-mainly composed of condensed tannins-obtained from Pinus radiata bark methanol-water extraction was carried out in pursuit of a renewable source of high-value chemicals, in particular catechols. Micropyrolysis in an isothermal furnace unit (Py-GC-MS/FID) was performed between 450-600°C. Catechin and W-I tannins were compared to establish thermal degradation behavior between this fraction and its representative monomer constituent. Additionally, W-I tannins were compared with typical sources of renewable phenols such as pine bark and organosolv-lignin in order to highlight its potential. Benchscale experiments of W-I tannins were performed in a fluidized bed reactor between 400-600°C to provide information related to yield and concentration of catechols. The Py-GC-MS/FID results showed that W-I tannins are prolific of catechol and 4-methylcatechol, similar to their most abundant monomer constituent catechin. However, W-I tannins are not only composed of condensed tannins and some substituted polycyclic aromatic hydrocarbons, triterpenes and carbohydrate-derived compounds were detected. The comparison of pyrolysis products among the renewable sources of phenols showed that W-I tannins yielded the highest relative content of catechols while guaiacols and carbohydrate-derived compounds predominated in the composition of lignin and bark products, respectively. The optimal pyrolysis-oil yield for bench scale assays (37 wt%) was found at 550°C and maximum yield of both catechol (4.4 wt%) and 4methylcatechol (2.3 wt%) were also obtained at 550°C.

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