Pyrolytic lignin

Pressure filtration of the liquid is very difficult due to the complex interaction of the char and pyrolytic lignin, which appears to form a gel-like phase that rapidly blocks the filter. Modification of the liquid micro-structure by addition of solvents such as methanol or ethanol that solubilise the less soluble constituents will improve this problem and also contribute to improvements in liquid stability as described below. 

Scholze B. Meier D. (2000) Characterization of the water-insoluble fraction from pyrolysis oil (pyrolytic lignin), Part I. Py- GC/MS, FTIR, and functional groups, J. Anal. Appl. Pyrolysis, in press. 

The main objective of the lEA PYRA Round Robin was to determine the interlaboratory precision and methods applied for elemental composition, water, pyrolytic lignin and main cotiqjounds. Two poplar oils were analysed by the lEA PYRA participants. It was concluded that the precision of carbon and hydrogen was very good, liquid sample handling plays a very important role in the C, H analysis, water by Karl-Fischer titration was acceptable, but should be checked carefully, and the method for the determination of pyrolytic lignin should be improved (3). 

Table 5.7.1. Assignments for the most important peaks in the C NMR spectrum of pyrolytic lignin.

Liquids obtained by fast pyrolysis of four different woods were analysed. On addition of excess water they separated into water-soluble and water-insoluble fractions. The former which is principally of carbohydrate origin was shown by HPLC analysis to consist of sugars, anhydrosugars and low molecular weight carbonyl compounds. The latter was shown by NMR to be a "pyrolytic lignin". In this way 81% to 92% of the organic content of the liquids has been characterised. 

Figure 2. C NMR spectra of A) milled wood lignin B) steam exploded lignin (from Marchessault et al [15]) C) Waterloo pyrolytic lignin. All from poplar wood.

Nsimba RY, Mullen CA, West NM, Boateng AA (2013) Structure-property characteristics of pyrolytic lignins derived from fast pyrolysis of a lignin rich biomass extract. ACS Sus Chem Eng 1 260... 

Water analysis of liquids was by Karl Fischer titration. Liquids were analyzed by GC for qualitative or semi-quantitative characterization. Quantitative analysis of selected liquid components was performed by HPLC. The sample was prepared by diluting it with two parts water to cause phase separation of pyrolytic lignin. Simple sugars, anhydrosugars, and other lower molecular weight components such as acetic acid and hydroxyacetaldehyde remain in the aqueous phase. 

Pyrolytic lignin is a major component of the bio-oil that is produced when whole biomass is pyrolyzed. Reacting pyrolytic lignin over HZSM-5 in a fixed-bed reactor... 

Methoxyphenols (e.g., guaiacol), 2,6-Dimethoxyphe-nols (eg., syringol), Catechols, Phenol, Alkyl phenols. Methanol, Other oxygenated aromatics (e.g., coumaran), furfural, acetic acid, other Cj-C4 oxygenates (e.g., formaldehyde, formic acid, acetone, acetol, lactones, etc.), pyrolytic lignin Extractives (e.g., terpenes). Charcoal, Pyrolysis oil. Gases (e.g., CO, CO2, CH4)... 

As described in the previous section, methanol addition increases the H/C ratio, resulting in an increased hydrocarbon yield. Moreover, co-feeding of methanol (around 70wt%) also decreases the cataljdic deactivation. Methanol inhibits condensation reactions between different products and consequently minimizes the pyrolytic lignin deposition within and outside the catalyst particles [245]. Next to methanol addition, water addition is effective... 

Gayubo AG, Valle B, Aguayo AT, Olazar M, Bilbao J. Pyrolytic lignin removal for the valorization of biomass pyrolysis crude bio-oU by catalytic transformation. J Chem Technol Biotechnol 2010 85 132-44. 

Zhao Y, Deng L, Liao B, Fu Y, Guo Q-X. Aromatics production via catalytic pyrolysis of pyrolytic lignins from bio-oU. Energy Fuels 2010 24 5735-40. 

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