GC/MS Characterization of Liquids Generated from Low-Temperature Pyrolysis of Wood

Abstract

Conventional pyrolysis of beech wood has been carried out for heating temperatures in the range 600−900 K, reproducing conditions of interest in countercurrent fixed-bed gasification. The yields of liquids (water and tars) increase with the heating temperature from about 40 to 55% of dry wood mass, confirming results previously obtained with a laboratory-scale gasifier. Apart from qualitative identification of ∼90 species, GC/MS techniques have been applied to quantify 40−43% of tars (40 species, with major contributions from acetic acid, hydroxypropanone, hydroxyacetaldehyde, levoglucosan, formic acid, syringol, and 2-furaldehyde). Decomposition of holocellulose leads to the formation of furan derivatives and carbohydrates, with a temperature-dominated selectivity toward hydroxyacetaldehyde against levoglucosan. Syringols and guaiacols, originating from primary degradation of lignin, present a maximum for heating temperatures of about 750−800 K whereas, owing to secondary degradation, phenols continuously increase. A comparison is also provided with fast pyrolysis liquids obtained from four commercial plants.

Lignin pyrolysis reactions

“…The chemical structures of the pyrolysis products of lignins have been evaluated by gas chromatography/mass spectrometry (GC/MS) [10][11][12], nuclear magnetic resonance (NMR) [12][13][14][15][16][17][18] and infrared (IR) spectroscopic [15,[19][20][21] analyses, along with pyrolysis directly coupled with GC/MS [22][23][24][25][26][27][28][29][30][31][32][33][34][35] and IR [19,[36][37][38][39] (Py-GC/MS, Py-IR). Aromatic methoxy groups are stable during the primary pyrolysis stage and become very reactive in the temperature range of 400-450 °C.…”

A model for the evaporation of biomass pyrolysis oil droplets

“…Complete chemical analyses for these fuels are not available: most composition information in the literature is in the form of mass fractions of selected components [5,8,10,13,19,20,21,22], mass fractions of groups (e.g. water-solubles and -insolubles) [5-8, 15, 16], or listings of components without quantitative concentrations [5,7,8,10,11,14,16,19].…”

“…The fuel was assumed to comprise four chemical groups: organic acids, aldehydes and ketones, pyrolytic lignin (lignin decomposition products: phenols, guaiacyl-and syringyl-based compounds, and lignin oligomers), and water. Most pyrolysis oils also contain around 10% of heavier cellulose decomposition products such as levoglucosan and cellobiose [5,7,10,13,22]; these are considered to be a pyrolyzing component and lumped in with the lignin fraction. All fractions were represented by gamma distributions as in earlier work [29,30] with distribution parameters as given in Table 1.…”

“…The main components are organic acids, aldehydes, ketones, phenols, anhydrosugars such as levoglucosan, pyrolytic lignin (comprising guaiacyl-and syringylbased fragments of the original lignin polymer) and substantial quantities of water, typically 25% [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Usually only trace amounts of hydrocarbons are present, the vast majority of the components being oxygenates.…”

Evaluation of Combustion Gas for Carbon Oxide of Wood Coated with Bis-(dialkylaminoalkyl) Phosphinic Acids Additives

“…After the moisture evaporates and the wood dries for a heating process, the complex polymers in wood break down to generate range of gases (H 2 , CO, CO 2 , H 2 O, CH 4 , C 2 H 4 , † Corresponding Author, E-Mail: yjchung@kangwon.ac.kr † TEL: +82-33-540-3121, FAX: +82-33-540-3119 한국화재소방학회 논문지, 제30권 제4호, 2016년 C 2 H 6 ), char and tar, which compose of heavy organic products (such as levoglucosan) that are condensable at ambient temperatures. The char and composition of The gaseous mixture produced by pyrolysis would depend on the type of wood and the heating history of the wood (3) . Cellulose, hemicelluloses, and lignin have specific thermal decomposition temperatures of 240 to 350 o C, 200 to 260 o C, and 280 to 500 o C, respectively (4) .…”