Structural Properties and Molecular Mass Distributions of Biomass-Coal Cogasification Tars as a Function of Aging

This work describes an analytical approach to determine changes in mass distributions and structural properties of biomass/coal co-gasification tars, after storage of these samples as a function of temperature, time and presence of ambient light. The samples examined were tars recovered during the co-gasification of pine and a sub bituminous coal (70:30 wt%). It is shown that the approach used was able to reveal even subtle differences in the tar, which occurred during its ageing under different storage conditions. Precipitation was observed to occur in the tars after <14 hours of storage at >5 °C, and in the presence of ambient light. Size exclusion chromatography and laser desorption mass spectrometry revealed the presence of molecular masses from <200 to >2000 u in the tars. UV-fluorescence spectroscopy provided information on extents of (aromatic) conjugation, providing evidence of sizes of fused-aromatic systems in these tars up to at least 8 rings. The study revealed that the molecules that contained the largest conjugated aromatic ring systems, rather than the molecules with the greatest masses, were primarily involved in the ageing reactions, resulting in precipitation occurring. Different ageing mechanisms were identified depending on whether the tar was stored cold (5°C) in the dark, at room temperature in the dark or in presence of ambient light.

GEORGE Anthe;  LORENTE ROYO Esther;  BERRUECO Cesar;  ÁLVAREZ Patricia;  MILLAN Marcos;  UNGEHEUER Juergen;  ANDERSEN Lars;  MORGAN Trevor; 

2013-08-16

AMER CHEMICAL SOC

JRC76539

0887-0624,   

http://pubs.acs.org/doi/abs/10.1021/ef400375m,    https://publications.jrc.ec.europa.eu/repository/handle/JRC76539,   

10.1021/ef400375m,