ARTIFICIAL COALIFICATION OF A FOSSIL WOOD FROM BROWN COAL BY CONFINEDSYSTEM PYROLYSIS

Artificial coalification of a sample of fossil wood of lignitic rank b y a confined system pyrolysis in gold tubes reveals that such a simula tion only partially mimics natural coalification processes. Analysis o f gaseous products by gas chromatography, Liquid products by gas chrom atography/mass spectrometry, and solid products by elemental analysis, quantitative solid-state C-13 NMR, and flash pyrolysis/gas chromatogr aphy/mass spectrometry allows mass balance calculations. It is clear t hat, for this sample, confined system pyrolysis reproduces well the na tural transformations of aromatic rings, but the reactions of aliphati c structures, derived predominantly from the side-chain carbons of lig nin, are not simulated by such an artificial maturation process. This partially explains the deviations from the normal van Krevelen diagram observed in most artificial maturation experiments. The primary gaseo us product, CO2, appears to originate from carboxyl and carbonyl group s and the methane, generated during the most severe stages of thermal treatment, appears to derive from methyl substituents on aromatic ring s. The main Liquid products observed are phenols, alkylbenzenes, and n aphthalenes, with the phenolic products predominating at low severity and the naphthalenes and alkylbenzenes at high severity.