Maria Sobkowiak

Determination of the aliphatic and aromatic CH contents of coals by FT-i.r.: studies of coal extracts

Abstract The pyridine-soluble extracts of 44 US coals and 17 Polish coals were characterized by FT-i.r. and proton n.m.r., allowing the determination of absorption coefficients for aliphatic and aromatic vibrational modes. Various aspects of methodology are discussed and it is demonstrated that the absorption coefficients of the stretching modes vary not only with rank — lignite and subbituminous coals being different from bituminous coals — but also with the origin of the parent coal. It is also demonstrated that the use of the out-of-plane bending modes to determine aromatic CH content introduces a systematic error into the results; although the size of this error remains undefined at this point, it is probably small.

Determination of aromatic and aliphatic CH groups in coal by FT-i.r.: 1. Studies of coal extracts

Abstract A set of coal extracts have been characterized by FT-i.r. and proton n.m.r. spectroscopy. The n.m.r. measurements of aliphatic and aromatic hydrogen allow a direct calibration of the absorption coefficients of appropriate i.r. bands. This allows methods for calculating these coefficients based on relating i.r.-band intensities to elemental hydrogen to be tested directly. Reasonable agreement was obtained.