Spectra of Coals and Coal Extracts: Proton Magnetic Resonance Spectra of Pyridine and Carbon Disulfide Extracts

Abstract

High-resolution proton magnetic resonance (¹H NMR) spectrometry is a technique that can be used to study the hydrogen distribution in liquid products and soluble materials from coal. The relative amounts of aromatic hydrogen, benzylic hydrogen, and other nonaromatic hydrogen can be determined directly. Because all protons have essentially the same NMR sensitivity, no intensity calibration of the spectrometer is required; thus, in this respect, ¹H NMR is far superior to many other techniques used in the investigation of coal structure. Unfortunately, high-resolution NMR is not applicable to whole coals, since the dipole-dipole interactions in solids generally prevent the observation of chemically shifted NMR absorption areas.⁽¹⁾ Nevertheless, coal extracts, which often represent a large amount of the whole coals, can be studied by the technique. The properties of extracts are thought to be similar to those of the whole coals from which they are derived.

Much of the experimental work was done while one of us (H.L.R.) was a Resident Industrial Scholar at Carnegie—Mellon University under the sponsorship of the Materials Advisory Panel, Pennsylvania Technical Assistance Program (MAP-PENNTAP).