Coal Gas

Coal is a mixture of many kinds of materials, organic and inorganic. This heterogeneity is readily seen visually, especially with lower rank coals. Microscopic examination of polished surfaces and thin sections reveals a richness of detail that is quite unexpected to the casual observer. Scientists studying the formation and chemistry of coals have used this kind of information as a useful tool.
Over the years, chemists have analyzed and studied thousands of coal samples using a variety of tools and methods. These include elemental analyses for the major elements, carbon, hydrogen, oxygen, sulfur, and nitrogen, as well as many measurements of the amounts of minor elements such as metals (iron, sodium, calcium, mercury, and so on). Pyrolysis and hydrogenation studies have isolated molecular fragments from the breakdown of the solid structure, identifying hundreds of different organic molecules.
Many coal chemists have attempted to use the resulting information to draw model molecules to represent what a “typical” molecule in the coal might look like. Here for your contemplation are two of the more famous models. They are presented with the knowledge that there are literally dozens more such models, each of which fits the data for some group of coals and each of which can provide stimulus to understanding coal chemistry.
The first rather fanciful model was developed by the late Peter Given, who declared that it was most certainly incorrect but that does an excellent job of portraying the kinds of functional groups we can expect to find in a typical molecule in a typical vitrinite in a typical bituminous coal.