Coal liquefaction chemical functions

The significance of the above-described work is that in all of the presently developing coal liquefaction processes, the initial step in the conversion is thermal fragmentation of the coal structure to produce very fragile molecules which are highly functional, low in solubility, and extremely reactive toward dehydrogenation and char formation. A more detailed discussion of the chemical nature of these initial products has been presented elsewhere (4). ... 

A corollary of this statement is the following If these polyaromatic or polycyclic saturated structures are present in the carbon skeleton of coal, they should be identified in the short-contact-time liquefaction products. The possibility of some isomerization reactions in the carbon skeleton cannot be excluded totally, but the most important fact is that no dramatic aromatization of hydroaromatic rings or saturation of aromatic rings takes place under these conditions. Many of the chemical functions also are stable under these conditions, especially the O, S, and N heterocyclic aromatic structures. Water formation by phenol dehydroxylation is minimal. In coal liquefaction under our conditions, even at long reaction times (up to 90 min) in the absence of an added catalyst, the -OH bonded to a monoaromatic ring is stable. Under the same conditions, dehydroxylation of polyaromatic phenols does occur (10). 

Petroleum chemicals fulfill two functions. They provide alternative and more economic routes to existing chemicals already made from other raw materials, and they lead to new industrial chemicals. The reactions of and outlets for chemicals more economically synthesized from petroleum have already been worked out, although perhaps not completely, in connection with the older routes. Those countries not favored with petroleum as an economic raw material have had to make use of alternative sources for these chemicals. In surveying the literature, it is, therefore, necessary to take account of the history of those petroleum chemicals which have been made from alternative sources. The reactions of methane are the same whether it is obtained from natural gas or as a by-product of the hydrogenation of coal or as a fraction in the liquefaction of coke oven gas depending on the source, the economics may be quite different. 

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