Patent US3700583
As we continue our chronological tramp through Exxon's development of Coal liquefaction technologies, we find that, in 1972, they figured out a way to increase the production of liquids from Coal, and to reduce the waste of Carbon.
Comment follows brief excerpts from:
"United States Patent 3,700,583 - Coal Liquefaction Using Carbon Scavengers
Date: October, 1972
Inventors: James Salamony, Summerville, SC, et. al.
Assignee: Esso Research and Engineering Company
Abstract: Coal liquefaction yields are increased in a liquefaction zone as a slurry in a hydrogen donor solvent in the presence of a carbon radical scavenger ... .
This invention relates to the production of coal liquids from solid coal ... .
One method of converting the coal into a liquid product involves heating the coal ... in a selected solvent (which is) usually an oil derived from the coal.
The coal which is liquefied in this process is ... a bituminous coal, a sub-bituminous coal, lignite, brown coal, and the like.
(In other words: You got Coal, any kind of Coal, we can liquefy it.)
Claims: A process for producing coal liquids, which comprises: liquefying a slurry of coal in a hydrogen donor solvent in the presence of a carbon radical scavenger ... in an amount effective to increase the yield of liquids produced from said coal."
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As is often the case, we must forego reproduction of the overly-tedious technical details.
The "carbon radical scavengers" specified by Esso are inexpensive and available compounds intended simply to prevent, as we understand it, the minute and reactive Coal carbon particles from clinging together and separating out of reactive suspension.
Keeping the Coal particles available for reaction will, thus, "increase the yield of liquids produced".
Of most interest to us, herein, is Esso's confirmation of earlier of our reports, wherein the solvent which can be used to liquefy Coal can itself be "usually an oil,derived from the coal".
And, like many of our selections from the petroleum industry's extraordinary reservoir of Coal liquefaction technologies, this process isn't intended to show us how to liquefy Coal and synthesize liquid hydrocarbon fuels from Coal. It is, rather, a procedure for helping to make such Coal liquefaction processes better and more productive, more profitable.
Exxon/Esso already knew, and had known for a long time, in 1972, that Coal could be liquefied. They were, herein, just finding ways to scavenge more radical profits from the carbon.