Last summer, as accessible via:
Exxon Improves Coal Liquefaction with Hydrogen Sulfide | Research & Development | News;
we sent you information concerning Exxon's development of Coal liquefaction technology as disclosed by:
"United States Patent 4,094,765 - Coal Liquefaction Process; 1978; Exxon Research and Engineering Company; Abstract: A coal liquefaction chargestock is first treated with a hydrogen sulfide-containing gas and thereafter subjected to coal liquefaction conditions"; wherein Hydrogen Sulfide, H2S, an otherwise objectionable product - even though it is closely related, on an elemental basis, to plain old Water, H2O - can be utilized, as can Water, in other, somewhat related, Coal liquefaction processes, to help promote the hydrogenation and liquefaction of Coal.
Herein, via the initial link in this dispatch, we see that the same team of Exxon scientists continued their research into the use of Hydrogen Sulfide in such Coal Liquefaction processes, and, a year later, were awarded another US Patent for what is clearly-stated by them to be closely-related technology.
Comment follows excerpts from:
"United States Patent 4,149,959 - Coal Liquefaction Process
Date: April, 1979
Inventors: Roby Beardon, et. al., Louisiana
Assignee: Exxon Research and Engineering Company, NJ
Abstract: A coal liquefaction chargestock is first treated with a gaseous mixture comprising ... hydrogen sulfide ... and thereafter subjected to coal liquefaction conditions.
This application is a continuation-in-part of U.S. application Ser. No. 751,385 now U.S. Pat. No. 4,094,765.
Claims: A process for the liquefaction of coal, which comprises ... treating a slurry comprising coal and a hydrogen donor diluent with a gaseous mixture comprising ... hydrogen sulfide (in specified amounts, under specified conditions).
Background and Description: The present invention relates to an improved coal liquefaction process. More particularly, the invention relates to a process comprising pretreatment of a coal liquefaction chargestock followed by coal liquefaction.
Coal liquefaction processes in which coal with or without a diluent is subjected to elevated temperatures and pressures to convert the coal to normally liquid hydrocarbonaceous products are well known.
Suitable aromatic hydrogen donor diluents (for use in the process) include hydrogenated creosote oil (and) other coal-derived liquids which are rich in ... tetralins ... and similar donor compounds.
It has now been found that pretreatment of the coal liquefaction feed with a hydrogen sulfide-containing gas for a specific residence time at a given temperature gives improved coal liquefaction results such as coke suppression and an increase of liquid yield."
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An objection that could be reflexively raised is that the Coal liquids would thus contain added Sulfur.
They would.
And, just like natural petroleum, some of which contains very high levels of Sulfur, the Sulfur entrained in Coal liquids, produced through Exxon's Hydrogen Sulfide-enhanced Coal liquefaction processes, could then be treated in "hydro-refining" units; petroleum processors that are fairly standard components of many modern conventional oil refineries that are already equipped to process high-Sulfur natural crude.
The Sulfur is recovered in such "hydro-processors", or "hydro-refiners", as we have been informed by consultants we believe to be knowledgeable, as Hydrogen Sulfide, which could then, it seems, be recycled back into the Coal liquefaction process, as defined by Exxon herein, to assist in the liquefaction of even more raw Coal.