Buried deep within this Exxon exposition of Coal liquefaction technology is the statement, which won't be repeated in our fuller excerpts:
"Tetralin has a donatable hydrogen concentration of about 3.0 weight percent and is therefore an extremely good hydrogen-donor solvent."
That is the only place that Tetralin, the hydrogenated derivative of the primary Coal oil, Naphthalene, which we believe, as indicated to us, for one example, in:
WVU Hydrogenates Coal Tar | Research & Development; concerning: "Hydrogenation of Naphthalene and Coal Tar Distillate; Abhijit Bhagavatula; West Virginia University, 2009";
to be the Hydrogen donor solvent specified by WVU, in their own "West Virginia Process" for the direct liquefaction of Coal, is actually specifically named.
Other than that, Exxon does specify the use of some free, elemental Hydrogen, which would be needed, in any case, to hydrogenate the Naphthalene, in the Coal liquefaction process they disclose herein; and, they explain how such Hydrogen can be produced by the further processing of by-products generated by the Coal conversion process itself, as in:
"Plants for carrying out processes of this type normally include facilities for generation of the needed molecular hydrogen by the gasification of heavy liquefaction bottoms produced in the liquefaction step, by the coking of liquefaction bottoms and subsequent gasification of the resultant coke, by the reforming of light hydrocarbon liquids and gases produced in the process, or by other means."
We'll have further comment concerning the need for Hydrogen, following excerpts from the initial link to:
"United States Patent 4,345,989 - Catalytic Hydrogen-donor Liquefaction Process
Date: August, 1982
Inventors: Lonnie Vernon, et. al., TX and NJ
Assignee: Exxon Research and Engineering Company, NJ
Abstract: Coal or a similar solid carbonaceous feed material is converted into lower molecular weight liquid hydrocarbons by contacting the feed material with a hydrogen-donor solvent containing above about 0.6 weight percent donatable hydrogen and molecular hydrogen in a liquefaction zone or a series of two or more liquefaction zones under liquefaction conditions in the presence of an added carbon-alkali metal catalyst comprising a carbon-alkali metal reaction product prepared by heating an intimate mixture of carbonaceous solids and an alkali metal constituent to a temperature above about 800 F. in a reaction zone external to the liquefaction zone.
Claims: A catalytic hydrogen-donor liquefaction process for converting a solid carbonaceous feed material into lower molecular weight liquid hydrocarbons which comprises contacting said feed material with a hydrogen-donor solvent ... and a hydrogen-containing gas in ... the presence of an added carbon-alkali metal catalyst comprising a carbon-alkali metal reaction product prepared by partially gasifying an intimate mixture of carbonaceous solids and an alkali metal constituent with steam in a reaction zone external to said liquefaction zone.
(And) wherein said solid carbonaceous feed material comprises coal.
(And) wherein said alkali metal compound comprises potassium carbonate or potassium hydroxide.
(Nothing too exotic, too expensive, or hard to come by.)
(And) wherein said hydrogen-containing gas comprises molecular hydrogen.
A process ... including the additional steps of recovering a heavy liquefaction bottoms fraction ... from the effluent of said final liquefaction zone; adding an alkali metal compound to said bottoms fraction to form an intimate mixture of said bottoms and said alkali metal compound; pyrolyzing said intimate mixture of said bottoms and said alkali metal compound to produce coke; gasifying said coke in the presence of steam; and using said gasified coke in each liquefaction zone in said series of liquefaction zones as said carbon-alkali metal catalyst.
(Note, that: "gasifying said coke in the presence of steam'" would generate some of any H2 needed.)
Background: This invention relates to coal liquefaction and is particularly concerned with catalytic hydrogen-donor coal liquefaction.
Processes for the direct liquefaction of coal and similar carbonaceous solids normally require contacting of the solid feed material with a hydrocarbon solvent and molecular hydrogen at elevated temperature and pressure to break down the complex high molecular weight starting material into lower molecular weight hydrocarbon liquids and gases. The most promising processes of this type are those carried out with a hydrogen-donor solvent which gives up hydrogen atoms in reaction with organic radicals liberated from coal or other feed material during the liquefaction step. In such a process, the hydrogen-donor solvent is subsequently regenerated in a downstream solvent hydrogenation step. Plants for carrying out processes of this type normally include facilities for generation of the needed molecular hydrogen by the gasification of heavy liquefaction bottoms produced in the liquefaction step, by the coking of liquefaction bottoms and subsequent gasification of the resultant coke, by the reforming of light hydrocarbon liquids and gases produced in the process, or by other means.
Summary: The present invention provides an improved process for converting coal or similar liquefiable solid carbonaceous feed material into lower molecular weight liquid hydrocarbons ... .
In accordance with the invention, it has now been found that high yields of liquid products can be obtained from bituminous coal, subbituminous coal, lignite or similar solid carbonaceous feed materials by contacting the feed material with a hydrogen-donor solvent ... and a hydrogen-containing gas, preferably molecular hydrogen, in a liquefaction zone under liquefaction conditions in the presence of an added carbon-alkali metal catalyst (as specified).
In the embodiments of the invention described ..., a portion of the solid carbonaceous feed material will remain unconverted after passing through the liquefaction zone or zones and is normally further converted in order to utilize the remaining carbon and thereby provide further economies to the overall liquefaction process. The further conversion will normally be carried out by gasifying the liquefaction bottoms or by coking the liquefaction bottoms and subsequently gasifying the resultant coke.
(The gasification of the carbonaceous residues is done with Steam, with the resultant production of useful Carbon Monoxide and Hydrogen.)
The feed material employed will normally consist of solid particles of bituminous coal, subbituminous coal, lignite, brown coal, or a mixture of two or more such materials. In lieu of coal, other solid carbonaceous materials may be introduced into the slurry preparation zone. Such materials include organic wastes ... .
(Yet again, as in the use, along with Coal, of "organic wastes", the potential for some Carbon recycling, via Coal liquefaction processing, does exist.)
The hydrogen-donor solvent used in preparing the slurry ... will normally be a coal-derived solvent, preferably a hydrogenated recycle solvent ... generally employed in coal liquefaction reactors.
(Did anyone, does anyone, any common citizen, in US Coal Country know that the conversion of Coal, into liquid hydrocarbons, is so common that a phrase like "generallyemployed in coal liquefaction reactors" could, with a straight face, be used?)
Representative compounds of this type include ... tetrahydronaphthalenes (i.e., "Tetralin"s.)
Such solvents have been described in the literature and will therefore be familiar to those skilled in the art.
(Far past time we all started reading "the literature", and getting ourselves "skilled", ain't it?)
The solvent composition resulting from the hydrogenation of a recycle solvent fraction will depend in part upon the particular coal used as the feedstock to the process, the process steps and operating conditions employed, and the conditions used in hydrogenating the solvent fractions selected for recycle following liquefaction.
The process of the invention is based in part upon the discovery that the heating of an intimate mixture of carbonaceous solids and an alkali metal constituent, preferably by partial steam gasification, ... will result in the formation of a carbon-alkali metal reaction product that exhibits hydrogenation activity and when introduced into a liquefaction zone is effective in increasing the conversion of high molecular weight solid carbonaceous feed material into lower molecular weight liquids in the presence of a hydrogen-donor solvent and molecular hydrogen."
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We don't have much to add, really.
Just note, again, that, at least some of the needed Hydrogen can be obtained, as above, by "gasifying the liquefaction bottoms" with Steam.
Or, as can be learned in:
Florida Hydrogen and Sulfur from H2S | Research & Development; concerning: "United States Patent 6,572,829 - Photocatalytic Process for Decomposing Hydrogen Sulfide; 2003; Assignee: University of Central Florida; Abstract: System for separating hydrogen and sulfur from hydrogen sulfide (H2S) gas produced from oil and gas waste streams";
we can just make some from the noxious effluents of conventional petroleum and natural gas refineries.
And, there shouldn't be much to add, since, as herein, three decades ago, as confirmed by our own US Government, there were, it seems, a whole flock of people out there, somewhere, who were "skilled in the art" of making "lower molecular weight liquid hydrocarbons" out of our abundant Coal.
What, do you suppose, ever became of them; and, of their "art"?