We've previously documented the Coal liquefaction technology that had been under development by California's Chevron, formed by the 1985 merger of Pittsburgh's Gulf Oil and Standard Oil of California.
We, in fact, insinuated that the merger of those two companies might have been motivated by their coincident, and extensive, separate development of Coal liquefaction technologies, which development continued jointly for a time after their 1985 merger.
One of our reports on that circumstance is available as:
Gulf and Chevron Convert Coal to Diesel Fuel and Gasoline | Research & Development;
wherein we documented at least ten technologies related to Coal conversion that had been developed both separately and jointly by Gulf and Chevron immediately prior, and subsequent, to their joining forces.
One of our previous reports documenting Chevron's independent work on Coal liquefaction technology is accessible via:
Chevron 1982 Clean Liquid Hydrocarbons | Research & Development; in which is detailed: "United States Patent 4,350,582 - Two-Stage Coal Liquefaction Process with Process-Derived Solvent; September, 1982; Inventor: Joel Rosenthal, et. al.; Assignee: Chevron Research Company, San Francisco; Abstract: Disclosed is a two-stage process for the production of clean liquid hydrocarbons from coal";
and, we wanted, herein to present yet another Chevron advancement on Coal conversion technology that had been developed coincident with that disclosed in USP 4,350,582, by the same team of Chevron scientists.
Comment follows excerpts from the initial link in this dispatch to:
"United States Patent 4,354,920 - Coal Liquefaction Process
Date: October, 1982
Inventors: Joel Rosenthal, et. al., California
Assignee: Chevron Research Company, San Francisco
Abstract: Disclosed is a two-stage process for the production of liquid hydrocarbons from coal. More particularly, disclosed is a two-stage coal liquefaction process wherein subdivided coal is substantially dissolved in a solvent in a first non-catalytic dissolving stage ... . In a second stage, the mixture of solvent, dissolved coal and insoluble solids is contacted with a hydrocracking catalyst ... . The normally liquid portion of the hydrocracker effluent product has a surprisingly low sulfur content ... .
Claims: A process for liquefying coal, which comprises: forming a coal-solvent slurry by mixing subdivided coal with a solvent;
(And) substantially dissolving said coal in said solvent by heating said slurry in a dissolving zone in the presence of added hydrogen, thereby forming a mixture comprising solvent, dissolved coal, and insoluble solids;
(And, further) contacting at least a portion of said mixture containing insoluble solids with hydrogen in a reaction zone by passing said portion with hydrogen upwardly through a fixed bed of hydrocracking catalyst at (specified conditions);
(And) withdrawing an effluent stream from said reaction zone.
(And) wherein the entire effluent from said dissolving zone is passed through said fixed bed of hydrocracking catalyst in said reaction zone.
(Note: Since free Hydrogen is required herein by Chevron, as it is required in many conventional operations that refine and upgrade natural petroleum, we remind you that we have a number of attractive options available to us for obtaining that Hydrogen. One of special interest might be that described in our report:
USDOE Algae Make Hydrogen for Coal and CO2 Hydrogenation | Research & Development; concerning: "Photosynthetic Hydrogen and Oxygen Production by Green Algae; 1999; USDOE; Abstract: Photosynthesis research at Oak Ridge National Laboratory is focused on hydrogen and oxygen production by green algae in the context of its potential as a renewable fuel and chemical feed stock";
wherein we learn that "bio-reactors" can be designed in which "green algae" would consume Coal-fired power plant exhaust, and produce not only "fuel and chemical feed stock", but, as well, "hydrogen".)
(And) wherein said coal is bituminous coal.
(And) wherein (the) effluent (has) a sulfur content less than 0.1 weight percent, and a nitrogen content less than 0.5 weight percent.
(As we've many times reported: Even "high-sulfur" Coal, can be converted into "low-sulfur" liquids.)
Background and Field: The present invention relates to the liquefaction of coal to produce a normally liquid product which is low in sulfur and nitrogen ... .
As a consequence of the increasing costs and diminishing supplies of petroleum much research is being conducted into better ways of obtaining synthetic fuels from solids such as coal. Furthermore, as a consequence of increased emphasis on the reduction of air pollution, fuels with low sulfur and low nitrogen contents are in great demand. Unfortunately, however, most coals contain large amounts of sulfur and nitrogen which end up in the synthetic liquids produced from the coal which necessitates additional costly sulfur and nitrogen removal steps, further increasing the costs of the synthetic fuels.
Numerous processes are well known in the art for the production of liquid products from coal.
In many processes for coal liquefaction, hydrogen is supplied by a liquid donor solvent. In such processes, the function of any catalyst is to rehydrogenate the solvent by adding molecular hydrogen to it. Thus the solvent acts as a medium to carry hydrogen from the catalyst to the solid coal. However, in such processes the catalyst is typically rapidly deactivated with the result that the process is highly inefficient and not conducive to a commercial coal hydrogenation process.
(We don't, unfortunately, know if the above is true of WVU's "West Virginia Process" for the direct liquefaction of Coal, as it, too, uses "liquid donor solvent". But, we have no information on how, or even if, the WVU reaction is catalyzed, and, if it is catalyzed, whether or not WVU's "catalyst is typically rapidly deactivated".)
Another problem with prior art processes results from the insoluble solids which are contained in the liquid product. Typically, the liquid product from a coal liquefaction process has a high molecular weight. The high molecular weight of the product makes it very difficult to separate the very fine insoluble solids (coal residue). Furthermore, it has generally been taught that these insoluble solids must be separated prior to further processing in order to prevent downstream catalyst deactivation.
A further problem of prior art coal liquefaction processes is that the normally liquid product typically contains 0.2 to 1.0 or more weight percent sulfur and nitrogen. These potential pollutants must be removed in order to produce a valuable clean fuel and the removal of these contaminants requires costly additional hydroprocessing steps which further increase the cost of the product.
Summary and Description: A process for liquefying coal, which comprises: forming a coal-solvent slurry by mixing subdivided coal with a solvent;
(And) substantially dissolving said coal in said solvent by heating said slurry (as specified) thereby forming a mixture comprising solvent, dissolved coal, and insoluble solids;
(And) contacting said mixture in a reaction zone with hydrogen and a hydrocracking catalyst under (specified) hydrocracking conditions ... .
(Once again: "Hydrocracking" is a well-known and long-established conventional petroleum refining technology. It wasn't invented just a few years ago specifically to process Coal liquids.)
(The) normally liquid portion of the product has an extremely low sulfur content of less than 0.10 weight percent and a nitrogen content less than 0.50 weight percent.
One object of the present invention is to provide an improved process for the liquefaction of coal whereby a normally liquid product is obtained ... .
Another object of the present invention is to produce a solids-free, normally liquid product which is particularly useful as a turbine fuel.
Still another object of the present invention is to produce a liquid product from which insoluble coal solids (coal ash) can be more easily and economically removed, for example, by gravity settling.
The basic feedstock of the present invention is a solid subdivided coal such as anthracite, bituminous coal, subbituminous coal, lignite and mixtures thereof. Particularly preferred are the bituminous and subbituminous coals.
The solvent materials are well known in the art and comprise aromatic hydrocarbons which are partially hydrogenated, generally having one or more rings at least partially saturated. Several examples of such materials are tetrahydronaphthalene, dihydronaphthalene, dihydroalkylnaphthalenes, dihydrophenanthrene, dihydroanthracene, dihydrochrysenes and the like. It will be understood that these materials may be obtained from any source, but are most readily available from the product of the present invention."
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We'll close right there to emphasize the critical point: "The solvent materials" needed to convert Coal into "a solids-free, normally liquid product which is particularly useful as a turbine fuel", which is pretty good stuff to have some of if we want to keep our jets flying, "are most readily available from the product of the present invention".
In other words, and in a way similar to most of the direct Coal liquefaction technologies we have already documented for you, much as in:
WVU Hydrogenates Coal Tar | Research & Development; concerning: "Hydrogenation of Naphthalene and Coal Tar Distillate; West Virginia University; 2009; Abstract: The hydrogenation of naphthalene and coal-tar distillates (to form) the hydrogenated product, tetralin ... (for use in the) conversion of coal to refinable crude hydrocarbons, from which liquid fuels such as gasoline, diesel, kerosene, etc., can be produced";
the Hydrogen-donor solvent, needed to convert Coal into "liquid fuels such as gasoline" and Chevron's specified "turbine fuel", is made in and derived from the Coal liquefaction process itself.
The only thing "extra" that really might be needed is molecular, elemental Hydrogen.
And, as seen, for just one further example, in:
Chicago Hydrogen from H2O | Research & Development; which contains discussion of: "United States Patent 4,793,910 - Photoelectrochemical Cell for Unassisted Photocatalysis; 1988; Assignee: Gas Research Institute, Chicago; Abstract: A multielectrode photoelectrochemical cell ... which ... contains two bipolar electrode panels for photoelectrochemical reactions such as water photolysis to produce H2 (and) O2";
we have many options available to us for the economical production of any needed Hydrogen, just as we have many, many options available to us for the economical conversion of our abundant Coal into "gasoline, diesel, kerosene", and, as in our subject, "United States Patent 4,354,920", a more generic, "turbine fuel".