We submit herein yet another example of the technology developed by a core team of scientists at California's Chevron, wherein a "slurry", or blend, of fine Coal particles in a carrier fluid is directly hydrogenated and converted into liquid hydrocarbons.
We have made report of closely-related Chevron developments previously, as in:
West Virginia Coal Association | Chevron 1982 Clean Liquid Hydrocarbons | Research & Development; which concerned both:
"United States Patent 4,350,582 - Two-Stage Coal Liquefaction Process; 1982; 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. In the process sub-divided coal is dissolved in a process-derived solvent. The dissolver effluent is passed through a catalytic reactor operating under hydrocracking conditions, to produce normally liquid products and recycle solvent"; and:
"United States Patent 4,358,359 - Two-Stage Coal Liquefaction Process; 1982; 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. In the process subdivided coal is dissolved in a process derived solvent. The dissolver effluent is passed through a catalytic reactor operating under hydrocracking conditions, to produce normally liquid products and recycle solvent. The solvent is further cooled to precipitate unconverted heptane-insolubles prior to recycle to the dissolution stage".
The United States Patent that is the subject of this dispatch represents a further refinement of the Chevron Coal liquefaction technology represented by those Disclosures; and, in plain fact, absent now the technical consultants we once relied on for guidance, we will have difficulty differentiating the technologies for you; that is, explaining how they differ enough, one from the other, to have warranted issuance of separate patents.
However, all these Chevron processes have been cited as precedent art by later Coal conversion inventions, some with intriguing implications; and, we wanted to make certain that we had them all recorded for you before introducing those later developments.
That said, following, with some explanatory comment appended, are excerpts from the initial link to:
"United States Patent 4,379,744 - Coal Liquefaction Process
Date: April, 1983
Inventors: Joel Rosenthal and Arthur Dahlberg, CA
Assignee: Chevron Research Company, San Francisco
Abstract: This invention is a process for liquefying coal in at least two stages, comprising (a) heating a slurry comprising a solid particulate coal, and an externally supplied dispersed dissolution catalyst in the presence of hydrogen in a first reaction zone to substantially dissolve the coal and provide a first effluent slurry having a normally liquid portion comprising solvent and dissolved coal and containing undissolved solids and dispersed dissolution catalyst; and (b) contacting at least a portion of said normally liquid portion containing undissolved solids and dispersed dissolution catalyst with hydrogen in a second reaction zone in the presence of a second externally supplied hydrogenation catalyst under hydrogenation conditions, including a temperature lower than the temperature to which said slurry is heated in step (a), to produce a second effluent slurry having a normally liquid portion. Preferably, the dispersed dissolution catalyst in the first hydrogenation zone is added as an emulsion of aqueous soluble compounds of transition elements, e.g. from Groups IV-B, V-B, VI-B or Group VIII of the Periodic Table.
(The "transition elements" indicated would include such non-exotic stuff as tin, molybdenum, tungsten and vanadium. Not exactly as common and cheap as dirt, but not rare blue diamonds, either.)
Claims: A process for liquefying coal which comprises:
(a) heating a slurry comprising a solvent, particulate coal, and an externally supplied dispersed dissolution catalyst in the presence of hydrogen in a first reaction zone to substantially dissolve the coal and provide a first effluent slurry having a normally liquid portion comprising solvent and dissolved coal and containing undissolved solids and dissolution catalyst; and
(b) contacting at least a portion of said normally liquid portion containing undissolved solids and dissolution catalyst with hydrogen in a second reaction zone in the presence of a second externally supplied hydrogenation catalyst under hydrogenation conditions, including a temperature lower than the temperature to which said slurry is heated in step (a), to produce a second effluent slurry having a normally liquid portion.
A process ... wherein said dispersed dissolution catalyst contains a catalytic element selected from the group consisting of lead, tin, and transition metal elements.
A process ... wherein said dispersed dissolution catalyst is selected from the group of alkali metal or ammonium molybdates, vanadates, or tungstates.
A process ... wherein said dispersed dissolution catalyst is added as an oil-soluble compound of said catalytic element.
A process ... wherein said dispersed dissolution catalyst is added as a particulate metal or compound of said catalytic element.
A process ... wherein said dispersed dissolution catalyst is added as an aqueous-oil emulsion of a water-soluble compound of said catalytic element.
(The claims go on at some even greater length about how the catalyst is to be "added", and it seems that just about any way you can get it in there will be just fine.)
A process ... wherein the second hydrogenation catalyst is present in a packed bed and said portion of said normally liquid portion of said first effluent slurry is passed upwardly through the packed bed in said second reaction zone.
A process ... wherein said second reaction zone is operated at a temperature below about 800 F (and) a pressure from 1000 to 3000 psi ... .
A process ... wherein said second hydrogenation catalyst comprises at least one hydrogenation component selected from Group VI-B and Group VIII, supported on an alumina support.
A process ... wherein said coal is subbituminous coal.
(Although the above claim specifies "subbituminous coal", Chevron explains further on that basically all ranks of Coal, including bituminous, are suitable; but, that, some Coals might have to be pretreated to reduce Iron and adjust Calcium contents.)
A process for liquefying coal which comprises:
(a) heating a slurry comprising a solvent, particulate coal and an externally supplied dispersed dissolution catalyst in the presence of hydrogen in a first reaction zone to substantially dissolve the coal and provide a first effluent slurry having a normally liquid portion comprising solvent and dissolved coal and containing undissolved solids and dissolution catalyst; and
(b) contacting at least a portion of said normally liquid portion containing undissolved solids and dissolution catalyst with hydrogen in a second reaction zone in the presence of a second externally supplied hydrogenation catalyst under hydrogenation conditions, including a temperature lower than the temperature to which said slurry is heated in step (a), to produce a second effluent slurry having a normally liquid portion; and:
(c) separating at least a portion of the insoluble solids from said normally liquid portion of said second effluent slurry to produce a solids-lean carbonaceous liquid containing non-distillable liquid components, and recycling at least a portion of the solids-lean carbonaceous liquid containing non-distillable liquid components to step (a).
(We'll close our excerpts from the lengthy Claims section there, so that we can emphasize the above point that "non-distallable liquid components" are recycled to the initial step of the process, where they can serve as a portion, at least, of the "solvent" in which the solid, particulate raw Coal is "slurried". However, as in other, similar technologies, some liquid hydrocarbon waste streams from conventional petroleum refineries, which are often already "contaminated" with the desired metal catalysts can also be utilized.)
Background and Summary: The present invention relates to the liquefaction of coal to produce a normally liquid product which is low in sulfur and nitrogen and has a high API gravity. The invention also relates to the upgrading of coal/heavy petroleum oil slurries to provide low sulfur, low nitrogen products.
As a consequence of the increasing cost and diminishing supplies of petroleum, much research is being conducted into better ways of obtaining synthetic fuels from solids such as coal and from heavy petroleum oils. 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 and heavy oils contain large amounts of sulfur and nitrogen which necessitate additional costly sulfur and nitrogen removal steps, further increasing the cost of fuels derived from these sources.
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. Numerous problems in prior art processes resulted from the presence of insoluble solids in the liquid product. Typically, the liquid product from a coal liquefaction process has a high molecular weight which makes it very difficult to separate fine insoluble solids, e.g., coal residue. It has generally been taught that these insoluble solids must be separated prior to further processing in order to prevent downstream catalyst deactivation.
Typical of the prior art processes is the Gulf catalytic coal liquefaction process ... .
(See, concerning the above, for one out of now many examples, our report of:
Pittsburgh Gulf Oil 1953 CoalTL | Research & Development; concerning: "US Patent 2,654,675 - Process for Preparing Liquid Hydrocarbons from Coal; 1953; Gulf Research and Development Company, Pittsburgh;
This invention involves an improved combination of steps for preparing liquid hydrocarbon fuels from coal.
Claims: The process of preparing a hydrocarbon fuel from coal which comprises in combination subjecting a first portion of coal to destructive hydrogenation by treatment with hydrogen (and) subjecting a second portion of coal to a simultaneous solvent extraction-hydrogenation".
As we read it, the "simultaneous solvent extraction-hydrogenation" specified above by Gulf is the core of the process of our subject herein, Chevron's "United States Patent 4,379,744 - Coal Liquefaction Process". In Gulf's process, the "solvent" is generated by the "destructive hydrogenation" of Coal itself, while in Chevron's process of "United States Patent 4,379,744" liquid, or semi-liquid, waste streams from petroleum refineries are preferably specified since, we conjecture, they are already contaminated with the needed catalytic metals; which catalysts could, of course, instead, if needed, be simply added, as in Gulf's process of "US Patent 2,654,675", to a Coal-derived solvent.
Keep in mind, too, that, as we've documented in many reports, Pittsburgh's Gulf Oil had, over the course of several decades, developed an extensive body of Coal conversion technology; which, we have speculated, led to them being courted by, and merged with, Standard Oil Company of California, back in the 1980's, to form Chevron in the first place.)
This invention comprises a process for liquefying coal which comprises: heating a slurry comprising a solid particulate coal, and an externally supplied dispersed dissolution catalyst in the presence of hydrogen in a first reaction zone to substantially dissolve the coal and provide a first effluent slurry having a normally liquid portion comprising solvent and dissolved coal and containing undissolved solids and dispersed dissolution catalyst; and contacting at least a portion of said normally liquid portion containing undissolved solids and dispersed dissolution catalyst with hydrogen in a second reaction zone in the presence of a second externally supplied hydrogenation catalyst under hydrogenation conditions, including a temperature lower than the temperature to which said slurry is heated in step (a), to produce a second effluent slurry having a normally liquid portion."
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Again, as we indicated above, the technical nuances of this Chevron Coal liquefaction technology, insofar as they differ from the others, very similar, about which we've reported, are beyond our ability to explain.
It seems, perhaps, to be a "consolidation", as it were, of Chevron's earlier US Patents, "4,350,582 - Two-Stage Coal Liquefaction Process" and "4,358,359 - Two-Stage Coal Liquefaction Process", as cited above, wherein the Coal liquefaction is conducted in one, more or less contiguous, processing stage, with consequent economies in physical plant and material handling/transfer.
In any case, we further note that free, elemental Hydrogen is required for the Coal, and Coal solvent, hydrogenation, to form hydrocarbon liquids; and, we remind you, that, as seen in:
Esso/Exxon 1973 Hydrogen from Coal and Steam | Research & Development; concerning: "United States Patent 3,740,193 - Hydrogen (from) Steam Gasification of Carbonaceous Materials; 1973; Assignee: Esso Research and Engineering Company; Abstract: A hydrogen-rich gaseous stream is produced by contacting in a reaction zone ... a carbonaceous material with steam ... . (Any) carbonaceous material could be used in this process. This would include ... coal (and) wood";
an excess of Hydrogen can be generated by gasifying Coal and Carbon-recycling, renewable organic matter with Steam.
If the Hydrogen generated by the above Exxon process of "United States Patent 3,740,193" were directed to a process such as that disclosed by our subject herein, "US Patent 4,379,744 - Coal Liquefaction Process", that would leave behind some "orphaned" Carbon Monoxide and a smaller amount of Carbon Dioxide, which could, variously and respectively, then be directed into processes such as those disclosed in:
Standard Oil Carbon Monoxide + Water = Gasoline | Research & Development; concerning: "United States Patent 4,559,363 - Process for Reacting Carbon Monoxide and Water; 1985; Abstract: A process for reacting carbon monoxide and water in the presence of a cadmium-containing catalyst ... for the direct production of gasoline"; and:
Texaco Recycles CO2 to Methanol & Methane | Research & Development; concerning: "United States Patent 4,523,981 - Means and Method for Reducing Carbon Dioxide to Provide a Product; 1985;
Assignee: Texaco, Incorporated, NY; Abstract: A process for reducing carbon dioxide to at least one useful product includes two redox couple electrolyte solutions separated by a first membrane having photosensitizers. The carbon dioxide to be reduced is separated from one of the redox couple electrolyte solutions by another membrane having a catalyst. Water provides hydrogen ions which participate in the reduction of carbon dioxide via a separator. In the operation both membranes are illuminated and produce excited solar sensitizers which cause electron transfer from a first redox solution to the second redox solution and then to the carbon dioxide to react with the hydrogen ions, reducing the carbon dioxide to provide at least one product. Claims: A process for reducing carbon dioxide to at least one useful product ... (including) formic acid (and/or) formaldehyde (and.or) methanol (and/or) methane";
and therein be combined with little else but Water, H2O, and be thereby made to form some seemingly desirable products.
Or, as seen in:
Shell Oil Coal + CO2 + H2O = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 7,829,601 - Partial Oxidation Process of a Solid Carbonaceous Feed; 2010; Assignee: Shell Oil Company, Texas; Abstract: The invention is directed to a process for preparing a mixture comprising CO and H2 by operating a partial oxidation process of a solid carbonaceous feed (and) wherein a CO2 containing transport gas is used to transport the solid carbonaceous feed to the burner (and) wherein the solid carbonaceous feed is coal"
we could utilize any excess Carbon Dioxide in a process that would convert both the CO2 and some more of our abundant Coal into a synthesis gas "mixture comprising CO and H2" that would be suitable for catalytic chemical condensation, as via, for one example, the now nearly ancient "Fischer-Tropsch reaction", as is specified by Shell Oil in the full Disclosure of the above-cited "United States Patent 7,829,601", to synthesize even more liquid hydrocarbon fuels.
Again, free and elemental Hydrogen is required by Chevron's "United States Patent 4,379,744 - Coal Liquefaction Process". And, we remind you, that, as seen for just one example in:
West Virginia Coal Association | Germany & Pennsylvania Hydrogen from Hydropower | Research & Development; concerning, in part: "US Patent 6,864,596 - Hydrogen Production from Hydro Power; 2005; Assignees: Voith Siemens Hydropower Generation GmbH and Incorporated, Germany and York, PA";
if we would prefer just to provide Hydrogen to the process, we do have some intriguing, non Coal-consuming Coal-country opportunities available for generating a little Hydrogen, by harnessing some of our available environmental energy resources.
Finally, since we cite one of Texaco's CO2-recycling technologies a little ways above, we remind you that they, too, like Pittsburgh's Gulf Oil in our earlier reference, were, in 2001, themselves merged into the Chevron carbon-converting combine out in California.
Someone really ought to give those good ole' beach boys a call, to see if they wouldn't be interested in at least informing some good ole' Coal-mining hillbillies about the truth of the matter, which is:
Coal, and Carbon Dioxide, can, on a practical basis, both be converted into liquid hydrocarbons.