United States Patent: 4728418

We first note that we have documented a number of times that various technologies for converting Coal into liquid hydrocarbon fuels had been developed at the University of Utah.

 

One of our reports, as accessible via:

Utah High-Speed Coal Liquefaction | Research & Development | News; concerns, primarily: 

"United States Patent 5,783,065 - Method for Coal Liquefaction; 1998; Inventors: Wendell H. Wiser, et. al., Utah; Assignee: University of Utah Research Foundation, Salt Lake City; Abstract: A process is disclosed for coal liquefaction in which minute particles of coal in intimate contact with a hydrogenation catalyst and hydrogen are reacted for a very short time at a temperature in excess of 400C. at a pressure of at least 250 psi to yield over 50% liquids with a liquid to gaseous hydrocarbon ratio in excess of 8:1.; Claims: A method for converting more than 50% by weight coal to liquids";

but, also contains links to other of our reports about the University of Utah's rather impressive body of work in the development of Coal liquefaction processes.

Herein, we submit another example of Coal conversion technology originating at the University of Utah; although one which follows a chemical route somewhat different from most others we've seen from them and other such Coal technology originators over the long course of our reportage.

We present it now because recent Coal-to-liquid achievements by our United States Department of Energy, about which we will soon be reporting, rely upon it as foundational technology; and, the USDOE identifies it specifically as being key to the establishment of new technology that enables the rather direct conversion of all ranks of Coal, in combination with a broad array of biomass materials and organic wastes of various sorts, into hydrocarbon liquids.

Most folks are familiar with the fact that highly-basic, or very alkaline, substances can be corrosive to, can dissolve, or can at least react with, various sorts of organic materials.

By familiar example, the common "lye", typically the compound Sodium Hydroxide for the most part, is known as a "drain cleaner" capable of clearing grease, and other organic material, clogs out of drainage pipes of various sorts.

If you've ever gotten a drop or flake of drain cleaner on your bare hand while trying to clear a drain, and didn't notice it right away and wash it right off, you know that it can be "caustic".

Very basic compounds such as lye react with organic materials via a process known as "hydrolysis", which is a complex collection of chemical reactions that can render water-insoluble biological and other organic materials soluble.

A once-common example of the hydrolysis reaction and it's use, which some old country folks might be familiar with, is in soap making. More can be learned via:   

Hydrolysis - Wikipedia, the free encyclopedia; "Perhaps the oldest commercially practiced example of ester hydrolysis is saponification (formation of soap). It is the hydrolysis of a triglyceride (fat) with an aqueous base such as sodium hydroxide (NaOH). During the process, glycerol is formed, and the fatty acids react with the base, converting them to salts. These salts are called soaps, commonly used in households".

Another, perhaps macabre to some, use of the hydrolysis reaction is a lesser-known alternative to both burial and cremation, wherein human bodies are, through hydrolysis, rendered into a disposable liquid and a small amount of "ash". If interested, see:

The Resomation Process.

Hydrolysis with lye is also a component of some processes for making paper out of wood pulp, as can be learned via:

Black liquor - Wikipedia, the free encyclopedia; wherein it's explained that Sodium Hydroxide, NaOH, or lye, is used to dissolve "Lignin" from raw wood pulp, forming organic-rich "black liquor", and leaving behind cellulose fibers.

The "black liquor" process for separating cellulose is actually dependent upon temperature and pressure, and, it is something we have treated previously in a few reports; although we will, for now, leave fuller exposition and review to our pending report on the recent US Department of Energy innovations noted in our above comments.

However, we will, as well, address that to a certain extent following excerpts from the initial link in this dispatch, disclosing the University of Utah's process for dissolving, "depolymerizing" Coal through the application of a water solution of Sodium Hydroxide:

"United States Patent 4,728,418 - Process for the Low-temperature Depolymerization of Coal and its Conversion to a Hydrocarbon Oil

Process for the low-temperature depolymerization of coal and its conversion to a hydrocarbon oil - University of Utah

Patent US4728418 - Process for the low-temperature depolymerization of coal and its conversion ... - Google Patents

Date: March 1, 1988

Inventors: Joseph Shabtai, UT, and Ikuo Saito, Japan

Assignee: The University of Utah, Salt Lake City

Abstract: A novel process for the low-temperature depolymerization and liquefaction of coal wherein the coal is subjected to sequential processing steps for the cleavage of different types of intercluster linkages during each processing step. A metal chloride catalyst is intercalated in finely crushed coal and the coal is partially depolymerized under mild hydrotreating conditions during the first processing step. In the second processing step the product from the first step is subjected to base-catalyzed depolymerization with an alcoholic solution of an alkali hydroxide, yielding an almost fully depolymerized coal, which is then hydroprocessed with a sulfided cobalt molybdenum catalyst in a third processing step to obtain a hydrocarbon oil as the final product.

Claims: A process for the low temperature depolymerization and liquefaction of fine particles of coal comprising the combined, sequential steps of:

- intercalating the fine particles of coal with a catalytic amount of a metal chloride catalyst;

- a first mild hydrotreating of the intercalated coal to produce a partially depolymerized coal as a first intermediate product mix, said product mix comprising depolymerizated coal particles containing catalyst and an organic liquid;

- separating substantially said coal particles from said organic liquid;

- removing substantially said catalyst from said coal particles;

- recombining said substantially catalyst depleted coal particles and organic liquid;

- reacting said first intermediate product with a base-catalyzed depolymerization agent consisting essentially of an alcoholic solution of an alkali metal hydroxide to produce depolymerized coal as a second intermediate product; and:

- hydroprocessing the second intermediate product with a sulfided cobalt molybdenum catalyst to produce a hydrocarbon oil as a final product.

(Note, in the above, that, as we have seen in many previous reports, some organic compounds in Coal are rather easily extracted through a straightforward solvent process. The initial "organic liquid" can be further processed via fairly standard processes to obtain hydrocarbons. It is the residual Carbon, which might comprise the bulk of the Carbon in Coal, which is being treated, "depolymerized" and liquefied by the process of our subject herein.) 

The process ... wherein the said fine coal particles have a mesh size (as specified, and) wherein the intercalating step comprises dissolving the catalyst in a suitable organic solvent (and) wherein the dissolving step comprises selecting the solvent from the group consisting of acetone, methyl ethyl ketone, diethyl ketone, and other low-boiling ketones.

The process ... wherein the intercalating step comprises selecting the metal chloride catalyst from the group comprising iron chloride and zinc chloride.

(We've previously documented the use of "metal chloride", especially "zinc chloride", or, more generally, "zinc haliide" catalysts in similar and related Coal liquefaction processes. See, for one example:

Consol 1967 Coal Tar to Gasoline | Research & Development | News; concerning: "United States Patent 3,355,376 - Hydrocracking of Polynuclear Hydrocarbons; 1967; Inventor: Everett Gorin, et. al.; Assignee: Consolidation Coal Company; Abstract: Polynuclear aromatic hydrocarbons such as coal extract are hydrogenated in the presence of molten zinc halide catalyst. Claims: (A) process for converting polynuclear aromatic hydrocarbonaceous feedstock to gasoline.") 

The process ... wherein the intercalating step comprises selecting and using a catalytic amount of metal chloride catalyst in an amount of between 1% and 20% by weight of metal chloride catalyst to coal (and) wherein the hydrotreating step comprises operating the process under mild conditions at a temperature within the range on the order of about 225 to 290 C and a hydrogen pressure within the range on the order of about 1000 psig to 2000 psig.

The process ...  wherein the reacting step with a base-catalyzed depolymerization agent is conducted at a temperature within the range on the order of about 225 to 290 C and under an inert gas at a pressure within the range on the order of about 10 psig to 1000 psig to exclude the presence of oxygen (and) wherein the inert gas is nitrogen.

The process ... wherein the reacting step comprises selecting the alkali metal hydroxide from the group consisting of potassium hydroxide and sodium hydroxide.

The process ... wherein the reacting step comprises selecting the alcohol for the alcoholic solution from the group consisting of methanol, ethanol and isopropanol.

(Taking needed "methanol" as an example, although the same is true of "ethanol", as well, we can make it, as seen for only one example in:

Pennsylvania Converts More Coal to Methanol | Research & Development | News; concerning: "United States Patent 5,284,878 - Liquid Phase Methanol Process with CO-rich Recycle; 1994; Assignee: Air Products and Chemicals, Incorporated, Allentown (PA); Methanol is produced by reacting a CO-rich synthesis gas in the presence of a powdered methanol synthesis catalyst suspended in an inert liquid in a liquid phase reactor system. Unreacted CO-rich synthesis gas is recycled to the reactor, thus increasing methanol production and reducing specific power compared with once-through operation without recycle or compared with recycle of hydrogen-rich gas recovered from unreacted synthesis gas. The process preferably is integrated with a coal gasification electric power generation system in which a portion of the unreacted synthesis gas is used as power generation fuel and a portion of the methanol product is used as additional power generation fuel during periods of peak power demand";

from Coal, as well. Or, if we wish to conserve our precious Coal resource, we can, as seen for only one example in: 

California July 2012 Efficient CO2 to Methanol | Research & Development | News; concerning: "United States Patent 8,212,088 - Efficient and Selective Chemical Recycling of Carbon Dioxide to Methanol, Dimethyl Ether and Derived Products; July 3, 2012; Inventors: George Olah and G.K. Surya Prakash, CA; Assignee: University of Southern California, Los Angeles;Abstract: An efficient and environmentally beneficial method of recycling and producing methanol from varied sources of carbon dioxide including flue gases of fossil fuel burning powerplants, industrial exhaust gases or the atmosphere itself. Converting carbon dioxide by chemical or electrochemical reduction secondary treatment to produce essentially methanol, dimethyl ether and derived products. Claims: An environmentally beneficial method of preparing a renewable fuel, which method comprises: obtaining carbon dioxide from a natural or chemical source that would otherwise be present in or discharged into the atmosphere; and producing an energy storage and transportation material or a fuel sufficient to generate energy by hydrogenatively converting the carbon dioxide thus obtained under conditions sufficient to produce methanol as the material or fuel";

make any needed Methanol out of Carbon Dioxide.)

The process ... wherein the hydroprocessing step comprises using a sulfided cobalt molybdenum catalyst prepared as a presulfided cobalt molybdenum on a gamma alumina support and containing 3-6% by weight of cobalt and 8% molybdenum (and) wherein the hydroprocessing step comprises protecting the sulfided cobalt molybdenum catalyst by adding hydrogen sulfide or carbon disulfide to the hydroprocessing step.

(As we've seen for one example in:

Allied Chemical Liquefies Coal with CO & H2S | Research & Development | News; concerning: "United States Patent 4,235,699 - Solubilization of Coal with Hydrogen Sulfide and Carbon Monoxide; 1980; Assignee: Allied Chemical Corporation, NJ; Abstract: Conversion of coal to products soluble in common solvents and conversion of coal tar to products of lower molecular weight, effected in liquid or fused reaction medium using a hydrogenating reactant, are carried out employing hydrogen sulfide and carbon monoxide as the sole or major hydrogenating reactant, without need of elemental hydrogen or a hydrogen donor solvent";

its been known for a number of decades in various quarters that "hydrogen sulfide", as above, can be used to good effect in Coal hydrogenation processes.

And, as seen for example in:

WVU - Coal Liquefaction with Ferric Sulfide | Research & Development | News; "Direct Liquefaction of Coal Using Aerosol-Generated Ferric Sulfide Based Mixed-Metal Catalysts; R. K. Sharma, J. S. MacFadden, A. H. Stiller, and D. B. Dadyburjor; West Virginia University, Morgantown, West Virginia";

metal catalysts which have been "sulfided", perhaps through reaction with Hydrogen Sulfide, have been noted as effective catalysts for Coal conversion and liquefaction processes. Further, as seen in:

More Dow Chemical Direct Coal Hydrogenation | Research & Development | News; concerning: "United States Patent 4,172,814 - Emulsion Catalyst for Hydrogenation Processes; 1979; Assignee: The Dow Chemical Company, MI; Abstract: In the catalytic hydrogenation of a substance in a water-immiscible organic liquid medium, a metallic hydrogenation catalyst is conveniently and effectively dispersed in the reaction mixture by addition as an emulsion of an aqueous solution of a salt of the metal in the liquid medium. The method is particularly applicable to the liquefaction of coal. ... The process ... wherein a hydrocarbonaceous substance is hydrogenated to lower boiling products by contacting a dispersion of said substance in a liquid hydrocarbon medium with hydrogen at elevated temperature and pressure. ... The process ... wherein the metal is molybdenum";

the "molybdenum" specified by our subject, the University of Utah's "United States Patent 4,728,418 - Process for the Low-temperature Depolymerization of Coal and it's Conversion to a Hydrocarbon Oil", has also been noted by others as an effective Coal, or Coal liquid, hydrogenation catalyst.) 

A process for the depolymerizing and liquefaction of coal to produce a high quality hydrocarbon oil comprising the combined, sequential steps (as specified)

The process ... (which) comprises: producing a finely dived coal, intercalating the coal with a metal chloride catalyst in an amount of between 1% and 20% by weight metal chloride catalyst to coal and hydrotreating the intercalated coal under mild conditions (as specified).

The process ... wherein the further depolymerization step comprises conducting the hydrolysis or alcoholysis step as a base-catalyzed depolymerization with an alkali metal hydroxide selected from the group consisting of potassium hydroxide and sodium hydroxide dissolved in an alcohol selected from the group consisting of methanol, ethanol and isopropanol (as specified) and under a nonreactive gas atmosphere to exclude the presence of oxygen.

Background and Field: This invention relates to the production of hydrocarbon oils from coal and, more particularly to a novel process involving the low-temperature depolymerization and liquefaction of coal whereby the depolymerization is achieved through a sequence of processing steps.

Coals vary in rank from peats to anthracites with a spectrum of grades in between such as lignites, sub-bituminous and bituminous coals. The fossilized remains of plant structures in coal indicate that plants were the source material for the coal. It has been commonly assumed that coals were formed by a variety of biodegradative and geochemical transformations of plant debris that have taken place over an extended period of time. The rank of the coal depends on the length and rate of the coalification process. The progress of the coalification of coal from lignite to anthracite results in a general decrease in hydrogen and oxygen contents of the organic matter. Carbon content, on the other hand, increases from about 70% and below in lignite to over 90% in anthracite. Oxygen functionality also varies with rank.

Because of its complexity, it is nearly impossible to assign a specific molecular structure to coal. There is no uniform repeating monomer unit in coal such as is found in saccharides, proteins, and cellulose. Results and interpretations derived from numerous studies of coal liquids, produced by high temperature liquefaction processes, have led to tentative proposals on the structure of coal. A general consensus has been reached that coal is made up of a variety of condensed naphthenoaromatic ring systems designated as "clusters" which are interconnected by linking groups, e.g., etheric groups and short (C1 - C3) alkylene chains. It has also been indicated that coal contains short aliphatic side chains and heteroatoms.

(We're including this extended discussion of background, which we don't usually do, so that those with a bent to such matters can have a better grounding for the more advanced, much more recent USDOE Coal depolymerization technology, about which we will soon be reporting. Those interested in even more chemical detail are urged to access the full patent, and it's associated documents, as accessible via the links.) 

During the 1960's and 1970's sustained efforts to improve and upscale some of the more promising liquefaction procedures were made. Examination of available publications and reports indicates, however, that in most cases optimization was sought mainly by improvement of the engineering aspects of these processes, with relatively lesser attention paid to the possibility of major modifications based on better understanding and control of the critically important organic-chemical aspects of coal liquefaction. This approach apparently did stem to a large extent from the insufficient knowledge on coal structure at a molecular level, as well as from a widely accepted belief that coal can be transformed into a desirable range of liquid products by application of drastic operating conditions, irrespective of its exact chemical structure and inherent chemical properties. The scientific inadequacy of this approach is best illustrated by the marked lack of novelty and imagination in catalyst development for coal liquefaction during the above indicated period.

Both physical and chemical methods have been extensively used in the investigation of coal structure. Physical studies have included application of spectral methods, e.g., X-ray scattering, ultraviolet and visible spectroscopy, reflectance, C-13 nuclear magnetic resonance (CMR), etc., as well as determination of physical properties, e.g. molar refraction, electrical conductivity, molar diamagnetic susceptibility, molar volume, dielectric constant, sound velocity, thermal stability, etc.

Parallel to the work on the engineering improvement of coal liquefaction processes, a large number of studies concerned with the organic chemistry of coal have been reported in the literature. These studies have significantly contributed to the understanding of the chemical functionality of coal, and have provided information on certain types of organic reactions which could be used to affect the extent of its solubilization.

(Again, there is extended discussion of Coal chemistry and molecular structure, which are critically important to the improvement of Coal conversion processes. Those genuinely interested might at least want to familiarize themselves with the terms. The full Disclosure represents a ground-up, analytical approach to the design of Coal liquefaction chemistries that is a departure from previous developments; and, we are not reproducing most of the technical minutia.)


Conventional high-temperature (>375 C) coal liquefaction processes are characterized by low selectivity for light liquid products and preferential production of heavy oils, which require extensive upgrading for use as conventional fuels. Some of the basic problems associated with such processes can be attributed to the relatively limited availability and reliance on data pertaining to coal structure at a molecular level ... .

In view of the numerous efforts to obtain a desirable coal-derived liquid from coal by means of a high temperature, single stage reaction process, and in view of the less than desirable results obtained thereby, it would be a significant advancement in the art to provide a novel, low-temperature process for the depolymerization and liquefaction of coal particularly through several sequential steps which will selectively cleave different types of bonds within the coal in each processing step. Such a novel process is disclosed and claimed herein.

On the basis of the above mentioned structural data, a new approach to low-temperature (less than or equal to 275 C) coal depolymerization was developed. It involves the application of two or more consecutive reaction steps in which different types of intercluster linkages are subjected to selective or preferential cleavage, leading ultimately to a low-molecular weight product. The present invention provides a first example of the use of such a multi-step procedure for conversion of a coal sample into a light hydrocarbon oil.

The procedure ... consists of the following sequential steps:

(1) intercalation (that is, the) deep-seated impregnation of the coal sample with catalytic amounts of a metal halide, in particular ZnCl2 or FeCl3, followed by mild hydrotreatment (HT) of the coal-metal halide intercalate;

(2) base-catalyzed depolymerization (BCD) of the product from step 1; and:

(3) hydroprocessing of the depolymerized product from the two preceding steps with a sulfided CobaltMolybdenum catalyst.

Step 1 results in partial depolymerization of the coal by preferential hydrogenolytic cleavage ... , while step 2 is designed to complete the depolymerization of the product from step 1 by base-catalyzed hydrolysis ... .

In step 3 the final depolymerized product is subjected to hydroprocessing .... .

The overall efficiency of the above depolymerization procedure was determined as a function of experimental variables (temperature, pressure, catalyst concentration, etc.), and suitable conditions for conversion of a coal sample into a light hydrocarbon oil were determined."

---------------------------

As we noted in introductory comments, "base-catalyzed depolymerization" is the same process used to extract "lignin" from "wood pulp", to, in essence, clean the cellulose, and, with the resultant production of what is known as "black liquor", which itself can be further processed into hydrocarbons.

And, since that reaction technology figures in reports to follow, as well, we note that, as seen in: 

 

"United States Patent: 5959167 - Process for Conversion of Lignin to Reformulated Hydrocarbon Gasoline

Patent US5959167 - Process for conversion of lignin to reformulated hydrocarbon gasoline - Google Patents

Date: September 28, 1999

Inventors: Joseph Shabtai, et. al., Utah and Colorado

Assignee: The University of Utah Research Foundation

Abstract: A process for converting lignin into high-quality reformulated hydrocarbon gasoline compositions in high yields is disclosed. The process is a two-stage, catalytic reaction process that produces a reformulated hydrocarbon gasoline product with a controlled amount of aromatics. In the first stage, a lignin material is subjected to a base-catalyzed depolymerization reaction in the presence of a supercritical alcohol as a reaction medium, to thereby produce a depolymerized lignin product. In the second stage, the depolymerized lignin product is subjected to a sequential two-step hydroprocessing reaction to produce a reformulated hydrocarbon gasoline product. In the first hydroprocessing step, the depolymerized lignin is contacted with a hydrodeoxygenation catalyst to produce a hydrodeoxygenated intermediate product. In the second hydroprocessing step, the hydrodeoxygenated intermediate product is contacted with a hydrocracking/ring hydrogenation catalyst to produce the reformulated hydrocarbon gasoline product which includes various desirable naphthenic and paraffinic compounds"; and, in:

"United States Patent: 6172272 - Process for Conversion of Lignin to Reformulated, Partially Oxygenated Gasoline

Patent US6172272 - Process for conversion of lignin to reformulated, partially oxygenated gasoline - Google Patents

Date: January 9, 2001

Inventors: Joseph Shabtai, et. al., Utah and Colorado

Assignee: The University of Utah, Salt Lake City

Abstract: A high-yield process for converting lignin into reformulated, partially oxygenated gasoline compositions of high quality is provided. The process is a two-stage catalytic reaction process that produces a reformulated, partially oxygenated gasoline product with a controlled amount of aromatics. In the first stage of the process, a lignin feed material is subjected to a base-catalyzed depolymerization reaction, followed by a selective hydrocracking reaction which utilizes a superacid catalyst to produce a high oxygen-content depolymerized lignin product mainly composed of alkylated phenols, alkylated alkoxyphenols, and alkylbenzenes. In the second stage of the process, the depolymerized lignin product is subjected to an exhaustive etherification reaction, optionally followed by a partial ring hydrogenation reaction, to produce a reformulated, partially oxygenated/etherified gasoline product ... .

Government Interests: The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant No. XAC-5-14411-01 awarded by the National Renewable Energy Lab and Grant No. AU-8876 and Amendment 1 awarded by Sandia National Labs (DOE Flowthru).

Claims: A process for converting lignin into reformulated, partially oxygenated gasoline, comprising the steps of: (a) providing a lignin material; (b) subjecting the lignin material to a base-catalyzed depolymerization reaction in the presence of a supercritical alcohol, followed by a selective hydrocracking reaction in the presence of a superacid catalyst to produce a high oxygen-content depolymerized lignin product; and: (c) subjecting the depolymerized lignin product to an etherification reaction to produce a reformulated, partially oxygenated/etherified gasoline product.

The process ... wherein the lignin material is selected from the group consisting of Kraft lignins, organosolve lignins, lignins derived from wood products or waste, lignins derived from agricultural products or waste, lignins derived from municipal waste, and combinations thereof. 

The process ... wherein the alcohol is methanol or ethanol";

------------------------

the University of Utah, in efforts led by Joseph Shabtai, went on to develop "base-catalyzed" processes for the "depolymerization" of  renewable "lignin" that could lead directly to "gasoline".

And, note that the USDOE, as evidenced by "Grant No. XAC-5-14411-01 awarded by the National Renewable Energy Lab and Grant No. AU-8876 and Amendment 1 awarded by Sandia National Labs", had become interested enough in "base-catalyzed depolymerization" technology to begin funding it's development.

That USDOE interest, as noted in opening comments, has now led to even additional developments, as we will see, wherein Coal, in combination with the renewable carbon, and CO2-recycling, products enumerated above by the University of Utah, can, through the action of inexpensive reagents like Sodium Hydroxide, and via the process of :"Hydrolysis" discussed in opening comments, be rather directly "depolymerized" and converted into "high quality hydrocarbon oil" and other substitute liquid petroleum products.


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