US 2476999 A
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UNITED STATES PATENT- OFFICE sows-non or r V rchin, United States of America as represented Pa While thesecretaryofthelntcrior No Drawing. Appli Serial N cation July 187,
Claims. (01. 10614) (Granted under the act of amended April 8., 1m;
The invention herein described and claimed may be manufactured and used by'or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
This invention relates to the conversion of solid carbonaceous materials, such as bituminous and subbituminous coals, lignites, peat and the like, to liquid products of enhanced value and utility. When such materials are treated in accordance with the invention the primary products are extracts containing little or no ash and which are suitable for direct use as. fuels or for use as raw materials for the production of industrial products such as carbon black. Such extracts of low ash content likewise may be used in hydrogenation processes for the production of synthetic liquid fuels corresponding to gasoline, kerosene, Diesel fuels and the like from petroleum sources.
Because of the highly aromatic character of the hydrogenation products 01' such extracts this process provides a means for greatly increasing the potential supply of benzene, toluene and related compounds.
It is an object of my invention to secure the solution of solid carbonizable fuels under the mildest possible conditions whereby secondary reactions will be minimized. A further object of the invention is the improvement of hydrogenation of coal and the like as an extract utilizing for the vehicle selected liquid fractions produced by the hydrogenation of such extracts. Other objects will be apparent from the following description.
A number of processes are known for the extraction of solid pyrobituminous materials such as coal, lignite, peat and the like. In general, all of these processes involve the use as the treating vehicle of mixtures comprising phenols and tetrahydronaphthalene as described, for example, in Pott and Broche Patent 2,147,753 and Pier and Donath Patent 2,215,190. In these prior art methods the ratio of hydrocarbon to phenols in the solvent mixture is customarily about 4:1.
I have found that greatly improved yields of soluble materials can be secured by the use as the solvent vehicle of dicyclic hydro-aromatic compounds containing a phenolic hydroxyl group. Examples of such compounds which are particularly efiective are orthoand para-cyclohexylphenol and tetrahydronaphthols, such as 1,23,4- tetrahydro-5-hydroxynaphthalene.
These solvents normally are employed in about equal parts by weight with the solid carbonizable fuel being extracted, that is a ratio of from 1:1 to
March 1, 1883, a 37. O- G. 78'" 3:2. Under some conditions of operations however the amount of solvent may be increased. al- 1 though in general it is not necessary or desirable to exceed a ratio of about 4:1.
The extraction is'carried out using finely ground or comminuted coal, limits and the like with the solvent in the desired ratio, under pressures of about 500 pounds per square inch and at temperatures or about 400 C. while the pressure may be higher or lower than 500 pounds per square inch, normally it should not exceed about 1500 pounds per square inch. Temperatures may vary from about 250 C. to as high as 450 0., although for typical American bituminous coals it is preferred to operate at approximately 400 C. The operating temperature, in any event, should not exceed that at which there is noticeable pyrolysis of the coal, etc., to be extracted.
This process may be carried out as a batch type operation or in continuous or semicontinuous manner as desired. Either a neutral or reducing atmosphere may be maintained during the extraction. Under my preferred conditions there is no substantial hydrogenation of the extract, the consumption of hydrogen representing from 1-2% by weight or the solid material being extracted.
It is not necessary to use substantially pure compounds in this class. Quite satisfactory results may be secured from crude compounds and mixtures, of course, will give equally desirable results. Thus, mixtures of orthoand paracyclohexylphenol are suitable for the process, as are mixtures of the tetrahydrohydroxynaphthalenes. The high boiling tar acid fractions from the hydrogenation of certain coals aflord a suitable source from which may be conveniently prepared crude mixtures of these novel solvents which may be used without further separation and/or purification.
Following the pressure extraction, the solid residual matter is separated from the extract by filtration or centrifuging. The separated solids consist for the most part of the mineral matter, or ash, of the coal or thelike starting material, together with unconverted or unextracted starting material. The separation may be effected with or without dilution with the same or other solvents. Such diluents, vhowever, should be chemically similar to the initial solvents, preferably containing a phenolic hydroxyl group in the molecule, as I have found that benzene and similar non-polar aromatic compounds are likely to precipitate some of the extracted material. Such precipitates, particularly when admixed Example I A Bruceton bituminous coal fromthe Pittsburgh bed was ground to pass 90% through a 100 mesh screen. This coal had the following analysis:
' Percent Proximate analysis: by weight Moisture V 2.1 Volatile matter 36.0 Fixed carbon 54.! Ash v 7.2
Hydrogen 5.2 Carbon 75.5 Nitrogen 1 1.5 Sulfur 1.5 Oxygen 9.1 Ash 7.2
One part of the ground coal was admixed with four parts by weight of o-cyclohexylphenol and charged to a stainless steel autoclave containing hydrogen at one atmospheric pressure. The sealed vessel and contents were heated to 400 C. while being rotated to agitate the contents.- The pressure, due to the vapors of the solvent and any permanent gases present, rose to about 500 pounds per square inch. After thirty minutes of treatment the contents of the autoclave were discharged and centrifuged to separate extract from the mineral residue (ash) and unconverted coal constituents. The percentage of extraction was determined as 81.6 calculated according to the following formula:
percentage extraction 100 weight of weight of dry, ash-free coal When the same coal is extracted under comiparable conditions with a solvent comprising naphthalene, phenol and tetralin (2:1:2) the percentage of extraction was 51.3, while with tetralin alone the percentage was 49.4.
Example II The autoclave was charged with asample of the same coal used in Example I, admixed with o-cyclohexylphenol in the same proportion, but
the treatment was continued for one hour.
There was a slight increase in the yield'of extracted material, the percentage of extraction calculated as in Example I being 82.8. Substantially the same yield was also obtained upon an increase in time to ninety minutes.
Example III The autoclave was charged with a mixture of residue(100per cent ash in residue).
1,2,3,4-tetrahydro 5 hydroxynaphthalene and the Bruceton coal used in Example I, in the ratio 4:1 and heated to 400 C. for 30 minutes under an initial hydrogen pressure of 1 atmosphere. The extraction products were separated by cen- 4 I extract, the latter may betreated by distillation v or any other conventional .process for recovery various ways not forming part of the present invention. 1 v
The solutions obtained according to this'invention are quite stable. A sample of the extract in o-cyclohexylphenol was exposed to air at 45 C. for'nineteen days withoutsignificant change in appearance or properties. The expressions solution, "extract and the like'used herein are intended to describe the liquid product from no material can be separated by further filtration or centrifuging. Microscopic examination at 400 magnification indicates substantial absence of solid particles. It is possible, however, that there is actually a form of colloidal dispersion rather than; true solution. Accordingly 7 it will be understood. that my invention is notv intended to be limited to any particular theory as to the mechanism of the action whereby a substantial proportion of the coal substance is extracted in soluble form.
According to the patent statutes, I- have set forth the principles and mode of operation of my invention and have described whatv I believe to represent its best embodiment. I desire it to' be understood, however, that within the scope 'of the appended claimsv the invention may be practiced otherwise than as specifically described herein.
l. A process for the solvation and depolymerization of solid carbonizable fuel for the production of extracts therefrom which comprises treating said fuel with at least an equal weightof a liquid dicyclic hydroaromatic compound containing at least one phenolic hydroxyl group in an'atmosphere rich in hydrogen at a temperature of from about300 C. to about 415 C. and at a pressure corresponding to the vapor pressure of said compound at said temperature and thereafter separating the resulting extract from solidv residues;
2. Ina process for the preparation of liquid products from solid carbonizable fuel. the improvement which comprises treating the fuel with a liquid dicyclic hydroaromatic compound containing at least one phenolic hydroxyl group in the presence of hydrogen at superatmospheric pressures and at elevated temperatures not in excess of those at which pyrolytic conversion of the fuel will occur.
3. A process for the production of extracts of coals lignite, peat and the like solid fuel comprisingcomminuting said fuel, admixing therewith a liquid'dicyclic hydroaromatic compound containing at least one phenolic hydroxyl group, heating said mixture to a temperature of about 400 C. in an atmosphere of hydrogen under a pressure corresponding to the vapor pressure of said imuid at said temperature and thereafter separating the extract from the insoluble residue of said fuel at reduced temperatures and pressures.
bituminous coal which comprises treating said coal with at least an equal weight of a solvent composed essentially of ortho-cyclohexylphenol in an atmosphere of hydrogen at a temperature trifuging as described above.- The yield was of about 400 C. and under a pressure notin excess of about 1500 pounds per square inch, separating the resulting extract from ash and other solid residues at substantially reduced pressures 8 and temperatures, recovering at least a major portion or the solvent from said extract and returning recovered solvent to the process for treatment of further quantities of coal therein.
5. A process for the production of extracts from bituminous coal which comprises treating said coal with at least an equal weight of a solvent composed essentially of para-cyclohexylphenol in an atmosphere of hydrogen at a temperature of about 400 C. and under a pressure not in excess of about 1500 pounds per square inch, separating the resulting extract from ash and other solid residues at substantially reducedtemperatures and pressures, recovering at least a major portion of the solvent from said extract and returning recovered solvent to the process for treatment offurther quantities of coal therein.
6; A process for the production of extracts from bituminous coal which. comprises treating said coal withat least an equal weight or a solvent composed essentially of 1,2,3,4-tetrahydro-5-hydroxynaphthalene in the presence or hydrogen at a temperature or about 400 C. and under a pressure not in excess of about 1500 pounds per square inch, and'separatlng the resulting extract from ash and other solid residues at substantially reduced temperatures and pressures.
- MILTON ORCHIN.
REFERENCES crrnn The following references are of record in the file of this patent:
UNITED STATES PATENTS OTHER-REFERENCES Bull. soc. -chim.vBelg., vol. 43, pages 382-391 (1934) by Gillet et 81., abstracted in Chem. A bstracts 29, page 16087.
Ellis, "Hydrogenation oi Organic Submnces." 3rd edition. page 236. published Nov.'1930, Van
- Nostrand & 00., New York.