GB1577464A

GB1577464A - Liquefaction of coal in a non-hydrogen donor solvent

Info

Publication number: GB1577464A
Application number: GB25020/77A
Authority: GB
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1976-10-12
Filing date: 1977-06-15
Publication date: 1980-10-22
Also published as: AU506863B2; JPS5347404A; FR2367813A1; FR2367813B1; AU2602177A; CA1107213A; BR7705747A; DE2735609A1; ZA773429B

Description

(54) LIQUEFACTION OF COAL IN A NON-HYDROGEN DONOR SOLVENT (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process for liquefying coal in a non-hydrogen donor solvent to liquid hydrocarbon products.

Liquefaction of coal to coal liquids in a hydrogen donor solvent process is weil known. In such a process, a slurry of coal in a hydrogen donor solvent is reacted in the presence of molecular hydrogen at elevate d temperature and pressure. The hydrogen donor solvent which becomes hydrogen depleted during the coal liquefaction reaction, in the prior art processes, is generally subjected to a hydrogen-action stage prior to its being recycled to the liquefaction zone.

It is also known to convert coal to liquid products by hydrogenation of coal which has been impregnated with an oil-soluble metal napthenate or by hydrogenation of coal in a liquid medium such as a hydrogen donor oil having a boiling range or 250 to 325"C.

containing an oil-soluble metal napthenate. Concentrations as low as 0.01% metal naphthenate catalysts, calculated as the metal, were found to be effective for the conversion of coal.

A process is known for the liquefaction of sub-bituminous coal in a hydrogen donor oil in the presence of hydrogen, carbon monoxide, water, and an alkali metal or ammonium molybdate in an amount ranging from 0.5 to 10 percent by weight of the coal. It is one object of the present invention to provide a process of coal liquefaction reaction employing molecular hydrogen and a non-hydrogen donor solvent.

In accordance with the present invention, there is provided, a process for liquefying coal to produce an oil product, which comprises the steps of: (a) forming a mixture of coal (as hereinafter defined), a non-hydrogen donor solvent (as hereinafter defined) and an added oil-soluble (as hereinafter defined) metal compound, said metal being selected from Groups VB, VIB, VIIB and VIII of the Periodic Table of Elements hereinafter defined; (b) converting said oil-soluble metal compound(s) to a catalyst within said mixture in the presence of a hydrogen-containing gas by heating said mixture with a gas comprising molecular hydrogen under coal liquefaction conditions, in a liquefaction zone, and (d) recovering a coal liquefaction product mixture comprising an oil product and solids.

A preferred embodiment of the inventiom is one wherein in step (a) a mixture is formed of wet coal, a non-hydrogen donor solvent and from 10 to 700 wppm (calculated as elemental metal and based on wt. of coal) of said oil-soluble metal compound, and wherein in step (c) said resulting mixture containing said catalyst is reacted with a gas comprising hydrogen and from 5 to 50 mole percent carbon monoxide.

Preferably the process of the invention is one in which said oil product is separated into fractions, including a solvent fraction having less than 0.8 weight percent donatable hydrogen, and wherein at least a portion of said solvent fraction, without intervening hydrogenation, is recycled to said liquefaction zone.

Advantageously the process of the invention comprises the additional steps of separating at least a portion of said solids from said liquefaction product mixture and recycling at least a portion of said separated solids to said liquefaction zone. Additionally, or alternatively, a portion of said separated solids can be recycled to step (a).

The term "hydroconversion" with reference to coal is used herein to designate conversion of coal to liquid hydrocarbons in the presence of hydrogen.

The term "oil-soluble" as applied to the metal compound(s) used in the invention means that those metal compound(s) are soluble in the non-hydrogen donor solvent employed.

The process of the invention is generally applicable to hydro-convert coal to produce coal liquids (i.e. normally liquid hydrocarbon products) in a non-hydrogen donor solvent process. The term "coal" is used herein to designate a normally solid carbonaceous material including all ranks of coal, such as anthracite coal, bituminous coal, semi-bituminous coal, subbituminous coal, lignite, peat and mixtures thereof.

The coal is desirably in particulate form, preferably of a size ranging up to about 1/8 inch particle size diameter, suitably 8 mesh (Tyler). The solvent and coal are preferably admixed in a solvent-to-coal weight ratio ranging from 0.8:1 to 4:1, most preferably from 1:1 to 2:1.

The non-hydrogen donor solvents employed in the process of the present invention are defined as solvents which contain less than 0.8 weight percent donatable hydrogen, based on the weight of the total solvent. Preferably, the solvent will be a non-hydrogen donor compound or mixture of compounds having an atmospheric boiling point ranging from about 350"F. to about 850"F., more preferably ranging from about 350"F. to less than about 650"F. Suitable non-hydrogen donor solvents include aromatic compounds such as alkylbenzenes, alkylnaphthalenes, alkylated polycyclic aromatics, heteroaromatics and mixtures thereof, and streams such as unhydrogenated creosote oil, intermediate product streams from catalytic cracking of petroleum feedstocks, coal derived liquids and shale oil.

An oil-soluble metal compound wherein the metal is selected from Groups VB, VIB, VIIB, VIII and mixtures thereof of the Periodic Table of Elements is added to the non-hydrogen donor solvent so as to form a mixture of oil soluble metal compound, non-hydrogen donor solvent and coal. The oil-soluble metal compound is added in an amount sufficient to provide from 10 to less than 2000 wppm, preferably from 25 to 950wppm, more preferably from 50 to 700 wppm, most preferably from 50 to 400 wppm, of the oil-soluble metal compound, calculated as the elemental metal, based on the weight of coal in the mixture.

Suitable oil-soluble metal compounds convertible to active catalysts under process conditions include (1) inorganic metal compounds such as halides, oxyhalides, hydrated oxides, heteropoly acids (e.g. phosphomolybdic acid, molybdosilisic acid); (2) metal salts of organic acids such as acyclic and alicyclic aliphatic carboxylic acids containing two or more carbon atoms (e.g. naphthenic acids); aromatic carboxylic acids (e.g. toluic acid); sulfonic acids (e.g. toluenesulfonic acid); sulfinic acids; mercaptans, xanthic acid; phenols, di and polyhydroxy aromatic compounds; (3) organometallic compounds such as metal chelates.

e.g. with 1,3-diketones, ethylene diamine and ethylene diamine tetraacetic acid; (4) metal salts of organic amines such as aliphatic amines, aromatic amines, and quarternary ammonium compounds.

The metal constituent of the oil soluble metal compound is selected from Groups VB, VIB, VIIB and VIII of the Periodic Table of Elements, and mixtures thereof, in accordance with the table published by E.H. Sargent and Company, copyright 1962, Dyna Slide Company, that is, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, cobalt, nickel and the noble metals including platinum, iridium, palladium, osmium, ruthenium and rhodium. The preferred metal constituent of the oil soluble metal compound is selected from molybdenum, vanadium and chromium. More preferably, the metal constituent of the oil soluble metal compound is selected from molybdenum and chromium. Most preferably, the metal constituent of the oil soluble metal compound is molybdenum.Preferred compounds of the metals include the salts of acyclic (straight on branched chain) aliphatic carboxylic acids, salts of alicyclic aliphatic carboxylic acids, heteropolyacids, hydrated oxides, carbonyls, phenolates and organic amine salts.

More preferred types of metal compounds are the heteropoly acids, e.g. phosphomolybdic acid. Anotherpreferred metal compound is a salt of an alicyclic aliphatic carboxylic acid such as a metal naphthenate. The most preferred compounds are molybdenum naphthenate, vanadium naphthenate and chromium naphthenate.

When the oil-soluble metal compound is added to the non-hydrogen donor solvent, it dissolves in the sovent. To form the catalyst, the metal compound (catalyst precursor) is converted within the slurry of coal and non-hydrogen donor solvent.

Various methods can be used to convert the dissolved metal compound in the coal-solvent slurry to an active catalyst. A preferred method (pretreatment method) of forming the catalyst from the oil-soluble compound is to heat the mixture of metal compound, coal and solvent to a temperature ranging from 325"C. to 438"C. The pressure preferably ranges from 500 to 5000 psig, in the presence of a hydrogen-containing gas. The hydrogen-containing gas may be pure hydrogen but will generally be a hydrogen stream containing some other gaseous contaminants, for example, the hydrogen-containing effluent produced in reforming processes, etc.

Preferably the hydrogen-containing gas also comprises hydrogen sulfide. The hydrogen sulfide may comprise from 1 to 90 mole percent, preferably from 1 to 50 mole percent, more preferably from 1 to 30 mole percent of the hydrogen-containing gas mixture. The pretreatment is preferably conducted for a period ranging from 5 minutes to 2 hours, more preferably for a period ranging from 10 minutes to 1 hour. The thermal treatment in the presence of hydrogen or in the presence of hydrogen and hydrogen sulfide is believed to facilitate conversion of the metal compound to the corresponding metal-containing active catalysts which act also as coking inhibitors.

The coal-solvent slurry containing the resulting catalyst is then introduced into a coal liquefaction zone which will be subsequently described.

Another method of converting the oil-soluble metal compound of the present invention is to react the mixture of metal compound, coal and non-hydrogen donor solvent with a hydrogen-containing gas at coal liquefaction conditions to produce a catalyst in the chargestock, in situ, in the liquefaction zone. The hydrogen-containing gas may comprise from about 1 to about 30 mole percent hydrogen sulfide.

Whatever the exact nature of the resulting conversion products of the given oil-soluble metal compound, the resulting metal component is a catalytic agent and a coking inhibitor.

The inventor will now be further illustrated, reference being made to the accompanying drawing, in which Figure 1 is a schematic flow plan of one embodiment of the invention.

Figure 2 is a schematic flow plan of a preferred feature of the invention.

In the process shown in Figure 1, a mixture of oil-soluble metal compound, a non-hydrogen donor solvent, such as alpha methylnapthalene, and coal (having the aforementioned preferred particulate size and solvent to coal wt. ratio) is removed from mixing zone 12 by line 18 and introduced into pretreatment zone 13 into which a gaseous mixture comprising hydrogen and from about 1 to about 90 mole percent, preferably from about 1 to 50 mole percent, more preferably from about 1 to 30 mole percent hydrogen sulfide is introduced by line 15. The pretreatment zone is maintained at a temperature ranging from about 342 C. to about 415"C and at a total pressure ranging from about 500 to about 5000 psig. The pretreatment is conducted for a period of time ranging from about 10 minutes to about 1 hour.The pretreatment zone effluent is removed by line 19. If desired, a portion of the hydrogen sulfide may be removed from the effluent. The pretreatment zone effluent is introduced by line 19 into liquefaction reaction 22. A hydrogen-containing gas is introduced into liquefaction reaction 22 by line 20. The hydrogen-containing gas may be pure hydrogen but will generally be a hydrogen stream containing some other gaseous contaminants, for example, the hydrogen-containing effluent produced in reforming.

Suitable hydrogen-containing gas mixtures for introduction into the liquefaction zone include raw synthesis gas, that is, a gas containing hydrogen and from about 5 to about 50, preferably from about 10 to 30 mole percent carbon monoxide. When wet coal (i.e. coal particles associated with water) is utilized as feed, it is particularly desirable to utilize a raw synthesis gas, that is, a gas comprising hydrogen and carbon monoxide. In such an embodiment, the metal compound, preferably a metal-containing organic compound, is added in an amount ranging from 10 to 700 wppm, preferably from 50 to 500 wppm, calculated as the elemental metal, based on the coal alone. The gas introduced by line 20 may additionally contain hydrogen sulfide in an amount ranging from about 1 to 30 mole percent.

The coal liquefaction zone is maintained at a temperature ranging from about 343 to 538"C. (649.4 to 1000"F.), preferably from about 416 to 468"C. (780.8 to 899.6"F), more preferably from about 440 to 468"C. (824 to 875"F.), and a hydrogen partial pressure ranging from about 500 psig to about 5000 psig, preferably from about 1000 to about 3000 psig. The space velocity, defined as volumes of the mixture of coal and solvent feedstock per hour per volume of reactor (V/Hr./V), may vary widely depending on the desired conversion level. Suitable space velocities may range broadly from about 0.1 to 10 volumes feed per hour per volume of reactor, preferably from about 0.25 to 6 V/Hr./V, more preferably from about 0.5 to 2 V/Hr./V.The coal liquefaction zone effluent is removed from the zone by line 24.

The effluent comprises gases, an oil product and a solid residue which is catalytic in nature. The effluent is passed to a separation zone 26 from which gases are removed overhead by line 28. This gas may be scrubbed by conventional methods to remove any undesired amount of hydrogen sulfide and carbon dioxide and thereafter it may be recycled into the coal liquefaction zone. The solids may be separated from the oil product by conventional means, for example, by settling or centrifuging or filtration of the oil-solids slurry. The separated solids are removed from separation zone 26 by line 30. If desired at least a portion of the separated solids or solids concentrate may be recycled directly to the coal liquefaction zone via line 31 or recycled to the coal-solvent chargestock.

The remaining portion of solids removed by line 30 may be discarded as such since normally they do not contain economically recoverable amounts of char. The oil product is removed from separation zone 26 by line 32 and passed to a fractionation zone 34 wherein a light fraction boiling below about 400"F. (204.44"C.) is recovered by line 36. A heavy fraction is removed by line 38 and an intermediate range boiling fraction, that is, a fraction boiling from about 400 to 7000F. (204.44 to 371.11"C) at atmospheric pressure, including the non-hydrogen donor solvent, is recovered by line 40.In a preferred embodiment of the present invention, at least a portion of the intermediate fraction having less than 0.8 weight percent donatable hydrogen, which includes the recovered non-hydrogen donor solvent, is recycled via line 42, without any intervening rehydrogenation, into mixing zone 12 or directly into the coal liquefaction zone.

It should also be noted that in non-catalyzed hydrogen donor coal liquefaction processes, the heavy bottoms product resulting from fractional distillation of the coal liquefaction oil product contains solids. The solids-containing heavy bottoms fraction is typically subjected to a fluid coking operation since a substantial portion of the carbon of the chargestock emerges with the solids in the form of char that must be recovered. In contrast, in the process of the present invention, since the solid residue of the liquefaction zone does not contain any significant amount of char, the solids can be separated from the coal liquefaction zone effluent by known means and discarded or used as catalyst. The process of the present invention would permit the elimination of the coking step.

Figure 2 shows various process options for treating the coal liquefaction zone effluent which is removed from the coal liquefaction reactor 22 by line 24. The feed to, liquefaction conditions in, and effluent from, reactor 22 are as described with reference to Figure 1. The effluent is introduced into a gas-liquid separator 26 where hydrogen and light hydrocarbons are removed overhead by line 28. Three preferred process options are available for the liquid stream containing dispersed catalyst solids which emerge from separator vessel 26 via line 30.

In process option to be designated "A", the liquid-solids stream is fed by line 32 to concentration zone 34 where by means, for example, of distillation, solid precipitation or centrifugation, the stream is separated into a clean liquid product, which is withdrawn through line 36, and a concentrated slurry (e.g. 20 to 40 percent by weight) in oil. At least a portion of the concentrated slurry can be removed as a purge stream through line 38 to control the buildup of solid materials in the coal liquefaction reactor, and the balance of the slurry is returned by line 40 and line 30 to liquefaction reactor 22. The purge stream may be filtered subsequently to recover catalyst and liquid product or it can be burned or gasified to provide, respectively, heat and hydrogen for the process.

In the process option to be designated "B", the purge stream from concentration zone 34 is omitted and the entire slurry concentrate withdrawn through line 40 is fed to separation zone 44 via lines 30 and 42. In this zone, a major portion of the remaining liquid phase is separated from the solids by means of centrifugation, filtration or a combination of settling and drawoff, etc. Liquid is removed from the zone through line 46 and solids through line 48. At least a portion of the solids and associated remaining liquid are purged from the process via line 50 to control the buildup of solids in the process and the balance of the solids is recycled to liquefaction reactor 22 via line 52 which connects to recycle line 30. The solids can be recycled either as recovered or after suitable cleanup (not shown) to remove heavy adhering oil deposits and coke.

In option designated "C", the slurry of solids in oil exiting from separator 26 via line 30 is fed directly to separation zone 44 by way of line 42 whereupon solids and liquid product are separated by means of centrifugation or filtration. All or part of the solids exiting from vessel 44 via line 48 may be purged from the process through line 50 and the remainder recycled to the liquefaction reactor. Liquid product is recovered through line 46. If desired, at least a portion of the heavy fraction of the hydroconverted oil product may be recycled to the coal liquefaction zone.

The process of the invention may be conducted either as a batch or as a continuous type process.

The following example is presented to illustrate the invention.

Example Comparative experiments were made in which molybdenum naphthenate was utilized as catalyst precursor in a non-hydrogen donor solvent, that is, in alpha methyl-naphthalene, compared to control runs in which hydrogenated creosote oil, having a donatable hydrogen content of 1.54 weight percent, a hydrogen donor solvent, was utilized.

The chargestock used in these experiments was a 50/50 mixture of Wyodak coal and solvent. The molybdenum concentration was 404 weight parts per million molybdenum, calculated as the elemental metal, based on coal alone. In the runs, in which pretreatment was performed, the pretreatment gas was a mixture of 18% H2S and 82% hydrogen. The pretreatment conditions were an initial pressure at room temperature of 1500 psig and a pretreatment temperature of 725 F. The liquefaction conditions were 820 F, and 2000+ psig hydrogen for 1 hour.The results of these experiments are summarized in the table. TABLE Coal Liquefaction 404 wppm Mo on Coal Added as Naphthenate 50/50 Wyodak Coal/Solvent 820 F., 1 Hr., 2000+ psig H2 Run No. 1 2 3 4 5 Solvent A* A B A B Pretreat - - Temperature, F. - - - 725 725 Pressure, psig(initial at room temp.) - - - 1500 1500 Time, Minutes - - - 30 30 Pretreat Gas - - - H2/18%H2S H2/18% H2S Treat Gas H2 H2 H2 H2 H2 Yields, Mole % C to: CO + CO2 6.1 5.84 6.21 6.00 5.10 C1-C3 Hydrocarbons 6.0 5.72 6.50 4.24 5.60 Oil 68.5 83.03 69.61 87.09 86.56 Coke 19.4 5.51 17.68 2.67 2.74 Conradson Carbon of Liquid Product 13.21 11.0 16.3 5.81 6.87 Solvent A = hydrogenated creosote oil Solvent B = 1-methylnaphthalene * No catalyst.

As can be seen from the table, run 3 compared with run 1 shows that non-hydrogen donor solvent with molybdenum added performs slightly better than conventional hydrogen donor solvent (run 1). Run 5 compared with run 1 shows that this process performs much better than conventional hydrogen donor solvent liquefaction. Run 5 compared with run 2 shows that preferred conditions for this process are superior to catalyzed hydrogen donor solvent liquefaction. Run 5 versus run 4 shows that under preferred conditioned, a non-hydrogen donor solvent has an equivalent performance to a hydrogen donor solvent.

Claims

WHAT WE CLAIM IS:

1. A process for liquefying coal to produce an oil product, which comprises the steps of: (a) forming a mixture of coal, (as herein described) a non-hydrogen donor solvent (as herein defined) and at least one added oil soluble (as herein defined) metal compound, said metal being selected from Groups VB, VIB, VIIB, and VIII of the Periodic Table of Elements herein defined: (b) converting said oil-soluble metal compound(s) to a catalyst for step (c) within said mixture in the presence of a hydrogen-containing gas by heating said mixture to an elevated temperature; (c) reacting the resulting mixture with a gas comprising molecular hydrogen under coal liquefaction conditions, in a liquefaction zone, and (d) recovering a coal liquefaction product mixture comprising an oil product and solids.

2. A process as claimed in claim 1, wherein said oil product is separated into fractions, including a solvent fraction having less than 0.8 weight percent donatable hydrogen, and wherein at least a portion of said solvent fraction, without intervening hydrogenation, is recycled to said liquefaction zone.

3. A process as claimed in claim 1, wherein said oil-soluble metal compound in step (a) is added in an amount ranging from 10 to less than 2000 weight parts per million, calculated as the elemental metal, based on the weight of the coal in said mixture.

4. A process as claimed in any preceding claim, wherein said oil-soluble metal compound is selected from inorganic compounds, salts of organic acids, organometallic compounds and salts of organic amines.

5. A process as claimed in claim 4, wherein said oil-soluble metal compound is selected from salts of acyclic aliphatic carboxylic acids and salts of alicyclic aliphatic carboxylic acids.

acids.

6. A process as claimed in claim 4, wherein said oil-soluble metal compound is a salt of naphthenic acid.

7. A process as claimed in any preceding claim, wherein the metal constituent of said oil-soluble metal compound is selected from molybdenum, chromium and vanadium.

8. A process as claimed in any one of claims 1 to 3, wherein the oil-soluble compound is a molybdenum-containing organic compound.

9. A process as claimed in claim 8 wherein said oil-soluble metal compound is molybdenum naphthenate.

10. A process as claimed in any one of claims 1 to 3, wherein said oil-soluble metal compound is phosphomolybdic acid.

11. A process as claimed in claim 11, wherein said hydrogen-containing gas also contains hydrogen sulfide.

12. A process as claimed in claim 11, wherein said hydrogen-containing gas of step (b) comprises from 1 to 90 mole percent hydrogen sulfide.

13. A process as claimed in claim 12, wherein said hydrogen-containing gas of step (b) comprises from 1 to 50 mole percent hydrogen sulfide.

14. A process as claimed in any preceding claim, wherein said oil-soluble metal compound is converted to a catalyst by subjecting said mixture to a temperature ranging from 325"C to 538"C. in the presence of said hydrogen-containing gas.

15. A process as claimed in claim 14, wherein said oil-soluble metal compound is converted by first heating the mixture of said oil-soluble metal compound, coal and non-hydrogen donor solvent to a temperature ranging from 325"C. to 438"C. in the presence of said hydrogen-containing gas to form a catalyst within said mixture and subsequently reacting the resulting mixture containing the catalyst with hydrogen under coal liquefaction conditions.

16. A process as claimed in any one of claims 1 to 10, wherein said oil-soluble metal compound is converted in the presence of a hydrogen containing gas in the coal liquefaction zone under coal liquefaction conditions thereby forming said catalyst in situ within said mixture in said liquefaction zone.

17. A process as claimed in any preceding claim, wherein said coal liquefaction conditions Include a temperature ranging trom 343ups to 538"C. (694.4 to 10000F.) and a hydrogen partial pressure ranging from 500 to 5000 psig.

18. A process as claimed in any preceding claim, wherein the space velocity of said mixture in said liquefaction zone ranges from 0.1 to 10 volumes of mixture per hour per volume of liquefaction zone.

19. A process as claimed in any preceding claim. comprising the additional steps of separating at least a portion of said solids from said liquefaction product mixture and recycling at least a portion of said separated solids to said liquefaction zone.

20. A process as claimed in any preceding claim, wherein said catalyst is the sole catalyst in said liquefaction zone.

21. A process as claimed in any preceding claim, wherein said solvent and coal are mixed in a solvent-to-coal weight ratio ranging from 0.8:1 to 4:1.

22. A process as claimed in claim 21, wherein said solvent and coal are mixed in a solvent-to-coal weight ratio ranging from 1:1 to 2:1.

23. A process as claimed in any preceding claim, wherein said non-hydrogen donor solvent comprises a compound or a mixture of compounds having an atmospheric boiling point ranging from 350''F. to 850"F.

24. A process as claimed in 23, wherein said non-hydrogen donor solvent comprises a compound or a mixture of compounds having an atmospheric boiling point ranging from 350"F. to less than 650"F.

25. A process as claimed in claim 1, wherein in step (a) a mixture is formed of wet coal, a non-hydrogen donor solvent and from 10 to 700 wppm (calculated as elemental metal and based on wt. of coal) of said oil-soluble metal compound, and wherein in step (c) said resulting mixture containing said catalyst is reacted with a gas comprising hydrogen and from 5 to 50 mole percent carbon monoxide.

26. A process as claimed in claim 25 wherein said oil-soluble metal compound is added to step (a) in an amount ranging from about 50 to 500 wppm, calculated as the elemental metal, based on the coal.

27. A process as claimed in claim 25 or claim 26, wherein said oil-soluble metal compound is a metal-containing organic compound.

28. A process as claimed in claim 27, wherein said oil-soluble metal compound is a molybdenum-containing organic compound.

29. A process as claimed in claim 25 or claim 26, wherein said oil-soluble metal compound is phosphomolybdic acid.

30. A process as claimed in claim 8, wherein in step (a) a mixture is formed of wet coal, a non-hydrogen donor solvent and an added oil-soluble molybdenum-containing organic compound, said organic compound being added in an amount ranging from 10 to less than 2000 wppm, calculated as the elemental metal, based on the wt. of the coal in said mixture, and wherein in step (c) said resulting mixture containing said catalyst is reacted with a gas comprising hydrogen and from 5 to 50 mole percent carbon monoxide.

31. A process as claimed in claim 30, wherein said organic compound is selected from salts of organic acids, organometallic compounds and salts of organic amines.

32. A process as claimed in claim 31, wherein said organic compound is selected from salts of acyclic aliphatic carboxylic acids and salts of alicyclic aliphatic carboxylic acids.

33. A process as claimed in claim 30, wherein said organic compound is molybdenum naphthenate.

34. A process as claimed in any one of claims 30 to 33, wherein said hydrogen containing gas of step (b) comprises from 1 to 90 mole percent hydrogen sulfide.

35. A process as claimed in claim 34, wherein the gas of step (c) additionally comprises from 1 to 30 mole percent hydrogen sulfide.

36. A process as claimed in any preceding claim, comprising the additional steps of separating at least a portion of the solids from step (d).

37. The solids product of a process claimed in claim 36.

38. A process as claimed in any one of claims 1 to 36 wherein at least a portion of said separated solids are recycled to step (a).

39. A process for liquefying coal as claimed in claim 1 and substantially as 'herein described with reference to the Example or to the accompanying drawings.

40. The oil product or fractions obtained from a process claimed in any preceding claim.