WO1981002422A1

WO1981002422A1 - Multidentate macromolecular complex salt clathrates

Info

Publication number: WO1981002422A1
Application number: PCT/US1981/000263
Authority: WO
Inventors: J Atwood
Original assignee: Univ Alabama
Priority date: 1980-02-28
Filing date: 1981-03-02
Publication date: 1981-09-03
Also published as: EP0046805A1

Abstract

A liquid clathrate of a multidentate macromolecular compound complex salt of the formula: (M(mmc)x)y(QnR3nX)z.pZ wherein M is a mono-, di, or trivalent cation, Q is Al or Ga, R is a lower alkyl group of 1 to 8 carbon atoms, X is a monovalent, divalent or trivalent anion, n is an integer of 2 to 4, x is 1 or 2, y and z are integers from 1 to 3, Z is an aromatic hydrocarbon compound and p is an integer from 1 to 40. A solid carbonaceous material such as coal is liquefied by admixing said material with a liquid clathrate, maintaining the admixture for a period sufficient to form a liquid clathrate layer containing liquefied petroleum oil products, and separating the petroleum oil from said clathrate.

Description

DESCRIPTION

Multidentate Macromolecular Complex Salt Clathrates

Technical Field

The present invention relates to liquid clathrates of aromatic hydrocarbon compounds and complex aluminum salts containing at least one multidentate macrocyclic compound complexed with the cationic portion of the complex salt. More particularly, the present invention relates to the low temperature liquefaction of coal using a liquid clathrate.

Background Art

Liquid clathrates of small ring aromatic compounds and complex metal salts formed by the reaction of simple alkali metal or ammonium salts with trimethy1aluminum in a mole ration of 1:2 are known as described in a series of publications authored by J.L. Atwood et al, in the Journal of Organometallic Chemistry (Vol. 66, pp. 15-21 (1974); Vol. 42, pp. C77-79 (1972); Vol. 61, pp. 43-48 (1973); and Vol. 65, pp. 145-154 (1974). The complex metal salts which form the liquid clathrates with certain aromatic solvents are prepared by reacting simple salts such as the alkali metal or ammonium halides, azides, thiocyanates and selenocyanates with trimethylaluminum in appropriate amounts such that salts of the stoichiometry M[A1₂ (CH₃) ₆X] are formed. When the complex metal salts are treated with certain aromatic compounds such as benzene or toluene, liquid complexes or clathrates form which contain at least two and up to about 13 aromatic molecules per complex salt molecule. The liquid clathrates can be distinguished from the rest of the parti cular aromatic hydrocarbon solvent to which the complex metal salt is exposed by the formation of a second liquid layer which is immiscible with the hydrocarbon solvent.

Liquid clathrates are also known as described in U.S. Patent 4,024,170 which are formed by the complexation of 1.5 to 30 moles of an aromatic hydrocarbon compound and a complex aluminum nitrate salt of the formula M {Al₂ [(CH₂)x CH₃)₆NO₃} wherein x is an integer of 1 to 3 and M is an alkali metal cation, ammonium ion, or the like. It is believed that the clathrate forming ability of the aluminum containing salts is attributable to the angular characteristics of the nitrate containing anion portion of the salt.

U.S. Patent 3,280,025 shows a method of extracting aromatic hydrocarbons from liquid hydrocarbon material by contacting the liquid hydrocarbon material with a complex of a. trialkylaluminum and a salt having the formula R_nMX, wherein R is alkyl, usually of 2 to 5 carbon atoms, M is one of the elements: nitrogen, arsenic, phosphorous, sulfur, selenium or telurium, X is a halogen and n is 3 or 4 depending upon the element M. The trialkylaluminum compound and R_nMX compound react to form a complex which selectively forms a clathrate with aromatic hydrocarbons in a liquid hydrocarbon. While the prior art complex salts all form liquid clathrates with aromatic hydrocarbons, the types of complexes which form clathrates are limited, and the extent of clathrate formation is also limited. A need, therefore, continues to exist for a greater array of complex salts which form clathrates of specific compositions involving a large number of aromatic hydrocarbon molecules per complex salt molecule thereby providing a broader spectrum of choices for a given separation process.

The oldest of the modern direct coal liquefaction processes, dating back to about 1962, is the Solvent Refined Coal (SRC) process, developed by Spencer Chemical.

In the original process, now known as SRC-I, pulverized raw coal is mixed with a process-derived solvent and a small amount of hydrogen at high temperature and pressure. The coal dissolves; most of its ash and much of its sulfur settle out and can be removed by filtration. The resulting relatively clean liquid can be burned in that form, or it can be cooled to a tarlike solid for easier transportation and storage.

A later, modified version, SRC-II, uses more hydrogen and operates under more severe conditions of temperature, pressure, and residence time. Most of the coal is converted to liquids mainly naphtha and boiler fuel.

Recently, two 6000 ton-per-day demonstration plants - a modified SRC-I in Kentucky and an SRC-II in West Virginia - have been proposed. Conceivably, commercialscale plants using either of these processes could be in operation by 1989 or 1990.

Another approach to coal dissolution is the Exxon Donor Solvent (EDS) process. Crushed, dried feed coal is slurried with a hydrogenated recycle solvent (the donor solvent) and fed, along with gaseous hydrogen into an upward plug-flow reactor of fairly simple design. The effluent is separated by distillation into several fractions: the recycle solvent, depleted of its hydrogen; light hydrocarbon gases; heavier distillates, boiling at up to 1000º F; and a heavy vacuum bottoms stream containing still heavier liquids, unconverted coal, and ash.

The recycle solvent is rehydrogenated catalytically in a conventional fixed-bed reactor. Bottoms are fed with steam and air to an Exxon Flexi-coking unit, which produces additional liquids and low Btu gas. In contrast to the other processes, hydrogen is obtained by steamreforming the light hydrocarbon gases.

The third direct liquefaction process currently being seriously considered for commercialization is the H-Coal process, developed by Hydrocarbon Research Inc. The H-Coal process employs no solvent. Instead, dried, crushed coal is slurried with heavy distillate from the process, pressurized, mixed with compressed hydrogen, preheated and fed to an ebullated-bed catalytic reactor. Effluent gases are cooled to separate heavier components as liquids. Light hydrocarbons, ammonia and hydrogen sulfide are absorbed from the remaining hydrogen-rich gas, which is recompressed and recycled to the input slurry. The liquid-solid portion, containing unconverted coal, ash and oil goes to a flash separator. The lighter portions go to an atmospheric distillation unit, while the bottoms are separated with a hydrocyclone, a liquid solid separator, and a vacuum still.

All of these direct liquefaction procedures require considerable energy input and are not truly cost effective techniques. A need therefore exists for the development of a low-energy input liquefaction process.

Disclosure of Invention

Accordingly, one object of the present invention is to provide multidentate macrocyclic compound containing complex salts.

Another object of the invention is to provide liquid clathrates of discrete compositons involving an aromatic hydrocarbon and a complex salt whose cationic portion contains a multidentate macrocyclic compound.

Yet another object of the present invention is to provide a method of forming multidentate macrocyclic com pound containing complex salts.

Still another object of the present invention is to provide a process for the liquefaction of solid carbonaceous material, particularly coal, at low temperatures with minimum input of energy.

Another, more particular, object of the present invention is to produce petroleum oil fractions from coal.

Briefly, these objects and other objects of the present invention as hereinafter will become more readily apparent can be attained by a multidentate macrocyclic compound complex salt liquid clathrate of the formula:

[M(mmc)_χ]_y[Q_nR_3nX]_z.pZ' wherein M is a monovalent divalent or trivalent cation, Q is aluminum or gallium, R is a lower alkyl group of 1 to 8 carbon atoms, X is a monovalent, divalent or trivalent anion, n is an integer of 2 to 4, y and z are integers from 1 to 3, x is 1 or 2, Z is an aromatic hydrocarbon compound and p is an integer of from 1 to 40 (mmc means multi-dentate macrocyclic compound). in another embodiment of the invention a method is provided for the liquefaction of solid carbonaceous material by admixing said carbonaceous material with a liquid clathrate, maintaining said admixture for a period sufficient to form a liquid clathrate layer containing liquified petroleum, oil products, decomposing said clathrate to separate said clathrate from said petroleum oil, whereby a petroleum oil phase is produced, and separating said petroleum oil phase from said decomposition products.

Best Mode for Carrying Out the Invention

The complex salts which are the basic ingredient of the multidentate macrocyclic compound complexes of the present invention have the following formula:

M_y(Q_nR_3nχ)_z wherein R is a lower alkyl radical of 1 to 8 carbon atoms, particularly the likes of methyl, ethyl, propyl and butyl; Q is Al or Ga; X is a monovalent, divalent or trivalent anion, M is a monovalent, divalent or trivalent cation, n is a value of 2 to 4 and y and z vary from 1 to 3 depending upon the valence states of the n and

cation. Suitable types of cationic species which form the complex salts include all those which complex with a multidentate macromolecule and include the alkali metals, the alkaline earth metals, quaternary ammonium ions, quaternary arsonium ions, quaternary sulfonium ions, quaternary telluronium ions and mixtures thereof. Specific examples of cationic species include K⁺, Rb⁺, Na⁺ , Cs⁺ ,

Ca⁺², Ba⁺², Sr⁺², Co⁺², Ag⁺, Hg⁺, ^{+2 2}, T Ce⁺³, La⁺³, Cd⁺², Cr⁺³, Fe⁺³, Mo⁺³, NR' PR^'+ T1

wherein R' is hydrogen, alkyl of C

1-C₁₀, enyl naphthyl and the like, particularly dialkylthallium ions. Suitable monovalent cations also include metals having a normal valence state greater than one such as the alkaline earth metals, and the transition metals such as chromium, iron, cobalt, molybdenum and the like which are covalently bonded to at least one other substituent such as an aromatic hydrocarbon radical or molecule including the likes of phenyl, naphthyl and the like or benzene, toluene and the like such that the net positive charge on the metal-radical entity is one. Examples o radical modif

ied metal species include diphenylchromiu

phenylmercur dibenzenechromiu

dicyclopentadienylcobal and the like.

Suitable examples of monovalent, divalent and trivalent anionic species include the likes of the halides, particularly C1-, F-, Br-, I-, azide, SCN-, SeCN-, nitrite, nitrate, loweralkylacylate such as CH₂CO₂- and HCO₂-, hydroxide, carbonate, bicarbonate, sulfate and phosphate.

Suitable multidentate macromolecular compounds which can be reacted with cationic species M to form complex cationic species include many types of compounds such as macrocyclic polyethers, macrocyclic polyamines, macrocyclic polythioethers and mixed donor macrocycles. These types of compounds are well known in the art as described by Christensen et al in Chemical Reviews, 74(3), pp 351+. The complex cationic species is formed by coordination of most or all of the available corrdination sites in cation M with the donor atoms of the given multidentate macromolecule employed.

A preferred class of complex cationic species within the scope of the present invention includes those species formed by the interaction of a cation M of the-above complex salt with one or two macrocyclic polyether or crown ether molecules. The crown ether-complex salt complex has the formula: [M (crown ether)_x]y[Q_nR_3nX]_z, wherein M, Q, R, X, n, y and z are as defined above and x is 1 or 2. Suitable crown ethers useful in forming a crown ether complex include those of the formula:

wherein q is 4-8 and R² is lower alkyl, aryl or aryl which is fused to said ring, and r is an integer of 0 4. Specific examples or crown ethers include 18-crown-6, 15-crown-5, dibenzo-18-crown-6, 21-crown-7, dicyclohexyl- 18-crown-6, benzo-15-crown-5, benzo-12-crown-4, dibenzo- 24-crown-8,, dibenzo-30-crown-10 and the like. 18-Crown6 and dibenzo-18-crown-6 are especially good coordinating agents for potassium ions. Sodium is generally best bound by 15-crown-5. The binding is directly related to the size of the cavity which in turn is related to the size of the crown for crown ethers, i.e. the larger the cation, the larger the crown needed.

In the formation of the crown ether-cation M complex one or more crown ether molecules may complex with a single M cation species as follows:

In addition to being one of the variety of monovalent cations described above, cation may also be a crown ether complex of one of the divalent metals or trivalent metals elucidated above. The liquid clathrates of the present invention are formed by the interaction between a multitude of aromatic hydrocarbon molecules and a single multidentate macromolecular compound containing salt complex and can be represented by the formula: [M(mmc)_χ]_y[Q_nR_3nχ]_z'pz, wherein M, Q, R, X, n, x, y and z are as defined above, p is a value ranging from 1 to 40 and Z is an aromatic hydrocarbon compound. Suitable hydrocarbon aromatic compounds which can be used in forming the clathrate include benzene, toluene, o-,m-or p-xylene, mesitylene, tetramethylbenzene, ethylbenzene, diethylbenzene, cumene, dipropylbenzene, diisopropylbenzene, naphthalene, tetralin, anthracene, or phenanthracene. Benzene and toluene have been demonstrated to give good results. It has been observed that the larger the cation M component of the clathrate, the greater will be the number of molecules of aromatic hydrocarbon compound which can be entrapped in the multidentate macromolecular compound containing complex salt complex. In general, the anionic component of the complex salt must have the angular geometry

in order to form the aromatic clathrate; whereas a symmetrical anionic structure

will not normally clathrate. (An exception which has been noted is NR₄[Al₂Me₆F].)

The nature of the clathrate interaction is thus related to the anion, the lattice energy, the size of the cation and the size of the aromatic molecule. It is expected that other clathrates based on systems other than the QR₃ model as discussed above will be useable, for instance, liquid clathrates of the formula: K[CH₃Se{Al(CH3)₃}₃].6C₆H₆ can be used herein.

"Liquid Clathrate" is a term of art which refers to certain enclosure compounds. A liquid clathrate is a loose structure of a complex salt and aromatic compound molecules whereby the aromatic compound is entrapped into layers in the liquid structure. The aromatic compound can be retrieved unchanged by lowering the temperature. The liquid clathrate will only accomodate a certain number of aromatic molecules and the excess aromatic molecules will be immiscible with the clathrate. See J. L. Atwood et al, Journal Organometallic Chemistry 66, 15-21 (1974); 42, C 77-79 (1972); 61, 43-48 (1973); 65, 145-154 (1974).

In order to prepare the complex salt, an alkyl aluminum (gallium) compound can be reacted with a simple salt such as an alkali metal nitrate, carbonate, sulfate, azide or the like. In order to form a multidentate macromolecule containing complex of the complex salt, the macrocyclic compound can simply be added to the complex salt in a one step process. Alternatively, the multidentate macromolecular compound containing complex salt can be formed by simultaneously mixing macrocyclic compound, a simple salt and an alkylaluminum (gallium) compound in a one step process, by adding an alkylaluminum (gallium) compound to a solution or suspension of a simple salt in a macrocyclic compound in a two step process or by adding a simple salt to a solution of an alkylaluminum (gallium) compound in a macrocyclic compound.

The liquid clathrate of the multidentate macrocyclic compound containing complex salt can be formed by any one of a number of single step and multi-step processes. Thus, the clathrate can be formed in a one step process by simultaneously mixing a simple salt, an alkylaluminum (gallium) compound and a macrocyclic compound in an aromatic hydrocarbon solvent. Alternatively, a solution of an alkylaluminum (gallium) compound in an aromatic hydrocarbon can be combined with a solution or suspension of a simple salt in a. macrocyclic compound. (A suspension will work as long as the salt has some slight solubility in the solvent. ) The order of addition of clathrate components is not critical and any such combination of the components of the liquid clathrate can be employed to successfully prepare the liquid clathrate of the present invention.

The alkylaluminum compound used in the preparation of the complexes of the present invention is normally a trialkylaluminum compound. The clathrate complex salt or multidentate macromolecular compound containing complex salt forming reaction can occur at room temperature or higher, up to about 190°C, depending on the particular choice of materials. Beyond 190°C, the aluminum alkyl will decompose. Good results are attainable in the range of 15°80°C. With respect to the clathrate, upon cooling from elevated temperatures, a temperature will be reached at which the clathrate will decompose back to the complex salt and the aromatic compound. The only important con- sideration which must be given with respect to any of the synthetic procedures by which the complex salt, multidentate macromolecular compound containing complex salt and liquid clathrate are prepared is that since the alkylaluminum (gallium) compound is sensitive to air and water, the synthesis reactions should be conducted in the absence of both air (oxygen) and water.

Specific examples of liquid clathrates of crown ether-complex salt complexes include: [Cs. crown ether]₂ [A1₂R₆CO₃] ^.p^Z

[K.dibenzo-18-crown-6] [Al₂(CH₃)₆N₃].9C₆H₆

As indicated above, the presence of the crown ether complex within the complex salt has the effect that clathrates of different, but discrete, compositions can be formed in contrast to conventional clathrates. Thus, for example, contrast the conventional clathrate:

K[Al₂(CH₃)₆NO₃].7.0 C₆H₆ with the corresponding dibenzo-18-crown-6 containing clathrate of the present invention, which has the following formula:

[K.dibenzo-18-crown-6] [Al₂(CH₃)₆NO₃].12.2 C₆H₆ Another representative comparison involves the known clathrate:

[Cs][Al₂(CH₃)₆ N0₃].12.0 CHgHg, and the corresponding dibenzo-18-crown-6 clathrate of the present invention:

[Cs.dibenzo-18-crown-6] [Al₂(CH₃) ₆NO₃] .20.2 C₆H₆

In an important aspect of the present invention a solid carbonaceous material such as coal is liquidfied by admixing the carbonaceous material with a liquid clathrate. The chemical mechanism for this phenomena is not fully known, but seems to have similarities to a solvent or catalytic effect. The really surprising aspect of this process is that it occurs at or near room tempera- ture, and in any event, at temperatures which are very far below those temperatures for any other known liquefaction technique. For instance, liquefaction can be effected at temperatures of from 10° - 80ºC and preferably 15°C - 50°C. In many cases, liquefaction will occur at or near room temperature with no application of heat.

The solid carbonaceous material used in this process can be any form of coal including bituminous and subbituminous coal, lignite, or such coal-like forms as oil shale or tar sands. The one which was used predominantly in the research leading to the present invention was bituminous which is mined locally at the Chetopa mine, Mary Lee Seam. The analysis of coal used can vary widely from 40 to 80% by weight carbon, 3 to 15% by weight hydrogen, 0 to 10% by weight oxygen, 0 to 15% by weight nitrogen and 0 to 7% by weight sulfur. Preferred carbon ranges from 80-100 parts per 60-80 parts hydrogen, 0 to 8 parts oxygen, 0 to 8 parts nitrogen and 0 to 4 parts sulfur. It is preferred to use very dry coal because many of the clathrates used herein are moisture sensitive. If necessary, the coal can be dried by conventional means to a dryness of 1 weight percent or less.

The coal may be used in rock form, as mined, or may be crushed to a size of 0.5 mm or smaller to increase the surface area to enable maximum contact with the liquid clathrate. It appears that the size of the coal used merely affects the period of time of liquid clathrate contact. Thus, the larger the coal formation, the longer will be the contact time necessary. The contact time can be reduced by applying mixing or gently agitation. Thus, the larger chunks of coal can be liquefied as fast as smaller particles if agitation or stirring is applied during the contact time. It is believed to be possible in some instances to pump the liquid clathrate into a coal mine shaft whereby the coal liquefaction will occur in situ within the mine and thereafter to pump out a petroleum oil-like product directly from the shaft. If this will work, the commercial advantages are, of course readily apparent.

In general, the clathrates used herein can be any of those disclosed and claimed in U.S. Patent 4,024,170 or the present liquid clathrates whose cationic portion contains at least one multidentate macromolecular ligand. When the clathrate does not contain a multidentate macromolecular ligand in the complex, the liquid clathrate has the formula: M(Q_nR_3nX).pZ wherein M is a mono-, di- or trivalent cation , X is an anion of a mono-, di- or tri-negative salt, Q is Al or Ga, n is 2-4, p is 1 to 40, preferably 4 to 40, and Z is an aromatic hydrocarbon compound. The mono-, di and trivalent cation and anion species include those described above for the multidentate macromolecular compound containing complex salts. R also has the meaning described above.

Mixtures of different clathrates can also be used to liquify the solid carbonaceous material.

Further information concerning liquid clathrates can be obtained by reference to Atwood "Liquid Clathrates," Recent Developments in Separation Sciences, CRC Press, Cleveland, 1977, pages 195-209 (1978).

In the processing of the solid carbonaceous material, a simple salt, an aluminum (gallium) alkyl and the aromatic component, such as benzene or toluene, are mixed together in one step to form the liquid clathrate and then the liquid clathrate is mixed with the solid carbonacious material, or the simple salt and the aromatic can first be admixed and then combined with the solid carbonaceous material and the aluminum (gallium) alkyl to form the clathrate in situ with the carbonaceous material. The former method is the method of choice. Any such combination of steps is suitable for forming the clathrate.

The only limitation on the contact conditions between the clathrate and the coal seems to be that the temperature must be selected such that the liquid clathrate will be in existence during the period of contact. If one is concerned with materials which will clathrate at a temperature of, say, 60°C but wherein the clathrate decomposes back to the complex salt below that temperature, of course, the temperature of coal-clathrate contact must be above 60°C. When the crown ether complex salt is used, the crown ether as the multidentate ligand, simple salt, aluminum alkyl and aromatic must all be brought together. The order of addition does not seem to be critical. In fact, the complex salt can first be formed, converted into a clathrate, and then admixed with the crown ether, whereupon the new ether containing complex will clathrate with additional aromatic compound, as compared to the quantity clathrated by the non-crown ether complex salt.

If the liquid clathrate is formed in an excess of the aromatic, which is usually the case, the existence of the clathrate can be visually detected by a phase separation between a top aromatic hydrocarbon compound solvent layer and the bottom liquid clathrate.

When the clathrate is admixed with the coal, the clathrate is immediately discolored by a black petroleum like product. Thereafter, the aromatic solvent layer gradually becomes discolored as the lighter liquified petroleum products are leached into that layer. The light oil dissolved in the solvent accounts for 5-10% of the oil recovery. From 250 parts to 2500 parts or more of liquid clathrate per part by weight of coal is sufficient to obtain the desired effect.

Petroleum oil separation is attainable almost immediately, with useable yields appearing after 30 minutes. Contact, however, can be maintained for an indefinite period of time and often 1-2 days is desirable.

At the termination of the contact period, the aromatic solvent layer can be decanted off and the hydrocarbon oils contained therein recovered by ordinary separtion means. If the contact time has been permitted for a sufficiently long period, most of the petroleum like oil will have been either solvent extracted into that solvent phase or, in particular, the heavier oils, will have been precipitated out at the bottom of the container. Alternatively, the temperature of the clathrate is reduced or the mixture is subjected to distillation in order to decompose the clathrate and to crystallize out the complex salt. A petroleum oil phase and a solvent (aromatic hydrocarbon) phase above it will appear upon the decomposition of the clathrate. An asphalt-like material is found to cover the complex salt crystals, which asphalt has been found to have an average molecular weight of 300-400 and a pour point above 200°C. The fact that the residue is an asphalt-like material evidences that the coal is being chemically modified in some manner although the precise mechanism for this modification is as yet unknown. The ability of the clathrate to be discolored rapidly after contact with the coal is evidence of a solvent type activity. On the other hand, the fact that the structure of the residue seems to be altered and the fact that no discernable amounts of the complex salt used to make the clathrate are lost, leads to a catalysis explanation. Instead of decomposing the clathrate by reduction in temperature, where the clathrate selected is water or oxygen sensitive, it can alternatively be decomposed by introduction of water moisture or oxygen into the system which attacks the aluminum alkyl component of the salt. For this reason, it is desirable to carry out the coalclathrate contact in a dry, inert atmosphere. A blanket of nitrogen, argon or other inert gas can be desirably maintained over the mixture during the period of contact. The petroleum oil layer formed after the decomposition of the clathrate, is then collected. Tests of the oil confirm that it is a petroleum oil having a weight average molecular weight of from 40 to 300 and a boiling point of from 30° to 300°C. Spectroscopic analysis has confirmed that the oil being produced is a hydrocarbon oil containing a multiplicity of different hydrocarbon products. In the 110°C boiling fraction, more than seventy different compounds result. The present inventor expects that the limitation in the yield of petroleum oil produced is a function of the amount of hydrogen present in the coal sample. Oil recovery amounts to about 10-15% by weight based on the weight of bituminous coal treated. Much higher yields have been obtained for lignite and for tar sands. Good results have been attained with clathrates of the form:

K [Al₂Me₆N₃] NMe₄[Al₂Me₆Cl] NMe₄[Al₂Me₆l] NEt₄[Al₂Me₆l] NPr₄[Al₂Me₆l]

NEt₄[Al₂Me₆NO₃] NEt₄[Al₂Et₆NO₃] K₂[Al₂Me₆SO₄] The economics of the present technique for coal liquefaction are extremely attactive. Unlike all other known liquefaction procedures, little or no heat input is required. Moreover, the cost of producing the clathrates is very modest and the loss factor of the complex salts used to produce the clathrates is small.

The clathrates of the present invention are also useful in the separation of an aromatic hydrocarbon compound from non-aromatic hydrocarbon compounds, as well as for the separation of a given aromatic compound from a different aromatic hydrocarbon compound. For instance, a given multidentate macromolecular compound containing complex salt can be mixed in a solution of benzene and a non-aromatic hydrocarbon such as hexane and the liquid clathrate with benzene will form. The liquid clathrate will separate from the non-aromatic hydrocarbon solution as a separate phase and therefore is easily recovered. The clathrate subsequently can be broken with release of the aromatic hydrocarbon by cooling the clathrate phase or by adding water to the clathrate phase which will destroy the multidentate macromolecular compound containing complex salt.

In another type of separation a mixture of aromatic compounds such as for instance, benzene and toluene can be separated by forming a liquid clathrate of the mixture with a given multidentate macromolecular compound containing complex salt. The liquid clathrate will preferentially form with the molecules of the aromatic hydrocarbon compound which has a greater tendency to form a clathrate with the given macrocyclic compound complex employed. When the clathrate phase is separated from the residual solution and the clathrate is broken, the aromatic hydrocarbon obtained will contain a greater percentage of the aromatic preferentially incorporated in the clathrate. By repeating the separation a sufficient number of times, the original solution can be separated into its individual components.

The multidentate macromolecular compound containing complex salt can also be used to separate an aromatic hydrocarbon dissolved in other non-hydrocarbon, non-active proton containing solvents such as ethers, thioethers, and the like as long as the donor .strength of the non- hydrocarbon solvent is not greater than that of the anion X of the complex salt. Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

EXAMPLE 1

Preparation of Liquid Clathrates

Two different ways by which liquid clathrates may be prepared are best illustrated by reference to the K[Al₂(CH₃)₆N₃] complex. 0.010 mol Al(CH₃)₃ was added to 0.005 mol KN₃ in an N₂ atmosphere dry box. The mixture was sealed in a Fischer-Porter tube, removed from the dry box, heated/ returned to the dry box, and opened. Another 0.005 mol Al(CH₃)₃ was then added to the powdered contents. After three cycles of grinding, adding Al(CH₃)₃, and heating the white crystalline product was dried under vacuum. Addition of benzene (~0.10 mol), followed by heating at 60ºC for 1 hour afforded the liquid clathrate K[A1₂(CH₃) ₆N₃] .5.8 C₆H₆.

Another method for production of the clathrates involves simply the addition of 0.005 mol KN₃ and 0.010 mol A1(CH₃)₃ to 0.10 mol C₆H₆ in the dry box. The liquid clathrate identical in composition to the one prepared by the previous method was obtained in 1 hour. All the following liquid clathrates were synthesized in this fashion.

As the reaction proceeds, a separation of two liquid layers (liquid clathrate and excess aromatic) becomes obvious; the layers appear upon shaking just as oil and water. Once a liquid clathrate has reached its maximum composition, it is not possible to cause a further uptake of aromatic molecules. The formulation of K[Al₂(CH₃)₆N₃] 5.8 C₆H₆ in the above Table represents a maximum aromatic anion ratio. Analysis of the liquid clathrates was done by the integration of NMR spectra recorded on a Perkin Elmer^RR20-B spectrometer. The aromatic stoichiometries quoted in the Table are in each case the average of three preparations and integrations. A realistic standard deviation for them would be ± 0.2 molecules.

The liquid clathrates, although water and oxygen sensitive, are much less reactive than the pure parent organometallic compounds.

EXAMPLE 2 Bituminous coal (Chetopa Mine, Mary Lee seam) was crushed to 1 mm diameter or less and dried at 110°C for 24 hours. One hundred ml of liquid clathrate ([N(C₃H₇)₄][Al₂Me₆l] .toluene) was contacted with 10 g of coal. Immediately 0.4 g dissolved. After heating at 80 C for 12 hours, 1.9 g of coal was extracted or dissolved. Three products resulted: (1) light oil, 0.4 g, toluene-soluble: (2) heavy oil, 0.9 g, toluene-insoluble: (3) asphalt-like residue mixed with unreacted coal. The total amount of material extracted from the coal was 14% by weight.

EXAMPLE 3

The experiment of Example 2 wherein the liquid clathrate-coal solution was not heated above room temperature was repeated, but the contact time was 48 hours. 1.2 g of coal was extracted or dissolved. The product distribution was 0.3 g light oil and 0.5 g heavy oil.

EXAMPLE 4

The coal of Example 2 was added to 100 ml of K[Al₂Meg_n3 . 4.0 toluene, and the mixture was heated to 60° for 4 days. 2.2 g of coal was extracted or dissolved. The product distribution was 0.5 g light oil and 0.9 g heavy oil.

EXAMPLE 5

High sulfur (3% by weight S) subbituminous coal (Walker Co., AL) was crushed to 1 mm diameter or less and dried at 110°C for 24 hours. One hundred ml of liquid clathrate ( [N(C₃H₇)₄][Al₂Me₆l].toluene) was contacted with 10 g of the coal. Immediately, 0.5 g dissolved. After heating to 60°C for 6 hours, 0.6 g of light oil was obtained. (This was measured as the total weight gain in the toluene layer of the two phase system.)

EXAMPLE 6

Lignite (East-Central AL) was dried at 110°C for 4 days. (The weight loss was considerable, and it is estimated that 30% of the "ore" was water.) One hundred ml of liquid clathrate ( [NEt₄][Al₂Et₆l] benzene) was contacted with 10 g of the dried lignite. Immediately 0.5 g dissolved. After 4 hours at room temperature, 1.0 g of light oil resulted.

EXAMPLE 7 Tar sand (North Alabama), 10 g, was added to 100 ml of [NEt4][Al₂Me₆NO₃].toluene. After 1 hour, the excess toluene layer was darker in color than the liquid clathrate layer itself. 1.8 g of light oil was extracted. This was approximately 40% by weight of the organic ma terial.

EXAMPLE 8

The coal of Example 2 was added to 100 ml of [K(18 crown-6)] [Al₂Me₆N₃]. toluene, and the mixture was shaken vigorously for 1 hour. 0.3 g of light oil resulted.

EXAMPLE 9

SEPARATION OF BENZENE (C₆H₆) FROM CYCLOHEXANE (C₆H_{1 2})

A 1.32g (0.005 mole) amount of 18-crown-6 was mixed with 0.40g KN₃ (0.005 mole) in a mixture of 3.52g C₆H₆(4.00ml) and 3.12g.C₆H₁₂ (4.00.ml). One ml of AlMe₃ (0.010 mole) was added, and the liquid clathrate immediately formed. After 15 minutes an nmr sample was taken from the bottom layer (the liquid clathrate). The complete mass balance was obtained as shown in the table below from the analysis of the nmr spectrum of the liquid clathrate, and confirmed by analysis via an nmr spectrum of the top layer.

The above experiment is completely reproducible. A better α value is obtained by longer residence before nmr analysis. After 3 days essentially pure C₆H₆ was found in the liquid clathrate layer. Note, however, at room temperature there is some tendency for the parent compound to crystallize.

A 1.32g amount of 18-crown-6 (0.005 mole) was mixed with 0.40g (0.005 mole) of KN₃ in a mixture of 4.40g C₆H₆ (approx. 5 ml.) and 4.30g C₆H₃Me₃ (approx. 5 ml). 1 ml (0.010 mole) of AlMe,. was added, and the liquid clathrate formed immediatley. After 15 min. an nmr sample was ta ken from the botton layer (the liquid clathrate) and the mass balance, obtained as in Example 1, is as follows:

The experiment is completely reproducible, and α values improve with time, although not as rapidly as in the case of Example 1. Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.

Claims

Claims A multidentate macromolecular compound containing complex salt of the formula: [M(mmc)_x]y[Q_nR3_nX]_z wherein M is a mono, di- or trivalent cation, Q is Al or Ga, R is a lower alkyl group of 1 to 8 carbon atoms, X is a mono-, di- or trivalent anion, n is an integer of 2 to 4, x is 1 or 2, y and z are integers from 1 to 3.

A liquid clathrate of a multidentate macromolecular compound containing complex salt of the formula:

[M(mmc)_χ]_y[Q_nR_3nX]₂.pZ wherein M, Q, R, X, n, x, y and z are as defined in Claim 1 , Z is an aromatic hydrocarbon compound and p is an integer of from 1 to 40.

The salt of Claim 1 or 2 , wherein said multidentate macromolecular compound is a crown ether.

The complex salt of Claim 1, 2 or 3 wherein M is a monovalent cation selected from the group consisting of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Hg⁺, Tl⁺, NR' '₄₊, PR'₄ ⁺ and TlR^, ₂ ⁺ wherein R' is hydrogen, phenyl, naphthyl or alkyl of 1 to 10 carbon atoms.

The complex salt of Claim 1, 2 or 3 wherein M is a divalent cation selected from the group consisting of Ca⁺², Ba⁺², Sr⁺², Hg⁺², Co⁺², Pb⁺² and Cd⁺² or a trivalent cation selected from the group consisting of Ce⁺³, La⁺³, Cr⁺³, Mo⁺³ and Fe⁺³.

The complex salt of Claim 1, 2 or 3 wherein M is a monovalent cation derived from a metal having a normal valence state greater than one but having at least one valence position occupied as a covalent bond with a substituent such that the net positive ionic charge on said metal is one.

The complex salt of Claim 1, wherein said R group is methyl, ethyl, propyl or butyl.

The complex salt of Claim 1, 2 or 3 wherein X is a halide, azide, SCN-, SeCN-, NO3-, NO₂-, lower alkylacylate, OH-, CO₃ ⁼, HCO₃-, SO₄ ⁼ or PO₄ ≡ .

The complex salt of Claim 1 or 2, wherein said multidentate macromolecular compound in said complex is a macrocyclic polyether (crown ether), a macrocyclic polyamine, a macrocyclic polythioether or a mixed donor macrocycle.

The complex salt of Claim 3, wherein said crown ether is 18-crown-6, 15-crown-5, dibenzo-18-crown-6, 21crown-7, dicyclohexyl-18-crown-6, benzo-15-crown-5, benzo-12-crown-4, dibenzo-24-crown-8 or dibenzo-30crown-10.

The complex salt of Claim 3, wherein said crown ether has the formula:

wherein q is 4-8 and R² is lower alkyl, aryl or aryl fused to said ring and r is 0-4. The complex salt of Claim 11, wherein said monovalent cation-crown ether complex has the structure:

The complex salt of Claim 11, wherein said monovalent cation-crown ether complex has the structure:

The clathrate of Claim 2, wherein said component Z is benzene, toluene, o-,m-, or p-xylene, mesitylene, tetramethylbenzene, ethylbenzene, diethylbenzene, dipropylbenzene, diisopropylbenzene, cumene, naphthalene, tetralin, anthracene, or phenanthracene.

A method for the liquefaction of coal, which com prises: admixing said coal with a liquid clathrate; maintaining said admixture for a period sufficient to form a liquid clathrate layer containing liquified petroleum oil products; and separating said petroleum oil from said clathrate. The method of Claim 15, wherein said coal is admixed with the liquid clathrate of Claim 2.

The method of Claim 15, wherein said coal is admixed with a liquid clathrate of the formula: M(Q_nR_3nX).p^Z wherein M is a mono-, di- or trivalent cation, X is an anion of a mono-, di- or trivalent negative salt, Q is Al or Ga, p is 1 to 40, and Z is an aromatic hydrocarbon compound .

The method of Claim 16 or 17, wherein Q is Al.

The method of Claim 16 or 17, wherein M is an alkali metal ion, an alkaline earth metal ion, a quaternary ammonium ion, phosphonium ion, arsonium ion, sulfonium ion, or telluronium ion.

The method of Claim 6, wherein said cation is selected from the group consisting of K ⁺ , Rb ⁺ , Cs ⁺ , NR'₄ ⁺, PR'₄ ⁺, Cr(C₆H₆)₂ ⁺, or TlR'₂ ⁺ wherein R' is hydrogen, an alkyl group of C₁-C₁₀, phenyl or naphthyl.

The method of Claim 15, wherein said admixture of coal and liquid clathrate is effected at a temperature of from 10°C to 80°C.

The method of Claim 15, wherein said admixture of coal and liquid clathrate is effected at a temperature of from 15°C - 50°C.

The method of Claim 15, wherein said admixture of coal and liquid clathrate is effected at room temperature. The method of Claim 15, wherein said petroleum oil product is separated from said clathrate by decomposing said clathrate and recovering said oil therefrom.

The method of Claim 16 or 17, wherein said anion is halide, azide, SCN-, SeCN-, nitrate, nitrite, lower alkylacylate, hydroxide, carbonate, sulfate, or phosphate.

The method of Claim 16 or 17, wherein R is selected from the group consisting of methyl, ethyl, propyl and butyl and n = 2.

The method of Claim 16 or 17, wherein said aromatic hydrocarbon compound is benzene, toluene, o-, m- or p-xylene, mesitylene, tetramethylbenzene, ethylbenzene, dimethylbenzene, cumene, trimethylbenzene, dipropylbenzene, diisopropylbenzene, naphthalene, tetralin, anthracene or phenanthrene.

The method of Claim 15, wherein said admixture of coal and liquid clathrate is maintained for a period of at least 30 minutes.

The method of Claim 15, wherein said admixture is maintained for 6 hours at a temperature of 30°-50°C, and thereafter the temperature of said admixture is reduced to 10°-25°C to effect decomposition of said clathrate.

The method of Claim 15, wherein the coal used in the process has an analysis of 40 to 80 wt.%C, 3 to 15 wt.%H, 0 to 15 wt.%N, 0 to 10 wt.%0, and 0 to 7 wt . %S .

The method of Claim 30, wherein the coal used in the process has an analysis of C 80-100, H 60-80, O 0-10, N 0-12, S 0-7.

The method of Claim 17, wherein said solid carbonaceous material is selected from the group consisting of bituminous and subbituminous coal, lignite, tar sands, and oil shale.

The method of Claim 32, wherein said coal is bituminous.

The method of Claim 15, wherein said liquid clathrate is an admixture of different clathrates.

The method of Claim 16, wherein said multidentate macromolecular compound is a crown ether.

The method of Claim 35, wherein said crown ether has the formula:

wherein q is 4-8 and R² is a lower alkyl, aryl or aryl fused to said ring and r is 0-4.

The method of Claim 36, wherein said cation, M (crown ether) ⁺ , has the formula:

wherein M, R , q and r are as defined above

The method of Claim 36, wherein said cation M (crown ether) has the formula:

wherein M, R , q and r are as defined above.

The method of Claim 15, wherein from 250 to 2500 parts of liquid clathrate is admixed per 1 part of coal by weight.

The method of Claim 15, wherein said petroleum oil product has a light average molecular weight of from 40 to 300 and a boiling point of from 30° to 250°C.

A method of separting an aromatic hydrocarbon compound from solution, comprising: mixing a multidentate macromolecular compound containing complex salt or the individual components of said complex salt and said compound with said aromatic hydrocarbon solution thereby forming a liquid clathrate of said aromatic hydrocarbon as a separate phase; isolating said liquid clathrate phase; and breaking said liquid clathrate phase thereby releasing said aromatic hydrocarbon.

The method of Claim 28, wherein said clathrate is broken by cooling said clathrate phase.

A method of separating an aromatic hydrocarbon compound admixed with a different aromatic hydrocarbon compound, comprising: mixing a multidentate macromolecular compound containing complex salt or the individual components of said complex salt and said compound with said aromatic compound mixture thereby forming a liquid clathrate wherein one of said aromatic compounds preferen- tially clathrates with said multidentate macromolecular compound containing complex salt as a separate phase; isolating said liquid clathrate phase; releasing bound aromatic hydrocarbon which is enriched in the aromatic compound preferentially bound in said clathrate; and repeating the above steps to achieve complete separation of said aromatic compounds.