US 3849287 A
Description (OCR text may contain errors)
United States Patent 91 Gleim et al.
[ Nov. 19,1974
[ COAL LIQUEFACTION PROCESS  Inventors: William K. T. Gleim, Island Lake;
Mark J. OHara, Mt. Prospect, both of Ill.
 Assignee: Universal Oil Products Company, Des Plaines, Ill.
22 Filed: Feb. 5, 1973 21 Appl. NO.2 329,507
3,607,718 9/1971 Leaders et al. 208/8 Primary ExaminerVeronica Ol(eefe Attorney, Agent, or Firm-James R. l-loatson, .lr.; Thomas K. McBride; William H. Page, ll
[5 7] ABSTRACT Coal is solvent extracted with a solvent containing a mixture of hydroaromatic hydrocarbons and saturated aliphatic hydrocarbons to produce a liquid coal extract which has a low asphaltenes content and is distillable without prior hydrogen treatment of the extract liquids.
2 Claims, No Drawings COAL LIQUEFACTION PROCESS BACKGROUND OF INVENTION This invention concerns a process for converting solid carbonaceous materials such as coal into liquid hydrocarbonaceous'products. More particularly, this invention relates to a process for solvent extracting coal to provide hydrocarbonaceous liquid suitable for use as substitutes for petroleum liquids.
Solvent extraction of coal and similar solid carbonaceous materials is known as a method for producing hydrocarbonaceous liquids. The liquid product from these extraction operations may be substituted for petroleum fractions and can be refined to produce gasoline, etc., in a manner analogous to that used to refine petroleum. Because of the abundance of coal reserves and decreasing petroleum resources, it is becoming increasingly important to develop practicalmethods for deriving petroleum substitutes from coal.
in a typical operation for solvent extraction of coal, the coal is pulverized and mixed with a hydrocarbonaceous solvent. The mixture of coal and solvent, generally with added hydrogen gas, is subjected to heat and pressure. A fraction of the coal is dissolved and mixes with the solvent. The liquid mixture of solvent and dissolved coal is then separated from the coal ash and undissolved coal by settling, filtration, etc.
Two problems in particular have caused substantial difficulties in developing an economical operation for solvent extracting coal. These can be characterized briefly as, first, inability to facilitate the transfer of sufficient hydrogen into the hydrogen-deficient coal during the extraction step, and second, lack of selectivity of the solvent in extracting particular components of the coal.
Since the coal to be extracted is relatively low in hydrogen content, it is necessary to add a significant amount of hydrogen to the coal during the solvent extraction operation. In order to form coal liquids which can be used as substitutes for petroleum fractions, the hydrogen content of the coal to be liquefied must be increased typically from about 5 wt.% up to about wt.% or more. Prior art has devised several methods for facilitating the necessary hydrogen addition. Of these, the most commonly suggested have been the use of extraneous catalysts and the use of hydrogen donor solvents. The use of extraneous catalysts has been found generally impractical. These catalysts rapidly become poisoned by the metals present in the coal, and are quite difficult to separate from the solid residue remaining after the extraction operation. Hydrogen donor solvents have provided a partial solution to the problem of transferring hydrogen into the coal. These solvents donate hydrogen to the coal molecule and simultaneously revert from a partially saturated to an aromatic structure. However, the amount of hydrogen which hydrogen donor solvents can typically transfer into the coal is quite limited, and a further hydrogenation treatment subsequent to the extraction operation is generally necessary when using them to extract the coal.
Lack of selectivity of coal solvents in extracting the various available components of coal is partly related to the inability of solvents to transfer sufficient hydrogen into the coal, as discussed above. Lack of selectivity is found generally in prior art solvents, but will be discussed hereinafter in terms of hydrogen donor solvents, since they have generally been employed to the exclusion of other solvents. Hydrogen donor solvents are capable of dissolving a large fraction of the solid coal, often as much as -80%. Unfortunately, the coal liquid obtained by using hydrogen donor solvents invariably contain as much as 40-50% of undesirable components which are substantially refractory to further refining, are severely hydrogen-deficient, and which severely inhibit separation and refining of the more valuable components of the coal extract. For convenience, these undesirable components of the coal extract can be characterized as benzene-insoluble components and benzene-soluble but heptane-insoluble components. The benzene-insoluble fraction of coal liquids is generally thought to result from polymerization of components of the coal after they are dissolved in the solvent. During the extraction operation, the coal molecules are depolymerized and partially hydrogenated. Because of the lack of available hydrogen, a sig nificant fraction of the liquefied material remains in an easily polymerizable state and tends to repolymerize rapidly to form undesirable, high molecular weight compounds which are even more refractory than the original solid coal. since prior art solvents, including the hydrogen donor type, are unable to supply enough hydrogen to saturate or crack these polymerizable compounds, they rapidly convert to undesirable, benzene-insoluble, refractory compounds in prior art operations. It is apparent that simply dissolving a very large fraction of the solid coal without adequate hydrogenation is not only futile, but actually undesirable. The polymerizable compounds which are thereby produced cannot be adequately hydrogenated using prior art solvents and will rapidly form undesirable and untreatable benzene-insoluble compounds. It has been found that a supply of hydrogen gas mixed with prior art solvents and coal during the extraction operation is not sufficient to provide an adequate source of hydrogen which can be effectively utilized in the extraction operation,
since uptake of the hydrogen gas into the solvent and transfer therefrom into the coal molecules is not rapid enough.
The benzene-soluble but heptane-insoluble fraction in coal liquids is hereintermed the asphaltene fraction. Generally, a hydrogen donor solvent dissolves a significantly large amount of asphaltenes, e.g., about l0% or more of the dissolved coal. Asphaltenes are high molecular weight, hydrogen-deficient compounds which are quite refractory to conventional refining techniques. A particular drawback of asphaltenes is that they are undistillable and heat sensitive, and tend to form coke when exposed to distillation temperatures. This property of asphaltene makes it quite difficult to distill the coal liquids recovered in-prior art operations. Asphaltenes are difficult to treat and to separate from more valuable components of the coal extract. They are, therefore, a highly undesirable fraction, and any reduction in the amount of asphaltenes contained in the coal liquid extracted is quite desirable.
Because of the refractory and/or heat sensitive nature of a substantial fraction of coal extracts produced in prior art operations, and because of the presence of readily polymerizable compounds in coal liquid after the extraction step, it has been found impractical to attempt to perform conventional refining operations,
e.g., catalytic cracking and distillation, on the coal liquids as they are recovered from the extraction operation. A further hydrogen treatment of the coal liquid after solvent extraction has been found "necessary in order to make the coal liquids suitable for catalytic cracking, etc. This type of hydrogenation is cumbersome and entails the use of expensive catalysts and high temperatures. The expense and difficulty of such postextraction hydrogenation operations has been a significant barrier to the development of a successful process for solvent extracting coal to provide petroleum substitutes. As described above, the use of extraneous catalysts during the solvent extraction step itself, although successful in producing distillable coal extracts, is technically difficult and also prohibitively expensive, partly because of the necessity for very large scale catalyst regeneration facilities. Such catalysts deactivate rapidly and are difficult to separate from solid residues.
A drawback generally found in prior art liquefaction solvents and processes is the effect of the extraction operation on coal subjected to extraction conditions which is not dissolved during the operation. Any coal which is not dissolved in a first extraction operation has been found quite refractory to any further extraction. This is partly the result of the failure, discussed above, of prior art solvents to transfer sufficient quantities of hydrogen into the coal during the extraction step. The coal not dissolved is quite hydrogen-deficient, and has, if anything, less hydrogen content than the original coal. Coal is thus degraded into a relatively undesirable form by prior art extraction methods, and is not further extractable in a practical manner. Since the object of a solvent extraction operation is to convert coal into petroleum substitutes, it is obviously desirable to treat the coal in a manner which converts any unliquefied, solid coal to a form susceptible to conversion to a liquid rather than degrade the unliquefied coal into merely a low value fuel source. This degradation of the unconverted coal has been a barrier to successful solvent extraction operations when selective conversion of only a fraction of the coal has been attempted using, for example, hydrogen donor solvents.
SUMMARY OF INVENTION An object of the present invention is to provide a process for the liquefaction of coal and similar carbonaceous solids to form distillable liquefaction products.
Another object of the present invention is to provide an extraction solvent capable of selectively extracting desirable components of a carbonaceous solid to to provide hydrocarbonaceous liquids.
Another object of the present invention is to provid a process for solvent extraction of coal in which the liquefaction product is substantially free from nondistillable, coke-forming components.
Another object of the present invention is to provide a solvent for the extraction of coal which facilitates the transfer of hydrogen into the coal during the extraction operation.
Another object of the present invention is to provide a coal liquefaction process in which the coal liquids recovered are suitable for conventional catalytic cracking without prior hydrogenation treatment.
Another object of the present invention is to provide a process for solvent extraction of coal in which the liquid extraction product is substantially free from polymerizable, high molecular weight components.
Another object of the present invention is to provide a process for solvent extraction of coal which does not degrade unliquefied coal into an unextractable state.
In an embodiment, the present invention relates to a process for producing a liquid hydrocarbonaceous product from a solid carbonaceous material which comprises contacting the solid material, at solvent extraction conditions, with a solvent comprising a combination of a hydroaromatic hydrocarbon component and saturated aliphatic hydrocarbon components with a hydroaromatic component/saturated aliphatic components weight ratio of about 1:2 to about 2:1, and recovering the liquid hydrocarbonaceous product from the resulting mixture.
We have found that when a coal extraction solvent containing a mixture of hydroaromatic hydrocarbons and saturated aliphatic hydrocarbons at a volume ratio of about 1:2 to about 2:1 is employed to solvent extract coal, the coal liquids recovered are substantially free from polymerizable and coke forming components. Even more desirably, coal which is not liquefied during the exraction operation of the present invention and remains in solid form, is not degraded in any respect and may be efficiently utilized in further extraction operations. Among the apparent advantages of the present invention are the desirable properties of the liquid coal extracts derived from the extraction operation, which obviate the need for cumbersome and expensive post-extraction hydrogenation operations in order to render the extracts suitable for conventional catalytic cracking operations and provide a distillable liquefaction product directly from the liquefaction step. Other significant advantages derive from the lack of degradation of undissolved coal in the present extraction process, facilitating further extraction or other desired modifications of the coal not converted to a liquid in the extraction step.
DETAILED DESCRIPTION OF INVENTION The solid carbonaceous materials which may be solvent extracted utilizing the process of the present invention include, in general, coal, lignite, peat, oil shale, tar sand, and like materials from naturally-occurring carbonaceous deposits. The present invention is particularly applicable to the conversion of bituminous coal. A typical preferred bituminous coal is an Illinois bituminous stoker coal having a volatiles content of about 5% or higher in the moisture and ash-free (MAF) coal. Although the following description is given with reference only to the preferred bituminous coal, the discussion is equally applicable to the other carbonaceous solid material noted above, unless otherwise stated. In general, better results are obtained in the present process when the coal to be extracted is pulverized to fairly small sized particles, e.g., mesh particle size or smaller. However, pulverization to extremely small size is not essential to the present operation.
The solvent utilized in the present process to extract liquid products from coal contains a combination of particular relative amount of two distinct types of hydrocarbon compounds. The operative components of the present coal solvent are, first, hydroaromatic hydrocarbon components, and second, saturated aliphatic hydrocarbon components. It is essential to the present process that the solvent employed contain compounds from both of these two groups. Other hydrocarbons or extraneous materials may or may not be present in varying amount up to about 20 wt.% of the total solvent without any particular adverse effect on the results obtained. Preferably, compounds not fitting into either of the two categories of essential components of the solvent are not present in the solvent at more than about wt.% of the total solvent. The weight ratio of the two essential types of components in the solvent is an important aspect of effective operation in the present process, since the best results can be obtained only by maintaining the weight ratio within a specified range. Good results are obtained when the weight ratio of the hydroaromatic compounds to the saturated aliphatic compounds is maintained between about 1:2 and about 2: l. A preferred weight ratio range of hydroaromatics to aliphatic components is from about 2:3 to about 3:2. The hydroaromatic components of the solvent employed in the present process may be selected from a broad range of compounds which are characterized as partially hydrogenated condensed aromatic rings with from 1 to 4 (adjacent) CH groups in which the carbon atom of the CH group forms part of the condensed ring structure. An example of a hydroaromatic compound having non-adjacent CH groups is 9,1 O-dihydroanthracene. An example of a hydroaromatic having two adjacent CH groups is 9,l0 dihydrophenanthrene. An example of a hydroaromatic having three adjacent CH groups is indane. An example of a hydroaromatic having four adjacent CH groups is tetrahydronaphthalene. The hydroaromatics suitable for use in the present process have boiling points above about 400F. and preferably above about 500F. It is generally preferred that the hydroaromatic fraction of the solvent of thepresent invention is a mixture of different partially hydrogenated polycyclic aromatic compounds, since pure hydroaromatic compounds, although giving equivalent results, are no more suitable than a mixture and are expensive to obtain. While the partially saturated naphthalenic hydrocarbons, i.e., dihydronaphthalene and tetrahydronaphthalene, are operative as hydroaromatic compounds in the present process, the preferred hydroaromatic hydrocarbons are higher boiling, partially saturated compounds with structures containing three or more condensed benzene nuclei. Examples of suitable compounds include partially hydrogenated anthracene'and phenanthrene derivatives, etc. Other suitable compounds, by way of example, include the partially hydrogenated derivatives of naphthacene, benzanthracene, chrysene, benzophenanthrene, triphenolene, py-
phenanthrene, dihydroanthracene, tetrahydroanthracene, dihydropyrene, tetrahydropyrene, and hexahydrocoronene. Partially saturated condensed ring compounds having one or more relatively short alkyl groups (e.g., l5 carbon atoms) in place of one or more of the hydrogen atoms in the condensed ring structure or similar phenyl group substituents are also suitable. It will be apparent to those skilled in the art that any mixture of partially hydrogenated polycyclic compounds which is derived from petroleum or coal liquids by, for example, partial hydrogenation of a particular fraction of the petroleum or coal oil, will generally contain at least a small fraction of most of the above listed compounds, their alkyl substituted or phenyl group substituted analogues, etc., in various states or partial saturation. As noted above, the compounds which are included in the term hydroaromatic hydrocarbon as used herein are those in which the condensed ring structure is at least partially aromatically unsaturated and at least partially saturated, with at least some of the saturated carbon atoms being bonded to hydrogen atoms. If this condition is satisfied, the presence or absence of short chain alkyl group substitutions, phenyl group substitutions, etc., is not of critical importance. These short alkyl chains and phenyl groups which replace the hydrogen atoms in the saturated portions of at least some of the condensed ring compounds are not believed to play any part in the solvent in the present process.
The saturated aliphatic components of the extraction solvent utilized in the present process include all types of alkanes and cycloalkanes having boiling points above about 400F. and preferably above about 500F. Thus, aliphatic saturates contained in a petroleum fraction which boils above about 400F. (which can be characterized broadly as the kerosene fraction and heavier) may suitably be used to provide saturated aliphatic components for the present solvent. A mixture of saturates such as are typically found in commercial sources such as petroleum fractions, tar sand fractions, etc., is preferred over any particular saturated compound, because best results are obtained when a mixture of both paraffins and naphthenes is employed. Examples of suitable saturated aliphatic compounds which may be used, preferably in admixture, include C and heavier normal paraffins and isoparaffins, with at least C or higher molecular weight preferred, C and longer-chain phenyl-substituted alkanes, alkyl naphthenes, fused ring naphthenic structures, etc. Specific examples of suitable saturated aliphatic structures include n-hexadecane and decahydronaphthalene.
A convenient and suitable solvent for use in the present process may be derived from the bottoms product remaining after vacuum distillation of crude petroleum. Critical to the use of any particular petroleum bottoms fraction is the requirement that the vacuum bottoms must contain condensed ring aromatic compounds and aliphatic compounds at an aromatic/aliphatic weight ratio of about 1:2 to about 2:1 and preferably about 2:3 to about 3:2. The vacuum bottoms are not, per se, employable as an adequate solvent, and must be treated to increase their hydrogen content to an adequate level before good results can be obtainedin solvent extraction. Various suitable methods for hydrogen treating a vacuum bottoms fraction are known to those skilled in the art. By way of example, one method which is suitable for hydrogenation of such a petroleum or tar sand fraction and which is a preferred method for deriving l-ethylthe solvent used in the present process, includes passing a vacuum bottoms petroleum fraction over a fixed bed of a suitable catalyst at a temperature of about 700 to 800F. and a hydrogen pressure of about 170 atmospheres or more. A suitable catalyst may, for example, be a combination of a Group VI metal and a Group VIII metal on a refractory inorganic support. One preferred catalyst for such an operation comprises a combination of nickel and molybdenum on an alumina-silica spherical support. Using such a catalyst, a suitable liquid hourly space velocity (total volume of charge per hour-divided by the volume of catalyst) of about 0.5 to about 1 is generally maintained. Hydrogen is typically recycled in such an operation at a rate of about 5,000 to 15,000 cubic feet per barrel of hydrocarbon charged. After the vacuum bottoms have been processed in this or any other suitable manner in order to provide sufficient fractions of the hydroaromatic compound and saturated aliphatic compounds essential to the solvent of the present process, the light ends (material boiling below about 400F. and preferably all materials boiling below about 500F.) are removed by distillation. The bottoms product remaining after removal of these light ends is a preferred solvent in the present process. It is essential to the use of any petroleum fraction as a solvent in the present process that such a fraction contain both hydroaromatic compounds and saturated aliphatic compounds in particular relative amounts. Unless a particular hydrocarbon fraction contains both types of compounds in sufficient relative quantity, it is unsuitable. For example, slurry oils have ben proposed as coal solvents but, unlike the suitable petroleum and tar sand vacuum bottoms, slurry oils are unsuitable for use in the present process even when subjected to hydrogen treatment as described above. This is believed to be the result of their composition, which is overly high in aromatics content and deficient in aliphatic compounds. Thus, unless a mixture of pure hydroaromatic compounds and saturated aliphatic compounds is specially prepared for use as a solvent, any particular hydrocarbon fraction sought to be employed as a solvent in the present process must be analyzed to determine its composition and, if either too high in aromatics content or aliphatic content, cannot be used. Those skilled in the art will recognize that the relative amount of aromatics and aliphatics in petroleum and tar sand fractions varies over a wide range depending on the source of the petroleum or tar sand, so that not all properly hydrogenated vacuum bottoms fractions are necessarily suitable. By analysis of particular petroleums, tar sands, and any other available sources of a heavy hydrocarbon fraction, and from the description herein, it will be apparent to those skilled in the art which hydrocarbon fraction may suitably by employed in the present process.
Solvent extraction conditions utilized in the present process include a temperature of about 600F to about 850F. and a pressure of about I atmospheres to about 350 atmospheres or more. A temperature of about 675F. to about 800F. and a pressure of about 150 atmospheres to about 250 atmospheres are preferred. The solvent and coal are admixed and charged to the extraction zone at a solvent/coal weight ratio of about 1:2 to about lOzl. A solvent/coal weight ratio of about 1:1 to about 3:1 is preferred. The process of the present invention may be embodied in either a batch type operation or a continuous type operation with good results. In a batch type operation, a quantity of solvent and coal are admixed and placed in a suitable solvent extraction reactor, such as an autoclave, subjected to solvent extraction conditions therein, and then withdrawn after a suitable residence time. A residence time of about /2 hour to about 24 hours may be employed with good results in such embodiments, with a residence time of about 2 hours to about 6 hours being particularly preferred. In a continuous type operation, solvent and coal are continuously admixed, charged to a suitable solvent extraction reactor, maintained therein at extraction conditions for a suitable time, and continuously withdrawn. A suitable liquid hourly space velocity (volume of reactants, solvent and hydrogen charged per hour divided by the volume of the reactor employed) of about 0.25 to about 4 may be employed. A liquid hourly space velocity of about 0.5 to about 1 is preferred in the present process. Any batch type or continuous type reactors employed in the prior art are suitable for use in the present process.
After the solvent extraction operation, the resulting mixture of solvent, liquefied coal, solid coal, ash and light gases is withdrawn from the solvent extraction reactor and the liquefied coalis recovered as the product of the process. Generally, it is preferred to separate the coal liquids and solvent from the solid materials at this time by settling, filtration, centrifugation, hydroclone, extraction with light solvents such as pentane, or other similar methods well known to the prior art. Any suitable method for separating the ash and other solids from the liquid materials may be utilized in the present process. After separation of the solid materials, the coal liquids and solvent may be fractionated directly without any further treatment (i.e., hydrogenation) which has been found necessary in prior art noncatalytic coal liquefaction operation. A fraction of the liquids recovered from the extraction zone may be recycled, in a continuous type operation, for use as a part of the solvent or the whole solvent if such a fraction conforms to the essential composition of the solvent necessary to the present process.
The foliowing examples are presented in order to contrast the process of the present invention with prior art coal liquefaction method and solvents. The examples are also presented in order to illustrate some preferred embodiments of the present process. The examples are presented for the purpose of illustration and contrast only, and are not to be considered as limitation on the generally broad scope of the present invention.
EXAMPLE I A hydrogen-treated vacuum bottoms petroleum fraction derived from a United States crude oil,and having an initial boiling point of 840F., was analyzed and found to contain 40 wt.% of a mixture of paraffins and naphthenes, 50 wt.% hydroaromatic compounds (hydroaromatics/saturated aliphatics weight ratio of 1.25:1) and 10 wt.% polycyclic aromatic compound. The asphaltenes (heptane-insoluble) content of this solvent was found to be 1.8 wt.%. In order to illustrate the process of the present invention, 200 grams of the above-described hydrogen-treated vacuum bottoms fraction and 200 grams of Belleville District, Randolph County Ill. stoker coal, pulverized to mesh size, were placed in an 1,800 cc. rocking autoclave. The autoclave was sealed and sufficient hydrogen was introduced to provide 100 atmospheres hydrogen pressure. The contents of the autoclave were heated to 750F. and agitated at that temperature for 4 hours. The autoclave was then cooled and excess pressure was released. The mixture of liquids and solids remaining in the autoclave was removed and the solid materials were separated from the liquids by centrifuging the mixture. The solids and liquids were analyzed. The results are tabulated under Run 1 in Table I.
EXAMPLE II A second 200 grams of 100 mesh size Illinois stoker coal was placed in the same 1,800 cc. autoclave along with 200 grams of tetrahydronaphthalene. The autoclave was sealed and sufficient hydrogen was charged to provide a hydrogen pressure of 100 atmospheres. In order to compare the process of the present invention, as embodied in Example I, with a conventional solvent extraction operation using a hydrogen donor solvent, the extraction in this run was performed in exactly the same manner as used in Example I. After 4 hours of agitation in the autoclave at 750F., the autoclave was cooled, excess pressure was released, and the liquid and solid contents were removed and separated by centrifugation. The solids and liquids were analyzed and the results are tabulated under Run 2 in Table I.
EXAMPLE III A third 200 gramsarnple of 100 mesh size Illinois stoker coal was placed in the same autoclave with 200 grams of a clarified slurry oil recovered from a catalytic cracking operation. Analysis of the slurry oil showedit to contain 7.2 wt.% hydrogen and 87.1 wt.% carbon. This solvent contained l.3 wt.% heptane-insolubles and had an initial boiling point of 545F.In order to compare the slurry oil as a coalv extraction solvent with the solvent of Example'l, which conformed to the specifications of the present process, the sample of coal in this run was extracted under the same conditions as used in Examples 1 and II. The autoclave was sealed and pressured to I atmospheres with hydrogen. The contents were then agitated at 750F. for 4 hours. Finally, the autoclave was cooled, excess pressure was released, and the mixture of solids and liquids was removed from the autoclave, separated by centrifugation, and analyzed. The results are shown under Run 3 in Table I.
EXAMPLE IV was obtained from the same United States petroleum source as the hydrogen-treated vacuum bottoms used in Example I and placed in the autoclave. This solvent had an API gravity of 8.2? and contained 4.7 wt.% asphaltenes. The autoclave was sealed and sufficient hydrogen was introduced to provide 100 atmospheres hydrogen pressure. The contents of the autoclave were heated to 750F. and agitated for 4 hours at that temperature. The autoclave was then cooled, excess pressure was released, the mixture of liquids and solids in the autoclave was removed. The liquids and solids were separated by centrifugation and analyzed. The results are tabulated under Run 4 in Table I.
EXAMPLE v In order to further illustrate the process of the present invention a sample of hydrogen-treated vacuum bottom from a Mideastern crude oil source was obtained and analyzed. Its initial boiling point was 475F. It contained 12 wt.% hydrogen and had an API gravity of l8.8.. This solvent contained 1.1 wt.% heptaneinsolubles. A 200 gram portion of this hydrotreated vacuum bottoms sample was placed in the 1,800 cc. autoclave with 200 grams of mesh size Illinois stoker coal. Sufficient hydrogen was charged to the autoclave, after it was sealed, to provide 100 atmospheres hydrogen pressure. The contents of the autoclave were then heated to 750F. and agitated at that temperature for 4 hours. The autoclave was cooled, excess pressure was released, and the liquid-solid mixture remaining in the autoclave was removed. The liquids were separated from the solids by centrifugation and both liquids and solids were analyzed. The results are shown under Run 5 in Table 1.
EXAMPLE VI The resulting hydrotreated slurry oil had an API number of 112 and contained 9.1 wt.% hydrogen. A 200 gram sample of this hydrogenated slurry oil was placed in the 1,800 cc. autoclave with'200 grams of 100 mesh size Illinois stoker coal. In order to compare the highly cyclic slurry oil with the hydroaromatic-saturatg solvent mixture of the present process (Runs 1 and 5), the coalin this rum was extracted in exactly the same procedure as used in Examples I and V which employed solvents conforming to the process of this invention. After the hydrogenated slurry oil and coal were placed in the autoclave, it was sealed and sufficient hydrogen was introduced to provide 100 atmospheres pressure. The contents were agitated at 750F. for 4 hours and then cooled. Excess pressure was released and the remaining liquid-solid mixture was removed from the autoclave and separated by centrifugation. The results of analysis of the solids and liquids are shown under Run 6 in Table I.
EXAMPLE vn sure was released, the liquids and solids remaining in p the autoclave were removed, separated by centrifugation, and analyzed. The results of the analysis are shown under Run 7 in Table I.
Referring to Table I, by comparison of the properties of the products obtained using solvents according to the present invention (Runs I, 5 and 8-A, described hereinafter) with a conventional hydrogen donor solvent (Runs 2 and 7) and with other solvents suggested by prior art (Runs 3 and 6), it is obvious that the process of the present invention provides a superior method for solvent extraction of coal. The solvents acagitated at 750F. for 4 hours and then cooled. Excess pressure was released and the liquid-solid mixture was removed. The solids and liquids were separated by centrifugation and analyzed. This Run was designated 8-A,
were placed in the autoclave it was sealed and sufficient hydrogen was charged to provide 100 atmospheres pressure. The contents of the autoclave were cording to the present invention provide a liquefaction and the results of the analysis of the solids and liquids product drastically lower in undesirable benzenefrom this run are tabulated in Table l and Table ll. ln insoluble Products and he ylower p order to illustrate the lack of degradation of the unconinSOlllblC, asphaltehe'eehtalhmg Product.S than the verted coal from Run 8-A, 100 grams of the solids rcconventional solvents can provide under identical excovered f R g were placed in the autoclave traction conditions. As indicated by comparison of Run a|0hg with 0 grams more f the Same 100 mesh coal] 1 (hydrogenated Vacuum bottoms Solvent) whh Run 4 and 200 grams of the same hydrogenated vacuum botf toms fraction solvent used in Run 8 -A. The autoclave TABLE 1 Run 1 2 3 4 5 6 7 8-A Properties of Liguid Product Wt.% MAF Coal Dissolved 48.4 23.4 83.5 10.5 56.4 84.4 87.4 40.3 Wz.% c, lnsolublc 3.7 13.7 20.1 4.4 1.7 13.0 9.0 0.9 Wt. Benzene v Insoluble 0.01 2.5 5.7 API Gravity 158 l8.6 4.3" 6.5" 21 3 Wt.% Hydrogen in liquid 11.5 8.4 7.: 10.6 11.4 8.2 8.1 11.5 Unconverted Solids Wt.% Hydrogen in Pcntane lnsolublc solids 5.9 4.9 4.0 4.6 Wt.% Hydrogen in solids 4.5 2.8 1.7 3.x
raw vacuum bottom solvent), a critical property of the was sealed and hydrogen was introduced sufficient to solvent of the present invention includes a sufficiently provide 100 atmopheres hydrogen pressure. The conhigh content of both hydroaromatics and saturated alitents of the autoclave were agitated at 750F. for 4 phatics in th solvent 35 n pp tCt hhours and then cooled. Excess pressure was released densed r1ng,.unsaturated aromatics and unsaturated al1- and the "quid and Solid contents f the autoclave were Phatlcs as m h" AS Show" Runs 2, 6 and 7, h removed, separated by centrifugation, and analyzed. presence of concentranohs of hydroaromatlc This run was designated Run 8-B and the results are eolhpehehts alone a e h wlthout the Presence of 40 shown thereunder in Table II. As a further indication 'i Salumted l g fi of the lack of degradation of the unextracted portions hlgh Converdslmg to hquld aRvery g s i of the coal, 100 grams of the solid residue resultin prqcess pro as compare 0 from Run 8-B were placed in the autoclave along with scnbed below). In both Table l and Table ll, absence of a numerical tabulation indicates data are not availa 200 gram sample of the Same hydrogenated vacuum able bottoms fraction solvent used in Runs 8-A and 8-B. The autoclave was sealed and sufficient hydrogen was EXAMPLE v1 charged to provide 100 atmospheres hydrogen pres- I d t d t t th lack of de radation of sure. The contents of the autoclave were ag1tated at n or em-ons m e g 750F. for 4 hours. The autoclave was then cooled and coal wh1ch 15 not liquefied during an extract1on operav excess pressure was released. The l1qu1d-sol1d mixture tlon, when usmg the solvents of the present invention,
was removed from the autoclave and separated by centhe following operatlon was performed. A 200 gram tr1fugatron. Thls run was deslgnated Run 8-C. The l1qsample of lll1no1s stoker coal was placed in the 1,800
u1ds and sol1ds were analyzed, and the results are tabucc. rocking autoclave. A 200 gram portion of a fraction med under Run in Table I] of a hydrogenated vacuum bottoms from an American s l By referring to Table ll, 1t w1ll be apparent to those petroleum source was un ize d as the so vent 1n this run. Skilled in the an that processing coal according to the The vaguum bottooms for run had been treated by present invention as described in Example Vlll does processmg at 760 and 200 atmqspheres hydrogen not result in any appreciable degradation of coal which pressure at LHSV over a corlvemlonalfatalyst The is not converted to a liquid during an extraction step. treated product had an API gravlty of 2 The hydro Thus, any coal which is left in a solid state after a pargehgtl'eated bottoms fraction F e dlstllled and the ticular extraction step using theprocess of the present 850 betteme preehlet from this dlshhaheh l used invention may be further extracted with the solvents of as the solvent m th1s run. This solvent contained 1.0 the present invention to provide complete Conversion wh% heptahe'lhselubles- After the Coal and the Solvent of the coal to desirable, distillable liquid products which are low in asphaltenes and polymerized benzeneinsoluble materials.
From the foregoing description and examples, it
is apparent that the process and solvents of the present invention provide a novel and superior method for producing liquid petroleum substitutes from coal. The coal liquids produced by the present process are superior to those produced using conventional hydrogen donor solvents and other solvents suggested by prior art. The
process of the present invention provides a method for transferring large amounts of hydrogen into the coal molecules during the solvent extraction step, a result which has not been achieved by the prior art although a large variety of additives and solvents have been employed in effort to obtain such hydrogen transfer rates.
We claim as our invention:
1. A process for the production of a hydrocarbonaceous liquid which comprises solvent extracting coal with a solvent at a temperature of about 600F. to about 850F., a pressure of about to about 350 atmospheres and a solvent/coal weight ratio of about 1:2 to about 10:1, said solvent being a hydrogenated bottoms product from vacuum distillation of crude petroleum and having an initial normal boiling point above about 400F.
2. A process according to claim 1 wherein said solvent has an initial normal boiling point of greater than about 500F.