Coal liquefaction process

A process for liquefying a particulate coal feed to produce useful petroleum-like liquid products which comprises contacting; in a series of two or more coal liquefaction zones, or stages, graded with respect to temperature, an admixture of a polar compound; or compounds, a hydrogen donor solvent and particulate coal, the total effluent being passed in each instance from a low temperature zone, or stage to the next succeeding higher temperature zone, or stage, of the series. The temperature within the initial zone, or stage, of the series is maintained about 70.degree. F and 750.degree. F and the temperature within the final zone, or stage, is maintained between about 750.degree. F and 950.degree. F. The residence time within the first zone, or stage, ranges, generally, from about 20 to about 150 minutes and residence time within each of the remaining zones, or stages, of the series ranges, generally, from about 10 minutes to about 70 minutes. Further steps of the process include: separating the product from the liquefaction zone into fractions inclusive of a liquid solvent fraction; hydrotreating said liquid solvent fraction in a hydrogenation zone; and recycling the hydrogenated liquid solvent mixture to said coal liquefaction zones.

BACKGROUND OF THE INVENTION 
Hydrogen donor solvent processes for use in the hydrogenation and 
liquefaction of coal are of particular interest among known coal 
conversion processes for the production of useful petroleum-like liquids, 
i.e., 1000.degree. F.- liquid products. In such processes, crushed coal is 
contacted at elevated temperature and pressure with a solvent, often a 
liquid fraction derived from within the process, which acts as a hydrogen 
transfer agent or donor. The solvent supplies hydrogen to the 
hydrogen-deficient coal molecules, as molecules are thermally cracked and 
cleaved from the disintegrating coal solids. 
Coal is largely comprised of polymerized multi-ring aromatic structures, 
and in the breaking coal molecules each bond rupture results in the 
formation of extremely reactive free radicals. These moities, when early 
stabilized by the addition of a hydrogen atom, if sufficiently small, may 
be evolved as a portion of the desired petroleum-like liquid product. If 
the moities become excessively large before they are stabilized, 
undesirable 1000.degree. F.+ liquid products can form. Also, the moities 
can form polymeric products, and the fragments may remain with, or form a 
part of the char or coke that is produced. Sufficient hydrogen must be 
available, and effectively utilized to avoid repolymerization of the 
moities to form char or choke. 
Coal, of course, is not a pure hydrocarbon. It contains volatile matter, 
fusain, mineral matter and sulfur, much as pyritic sulfur, inorganic 
sulfates and organic sulfur compounds. Coal also contains bitumin and 
humin which have large, flat, aromatic, lamellar structures that differ in 
molecular weight, degree of aromaticity, oxygen and nitrogen contents and 
degree of cross-linking. The product liquids produced from coal thus vary 
widely in composition. Whereas much of the coal has been successfully 
converted to useful petroleum-like liquids, the amount of such liquids 
which can be produced is quite variable. The liquid products themselves 
also vary considerably in composition, and liquids are only a portion of 
the total products that are produced. The product liquids contain fusinite 
and ash, as well as char and sludge, which must be separated from the 
liquids. The heavy products from such coal liquefaction processes, 
characterized as "liquefaction bottoms" and consisting of 1000.degree. F.+ 
organics, ash and carbon residue (fusinite), consist largely of carbon, 
60-70 weight percent, and about 20 weight percent ash. The liquefaction 
bottoms, which are less useful than the 1000.degree. F.- liquids, 
generally contain 45-55 weight percent of the original feed coal to the 
process. 
Various attempts have been made to convert more of the carbon of the coal 
to useful liquid products. It is thus desirable to obtain higher levels of 
conversion, and to reduce the level of formation of the excessively high 
molecular weight hydrocarbons which occur in the process. One approach to 
improving carbon efficiency is described, e.g., in U.S. Pat. No. 3,700,583 
issued to Salamony et al on Oct. 24, 1972. This process describes the use 
of quinones, particularly quinone derivatives of mono- and/or polynuclear 
aromatic compounds, certain halogens and halogen halides thereof as 
carbon-radical scavengers which are added with the hydrogen donor solvent 
to the coal liquefaction zone to increase the amount of low molecular 
weight hydrocarbons which are formed within the liquid product, as 
measured by an increase in the total amount of benzene-soluble liquids in 
the product. 
Higher levels of conversion have also been obtained by the use of polar 
solvents added to the coal liquefaction zone as described in application 
Ser. Nos. 607,433 and 641,489, supra. In accordance with the processes 
described in the former application, a heterocyclic nitrogen compound, or 
mixture of heterocyclic nitrogen compounds, and in the latter application 
a heterocyclic oxygen or sulfur compound, or admixture of such compounds, 
is added to a donor solvent fraction indiginous to the process, and the 
donor solvent, containing the added polar-solvent in suitable 
concentration, is recycled to the coal liquefaction zone, thus increasing 
the conversion of coal to lower molecular weight, more useful 
petroleum-like liquid products than obtainable in a process otherwise 
similar except that no polar solvent was employed. It is believed that the 
polar compounds progressively enhance dispersion of the high molecular 
weight compounds, notably those boiling at 1000.degree. F.+, as 
liquefaction of the coal proceeds. The free radicals produced by the 
thermal cracking of the large coal molecules are thus known to be 
extremely short-lived, and are formed principally at the solid interfaces 
wherein the coal solids particles are being dissolved. By improving 
contact between the hydrogen donor solvent and these moities, 
repolymerization of some of these moities with other molecules or with 
each other is suppressed. The greater effectiveness of the hydrogen donor 
molecules in their role of reaching the extremely reactive-free radicals 
as they are formed, and more effectively hydrogenating said radicals is 
thus believed to account largely for these improvements. 
Whereas processes utilizing the addition of polar solvents to the donor 
solvent offer advantages over prior art processes, such process has, 
nonetheless, been found susceptible of further improvement. 
Among the objects of this invention are: 
To provide a new and improved process wherein polar solvents are employed 
to provide further increased yields of the desirable 1000.degree. F.- 
petroleum-like liquid products with further decreased levels of coke or 
char. 
To provide a new and improved hydrogen donor coal liquefaction process, 
particularly one which utilizes a polar solvent or compound to produce 
greater quantities of the more useful petroleum-like liquids, with 
decreased amounts of char and coke. 
SUMMARY OF THE INVENTION 
These and other objects are achieved in accordance with the present 
invention characterized generally as a process for liquefying a coal feed 
to produce useful petroleum-like liquid products which comprises 
contacting, in a series of coal liquefaction zones or stages, graded with 
respect to temperature such that the temperature ascends from the initial 
to the final zone, or stage, of the series, an admixture of a polar 
compound, or polar compounds, a hydrogen donor solvent and particulate 
coal, the total effluent being passed in each instance from a low 
temperature zone, or stage, to a next succeeding higher temperature zone, 
or stage, of the series.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The temperature within the initial zone, or stage, is maintained between 
about 70.degree. F. and 750.degree. F., preferably between about 
600.degree. F. and 720.degree. F., and the temperature within the final 
zone, or stage, being maintained between about 750.degree. F. and 
950.degree. F., preferably between about 800.degree. F. and 880.degree. F. 
Suitably, the liquefaction of the coal feed is conducted in a series of 
from 2 to about 10 zones, or stages, preferably from 2 to about 5 zones, 
or stages, the temperature gradient between the several zones, or stages, 
being regular or irregular, i.e., substantially exponential, linear or 
nonlinear, as measured from the first to the last zone, or stage, of the 
series. The residence time within each of the low temperature zones, or 
stages, of the series ranges from about 20 minutes to about 150 minutes, 
preferably from about 30 minutes to about 120 minutes. The residence time 
within each of the high temperature zones or stages of the series ranges 
from about 10 minutes to about 70 minutes, preferably from about 15 
minutes to about 50 minutes. Whereas it is quite feasible to employ a 
higher residence time in the high temperature zones or stages, no 
significant benefit results from such increase in residence time. The 
product of the liquefaction which is taken from the final stage or zone of 
the series is then separated, suitably by distillation, into fractions 
inclusive of a liquid solvent fraction which contains at least 30 weight 
percent and, preferably, at least 50 weight percent hydrogen donor 
compounds, particularly those fractions boiling within about the 
350.degree.-850.degree. F. range, and preferably within about the 
400.degree.-700.degree. F. range; the liquid solvent fraction is then 
hydrogenated in a hydrogenation zone and the liquid solvent fraction and, 
preferably, the polar compound is then recycled to the first coal 
liquefaction stage. 
By staging the coal liquefaction portion of the process in terms of an 
ascending temperature gradient, measured from the first to the last coal 
liquefaction stage of the series, there results an increase of the 
desirable 1000.degree. F.- liquids and a corresponding decrease in the 
production of 1000.degree. F.+ liquids and solids; vis-a-vis a process 
similarly conducted except that the coal liquefaction portion of the 
process is not staged. The reason for the effectiveness of the staging is 
not understood though it is believed that the staging in effect regulates 
the type of free radical formation in the different stages and provides 
better timing and opportunity for the transport of hydrogen to the 
reactive sites for the early, or timely, healing of the extremely reactive 
moities, or free radicals that are generated. This type of staging is 
believed to provide more opportunity for the formation of the desirable 
1000.degree. F.- liquids and, conversely, less opportunity for 
repolymerization of the reactive moities. 
In its preferred aspects the polar compound in terms of its chemical 
composition is characterized as 
(i) a heterocyclic nitrogen compound which contains from 4 to 5 carbon 
atoms in its nucleus, and one or more atoms of nitrogen preferably one 
nitrogen atom; 
(ii) a low molecular weight heterocyclic oxygen compound containing from 2 
to about 6 and, preferably, from 2 to 3 fused rings, one or more and 
preferably one of which is a five- or six-membered heterocyclic ring 
having from 4 to 5 carbon atoms in the nucleus, preferably 4 carbon atoms, 
and from 1 to 2 atoms of oxygen preferably one atom of oxygen; or 
(iii) a low molecular weight heterocyclic sulfur compound containing from 2 
to about 6, and preferably from 2 to 3 fused rings, one or more and 
preferably one of which is a five- or six-membered heterocyclic ring 
having from 4 to 5 carbon atoms in the nucleus, preferably 4 carbon atoms, 
and from 1 to 2 atoms or sulfur, preferably one atom of sulfur. 
The heterocyclic nitrogen compound or mixture of heterocyclic nitrogen 
compounds added to the coal generated solvent fraction is one which is 
polar, stable, and capable of dissolving at the conditions of operation, 
the high molecular weight hydrocarbons within the reaction mixture, 
particularly the 1000.degree. F.+ hydrocarbons. It is thus a strong 
solvent whether or not it possesses hydrogen donor capabilities, but it 
may be both a strong solvent and a hydrogen donor compound or mixture of 
such compounds. In terms of chemical composition, the heterocyclic 
nitrogen compound is one which contains from 4 to 5 carbon atoms and one 
or more, suitably 1 or 2 and preferably one, nitrogen atom in its nucleus. 
The ring structure can be fused or nonfused, substituted or 
nonsubstituted, and in terms of carbon atoms the total molecule can 
contain from 4 to about 36 carbon atoms preferably from 4 to about 20 
carbon atoms, and most preferably from 5 to about 12 carbon atoms. Ring 
substituents which increase the polarity of the total molecule are 
particularly desirable, such groups as oxy, hydroxy, nitro, amino, 
acetamide, carboxy, carboxy amide, halo, alkyl, alkoxy, phenoxy, and the 
like being preferred substituents, notably the methyl, methoxy, ethyl and 
ethoxy substituents. The substituting groups themselves can be substituted 
or unsubstituted, and more than one substituent, or substituting group can 
be contained upon the ring of the heterocyclic nitrogen compound. Where 
the substituent ring is fused, the fused substituent groups preferably 
contain from 3 to 4 carbon atoms within a substituent ring (ex those 
carbon atoms constituting a portion of the nucleus of the heterocyclic 
nitrogen compound), and preferably from about 1 to 2 substituent rings, 
which can contain atoms which are the same or different from those 
constituting the basic heterocyclic nitrogen compound, and can contain 
oxygen, nitrogen or sulfur within the ring, or attached to a ring carbon 
atom. Exemplary of such heterocyclic nitrogen compounds of this character 
are pyrrole, pyrrolidone, n-methyl pyrrolidone, pyridine, .beta.-picoline, 
.beta.-phenoxy-picoline, .beta.-cresyl-picoline, 2-acetamido-pyridine, 
1-acetyl-piperidine, 1,2,3,4-tetrahydroquinoline, 2-acetamidoquinoline, 
10-benzylacridan, and the like. 
The heterocyclic oxygen or heterocyclic sulfur compound is one comprised of 
fused polycyclic rings, suitably containing from 2 to about 6 and, 
preferably, from 2 to 3 fused rings, at least one and, preferably, one of 
which is a five- or six-membered heterocyclic ring having from 4 to 5 
carbon atoms in its nucleus, preferably 4 carbon atoms, and from 1 to 2, 
preferably one, atom which is either oxygen or sulfur. The heterocyclic 
ring is fused to another ring or to more than one other ring which can be 
heterocyclic or nonheterocyclic, particularly aromatic. The molecule can 
be substituted or unsubstituted and in terms of carbon atoms the total 
molecule can contain from 8 to about 36 carbon atoms, preferably 8 to 
about 20 carbon atoms, and most preferably from 8 to about 12 carbon 
atoms. Ring substituents which increase the polarity of the total molecule 
are particularly desirable, such groups as oxy, hydroxy, nitro, amino, 
acetamide, carboxy, carboxy amide, halo, alkyl, alkoxy, phenoxy and the 
like, be preferred substituents, notably the methyl, methoxy, ethyl and 
ethoxy substituents. The substituting groups, themselves, can be 
substituted or unsubstituted and more than one substituent, or 
substituting group can be present in the molecule. The substituent group, 
or groups, can contain oxygen, nitrogen, or sulfur within the ring or 
attached to a ring carbon atom. Exemplary of heterocyclic oxygen compounds 
of this character are benzofuran, naphthenobenzofuran, dibenzofuran, 
naphthenodibenzofuran, phenanthrenofuran, naphthenophenanthrenofuran, 
1,2-benzopyran, 2-furo[3,4-c]-pyrazole, 2,7-dioxapyrene, 
spiro[benzofuran-3(2),4'-piperidine], and the like, and exemplary of 
heterocyclic surfur compounds of this character are benzothiophene, 
naphthenobenzothiophene, dibenzothiophene, naphthenodibenzothiophene, 
phenanthrenothiophene, naphthenophenanthrenothiophene, 
2-(o-nitropheyldithio)benzothiazole, 10-thiaxanthenol, and the like. 
The polar compound is desirably one which also either possesses or can be 
hydrogenated such that it will possess donatable hydrogen in or near the 
ring, or both. Where the hydrogen donor quality does not exist in the 
polar compound, however, this function can and must be added by admixture 
with a compound, or admixture of compounds, which supplies this 
characteristic. The polar compound in its role as a hydrogen donor is thus 
an unsaturated compound of considerable stability at coal liquefaction 
conditions which can be further hydrogenated, preferably an aromatic 
compound which can be hydrogenated in situ or ex situ of the coal 
liquefaction zone or zones. On donation of the hydrogen at coal 
liquefaction conditions, the stability of the now unsaturated compound is 
retained. In the instance of an aromatic compound, the aromatic compound 
contains hydroaromatic hydrogen which can be donated while the aromatic 
compound remains stable at coal liquefaction conditions. In general, the 
heterocyclic oxygen or sulfur compound, or admixture of such compounds, 
boils within the range from about 250.degree. F. to about 850.degree. F., 
and preferably from about 290.degree. F. to about 700.degree. F. 
In accordance with the practice of this invention, the polar compound, or 
admixture of such compounds, is added to a liquid fraction separated from 
the liquid boiling within the range from about 350.degree. F. to about 
850.degree. F. and, preferably, from about 400.degree. F. to about 
700.degree. F. These fractions have been found admirably suitable as a 
solvent donor, solvent donor vehicle or precursor, and generally contain 
about 30 percent and, most often, about 50 percent of an admixture of 
hydrogen donor compounds adequate to supply the necessary hydrogen under 
coal liquefaction conditions based on the total weight of the recycled 
solvent. Where such amounts of hydrogen donor compounds are not present in 
a given solvent vehicle, additional amounts of these materials can be 
added. Suitably, the polar compound is added to the solvent fraction in 
quantity ranging from about 3 to about 50 percent, preferably from about 5 
to about 20 percent based on the weight of total solvent fed into the coal 
liquefaction zone. 
Preferred hydrogen donor compounds added to, or originally contained within 
a suitable solvent donor vehicle, include indane, dihydronaphthalene, 
C.sub.10 -C.sub.12 tetrahydronaphthalenes, hexahydrofluorine, the 
dihydro-, tetrahydro-, hexahydro- and octahydrophenanthrenes, C.sub.12 
-C.sub.13 acenaphthlenes, the tetrahydro-, hexahydro- and 
decahydro-pyrenes, the dihydro-, tetrahydro-, hexahydro-, and 
octahydro-anthacenes, and other derivatives of partially saturated 
aromatic compounds. In terms of hydrogen donor potential, the solvent to 
which the heterocyclic oxygen or sulfur compound is added, at the time of 
its introduction into or use within the coal liquefaction zone, 
necessarily contains at least about 0.8 percent, and preferably from about 
1.2 to about 3 percent of donatable hydrogen based on the weight of total 
solvent introduced into the coal liquefaction zones. The preferred 
hydrogen donor solvent is one produced within the coal liquefaction 
process and one which contains suitable quantities of hydrogen donor 
precursors to which the polar compound is added. 
In the best mode of practicing the present invention, schematically 
illustrated by reference to the figure, the required process steps 
include, generally (a) a mixing zone 10 within which particulate coal is 
slurried with an internally generated liquid solvent donor fraction, (b) a 
series of two coal liquefaction stages or zones, 20A, 20B, to the first of 
hich the coal slurry is fed and heated to a low temperature ranging from 
about 70.degree. F. to about 750.degree. F., preferably from about 
600.degree. F. to about 720.degree. F. and the total effluent then fed to 
the second stage, or zone, and heated to a higher temperature, suitably to 
a temperature ranging from about 750.degree. F. to about 950.degree. F., 
preferably from about 800.degree. F. to about 880.degree. F. and the coal 
liquefied (c) a distillation and solids separation zone 30 within which a 
liquid solvent fraction, a 1000.degree. F.+ heavy bottoms fraction, and a 
liquid product fraction are separated, and (d) a catalytic solvent 
hydrogenation zone 40 wherein the liquid solvent fraction is hydrogenated, 
and the hydrogenated solvent recycled as a hydrogen donor solvent to said 
coal liquefaction zones. Preferably, the polar compound is recycled with 
the solvent to the coal liquefaction zone but, if desired, can be removed 
from the recycle solvent. 
Referring now to specific features of the process: In the mixing zone 10, 
particulate coal of size ranging up to about 1/8-inch particle size 
diameter, suitably 8 mesh (Tyler), is slurried in recycle solvent. The 
solvent and coal are admixed in a solvent-to-coal ratio ranging from about 
0.8:1 to about 2:1, preferably about 1.2:1 to about 1.6:1 based on weight. 
The solvent is one which boils within the range from about 350.degree. F. 
to about 850.degree. F., preferably from about 400.degree. F. to about 
700.degree. F. The coal slurry is fed, with molecular hydrogen, into the 
coal liquefaction zone 20. 
Within the coal liquefaction zone 20A, the coal is heated to a relatively 
low temperature, preferably to a temperature within the range from about 
600.degree. F. to about 720.degree. F., at which temperature the coal may 
be dispersed and solubilized. The total effluent is then fed into coal 
liquefaction zone 20B and the coal is therein heated to a higher 
temperature, preferably at a temperature ranging from about 800.degree. F. 
to about 880.degree. F. Residence time within zones 20A, 20B, 
respectively, ranges from about 20 minutes to about 150 minutes, 
preferably from about 30 minutes to about 120 minutes and from about 10 
minutes to about 70 minutes, preferably from about 15 minutes to about 50 
minutes. Pressures are not critical, ranging from about 300 psig to about 
3000 psig, preferably from about 800 psig to about 2000 psig. Preferably 
molecular hydrogen is also added to the liquefaction zones 20A, 20B at a 
rate from about 1 to about 6 weight percent (MAF coal basis). 
The product from the coal liquefaction zones 20A, 20B consist of gases and 
liquids, the liquids including a mixture of undepleted hydrogen-donor 
solvent, depleted hydrogen-donor solvent, dissolved coal, undissolved coal 
and mineral matter. The liquid matter is then transferred into a 
separation zone 30 wherein light fractions boiling below 400.degree. F. 
useful as fuel gas are recovered, and intermediate fractions boiling from 
about 400.degree. F. to about 850.degree. F. are recovered for use as a 
hydrogen donor solvent. Heavier fractions boiling from about 700.degree. 
F. to 1000.degree. F. are also recovered, and bottoms fractions boiling 
above 1000.degree. F., including char, are withdrawn for use in 
gasification or for coking, as desired. 
The solvent fraction, or 400.degree.-850.degree. F. fraction, is introduced 
into a solvent hydrogenation zone 40 and hydrogenated in the presence of a 
polar compound to upgrade the hydrogen content of that fraction. The 
conditions maintained in hydrogenation zone 40 effectively hydrogenate 
and, if desired, conditions can be provided which produce substantial 
cracking. Temperatures normally range from about 500.degree. F. to about 
1000.degree. F., preferably from about 640.degree. F. to about 750.degree. 
F., and pressures suitably range from about 650 psig to about 2000 psig, 
preferably from about 1000 psig to about 1400 psig. The hydrogen treat 
rate ranges generally from about 500 to about 10,000 SCF/B, preferably 
from about 1000 to about 5000 SCF/B. 
Conventional hydrogenation catalysts can be employed in the hydrogenation 
zone 40. Typically, such catalysts comprise an alumina or silica-alumina 
support carrying one or more Group VIII non-noble, or iron group metals 
and one or more Group VIB metals of the Periodic Table. In particular, 
combinations of one or more Group VIB metal oxides or sulfides with one or 
more Group VIII metal oxides or sulfides are preferred. Typical catalyst 
metal combinations include oxides and/or sulfides of cobalt-molybdenum, 
nickel-molybdenum, nickel-tungsten, nickel-molybdenum-tungsten, 
cobalt-nickel-molybdenum and the like. A suitable cobalt molybdenum 
catalyst is one comprising from about 1 to about 10 weight percent cobalt 
oxide and from about 5 to about 40 weight percent molybdenum oxide, 
especially about 2 to 5 weight percent cobalt and about 10 to 30 weight 
percent molybdenum. Methods for the preparation of these catalysts are 
well known in the art. The active metals can be added to the support or 
carrier, typically alumina, by impregnation from aqueous solutions 
followed by drying and calcining to activate the composition. Suitable 
carriers include, for example, activated alumina, activated 
alumina-silica, zirconia, titania, etc., and mixtures thereof. Activated 
clays, such as bauxite, bentonite and montmorillonite, can also be 
employed. 
These and other features of the present process will be better understood 
by reference to the following exemplary data. All units are in terms of 
weight unless otherwise specified. 
EXAMPLES 
Examples 1 and 2 
Comparative tests, recorded herein as Runs 323, 324, were conducted to 
demonstrate the effectiveness of staged temperature coal liquefaction. In 
these tests, specified quantities of Illinois #6 coal and donor solvent 
were charged into each of four tubing bombs. 
The coal used was crushed to -100 mesh (Tyler) and sifted to the desired 
size to provide a representative sample. A partially hydrogenated creosote 
oil (pHCO) which contained 2.0 weight percent of donatable hydrogen was 
employed as the solvent, and the solvent-to-coal ratio was 1.6:1. Twenty 
weight percent of .beta.-picoline (Run 324) was added to two of the bombs. 
No .beta.-picoline was added to the other two bombs (Run 323). 
The initial hydrogen gas charge to each bomb was 500 psig at 75.degree. F., 
this corresponding to about 2.3 Wt% of molecular hydrogen based on coal. 
Each of the bombs was then sealed, and each sealed tubing bomb was first 
fixed in a bomb holder and attached to an agitating system before it was 
lowered into a heated sandbath. In a first stage (predissolving stage), a 
tubing bomb was heated to a temperature of 690.degree. F. by immersing the 
bomb in a preheated sandbath and, after a predetermined residence time of 
25 minutes, at this temperature the bomb was then withdrawn from the 
sandbath. In this second stage (liquefaction stage), the bomb was heated 
to a temperature of 840.degree. F. at a residence time of 25 minutes. In 
each instance, the agitation was controlled at a frequency of 120 cycles 
per minute. 
After liquefaction, each bomb was depleted of gas. The gas volume was 
measured by displacement of water in a glass bomb and the gas composition 
was measured by gas chromatography. The slurry recovered from each bomb 
was washed by mixing it for five minutes with cyclohexane in an amount 
equal to ten times its weight. The mixture was then centrifuged for ten 
minutes at a speed of 2000 RPM. The upper layer, which was rich in 
cyclohexane, was decanted and the remaining bottom layer was remixed with 
cyclohexane and again washed. This procedure was performed a total of ten 
times. The amount of slurry from each bomb that did not dissolve in the 
cyclohexane was measured and the respective values of two bombs for each 
run was averaged to yield an average cyclohexane insoluble. 
The results are given in Table I, comparisons being made between Runs 323 
and 324 respectively, these sets of runs having been made on the same date 
at the same time in duplicate runs. 
TABLE I 
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STAGED TEMPERATURE LIQUEFACTION 
Run No. 323 324 
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Liquefaction Information 
Temperature, .degree. F 
690,840 690,840 
Pressure, psig 1310,1970 1310,1790 
Residence Time, Min. 
25,25 25,25 
Coal Type Ill. #6 Ill. #6 
-100 Mesh 100 Mesh 
Solvent Type PHCO-31 PHCO-31 
(D.H.-2.0%) 
.beta.-Picoline 
Dry Feed, g 3.00 3.00 
Solvent, g 4.80 4.80 
0.60 
Solvent/Feed, Wt. Ratio 
1.6/1 1.8/1 
H.sub.2 Feed, Wt% Dry Coal 
2.3 2.3 
Agitation Rate, Cycle/Min 
120 120 
Yields, Wt% Dry Coal 
Molecular H.sub.2 Consumption 
0.30 0.35 
Gas Make 6.35 6.25 
CO.sub.x 1.96 1.66 
H.sub.2 S 0.48 0.49 
C.sub.1 -C.sub.3 3.24 3.72 
C.sub.4 + 0.67 0.37 
Solid Residue 52.5 46.1 
Liquid Make + H.sub.2 O Make 
41.4 48.0 
.DELTA. Liquid Make 
Base 6.6 
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