Integrated process for the solvent refining of coal

A process is set forth for the integrated liquefaction of coal by the catalytic solvent refining of a feed coal in a first stage to liquid and solid products and the catalytic hydrogenation of the solid product in a second stage to produce additional liquid product. A fresh inexpensive, throw-away catalyst is utilized in the second stage hydrogenation of the solid product and this catalyst is recovered and recycled for catalyst duty in the solvent refining stage without any activation steps performed on the used catalyst prior to its use in the solvent refining of feed coal.

TECHNICAL FIELD 
The present invention is directed to the field of solvent refining or 
liquefaction of coal. More specifically, the present invention is directed 
to the solvent refining of coal to produce liquid and normally solid 
products wherein the normally solid products are further catalytically 
processed to provide additional liquid product. The invention contemplates 
the recycle of catalyst from the processing of the normally solid product 
to the solvent refining of coal. 
BACKGROUND OF THE PRIOR ART 
With the reduction in availability of traditional petroleum sources for 
liquid fuels, increased activity has occurred in the processing of solid 
fuel sources such as various rankings of coal. Attempts have been made to 
provide a commercially attractive process for the production of liquid 
fuels which are economically competitive with the remaining petroleum 
fuels which are still currently available. Traditionally, coal 
liquefaction has been performed at exceedingly high pressures and with the 
need for large quantities of expensive hydrogen. Additionally, in order to 
produce improved yields of liquid product from coal, expensive metal 
catalysts of the molybdenum, cobalt and nickel type in various physical 
forms have been utilized. All of these aspects of the previous attempts to 
provide commercially viable liquid fuels from coal have significantly 
affected the costs of producing such fuels. 
Subsequently, attempts have been made to reduce the processing costs for 
the liquefaction of coal to liquid fuels. Generally, liquefaction 
pressures have been reduced from the 5,000 to 10,000 psi processing range 
to a range of 2,000 psi or less. Catalysts for the coal liquefaction have 
also been chosen for their lack of initial expense, as well as their 
selective activity for the liquefaction reactions. 
In this light, U.S. Pat. No. 3,162,594 discloses the use of an inexpensive 
disposable catalyst, such as red mud, in hydrogenating coal extract. The 
spent catalyst from a coal extract hydrogenator is recovered by 
conventional solid/liquid separation and is recycled to a coal extract 
hydrogenator either without any treatment or after regeneration. 
Furthermore, U.S. Pat. No. 3,162,594 discloses the recycling of a spent 
supported catalyst from a downstream hydrocracker, after crushing, to a 
coal extract hydrogenation zone. Coal extract is the material obtained by 
the solvent extraction of coal after being separated from the mineral 
matter and the undissolved coal. It contains a minute, unfilterable amount 
of metallic contaminants, commonly referred to as ash. This recycle 
concept has been used not only for catalysts, but also for the solvent for 
a coal liquefaction reaction as taught in U.S. Pat. No. 3,188,179. 
Recycling spent catalysts diminishes the catalyst expense, but involves a 
reduction in catalyst activity. Various techniques have been utilized to 
improve recycle catalyst activity, and exemplary of such techniques is 
U.S. Pat. No. 3,232,861 in which a supported catalyst from a coal extract 
hydrocracker is ground to expose previously unexposed internal surface 
area of the catalyst and to renew its activity before reintroducing the 
catalyst into a coal extract hydrotreater. 
U.S. Pat. No. 3,488,279 discloses the recycle of a supported catalyst from 
a liquid coal product hydrocracker to a catalytic hydrogenation zone to 
hydrotreat coal extract before feeding it to a hydrocracker. 
The recycle of catalyst in a coal liquefaction process is further described 
in U.S. Pat. Nos. 3,527,691 and 3,549,512 wherein the process is practiced 
in the absence of any substantial liquid phase and the catalyst functions 
as an adsorbent for the product of the coal conversion. 
In U.S. Pat. No. 4,159,238, a coal liquefaction mineral residue and solid 
SRC are recycled from a downstream separator tower back to the coal 
liquefaction reactor. 
U.S. Pat. No. 4,189,372 discloses the recycle of solvent from a coal 
extract hydrocracker back to the coal liquefier vessel. 
The use of spent hydrotreating catalysts from the hydrogenation of 
petroleum, petroleum-derived liquids, Fischer-Tropsch liquids and shale 
oil hydrocarbon processes to a coal liquefaction process is described in 
U.S. Pat. No. 4,295,954. The recycled catalysts are taught to be selected 
from those catalysts used for the hydrogenation of high quality 
hydrocarbons. 
Metal compounds such as oxides and sulfides of elements from Groups VI and 
VII of the Periodic Table are known to be good hydrogenation catalysts. 
Silica and alumina alone are also known to be good cracking catalysts in 
petroleum refining industry because of their acidity. It is also known 
that when metals from Group VI and VIII are deposited on either silica or 
alumina or both, they produce good hydrocracking catalysts. 
The activity of any hydrocracking catalyst depends greatly on the metal 
loading, surface area and pore volume of the catalyst. If ash is not 
removed from coal extract prior to catalytic hydrocracking using a 
supported catalyst, the ash tends to deposit on the catalyst causing a 
reduction in surface area, as well as a reduction in the pore volume of 
the catalyst and eventually catalyst deactivation. 
Coal extract is not similar to, nor does it behave similarly to other 
hydrocarbon materials, such as petroleum derived material, primarily 
because coal extract has a significantly different chemical structure from 
that of other hydrocarbon materials. Coal extract is solid at room 
temperature, whereas the petroleum-derived materials are liquid. Coal 
extract is rich in asphaltenes and preasphaltenes (high molecular weight 
compounds having low hydrogen content), while other hydrocarbonaceous 
materials contain small amounts of asphaltenes and do not contain 
preasphaltenes at all. In comparison with petroleum fuels and residue, 
coal liquids generally exhibit slightly higher carbon content, but 
significantly lower hydrogen content. The coal liquids have a higher 
degree of aromaticity and a more highly condensed ring structure than 
petroleum. A more striking difference between the coal liquids and 
petroleum fuels is the heteroatom content. Nitrogen and oxygen in coal 
liquids are much higher than in petroleum, but sulfur is somewhat lower. 
Coal extract ash is not similar nor does it behave similarly to ash 
contained in petroleum and other materials. The metallic contaminants, 
i.e., ash contained in petroleum derived liquids generally are associated 
with a porphyrin type of molecule which is to a large extent soluble in 
the petroleum. In contrast, up to 50 wt% of the metallic contaminants in 
coal extract are insoluble and finely divided particles. The metals in 
coal extract include Na, Si, Fe, Ca, Mg, Al, Ti, and Boron. The petroleum 
derived material contain predominantly Ni, Ti, and Vanadium. 
It is known that coal extract readily undergoes degradation when it is 
subjected to thermal treatment. The degradation is manifested by the 
formation of coke, hydrocarbon gases and by the increase in the high 
molecular weight, hydrogen deficient portion of the extract. The 
benzene-insoluble (preasphaltene) content of the extract is a measure of 
this undesirable, high molecular weight extract portion. 
The finely divided ash present in the coal extract can diffuse through the 
fine pore structure of a supported catalyst and deposit thereon during 
hydrocracking. This significantly reduces the surface area and pore volume 
of the catalyst. Metal deposition coupled with coke deposition drastically 
reduces the activity of the supported catalyst. Such decrease in activity 
forces resort to more frequent replenishment of the catalyst with fresh 
catalyst. 
The prior art has made many attempts to provide an economic process for the 
liquefaction of coal to liquid fuel products. However, the full 
utilization of inexpensive catalyst material in a process for the 
production of liquid fuels from coal wherein the liquid fuels produced 
constitute a predominent portion of the product of the process has not 
been taught in the prior art. Such an advantage is realized in the process 
of the present invention as described below. 
BRIEF SUMMARY OF THE INVENTION 
The present invention contemplates a process for the solvent refining of 
coal to produce liquid and solid products with the subsequent upgrading of 
the normally solid coal product in a hydrogenation zone in the presence of 
a hydrogenation catalyst which catalyst comprises an inexpensive, 
throw-away catalyst which is unsupported. The hydrogenation catalyst, 
after duty in the hydrogenation of normally solid solvent refined coal 
product, is separated from the hydrogenation product and recycled to the 
initial coal processing stage wherein solvent refining of fresh coal is 
conducted in the presence of this used hydrogenation catalyst. The process 
produces additional quantities of liquid fuel product from the solid, 
fresh coal feed, while utilizing only a single inexpensive catalyst for 
both post-hydrogenation of solvent refined coal and initial solvent 
refining of fresh coal feed. 
The catalyst of the present invention is added to normally solid, 
previously solvent refined coal product along with a solvent and hydrogen 
before being introduced into a hydrogenation zone for the production of 
additional liquid from the solvent refined coal. Distillable liquid 
product is separated from the residual coal product and catalyst 
preferably by distillation. A portion of the liquid product can be 
recycled as the solvent for the hydrogenation treatment. Unconverted 
solvent refined coal is separated from the used catalyst either by 
centrifugation or filtration. The centrifugation or filtration step also 
aids in removing some of the finely divided ash from the unconverted 
solvent refined coal. The recovered solvent refined coal can be further 
treated in a catalytic hydrocracker to produce additional distillable 
liquids. The used catalyst is recycled without further activation 
treatment to the initial process stage of the coal liquefaction for the 
solvent refinement of fresh coal. It is utilized as a catalyst along with 
solvent to convert fresh coal feed into a liquid product and a normally 
solid solvent refined coal product. Again, a portion of the liquid product 
can be recycled as solvent for the solvent refining stage. The normally 
solid coal product from the initial solvent refining stage is separated 
from the spent catalyst from said stage as well as from the ash, 
unconverted coal and mineral matter derived from the feed coal. The 
remaining normally solid solvent refined coal is then slurried with 
solvent and fresh hydrogenation catalyst before being introduced into the 
hydrogenation stage of the process, as described above. 
This cyclic utilization of the hydrogenation catalyst allows for the 
production of additional quantities of liquid product from a set amount of 
solid coal feed without incurring additional expense for the catalysis of 
the initial solvent refining stage of the overall process. 
It has been unexpectedly discovered that the hydrogenation catalyst from a 
solvent refined coal hydrogenation upgrading reaction, in which the 
catalyst experiences the severe environment of the metals and crude 
components of coal, is still significantly active without treatment to 
catalyze the initial solvent refining stage of a coal liquefaction process 
in order to allow the recycle and combined use of the catalyst for not 
only hydrogenation of solvent refined coal, but also the initial solvent 
refining of fresh coal.

DETAILED DESCRIPTION OF THE INVENTION 
Coal liquefaction can be performed in a number of processes. However, the 
coal liquefaction process which is contemplated by the present invention 
is where coal is reacted in the presence of a solvent, particularly a 
hydrogen-donor solvent, in order to convert the solid coal to liquid 
products and a normally solid, solvent refined coal product. The present 
invention subsequently contemplates the treatment of the normally solid, 
solvent refined coal with a fresh hydrogenation catalyst in a 
hydrogenation environment, which is not as severe as a hydrocracking 
environment, wherein the solvent refined coal is further treated to 
extract additional liquid product values and a residual solid product. 
The present invention is a method for producing liquid fuels from coal at a 
lower processing cost. By recycling the used catalyst from the coal 
extract hydrogenation stage of the method to the fresh coal solvent 
refining or liquefaction zone, the method economizes on catalyst 
requirements. This is a significant cost reduction because of the more 
severe environment catalysts must experience in coal liquefaction and coal 
extract hydrogenation in comparison to comparable petroleum upgrading 
processes wherein catalysts are utilized. 
The recycling of supported hydrocracking catalysts has been attempted as 
discussed above. The major obstacle of that recycling attempt has been the 
need to re-activate the hydrocracker catalyst usually by grinding or 
abrading to expose new catalyst surface areas. Hydrocracker catalyst is 
dependent on surface area and pore size to provide catalytic activity. 
Therefore, that type of catalyst is highly susceptible to coke fouling and 
metal fouling, both of which are heightened in coal processing. 
The extent of fouling of a supported hydrocracker catalyst used in solvent 
refined coal processing is apparent from a comparison of the catalyst 
before and after use. A typical analysis of a fresh and a deactivated 
nickel-molybdenum supported on alumina catalyst obtained from 
hydrocracking of solvent refined coal is given below. 
TABLE 1 
______________________________________ 
CATALYST (wt %) 
Fresh Deactivated 
______________________________________ 
carbon -- 18.4 
sulfur -- 6.3 
Fe -- 0.2 
Ti -- 0.3 
Ca -- 0.1 
Na -- 4.2 
Surface Area m.sup.2 /g 
152 89 
Pore Diameter A 96 49 
Pore Volume ml/g 0.38 0.14 
______________________________________ 
The coke and metal deposition on the catalyst is high, but more important 
to hydrocracker catalyst, the surface area, the pore diameter, and the 
pore volume, which are very critical to the performance of such a 
catalyst, decreased significantly. 
In relatively clean hydrocarbon processing systems, such as 
Fischer-Tropsch, the catalyst deactivation is primarily due to coke 
formation (up to 50%) and the activity of the catalyst is regenerated to a 
large extent by burning off the carbon. Similarly, catalyst deactivation 
in a petroleum refining operation is due to coke formation because there 
are no ash or metals in the feed. The catalyst normally has a long life. 
Deactivation of hydrocracking catalyst in resid hydroprocessing is the 
result of coking as well as metal deposition. Still, such catalyst 
deactivation is not as severe as in the hydrocracking of solvent refined 
coal. 
The problem of supported catalyst deactivation can be greatly reduced by 
hydrogenating coal extract, before hydrocracking the extract, in which the 
hydrogenation is performed with finely divided metal compounds as a slurry 
catalyst, as in the present invention. Since this type of catalyst is 
non-porous, the ash and metals present in the coal extract do not deposit 
on the catalyst and the activity is maintained for a longer period of use 
than with supported catalysts. 
The reaction severity of hydrocracking operations is also distinctly 
different than that of hydrogenation operations. Hydrocracking usually 
effects the removal of heteroatoms from the hydrocarbon stock being 
processed, as well as successfully breaking and hydrogenating complex 
aromatic structures. On the other hand, hydrogenation is effective for 
hydrogenating large molecular weight aromatic compounds and reducing their 
molecular size, but is not sufficiently severe to significantly effect 
heteroatom removal or the cracking of aromatic hydrocarbons. The formation 
of hydrocarbon and heteroatom gases, therefore, is much lower in 
hydrogenation reactions than in hydrocracking reactions. 
The process of the present invention is best understood and is easily 
demonstrated by reference to FIG. 1 wherein a preferred embodiment of the 
present invention is set forth. A particulate coal feed material, such as 
bituminous coal or lignite is introduced into the system through line 10. 
The particulate coal is mixed with a recycled hydrogenation catalyst, such 
as an inexpensive pyrite and residual solvent refined coal introduced in 
line 12 from a downstream portion of the process. Other suitable catalysts 
include any of the known hydrogenation catalysts, such as the oxides and 
sulfides of transition metals, particularly Group VIII and VIB. Typical 
catalysts include metals from Groups IVB, VB, VIB, VIIB and VIII. The 
metals can be used individually or in various combinations as taught in 
U.S. Pat. No. 2,227,672 incorporated herein by reference. Preferably, 
metals as their oxides and sulfides are utilized. The catalyst can be in 
the form of water-soluble or organic compound (thermally unstable) soluble 
salts, which are either emulsified or mixed in the process solvent. 
Oil-soluble metal compound catalysts can also be used. Suitable 
oil-soluble catalysts include: (1) inorganic metal halides, oxyhalides and 
heteropoly acids, (2) metal salts of organic acids, such as acyclic, 
alicyclic-aliphatic organic acids, (3) organometallic compounds and (4) 
metal salts of organic amines. Particulate catalysts can also be used, 
such as pyrite, iron oxide, red mud, low concentration of metals, such as 
molybdenum and their compounds and combinations. However, the important 
attribute of the present invention is that the hydrogenation catalyst has 
an extremely small particle size, preferably less than 200 mesh, and that 
its activity is not dependant on pore attributes or surface area of 
catalyst particles individually, as is the case with hydrocracker 
catalysts. 
The mixture of catalyst and particulate coal is slurried in a coal solvent, 
such as creosote oil, tetralin, naphthalene or other coal or petroleum 
produced solvent, such solvent being introduced through line 16. Hydrogen 
is added through line 14 at a pressure in the range of 500 psia to 10,000 
psia. The coal-solvent slurry is then heated to an elevated temperature in 
the preheater 18. The temperature is generally in the range of 400.degree. 
F. to 780.degree. F. The heated slurry is then combined with additional 
hydrogen from line 20. This hydrogen is also supplied at a pressure range 
of 500 psia to 10,000 psia. The heated slurry is then introduced into the 
dissolver 22 wherein the liquefaction and solvent refining of the 
particulate coal material is performed in a catalytic manner in the 
presence of the used and recycled hydrogenation catalyst. The temperature 
in the dissolver is generally maintained in the range of 780.degree. F. to 
900.degree. F., while the pressure is maintained in the range of 500 psia 
to 10,000 psia and a hydrogen feed rate of 5-50 s.c.f./lb of feed coal. 
After a residence time in the dissolver 22 which is generally from 5 
minutes to 100 minutes, the products of the solvent refining of the coal 
are removed for separation and recovery. The product gases are separated 
from the liquefied coal slurry in a gas/liquid separator, not shown in 
FIG. 1. The slurry is then fractionated into various fractions. 
Preferably, this separation is performed in a distillation column 24. A 
light liquid product including some gases is removed as an overhead stream 
in line 26 from the distillation column. this product stream includes 
initial boiling point hydrocarbons up to hydrocarbons boiling at 
550.degree. F. An intermediate cut of hydrocarbon is removed from the 
mid-portion of the distillation column in line 28 and constitutes a liquid 
hydrocarbon fraction in the range of 550.degree. to 850.degree. F. boiling 
point materials. A portion of this product is recycled 16 as a process 
solvent for the feed slurry which is fed to the preheater 18 and dissolver 
22. 
Not all of the coal feed material is converted to distillable liquid in the 
solvent refining process which is performed in the dissolver 22. A portion 
of the coal remains in the solid phase at room temperature although it is 
fluid at the reaction temperature used in the solvent refining process. 
Despite this product being normally solid at room temperature, it is 
significantly more refined than the initial coal material and is referred 
to as solvent refined coal (SRC). This normally solid solvent refined 
coal, along with spent catalyst and unconverted coal and coal mineral 
matter is removed in line 30 from the base of the distillation column 24. 
This material is generally catagorized as having a boiling point in the 
range of 850.degree. F. and above. 
The solvent refined coal mixture in line 30 is introduced into a separation 
unit 32, wherein various fractions of the solvent refined coal mixture are 
isolated, preferably by a critical solvent deashing method. In this 
manner, ash, unreacted coal, mineral matter and spent catalyst are removed 
in line 34 either for disposal or for the production of hydrogen by 
partial oxidation. A heavy solvent refined coal (HSRC) is removed from the 
separation unit 32 in line 36 as a solid product. HSRC is a solid solvent 
refined coal having a high benzene insolubles content normally comprising 
a significant level of preasphaltenes. The final fraction which is removed 
in the separation unit 32 is a light solvent refined coal (LSRC), which is 
removed in line 40. LSRC comprises a solid refined coal material which is 
high in benzene solubles, which are normally referred to as asphaltenes. 
This fraction is desirably further processed for the production of 
additional distillable liquid fuel recovery. Alternately, some portion of 
the HSRC fraction may also be further processed with the LSRC. The HSRC 
would be supplied through line 38. 
The solvent refined coal in line 40, now free of unconverted coal, mineral 
matter, spent catalyst and ash, is then mixed with fresh catalyst from 
line 42. This catalyst is preferably an inexpensive, throw-away catalyst 
such as iron oxide, pyrite or one of the previously mentioned catalysts. 
The catalyst would be an unsupported catalyst in order to avoid the costs 
and deactivation susceptability of such catalysts when used in a 
once-through manner as the present catalyst will be used. The catalyst and 
solvent refined coal mixture in line 40 is slurried with a solvent from 
line 48. The solvent can be similar to the solvent previously supplied to 
the process in line 16 or it can be recovered from the downstream 
distillation unit or generated in the downstream hydrocracking reactor. 
Again, hydrogen in line 44 is supplied to the slurried mixture and the 
composite slurry is introduced into a hydrotreating unit 46. The 
conditions in the hydrogenation reactor 46 are as follows: 
750.degree.-900.degree. F., 500-10,000 psig, a hydrogen feed rate in the 
range of 5-50 s.c.f./lb of feed and a residence time of 20 minutes to 10 
hours. The hydrogenation reactor differs from hydrocracking operations in 
that the severity of the reaction in hydrogenation is much less than in 
hydrocracking. The extent of conversion to distillable material and gases 
in hydrogenation is considerably lower than in hydrocracking. In addition 
to the severity of the reaction, the catalysts employed in hydrogenation 
and hydrocracking reactions are distinctly different. Metals of Groups VI 
and VIII are known to be good hydrogenation catalysts, but have very 
little cracking activity. In order to have good cracking activity, these 
metals are combined with silica or alumina or both. This combination thus 
produces a good hydrocracking catalyst. 
The product from the hydrogenation reactor 46 is removed in line 50 and 
treated in a gas/liquid separator not shown in FIG. 1 to remove 
hydrocarbon and other gases. The liquid product is then transported for 
separation into distillable and non-distillable products. Preferably, this 
separation is performed in a distillation column 52. Liquid products are 
removed from the overhead of the distillation column in line 54. A portion 
of the liquid product can be recycled in line 48 as solvent for the 
hydrogenation performed in the hydrogenation reactor 46. The composite 
non-distillable product is referred to as distillation bottoms. The used 
hydrogenation catalyst which would normally be considered to be inactive 
or reduced in activity below a practical level, especially in treating a 
coal feedstock, is separated by filtration or centrifuge 58 from the 
unconverted solvent refined coal and is then recycled in line 12 to the 
front end of the process to be mixed with particulate feed coal and 
slurried with solvent as the influent to the preheater and dissolver 18 
and 22, respectively. The centrifugation or filtration step also aids in 
removing some of the finely divided ash from the unconverted solvent 
refined coal. The separated unconverted solvent refined coal material from 
the filtration or centrifuge device 58 is removed in line 60 for further 
treatment, such as in a hydrocracker. In this manner, the hydrogenation 
catalyst added in line 42 for the hydrogenation reactor 46 is subsequently 
utilized in the dissolver 22 for the catalytic solvent refining of feed 
coal, before the catalyst, having been twice used in a catalytic manner, 
is removed as spent catalyst from the solvent separation unit 32 in line 
34 along with the ash and mineral matter separated from the liquefied coal 
slurry. 
The following examples demonstrate the manner in which the various stages 
of the process of the present invention are performed, but also the marked 
increase in product conversion in comparison to the prior art. 
EXAMPLE 1 
This example illustrates the hydrogenation of LSRC in the absence of a 
catalyst. A 5 g sample of process solvent having elemental composition 
shown in Table 2 and 5 g LSRC having the elemental composition shown in 
Table 3, were charged to a tubing-bomb reactor having a volume of 46.3 ml. 
The reactor was sealed, pressurized with hydrogen to 1250 psig at room 
temperature and heated to 425.degree. C. It was maintained at the reaction 
temperature for 60 minutes and then cooled to room temperature. The 
reaction product was analyzed to give a product distribution as shown in 
Table 4. SRC conversion due to this thermal reaction was only 13.1 wt%. 
Conversion is the transformation of SRC to oils and gases. 
EXAMPLE 2 
This example illustrates the hydrogenation of LSRC in the presence of a 
pyrite catalyst. The process solvent, and LSRC mixture described in 
Example 1 was mixed with 1 g of pyrite and reacted in the tubing-bomb 
reactor at the same reaction conditions described in Example 1. The 
reaction product distribution obtained is shown in Table 4. The conversion 
of SRC to distillate oil was significantly higher than shown in Example 1. 
The production of gases was lower than shown in Example 1. Most of the 
preasphaltene present in LSRC was converted to oil and gases. 
EXAMPLE 3 
This example illustrates the hydrocracking of LSRC in the presence of a 
commercial Co-Mo hydrocracking catalyst supported on alumina. The reaction 
mixture described in Example 1 was mixed with 1 g Co-Mo-Al and reacted in 
the tubing-bomb reactor at the same reaction conditions described in 
Example 1. The reaction product distribution obtained is again shown in 
Table 4. The conversion of SRC to oil was higher than shown in Examples 1 
and 2. The production of gases was comparable to that shown in Example 1, 
but was higher than Example 2. Most of the preasphaltene present in LSRC 
was converted to oil and gases. The higher gas and oil production in this 
example in comparison to Example 2 demonstrates the difference in severity 
between hydrogenation and hydrocracking reactions. 
TABLE 2 
______________________________________ 
Analysis of the Process Solvent 
Weight % 
______________________________________ 
Fraction 
Oil 92.8 
Asphaltene 5.8 
Preasphaltene 0.7 
Residue 0.7 
Element 
Carbon 89.44 
Hydrogen 7.21 
Oxygen 1.70 
Nitrogen 1.10 
Sulfur 0.55 
______________________________________ 
TABLE 3 
______________________________________ 
Analysis of the LSRC Sample 
Fraction Weight % 
______________________________________ 
Oil 12.0 
SRC 85.8 
Asphaltene 71.4 
Preasphaltene 14.4 
Residue 2.2 
C 85.4 
H 6.8 
O 4.3 
N 1.7 
S 1.0 
______________________________________ 
TABLE 4 
______________________________________ 
Conversion and Product Distribution of LSRC 
Example 1 
Example 2 Example 3 
______________________________________ 
Catalyst None Pyrite Co--Mo--Al 
Gases 4.6 2.7 4.7 
Oil 18.5 41.4 72.5 
SRC 74.6 55.9 21.0 
Asphaltene 65.4 55.1 20.8 
Preasphaltene 
9.2 0.8 0.2 
Residue 2.2 0.0 1.8 
SRC Conversion 
13.1 34.9 75.5 
______________________________________ 
EXAMPLE 4 
This example illustrates the hydrogenation of HSRC in the absence of a 
catalyst. A 1.2 g sample of process solvent having elemental composition 
shown in Table 5 and 2.8 g HSRC having the elemental composition shown in 
Table 5, were charged to a tubing-bomb reactor having a volume of 50 ml. 
The reactor was sealed, pressurized with hydrogen to 850 psig at room 
temperature and heated to 806.degree. F. It was maintained at the reaction 
temperature for 2 hours and then cooled to room temperature. The reaction 
product was analyzed to give a product distribution as shown in Table 6. 
HSRC conversion due to this thermal reaction was 22.8%. 
EXAMPLE 5 
This example illustrates the hydrogenation of HSRC in the presence of a 
molybdenum catalyst. The process solvent and HSRC mixture described in 
Example 4 was mixed with 500 ppm molybdenum (as molybdenum octoate) by wt. 
of HSRC and reacted in the tubing-bomb reactor at the same reaction 
conditions described in Example 4. The reaction product distribution 
obtained is shown in Table 6. The conversion of SRC to distillate oil was 
significantly higher than shown in Example 4. The production of gases was 
lower than shown in Example 4. 
EXAMPLE 6 
This example illustrates the hydrocracking of HSRC in the presence of a 
commercial hydrocracking Ni-Mo catalyst supported on alumina. A mixture of 
HSRC and process solvent having a similar composition as used in Examples 
4 and 5 was hydrocracked in a continuously stirred first basket catalytic 
reactor. The reaction conditions were as follows: 800.degree. F. 
temperature, 2,000 psig pressure, WHSV=1.0 hr.sup.-1 (g feed/g cat. hr.), 
LHSV=0.1 hr.sup.-1 (ml feed/ml reactor hr), and a hydrogen flow rate of 16 
s.c.f./lb of feed. The reaction product distribution obtained is shown in 
Table 6. The data actually represent the initial activity of the catalyst 
which generally drops drastically with time on stream. The production of 
oil was higher than Example 4. Significantly higher production of gases in 
Example 6 than Examples 4 and 5 clearly shows the hydrocracking activity 
and higher heteroatom removal activity of the hydrocracking catalyst. 
TABLE 5 
______________________________________ 
Analysis of HSRC and Process Solvent 
Weight % 
HSRC Process Solvent 
______________________________________ 
Fraction 
Oil 6.0 100.0 
SRC 94.0 0.0 
Element 
Carbon 86.9 89.3 
Hydrogen 6.0 9.7 
Oxygen 4.1 0.5 
Nitrogen 2.0 0.5 
Sulfur 1.0 0.1 
______________________________________ 
TABLE 6 
______________________________________ 
Conversion and Product Distribution of HSRC 
Example 4 
Example 5 Example 6 
______________________________________ 
Catalyst None Molybdenum Ni--Co--Al 
Gases 6.8 6.4 18.3 
Oil 15.9 58.7 60.9 
SRC 77.3 34.9 20.9 
SRC Conversion 
22.7 65.1 79.1 
______________________________________ 
EXAMPLE 7 
This example illustrates the hydrogenation of a process solvent in the 
absence of a catalyst. The elemental composition and boiling point 
distribution of the process solvent are shown in Tables 7 and 8, 
respectively. The process solvent was passed into a one-liter continuous 
stirred tank reactor at a total pressure of 2000 psig and a hydrogen flow 
rate of 2.2 wt% solvent. The reaction temperature was 850.degree. F. and 
the nominal residence time was 61 minutes. The reaction product 
distribution obtained is shown in Table 9. The concentrations of oil and 
asphaltene were lower compared to untreated original solvent as shown in 
Table 9. The concentration of preasphaltene was higher than that in 
original solvent. There was a net production of hydrogen by hydrotreating 
process solvent alone. These data indicate that the process solvent was 
dehydrogenated when treated alone. 
EXAMPLE 8 
This example illustrates the catalytic activity of pyrite in hydrogenation 
of a process solvent. The process solvent described in Example 7 was 
processed at the same reaction conditions as described in Example 7. The 
pyrite was obtained from the Robena Mine at Angelica, Pa. The chemical 
composition of pyrite is given in Table 10. The pyrite was added at a 
concentration level of 10.0 wt% of slurry. The product distribution 
obtained is shown in Table 9. The concentration of oil with pyrite was 
higher than both shown in Example 7 and present in the original solvent. A 
major portion of asphaltene was converted to oil and hydrocarbon gases 
with pyrite which indicates its hydrogenation activity. The hydrogen 
consumption was 0.5 wt% of solvent. X-ray diffraction analysis of the 
solid residue obtained by solvent hydrogenation reaction with pyrite 
showed complete conversion of pyrite to pyrrhotite 11C, which is 
FeS.sub.1.099. 
EXAMPLE 9 
This example illustrates the reaction of coal without a catalyst. A 3 g 
sample of Kentucky Elkhorn #3 coal having the composition shown in Table 
11 was charged to a tubing-bomb reactor having a volume of 46.3 ml. A 6 g 
quantity of solvent described in Example 7 was then added to the reactor. 
The reactor was sealed, pressurized with hydrogen to 1250 psig at room 
temperature and heated to 450.degree. F. for 60 minutes. The reactor was 
then cooled and the reaction product was analyzed to give a product 
distribution as shown in Table 12. Conversion of coal was 77% and the oil 
yield was 16% of maf coal. 
EXAMPLE 10 
This example illustrates the activity of the used catalyst recovered from 
the solvent hydrogenation reaction (Example 8) in a coal liquefaction 
reaction. To the reactor described in Example 9 was added 3 g of coal 
described in Example 9 and 6 g of solvent described in Example 7. Two 
different amounts (0.25 g and 1.0 g) of used catalyst (Pyrrhotite, 
FeS.sub.1.099) recovered from Example 8 were added to the coal-solvent 
reaction mixture. The reaction and product analysis were carried out in 
the same way as described in Example 9. The conversion of coal and oil 
production shown in Table 12 were significantly higher when either 0.25 g 
or 1.0 g of spent catalyst were used than shown in Example 9. 
TABLE 7 
______________________________________ 
Elemental Composition of Solvent 
Weight % 
______________________________________ 
Element 
Carbon 88.79 
Hydrogen 7.40 
Oxygen 1.96 
Nitrogen 1.20 
Sulfur 0.48 
99.83 
Molecular Weight 
210 
NMR Distribution of 
Hydrogen, % 
H.sub.Aromatic 42.0 
H.sub.Benzylic 29.3 
H.sub.Other 28.7 
______________________________________ 
TABLE 8 
______________________________________ 
Simulated Distillation of Solvent 
Weight % Off Temperature .degree.F. 
______________________________________ 
I.B.P. 513 
5% 536 
10% 547 
11% 550 
20% 576 
30% 597 
40% 615 
50% 638 
60% 663 
70% 690 
80% 721 
90% 773 
95% 820 
97% 850 
99% 900 
F.B.P. 921 
______________________________________ 
TABLE 9 
______________________________________ 
Hydrogenation of Process Solvent 
Original 
Process 
Solvent 
Example 7 Example 8 
______________________________________ 
Feed Composition 
-- 100% 90% Solvent + 
Solvent 10% Pyrite 
Temp., .degree.F. 
-- 850 850 
Pressure, psig 
-- 2000 2000 
Hydrogen Flow Rate, 
-- 2.2 2.0 
Wt % Solvent 
Reaction Time, Min. 
-- 61 60 
Product Distribution, 
Wt % 
HC -- 0.9 1.8 
CO, CO.sub.2 -- 0.3 0.2 
H.sub.2 S -- 0.2 0.2 
NH.sub.3 -- 0.0 0.4 
Oil 90.8 87.3 92.9 
Asphaltene 8.9 7.6 3.2 
Preasphaltene 0.4 3.3 0.7 
I.O.M. 0.0 0.2 0.0 
Water -- 0.1 0.8 
Hydrogen Consumption, 
-- -0.2 0.5 
Wt % Solvent 
______________________________________ 
TABLE 10 
______________________________________ 
Analysis of Robena Pyrite 
Weight % 
______________________________________ 
C 4.5 
H 0.3 
N 0.6 
S 41.3 
O 6.0 
Fe 42.3 
Sulfur Distribution 
Pyritic 40.4 
Sulfate 0.7 
Organic 0.6 
______________________________________ 
Other Impurities -- Al, Si, Na, Mn, V, Ti, Cr, Sr, Pb, Co, Mg, Mo, Cu and 
Ni 
TABLE 11 
______________________________________ 
Analysis of Elkhorn #3 Coal 
Obtained From Floyd County, Kentucky 
Weight % 
______________________________________ 
Proximate Analysis 
Moisture 1.81 
Volatile 37.56 
Fixed Carbon 46.03 
Dry Ash 14.60 
Ultimate Analysis 
C 69.40 
H 4.88 
N 1.00 
S 1.94 
O (by difference) 
8.18 
Distribution of Sulfur 
Total Sulfur 1.94 
Sulfate Sulfur 0.04 
Pyrite Sulfur 1.19 
Organic Sulfur 0.75 
______________________________________ 
TABLE 12 
______________________________________ 
Conversion and Product Distribution Based on MAF Coal 
Example 9 
Example 10 
______________________________________ 
Catalyst None Pyrrhotite, 
FeS.sub.1.099 
Amount of Catalyst, g 
-- 0.25 1.0 
Oil 16 42 41 
Asphaltene 48 33 40 
Preasphaltene 
13 13 9 
I.O.M. 23 12 10 
Conversion 77 88 90 
______________________________________ 
The hydrogenation of coal process solvent is deemed to be a representative 
model of the catalyst duty that would be experienced by the catalyst of 
the present invention in the hydrogenation of normally solid solvent 
refined coal, such as takes place in the hydrogenator 46. The examples 
show that catalyst, including inexpensive, relatively low activity 
catalysts such as pyrite, maintain sufficient activity after catalytic 
duty in hydrogenating coal process solvent to still provide a significant 
level of catalytic affect to the solvent refining of feed coal, as is 
demonstrated in a comparison of Example 9 and Example 10, recited above. 
In those examples, the catalytic affect of the previously used 
hydrogenation catalyst, pyrite (converted in situ to pyrrhotite), is 
easily discerned from the conversion ratios listed in Table 12. 
Particularly, the oil value, which is one of the most important product 
components which is sought from the solvent refining or conversion of coal 
feedstocks, is remarkably increased from the non-catalytic Example 9, in 
which only 16% oil is produced, to the catalytic runs in Example 10 
wherein the oil component is 42% and 41%, respectively. It is also 
demonstrated in a comparison of the results of Example 9 and Example 10 in 
Table 12 that the overall conversion is also significantly affected by the 
previously used catalyst in terms of the conversion of the feed coal 
material in those examples. Example 9 has a 77% conversion, while the 
several runs of Example 10 in which used catalyst was present have a 
conversion of 88% and 90%, respectively. 
This demonstrated activity of the catalyst shows that it is economically 
feasible to utilize an inexpensive, throw-away hydrogenation catalyst, 
which has less overall activity than the expensive metal supported 
hydrocracking catalysts, for the hydrogenation of the solid products from 
a solvent refining of coal and, in addition, recycling this used catalyst 
for significant catalytic activity in the initial solvent refining stage 
of a coal processing system, as set forth in the present invention. This 
provides not only economic operation, but conservation of resources in 
that less catalyst is necessary to perform the overall processing of coal 
feedstocks. 
The present invention has been demonstrated in a particular preferred 
embodiment, but it is deemed to be within the skill of those in the art to 
vary specific details of the overall process and such details are deemed 
to be contemplated by the present process. Therefore, the scope of the 
present invention should not be limited to this preferred embodiment, but 
rather should be ascertained by the claims which follow.