U.S. patent application number 14/463923 was filed with the patent office on 2015-05-21 for process for hydrotreating a coal tar stream.
The applicant listed for this patent is UOP LLC. Invention is credited to Paul T. Barger, Maureen L. Bricker, Joseph A. Kocal, Matthew Lippmann, Kurt M. Vanden Bussche.
Application Number | 20150141723 14/463923 |
Document ID | / |
Family ID | 53173960 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150141723 |
Kind Code |
A1 |
Bricker; Maureen L. ; et
al. |
May 21, 2015 |
PROCESS FOR HYDROTREATING A COAL TAR STREAM
Abstract
A process for hydrotreating a coal tar stream is described. A
coal tar stream is provided, and the coal tar stream is
fractionated into at least a light naphtha range hydrocarbon stream
having a boiling point in the range of about 85.degree. C.
(185.degree. F.) to about 137.8.degree. C. (280.degree. F.). The
light naphtha range hydrocarbon stream is hydrotreated by
contacting the light naphtha range hydrocarbon stream with a
naphtha hydrotreating catalyst.
Inventors: |
Bricker; Maureen L.;
(Buffalo Grove, IL) ; Barger; Paul T.; (Arlington
Heights, IL) ; Kocal; Joseph A.; (Glenview, IL)
; Lippmann; Matthew; (Chicago, IL) ; Vanden
Bussche; Kurt M.; (Lake in the Hills, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UOP LLC |
Des Plaines |
IL |
US |
|
|
Family ID: |
53173960 |
Appl. No.: |
14/463923 |
Filed: |
August 20, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61906003 |
Nov 19, 2013 |
|
|
|
Current U.S.
Class: |
585/319 ;
208/211; 208/254H; 208/400 |
Current CPC
Class: |
C10G 2400/02 20130101;
C10G 45/04 20130101; C10G 45/02 20130101; C10G 2400/04
20130101 |
Class at
Publication: |
585/319 ;
208/211; 208/254.H; 208/400 |
International
Class: |
C10G 1/00 20060101
C10G001/00; C10G 69/08 20060101 C10G069/08; C10G 45/08 20060101
C10G045/08 |
Claims
1. A process comprising: providing a coal tar stream; fractionating
the coal tar stream into at least a light naphtha range hydrocarbon
stream having a boiling point in a range of about 85.degree. C.
(185.degree. F.) to about 137.8.degree. C. (280.degree. F.); and
hydrotreating the light naphtha range hydrocarbon stream by
contacting the light naphtha range hydrocarbon stream with a
naphtha hydrotreating catalyst.
2. The process of claim 1 wherein hydrotreating the light naphtha
range hydrocarbon stream removes sulfur, nitrogen, or both.
3. The process of claim 1 wherein hydrotreating the light naphtha
range hydrocarbon stream removes sulfur to provide a hydrotreated
stream having a sulfur concentration of less than about 0.2
ppm.
4. The process of claim 1 wherein the naphtha hydrotreating
catalyst comprises molybdenum and one or more of cobalt and
nickel.
5. The process of claim 1 wherein the naphtha hydrotreating
catalyst comprises nickel and molybdenum.
6. The process of claim 1 wherein the light naphtha range
hydrocarbon stream comprises a hexane insoluble stream, a benzene
insoluble stream, or both.
7. The process of claim 1 further comprising: blending the
hydrotreated stream with a gasoline stream.
8. The process of claim 1 further comprising: reforming the
hydrotreated stream to provide an aromatics stream.
9. The process of claim 1 wherein providing a coal tar stream
comprises pyrolyzing a coal feed in a pyrolysis zone to provide the
coal tar stream and a coke stream.
10. A process comprising: pyrolyzing a coal feed into at least a
coke stream and a coal tar stream in a pyrolysis zone, the coal tar
stream having a boiling point greater than about 400 C;
hydrotreating the coal tar stream by contacting the coal tar stream
with a naphtha hydrotreating catalyst; and fractionating the
hydrotreated stream to provide at least one light hydrocarbon
stream.
11. The process of claim 10 wherein the coal tar stream has a
molecular weight distribution between about 100 and about
4,000.
12. The process of claim 10 wherein the coal tar stream has a
molecular weight distribution between about 250 and about 700.
13. The process of claim 10 wherein hydrotreating the coal tar
stream removes sulfur, nitrogen, or both.
14. The process of claim 10 wherein hydrotreating the coal tar
stream removes sulfur to provide a hydrotreated stream having a
sulfur concentration of less than about 0.2 ppm.
15. The process of claim 10 wherein the naphtha hydrotreating
catalyst comprises nickel and molybdenum.
16. A process comprising: pyrolyzing a coal feed into at least a
coke stream and a coal tar stream in a pyrolysis zone, the coal tar
stream having a boiling point greater than about 400.degree. C.;
contacting the coal tar stream with a solvent in a solvent
extraction zone to provide a heavy insoluble fraction and a light
soluble fraction; separating the heavy insoluble fraction from the
light soluble fraction; and hydrotreating the heavy insoluble
fraction by contacting the heavy insoluble fraction with a kerosene
or distillate hydrotreating catalyst at a temperature of between
about 550.degree. C. and about 700.degree. C. and at a pressure of
between about 4.8 MPa (700 psi) and about 8.3 MPa (1,200 psi).
17. The process of claim 16 wherein the coal tar stream has a
molecular weight distribution between about 100 and about 4000.
18. The process of claim 16 wherein the coal tar stream has a
molecular weight distribution between about 250 and about 700.
19. The process of claim 17 wherein the solvent is a hydrocarbon
fraction.
20. The process of claim 19 wherein the solvent is selected from
the group consisting of benzene and hexane.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/906,003 filed on Nov. 19, 2013, the entirety of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Many different types of chemicals are produced from the
processing of petroleum. However, petroleum is becoming more
expensive because of increased demand in recent decades.
[0003] Therefore, attempts have been made to provide alternative
sources for the starting materials for manufacturing chemicals.
Attention is now being focused on producing liquid hydrocarbons
from solid carbonaceous materials, such as coal, which is available
in large quantities in countries such as the United States and
China.
[0004] Pyrolysis of coal produces coke and coal tar. The
coke-making or "coking" process consists of heating the material in
closed vessels in the absence of oxygen to very high temperatures.
Coke is a porous but hard residue that is mostly carbon and
inorganic ash, which may be used in making steel.
[0005] Coal tar is the volatile material that is driven off during
heating, and it comprises a mixture of a number of hydrocarbon
compounds. It can be separated to yield a variety of organic
compounds, such as benzene, toluene, xylene, naphthalene,
anthracene, and phenanthrene. These organic compounds can be used
to make numerous products, for example, dyes, drugs, explosives,
flavorings, perfumes, preservatives, synthetic resins, and paints
and stains. The residual pitch left from the separation is used for
paving, roofing, waterproofing, and insulation.
[0006] Coal tar includes many contaminants that make it unsuitable
for certain end products. Because of increasingly stringent
standards, it is imperative to provide ways to treat coal tar to
remove contaminants.
[0007] There is a need for an improved process for removing
contaminants from coal.
SUMMARY OF THE INVENTION
[0008] One aspect of the invention involves a process for
hydrotreating a coal tar stream. A coal tar stream is provided, and
the coal tar stream is fractionated into at least a light naphtha
range hydrocarbon stream having a boiling point in the range of
about 85.degree. C. (185.degree. F.) to about 137.8.degree. C.
(280.degree. F.). The light naphtha range hydrocarbon stream is
hydrotreated by contacting the light naphtha range hydrocarbon
stream with a naphtha hydrotreating catalyst.
[0009] Another aspect of the invention involves a process for
providing a light hydrocarbon stream. A coal tar feed is pyrolyzed
into at least a coke stream and a coal tar stream. The coal tar
stream has a boiling point greater than about 400.degree. C. The
coal tar stream is hydrotreated by contacting the light hydrocarbon
stream with a naphtha hydrotreating catalyst. The hydrotreated
stream is fractionated to provide at least one light hydrocarbon
stream.
[0010] Another aspect of the invention involves a process for
hydrotreating a coal tar stream. A coal feed is pyrolyzed into at
least a coke stream and a coal tar stream in a pyrolysis zone. The
coal tar stream has a boiling point greater than about 400.degree.
C. The coal tar stream is contacted with a solvent in a solvent
extraction zone to provide a heavy insoluble fraction and a light
soluble fraction. The heavy insoluble fraction is separated from
the light soluble fraction. The heavy insoluble fraction is
hydrotreated by contacting the heavy insoluble fraction with a
kerosene or distillate hydrotreating catalyst at a temperature of
between about 550.degree. C. and about 700.degree. C. and at a
pressure of between about 4.8 MPa (700 psi) and about 8.3 MPa,
(1200 psi).
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an illustration of a first embodiment of the
process of the present invention.
[0012] FIG. 2 is an illustration of a second embodiment of the
process of the present invention.
[0013] FIG. 3 is an illustration of a third embodiment of the
process of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] FIG. 1 shows a first embodiment of the process 5. A coal
feed 10 can be sent to a pyrolysis zone 15, such as a coking oven.
Alternatively or additionally, a portion of the coal feed 10 can be
sent to a gasification zone (not shown). In the pyrolysis zone 15,
the coal is heated at high temperature, e.g., up to about
2,000.degree. C. (3,600.degree. F.), in the absence of oxygen to
drive off the volatile components. Coking produces a coke stream 20
and a coal tar stream 25. The coke stream 20 can be used in other
processes, such as the manufacture of steel.
[0015] The coal tar stream 25 obtained from the pyrolysis zone 15,
or from other sources, is separated in fractionation zone 30. Coal
tar comprises a complex mixture of heterocyclic aromatic compounds
and their derivatives with a wide range of boiling points. The
number of fractions and the components in the various fractions can
be varied as is well known in the art. A typical separation process
involves separating the coal tar into four to six streams. For
example, there can be a fraction comprising NH.sub.3, CO, and light
hydrocarbons, a light oil fraction with boiling points between
0.degree. C. and 180.degree. C., a middle oil fraction with boiling
points between 180.degree. C. to 230.degree. C., a heavy oil
fraction with boiling points between 230 to 270.degree. C., an
anthracene oil fraction with boiling points between 270.degree. C.
to 350.degree. C., and pitch.
[0016] The light oil fraction contains compounds such as benzenes,
toluenes, xylenes, naphtha, coumarone-indene, dicyclopentadiene,
pyridine, and picolines. The middle oil fraction contains compounds
such as phenols, cresols and cresylic acids, xylenols, naphthalene,
high boiling tar acids, and high boiling tar bases. The heavy oil
fraction contains and creosotes. The anthracene oil fraction
contains anthracene. Pitch is the residue of the coal tar
distillation containing primarily aromatic hydrocarbons and
heterocyclic compounds.
[0017] In the process 5 shown in FIG. 1, the coal tar stream 25 is
fractionated into at least a light naphtha range hydrocarbon stream
40 having a boiling point in a range of about 85.degree. C.
(185.degree. F.) to about 137.8.degree. C. (280.degree. F.). This
can be, as one example, the lightest cut from the coal tar stream
25 produced from the pyrolysis zone 15. The fractionation zone 30
can further provide a heavier hydrocarbon stream or streams 45, a
fraction 35 comprising NH.sub.3, CO, H.sub.2S, and light
hydrocarbons, and a pitch stream 50. The light naphtha range
hydrocarbon stream 40 can include a hexane insoluble stream, a
benzene insoluble stream, or both, but this is not required in all
processes.
[0018] The light naphtha range hydrocarbon stream 40 is sent to a
hydrotreating zone 55, where the light naphtha range hydrocarbon
stream is hydrotreated. Hydrotreating is a process in which
hydrogen gas is contacted with the hydrocarbon stream 40 in the
presence of suitable catalysts which are primarily active for the
removal of heteroatoms, such as sulfur, nitrogen, and metals from
the hydrocarbon feedstock. In hydrotreating, hydrocarbons with
double and triple bonds may be saturated. Aromatics may also be
saturated.
[0019] Typical hydrotreating reaction conditions include a
temperature of about 290.degree. C. (550.degree. F.) to about
455.degree. C. (850.degree. F.), a pressure of about 3.4 MPa (500
psig) to about 26.7 MPa (4,000 psig), a liquid hourly space
velocity of about 0.5 hr.sup.-1 to about 4 hr.sup.-1, and a
hydrogen rate of about 168 to about 1,011 Nm.sup.3/m.sup.3 oil
(1,000 to 6,000 scf/bbl). Preferably, the light naphtha range
hydrocarbon stream 45 is hydrotreated under conditions such that
cracking does not take place.
[0020] Typical hydrotreating catalysts include at least one Group
VIII metal, preferably iron, cobalt and nickel, and at least one
Group VI metal, preferably molybdenum and tungsten, on a high
surface area support material, preferably alumina. Other typical
hydrotreating catalysts include zeolitic catalysts, as well as
noble metal catalysts where the noble metal is selected from
palladium and platinum. Preferably, the naphtha hydrotreating
catalyst includes molybdenum and either cobalt, nickel, or a
combination of cobalt and nickel. A particular example
hydrotreating catalyst is nickel and molybdenum. Preferably, the
hydrotreating removes sulfur to provide a hydrotreated stream 60
having a sulfur concentration of less than about 0.2 ppm, which is
useful for downstream processes.
[0021] The hydrotreated stream 60 may be blended with a gasoline
stream. Alternatively, the hydrotreated stream 60 can be fed to a
processing zone 65 for providing one or more products 70. For
example, the hydrotreated stream 60 can be reformed to provide an
aromatics stream. Reforming is a catalytic process for producing
aromatics from paraffins and naphthenes by rearranging or
restructuring hydrocarbon molecules and breaking larger hydrocarbon
molecules into smaller ones. Hydrogen is produced as a byproduct.
An example reforming process is the CCR PLATFORMING.TM. catalytic
reforming process (UOP, Des Plaines, Ill.), which includes
dehydrogenation of naphthenes, isomerization of paraffins and
naphthenes, dehydrogenation of paraffins, paraffin hydrocracking,
and dealkylation of aromatics. Typical reaction conditions include
operating pressures from about 345 to about 4,830 kPa, and reactor
weighted-average inlet temperatures (WAIT) between about
490.degree. C. to about 540.degree. C. Liquid hourly space velocity
(LHSV) can vary, and the LHSV and reaction temperature can be
configured to produce a particular octane product. An example
reforming process includes a catalyst that is continuously
regenerated in a regeneration section.
[0022] As other examples, the hydrotreated stream 60 can undergo
conversion by hydrocracking, fluid catalytic cracking, alkylation,
transalkylation, oxidation, or hydrogenation.
[0023] Hydrocracking is a process in which hydrocarbons crack in
the presence of hydrogen to lower molecular weight hydrocarbons.
Typical hydrocracking conditions may include a temperature of about
290.degree. C. (550.degree. F.) to about 468.degree. C.
(875.degree. F.), a pressure of about 3.5 MPa (500 psig) to about
20.7 MPa (3,000 psig), a liquid hourly space velocity (LHSV) of
about 1.0 to less than about 2.5 hr.sup.-1, and a hydrogen rate of
about 421 to about 2,527 Nm.sup.3/m.sup.3 oil (2,500 to 15,000
scf/bbl). Typical hydrocracking catalysts include amorphous
silica-alumina bases or low-level zeolite bases combined with one
or more Group VIII or Group VIB metal hydrogenating components, or
a crystalline zeolite cracking base upon which is deposited a Group
VIII metal hydrogenating component. Additional hydrogenating
components may be selected from Group VIB for incorporation with
the zeolite base.
[0024] Fluid catalytic cracking (FCC) is a catalytic hydrocarbon
conversion process accomplished by contacting heavier hydrocarbons
in a fluidized reaction zone with a catalytic particulate material.
The reaction in catalytic cracking is carried out in the absence of
substantial added hydrogen or the consumption of hydrogen. The
process typically employs a powdered catalyst having the particles
suspended in a rising flow of feed hydrocarbons to form a fluidized
bed. In representative processes, cracking takes place in a riser,
which is a vertical or upward sloped pipe. Typically, a pre-heated
feed is sprayed into the base of the riser via feed nozzles where
it contacts hot fluidized catalyst and is vaporized on contact with
the catalyst, and the cracking occurs converting the high molecular
weight oil into lighter components including liquefied petroleum
gas (LPG), gasoline, and a distillate. The catalyst-feed mixture
flows upward through the riser for a short period (a few seconds),
and then the mixture is separated in cyclones. The hydrocarbons are
directed to a fractionator for separation into LPG, gasoline,
diesel, kerosene, jet fuel, and other possible fractions. While
going through the riser, the cracking catalyst is deactivated
because the process is accompanied by formation of coke which
deposits on the catalyst particles. Contaminated catalyst is
separated from the cracked hydrocarbon vapors and is further
treated with steam to remove hydrocarbon remaining in the pores of
the catalyst. The catalyst is then directed into a regenerator
where the coke is burned off the surface of the catalyst particles,
thus restoring the catalyst's activity and providing the necessary
heat for the next reaction cycle. The process of cracking is
endothermic. The regenerated catalyst is then used in the new
cycle. Typical FCC conditions include a temperature of about
400.degree. C. to about 800.degree. C., a pressure of about 0 to
about 688 kPag (about 0 to 100 psig), and contact times of about
0.1 seconds to about 1 hour. The conditions are determined based on
the hydrocarbon feedstock being cracked, and the cracked products
desired. Zeolite-based catalysts are commonly used in FCC reactors,
as are composite catalysts which contain zeolites, silica-aluminas,
alumina, and other binders.
[0025] Alkylation is typically used to combine light olefins, for
example mixtures of alkenes such as propylene and butylene, with
isobutane to produce a relatively high-octane branched-chain
paraffinic hydrocarbon fuel, including isoheptane and isooctane.
Similarly, an alkylation reaction can be performed using an
aromatic compound such as benzene in place of the isobutane. When
using benzene, the product resulting from the alkylation reaction
is an alkylbenzene (e.g. toluene, xylenes, ethylbenzene, etc.). For
isobutane alkylation, typically, the reactants are mixed in the
presence of a strong acid catalyst, such as sulfuric acid or
hydrofluoric acid. The alkylation reaction is carried out at mild
temperatures, and is typically a two-phase reaction. Because the
reaction is exothermic, cooling is needed. Depending on the
catalyst used, normal refinery cooling water provides sufficient
cooling. Alternatively, a chilled cooling medium can be provided to
cool the reaction. The catalyst protonates the alkenes to produce
reactive carbocations which alkylate the isobutane reactant, thus
forming branched chain paraffins from isobutane. Aromatic
alkylation is generally now conducted with solid acid catalysts
including zeolites or amorphous silica-aluminas.
[0026] The alkylation reaction zone is maintained at a pressure
sufficient to maintain the reactants in liquid phase. For a
hydrofluoric acid catalyst, a general range of operating pressures
is from about 200 to about 7,100 kPa absolute. The temperature
range covered by this set of conditions is from about -20.degree.
C. to about 200.degree. C. For at least alkylation of aromatic
compounds, the temperature range is from about 100.degree. C. to
about 200.degree. C. at the pressure range of about 200 to about
7,100 kPa.
[0027] Transalkylation is a chemical reaction resulting in transfer
of an alkyl group from one organic compound to another. Catalysts,
particularly zeolite catalysts, are often used to effect the
reaction. If desired, the transalkylation catalyst may be metal
stabilized using a noble metal or base metal, and may contain
suitable binder or matrix material such as inorganic oxides and
other suitable materials. In a transalkylation process, a
polyalkylaromatic hydrocarbon feed and an aromatic hydrocarbon feed
are provided to a transalkylation reaction zone. The feed is
usually heated to reaction temperature and then passed through a
reaction zone, which may comprise one or more individual reactors.
Passage of the combined feed through the reaction zone produces an
effluent stream comprising unconverted feed and product
monoalkylated hydrocarbons. This effluent is normally cooled and
passed to a stripping column in which substantially all C.sub.5 and
lighter hydrocarbons present in the effluent are concentrated into
an overhead stream and removed from the process. An aromatics-rich
stream is recovered as net stripper bottoms, which is referred to
as the transalkylation effluent.
[0028] The transalkylation reaction can be effected in contact with
a catalytic composite in any conventional or otherwise convenient
manner and may comprise a batch or continuous type of operation,
with a continuous operation being preferred. The transalkylation
catalyst is usefully disposed as a fixed bed in a reaction zone of
a vertical tubular reactor, with the alkylaromatic feed stock
charged through the bed in an upflow or downflow manner. The
transalkylation zone normally operates at conditions including a
temperature in the range of about 130.degree. C. to about
540.degree. C. The transalkylation zone is typically operated at
moderately elevated pressures broadly ranging from about 100 kPa to
about 10 MPa absolute. The transalkylation reaction can be effected
over a wide range of space velocities. That is, volume of charge
per volume of catalyst per hour; weight hourly space velocity
(WHSV) generally is in the range of from about 0.1 to about 30
hr.sup.-1. The catalyst is typically selected to have relatively
high stability at a high activity level.
[0029] Oxidation involves the oxidation of hydrocarbons to
oxygen-containing compounds, such as aldehydes. The hydrocarbons
include alkanes, alkenes, typically with carbon numbers from 2 to
15, and alkyl aromatics, linear, branched, and cyclic alkanes and
alkenes can be used. Oxygenates that are not fully oxidized to
ketones or carboxylic acids can also be subjected to oxidation
processes, as well as sulfur compounds that contain --S--H
moieties, thiophene rings, and sulfone groups. The process is
carried out by placing an oxidation catalyst in a reaction zone and
contacting the feed stream which contains the desired hydrocarbons
with the catalyst in the presence of oxygen. The type of reactor
which can be used is any type well known in the art such as
fixed-bed, moving-bed, multi-tube, CSTR, fluidized bed, etc. The
feed stream can be flowed over the catalyst bed either up-flow or
down-flow in the liquid, vapor, or mixed phase. In the case of a
fluidized-bed, the feed stream can be flowed co-current or
counter-current. In a CSTR the feed stream can be continuously
added or added batch-wise. The feed stream contains the desired
oxidizable species along with oxygen. Oxygen can be introduced
either as pure oxygen or as air, or as liquid phase oxidants
including hydrogen peroxide, organic peroxides, or peroxy-acids.
The molar ratio of oxygen (O.sub.2) to alkane can range from about
5:1 to about 1:10. In addition to oxygen and alkane or alkene, the
feed stream can also contain a diluent gas selected form nitrogen,
neon, argon, helium, carbon dioxide, steam or mixtures thereof. As
stated, the oxygen can be added as air which could also provide a
diluent. The molar ratio of diluent gas to oxygen ranges from
greater than zero to about 10:1. The catalyst and feed stream are
reacted at oxidation conditions which include a temperature of
about 300.degree. C. to about 600.degree. C., a pressure of about
101 kPa to about 5,066 kPa and a space velocity of about 100 to
about 100,000 hr.sup.-1.
[0030] Hydrogenation involves the addition of hydrogen to
hydrogenatable hydrocarbon compounds. Alternatively hydrogen can be
provided in a hydrogen-containing compound with ready available
hydrogen, such as tetralin, alcohols, hydrogenated naphthalenes,
and others via a transfer hydrogenation process with or without a
catalyst. The hydrogenatable hydrocarbon compounds are introduced
into a hydrogenation zone and contacted with a hydrogen-rich
gaseous phase and a hydrogenation catalyst in order to hydrogenate
at least a portion of the hydrogenatable hydrocarbon compounds. The
catalytic hydrogenation zone may contain a fixed, ebulated or
fluidized catalyst bed. This reaction zone is typically at a
pressure from about 689 kPag (100 psig) to about 13,790 kPa gauge
(2,000 psig) with a maximum catalyst bed temperature in the range
of about 177.degree. C. (350.degree. F.) to about 454.degree. C.
(850.degree. F.). The liquid hourly space velocity is typically in
the range from about 0.2 hr.sup.-1 to about 10 hr.sup.-1 and
hydrogen circulation rates from about 200 standard cubic feet per
barrel (SCFB) (35.6 m.sup.3/m.sup.3) to about 10,000 SCFB (1778
m.sup.3/m.sup.3).
[0031] FIG. 2 shows a second embodiment of a process 72 of the
present invention, in which like reference characters apply to
similar features. In the process of FIG. 2, the coal feed 10 is
pyrolyzed in the pyrolysis zone 15 into at least the coke stream 20
and the coal tar stream 25. An example coal tar stream 25 in this
embodiment has a boiling point greater than about 400.degree. C.
The coal tar stream 25 can also have a molecular weight
distribution between about 100 and about 4,000, and preferably a
molecular weight distribution between about 250 and about 700.
[0032] The coal tar stream 25 is hydrotreated in a hydrotreating
zone 75. As with the hydrotreating zone 30 shown in FIG. 1, in the
hydrotreating zone 75, the coal tar stream 25 is contacted with a
naphtha hydrotreating catalyst. The naphtha hydrotreating catalyst
preferably includes molybdenum and either cobalt, nickel, or both
cobalt and nickel. Preferably, the naphtha hydrotreating catalyst
includes nickel and molybdenum. The hydrotreating in the
hydrotreating zone 75 can remove sulfur, nitrogen, or both. The
hydrotreating preferably removes sulfur to provide a hydrotreated
coal tar stream 80 having a sulfur concentration of less than about
0.2 ppm. Hydrotreating conditions can be similar to those disclosed
above.
[0033] The hydrotreated coal tar stream 80 is fractionated in
fractionation zone 85 to provide at least one light hydrocarbon
stream 95. Preferably, this light hydrocarbon stream 95 is a light
naphtha range hydrocarbon stream having a boiling point in a range
of about 85.degree. C. (185.degree. F.) to about 137.8.degree. C.
(280.degree. F.). The fractionation zone 85 can also produce other
hydrocarbon streams such as a middle oil fraction 100 with boiling
points between 180.degree. C. to 230.degree. C., a heavy oil
fraction 105 with boiling points between 230.degree. C. to
270.degree. C., an anthracene oil fraction (not shown) with boiling
points between 270.degree. C. to 350.degree. C., and a pitch stream
110. A fraction 90 comprising NH.sub.3, CO, H.sub.2S, and light
hydrocarbons can also be provided by the fractionation zone 85. One
or more of the hydrocarbon streams, such as the light hydrocarbon
stream 95 as shown in FIG. 2, or other hydrocarbon streams can be
fed to a processing zone 115 as described above to produce one or
more products 120.
[0034] FIG. 3 shows a third embodiment of the process 128 of the
present invention, where like reference characters refer to similar
features. The coal stream 10 is pyrolyzed in the pyrolysis zone 15
into at least the coke stream 20 and the coal tar stream 25.
Preferably, the coal tar stream 25 has a boiling point greater than
about 400.degree. C. Further, the coal tar stream 25 can have a
molecular weight distribution between about 100 and about 4000.
Preferably, the coal tar stream 25 has a molecular weight
distribution between about 250 and about 700. The coal tar stream
25 enters a solvent extraction zone 130. A solvent 135, which
preferably comprises a hydrocarbon fraction, and more preferably
comprises benzene, hexane, or a combination, is fed to the solvent
extraction zone 130. Solvent extraction conditions include a device
allowing for intense contacting of the coal tar stream 25 and the
solvent 135, at temperatures and pressures where both streams are
in the liquid phase and are unlikely to react or degrade. An output
stream 140 of the solvent extraction zone 130 is fed to a
separation zone 145, such as a settling vessel, where the light
soluble and heavy insoluble fractions can be separated due to the
difference in their specific density. The separation zone 145
separates a light soluble fraction 150 from a heavy insoluble
fraction 155. The light soluble fraction 150 can be processed using
any of the processes disclosed elsewhere herein.
[0035] The heavy insoluble fraction 155 is fed into a hydrotreating
zone 160. In the hydrotreating zone 160, the heavy insoluble
fraction 155 is contacted with either a kerosene or distillate
hydrotreating catalyst for hydrotreatment. Example kerosene or
distillate hydrotreating catalysts include Co/Mo/Alumina and
Ni/Mo/Alumina of a type that is traditionally used in this service.
Example conditions for the hydrotreating zone 160 include a
temperature of between about 550.degree. C. and about 700.degree.
C., and a pressure of between about 4.8 MPa (700 psi) and about 8.3
MPa (1200 psi). The hydrotreated heavy insoluble fraction 165 can
be fed to a processing zone 170 for further processing, including
any of the downstream processes described elsewhere herein, to
provide one or more products 175.
[0036] While at least one exemplary embodiment has been presented
in the foregoing detailed description of the invention, it should
be appreciated that a vast number of variations exist. It should
also be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention. It being understood that
various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope of the invention as set forth in the appended
claims.
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