U.S. patent application number 14/472127 was filed with the patent office on 2015-05-21 for process for removing mercury from a coal tar product.
The applicant listed for this patent is UOP LLC. Invention is credited to Robert L. Bedard, Jayant K. Gorawara, Deng-Yang Jan, Gregory F. Maher, Dean E. Rende.
Application Number | 20150136650 14/472127 |
Document ID | / |
Family ID | 53172208 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150136650 |
Kind Code |
A1 |
Gorawara; Jayant K. ; et
al. |
May 21, 2015 |
PROCESS FOR REMOVING MERCURY FROM A COAL TAR PRODUCT
Abstract
A process for removing mercury from a coal tar product is
described. A coal tar stream is contacted with a solvent to remove
a product, and the product stream is contacted with an adsorbent
material to remove elemental mercury, organic mercury compounds,
and/or inorganic mercury compounds. Alternatively, the coal tar
stream can be treated in a catalytic distillation zone of a
fractionation zone.
Inventors: |
Gorawara; Jayant K.;
(Buffalo Grove, IL) ; Bedard; Robert L.; (McHenry,
IL) ; Jan; Deng-Yang; (Elk Grove Village, IL)
; Maher; Gregory F.; (Aurora, IL) ; Rende; Dean
E.; (Arlington Heights, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UOP LLC |
Des Plaines |
IL |
US |
|
|
Family ID: |
53172208 |
Appl. No.: |
14/472127 |
Filed: |
August 28, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61905902 |
Nov 19, 2013 |
|
|
|
Current U.S.
Class: |
208/253 ;
208/251R |
Current CPC
Class: |
C10G 21/16 20130101;
C10G 2300/205 20130101; C10G 21/14 20130101; C10G 45/02 20130101;
C10G 45/08 20130101; C10G 45/12 20130101; C10G 21/28 20130101; C10G
2300/4087 20130101; C10G 21/06 20130101; C10G 21/27 20130101 |
Class at
Publication: |
208/253 ;
208/251.R |
International
Class: |
C10G 53/08 20060101
C10G053/08 |
Claims
1. A process for removing mercury from a coal tar product
comprising: providing a coal tar stream; contacting the coal tar
stream with a solvent in a solvent extraction zone to remove at
least one product from the coal tar stream forming at least one
product stream and a remainder coal tar stream, the at least one
product stream containing one or more of elemental mercury, organic
mercury compounds, and inorganic mercury compounds; contacting the
at least one product stream with an adsorbent material in an
mercury removal zone, the adsorbent material comprising one or more
adsorbents, an ion exchange material, or mixtures thereof to remove
the one or more of elemental mercury, organic mercury compounds,
and inorganic mercury compounds; and separating the remainder coal
tar stream into at least two fractions.
2. The process of claim 1 further comprising separating the solvent
from the at least one product stream before contacting the at least
one product stream.
3. The process of claim 1 further comprising separating the solvent
from the at least one product stream and recycling the separated
solvent to the solvent extraction zone.
4. The process of claim 1 wherein the at least one product stream
contains organic mercury compounds, and further comprising
converting the organic mercury compounds to elemental mercury
before contacting the at least one product stream.
5. The process of claim I wherein the solvent comprises a
supercritical fluid, an ionic liquid, a polar solvent, and
combinations thereof.
6. The process of claim 5 wherein solvent comprises the
supercritical fluid and wherein the supercritical fluid is selected
from the group consisting of supercritical NH3, supercritical
CO.sub.2, supercritical ethane, supercritical propane,
supercritical butane, supercritical water, and combinations
thereof.
7. The process of claim 5 wherein the solvent comprises the ionic
liquid, and wherein the ionic liquid is selected from the group
consisting of imidazolium-based ionic liquid, pyrrolidinium-based
ionic liquid, pyridinium-based ionic liquid, sulphonium-based ionic
liquids, phosphonium-based ionic liquids, ammonium-based ionic
liquids, caprolactam-based ionic liquids, and combinations
thereof.
8. The process of claim 5 wherein the solvent comprises the polar
solvent, and wherein the polar solvent is selected from the group
consisting of pyridine, N-methyl pyrrolidone, methylene chloride,
benzyl alcohol, formamide, dimethylformamide, dimethylsulfoxide,
dimethylsuccinate, dimethyladipate, dimethylglutarate, propylene
carbonate, methyl soyate, ethyl lactate, tripropylene glycol
(mono)methyl ether 1,3-dioxolane and combinations thereof.
9. The process of claim 1 wherein the adsorbent material is the one
or more adsorbents and wherein the adsorbent is a noble metal
deposited on a support selected from the group consisting of
molecular sieves, alumina, activated carbons, and silica gel.
10. The process of claim 1 wherein the adsorbent material is the
one or more adsorbents and wherein the adsorbent is a silver
impregnated zeolite selected from the group consisting of
faujasites (13X, CaX, NaY, CaY, and ZnX), chabazites,
clinoptilolites and LTA (3A, 4A, 5A) zeolites.
11. The process of claim 1 wherein the adsorbent material is the
one or more adsorbents and wherein the adsorbent is sulfur or a
metal sulfide on an activated carbon support or an activated
alumina support or other supports to bind the active reagents for
mercury removal in the form of beads or pellets.
12. The process of claim 1 wherein the adsorbent material is the
one or more adsorbents and wherein the adsorbent is a metal
sulfide, metal oxide, or metal carbonate on a support, the metal is
selected from the group consisting of copper, silver, gold,
antimony, lead, and manganese, and the support selected from the
group consisting of activated alumina, clay, or activated
carbon.
13. The process of claim 1 wherein the adsorbent material is the
one or more adsorbents and wherein the adsorbent is a metal, a
metal oxide, or a metal carbonate on a support, the metal selected
from the group consisting of copper, silver, gold, antimony, lead
and manganese, and the support selected from the group consisting
of activated alumina, clay, and activated carbon, wherein the
adsorbent is sulfided by sulfur compounds in the mercury removal
zone to produce a sulfided adsorbent and wherein the sulfided
adsorbent removes mercury.
14. The process of claim 1 wherein the adsorbent material is the
ion exchange material and wherein the ion exchange material
contains chemically bound sulfide groups.
15. The process of claim 1 wherein the adsorbent material is the
ion exchange material and wherein the ion exchange material
comprises a cation exchange material.
16. The process of claim 1 further comprising processing at least
one of the fractions to produce at least one additional
product.
17. A process for removing mercury from a coal tar product
comprising: providing a coal tar stream, the coal tar stream
containing one or more of elemental mercury, organic mercury
compounds, and inorganic mercury compounds; introducing the coal
tar stream into a catalytic distillation zone of a fractionation
zone to separate the coal tar stream into at least two fractions,
the catalytic distillation zone positioned above a bottoms outlet
and below a first product draw of the fractionation zone, the
catalytic distillation zone containing a catalyst, the organic and
ionic mercury compounds reacting in the presence of the catalyst to
form elemental mercury in the catalytic distillation zone; and
treating at least one of the fractions to remove the elemental
mercury.
18. The process of claim 17 further comprising introducing hydrogen
into the catalytic distillation zone.
19. The process of claim 17 wherein the catalyst comprises at least
one Group VIB, Group VIIB, or Group VIIIB metal, a noble metal
catalyst, or a zeolitic catalyst.
20. The process of claim 17 wherein the catalytic distillation zone
operates at a temperature in a range of about 35.degree. C. to
about 320.degree. C.
Description
[0001] This application claims the benefit of Provisional
Application Ser. No. 61/905,902 filed Nov. 19, 2013, entitled
Process for Removing Mercury from a Coal Tar Product.
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 is 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] The products from the coal tar often contain undesirable
compounds, such as mercury, which must be removed.
[0007] Thus, there is a need for improved processes for removing
mercury from coal tar products.
SUMMARY OF THE INVENTION
[0008] One aspect of the invention is a process for removing
mercury from a coal tar product. In one embodiment, the process
includes providing a coal tar stream. The coal tar stream is
contacted with a solvent in a solvent extraction zone to remove at
least one product from the coal tar stream forming at least one
product stream and a remainder coal tar stream, the at least one
product stream containing one or more of elemental mercury, organic
mercury compounds, and inorganic mercury compounds. The at least
one product stream is contacted with an adsorbent material in an
mercury removal zone, the adsorbent material comprising one or more
adsorbents, an ion exchange resin, or mixtures thereof to remove
the one or more of elemental mercury, organic mercury compounds,
and inorganic mercury compounds. The remainder coal tar stream is
separated into at least two fractions.
[0009] In another embodiment, the process includes providing a coal
tar stream, the coal tar stream containing one or more of elemental
mercury, organic mercury compounds, and inorganic mercury
compounds. The coal tar stream is introduced into a catalytic
distillation zone of a fractionation zone to separate the coal tar
stream into at least two fractions, the catalytic distillation zone
positioned above the bottoms outlet and below the first product
draw of the fractionation zone, the catalytic distillation zone
containing a catalyst, the organic and ionic mercury compounds
reacting in the presence of the catalyst to form elemental mercury
in the reactive fractionation zone. At least one of the fractions
is treated to remove the elemental mercury.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an illustration of one embodiment of the process
of the present invention.
[0011] FIG. 2 is an illustration of another embodiment of the
process of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] FIG. 1 shows one embodiment of a mercury removal process 5
of the present invention. The coal feed 10 can be sent to the
coking oven zone 15, the gasification zone 20, or the coal feed 10
can be split into two parts and sent to both.
[0013] In the coking oven zone 15, the coal is heated at high
temperature, e.g., up to about 2,000.degree. C. (3600.degree. F.),
in the absence of oxygen to drive off the volatile components.
Coking produces a coke stream 25 and a coal tar stream 30. The coke
stream 25 can be used in other processes, such as the manufacture
of steel.
[0014] The coal tar stream 30 which comprises the volatile
components from the coking process can be sent to an optional
contaminant removal zone 35, if desired.
[0015] The contaminant removal zone 35 for removing one or more
contaminants from the coal tar stream or another process stream may
be located at various positions along the process depending on the
impact of the particular contaminant on the product or process and
the reason for the contaminant's removal, as described further
below. For example, the contaminant removal zone can be positioned
upstream of the separation zone 45. Some contaminants have been
identified to interfere with a downstream processing step or
hydrocarbon conversion process, in which case the contaminant
removal zone 35 may be positioned upstream of the separation zone
45 or between the separation zone 45 and the particular downstream
processing step at issue. Still other contaminants have been
identified that should be removed to meet particular product
specifications. Where it is desired to remove multiple contaminants
from the hydrocarbon or process stream, various contaminant removal
zones may be positioned at different locations along the process.
In still other approaches, a contaminant removal zone may overlap
or be integrated with another process within the system, in which
case the contaminant may be removed during another portion of the
process, including, but not limited to the separation zone or the
downstream hydrocarbon conversion zone. This may be accomplished
with or without modification to these particular zones, reactors or
processes. While the contaminant removal zone is often positioned
downstream of the hydrocarbon conversion reactor, it should be
understood that the contaminant removal zone in accordance herewith
may be positioned upstream of the separation zone, between the
separation zone and the hydrocarbon conversion zone, or downstream
of the hydrocarbon conversion zone or along other streams within
the process stream, such as, for example, a carrier fluid stream, a
fuel stream, an oxygen source stream, or any streams used in the
systems and the processes described herein. The contaminant
concentration is controlled by removing at least a portion of the
contaminant from the coal tar stream 30. As used herein, the term
removing may refer to actual removal, for example by adsorption,
absorption, or membrane separation, or it may refer to conversion
of the contaminant to a more tolerable compound, or both.
[0016] The decontaminated coal tar stream 36 from the contaminant
removal zone 35 is sent to a solvent extraction zone 37.
[0017] In the solvent extraction process, a solvent stream 38 is
introduced into the solvent extraction zone 37 and contacts the
decontaminated coal tar stream 36. At least one product 39
containing one or more of elemental mercury, organic mercury
compounds, and inorganic mercury compounds is removed from the
decontaminated coal tar stream 36.
[0018] The solvents used in the solvent extraction process can
include, but are not limited to, supercritical fluids, ionic
liquids, polar solvents, and combinations thereof.
[0019] Supercritical fluids are substances at a temperature and
pressure above the critical point, where distinct liquid and gas
phases do not exist. They have properties of both liquids and
vapors. Suitable supercritical fluids include, but are not limited
to, supercritical carbon dioxide, supercritical ammonia,
supercritical ethane, supercritical propane, supercritical butane,
and supercritical water.
[0020] Ionic liquids are non-aqueous, organic salts composed of
ions where the positive ion is charge balanced with a negative ion.
These materials have low melting points, often below 100.degree.
C., undetectable vapor pressure, and good chemical and thermal
stability. The cationic charge of the salt is localized over hetero
atoms, such as nitrogen, phosphorous, sulfur, arsenic, boron,
antimony, and aluminum, and the anions may be any inorganic,
organic, or organometallic species. Suitable ionic liquids include,
but are not limited to, imidazolium-based ionic liquids,
pyrrolidinium-based ionic liquids, pyridinium-based ionic liquids,
sulphonium-based ionic liquids, phosphonium-based ionic liquids,
ammonium-based and caprolactam-based ionic liquids, and
combinations thereof.
[0021] Suitable polar solvents include, but are not limited to,
pyridine, N-methyl pyrrolidone, methylene chloride, benzyl alcohol,
formamide, dimethylformamide, dimethylsulfoxide, dimethylsuccinate,
dimethyladipate, dimethylglutarate, propylene carbonate, methyl
soyate, ethyl lactate, tripropylene glycol (mono)methyl ether
1,3-dioxolane, and combinations thereof.
[0022] Alternatively, the extraction/adsorption zone described in
U.S. application Ser. No. 61/905,898, entitled Process for Removing
a Product from Coal Tar, filed Nov. 19, 2013 (Attorney Docket No.
H0042311), which is incorporated herein by reference, could be used
in place of the solvent extraction zone 37, if desired.
[0023] The products 39 from the solvent extraction process include,
but are not limited to, hydrocarbons that distill in the range of
approximately 0.degree. C. to 350.degree. C. Depending upon the
solvent used, the predominant functional groups may be heterocyclic
aromatic, naphthenic or paraffinic, and may be ionic or neutral,
acidic, or basic.
[0024] The product(s) 39 containing the elemental mercury, organic
mercury compounds, and inorganic mercury compounds is sent to a
separation zone 110 where a solvent stream 120 is separated from
the product 115 containing the elemental mercury, organic mercury
compounds, and inorganic mercury compounds. The solvent stream 120
can be recycled to the solvent extraction zone 37, if desired.
[0025] When organic mercury compounds are present, the product(s)
115 can be sent to an optional conversion zone 125 where the
organic mercury compounds are converted to elemental mercury or
inorganic mercury compounds. Suitable conversion processes include,
but are not limited to, catalytic or thermal decomposition,
catalytic reaction with hydrogen, reduction by transfer
hydrogenation, precipitation with sulfide sources or elemental
sulfur, and oxidation followed by reduction.
[0026] In one embodiment, the product(s) 115 containing the
elemental mercury, organic mercury compounds, and inorganic mercury
compounds is subjected to hydroprocessing to convert the organic
mercury compounds to inorganic or elemental mercury, followed by
passage through a multi-layer bed for removal of more than one type
of contaminant. Other contaminants may also be converted to a form
that is more easily removed by adsorption.
[0027] In another embodiment, the product(s) 115 containing the
elemental mercury, organic mercury compounds, and inorganic mercury
compounds is subjected to thermal processing at a temperature from
about 100.degree. C. to about 900.degree. C. in accordance with the
teachings found in U.S. Pat. No. 5,510,565 incorporated herein in
its entirety. Organic mercury and other impurities are broken down
to a form that is easier to remove by adsorption.
[0028] Alternatively, the separation zone 110 can be located after
the conversion zone 125, if desired. However, the separation zone
110 is desirably positioned before the conversion zone 125 because
removing the solvent first would result in less material being
processed in the conversion zone 125.
[0029] The effluent 130 from the conversion zone 125 comprising the
product(s) containing the elemental mercury, inorganic mercury
compounds (whether original or converted organic mercury compounds
(if present)), and any unconverted organic mercury compounds is
sent to a mercury removal zone 135. The effluent 130 is contacted
with an adsorbent material in the mercury removal zone 135 to
remove the elemental mercury and inorganic mercury compounds
(whether original or converted organic mercury compounds (if
present)). A stream 140 of elemental mercury and inorganic mercury
compounds is removed from the mercury removal zone 135 and further
treated and/or recovered, if desired. The product(s) 145 with a
reduced mercury level is then recovered.
[0030] The elemental mercury and inorganic mercury compounds may be
removed by adsorption, typically with transition metal sulfides,
such as copper sulfide, or sulfur on activated carbon, activated
aluminas, silica gel or molecular sieves. In addition, supported
noble metals such as silver, palladium or platinum on molecular
sieves or aluminas can be used. Certain zeolite/alumina hybrid
adsorbents may also be used. The zeolites that can be used include,
but are not limited to, faujasites (13X, CaX, NaY, CaY, ZnX),
chabazites, clinoptilolites and LTA (3A, 4A, 5A) zeolites. Other
adsorbents may be used including transition metals (such as,
copper, lead, antimony, manganese) oxides and carbonates in
hydrocarbon streams that may contain sulfur compounds to convert
the metals to a sulfide form that is active for mercury
removal.
[0031] Another type of layer for mercury removal that is effective
in the practice of the present invention is sulfides of transition
metals, such as copper, silver, gold, lead, antimony and
manganese.
[0032] Ion exchange materials may be used to remove mercury
compounds. Ion exchange materials include, but are not limited to,
ion exchange resins and inorganic ion exchange materials. The ion
exchange material can be an anionic exchange material or a cationic
exchange material. One suitable adsorbent is an ion exchange resin
that contains chemically bound sulfide groups.
[0033] In some cases when the product(s) also contain H.sub.2S or
organic sulfur compounds, the oxide or carbonate forms of the
metals may be used to sulfide the metal in the adsorbent bed insitu
and make it active for mercury removal. This method of mercury
scavenging may be used effectively for simultaneous removal of
sulfur compounds and mercury.
[0034] In some case, the adsorbent is sulfur or a metal sulfide on
an activated carbon support or an activated alumina support or
other supports, such as clays, to bind the active reagents for
mercury removal in the form of beads or pellets.
[0035] In some embodiments, at least two products 39 are removed
from the decontaminated coal tar stream 36. The first product can
be removed using a first solvent, and then the second product can
removed using a second solvent, if desired.
[0036] The decontaminated coal tar feed 40 with at least one
product removed is sent to a separation zone 45 where it is
separated into two or more fractions. 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.
[0037] 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 benzene absorbing oil and creosotes. The
anthacene oil fraction contains anthracene. Pitch is the residue of
the coal tar distillation containing primarily aromatic
hydrocarbons and heterocyclic compounds.
[0038] As illustrated, the coal tar feed 40 is separated into gas
fraction 50 containing gases such as NH.sub.3 and CO as well as
light hydrocarbons, such as ethane, hydrocarbon fractions 55, 60,
and 65 having different boiling point ranges, and pitch fraction
70.
[0039] Suitable separation processes include, but are not limited
to fractionation, crystallization, and inclusion compound
formation.
[0040] One or more of the fractions 50, 55, 60, 65, 70 can be
further processed, as desired. As illustrated, fraction 60 can be
sent to one or more hydrocarbon conversion zones 75, 80. For
example, where hydrocarbon conversion zone 80 includes a catalyst
which is sensitive to sulfur, fraction 60 can be sent to
hydrocarbon conversion zone 75 for hydrotreating to remove sulfur
and nitrogen. Effluent 85 is then sent to hydrocarbon conversion
zone 80 for hydrocracking, for example, to produce product 90.
[0041] Suitable hydrocarbon conversion zones include, but are not
limited to, hydrotreating zones, hydrocracking zones,
transalkylation zones, selective hydrogenation or complete
hydrogenation zones, oxidation zones, and thermal conversion
zones.
[0042] Hydrotreating is a process in which hydrogen gas is
contacted with a hydrocarbon stream 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.
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
6.2 MPa (900 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 (1,000-6,000 scf/bbl). Typical
hydrotreating catalysts include at least one Group 8 metal,
preferably iron, cobalt and nickel, and at least one Group 6 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.
[0043] 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 (3000 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 (2,500-15,000
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.
[0044] 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 kPa g (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.
[0045] 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 C5 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.
[0046] 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.
[0047] 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.
Typical hydrogenation catalyst include Group VIB (Cr, Mo, W), Group
VIIB (Mn, Tc, Re) or Group VIIIB (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir,
Pt) metals and combinations thereof supported on an inorganic
oxide, carbide or sulfide support, including Al.sub.2O.sub.3,
SiO.sub.2, SiO.sub.2--Al.sub.2O.sub.3, zeolites, non-zeolitic
molecular sieves, ZrO.sub.2, TiO.sub.2, ZnO, and SiC. The catalytic
hydrogenation zone may contain a fixed, ebulated or fluidized
catalyst bed. This reaction zone is typically at a pressure from
about 689 k Pa gauge (100 psig) to about 13790 k Pa gauge (2000
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).
[0048] 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 substrate to be oxidized 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 25.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.
[0049] Thermal conversion involves heating the composition to
effect the chemical change. The thermal conversion can be any
suitable process, such as a delayed coking or slurry hydrocracking
zone. The hydrocarbons are heated and fed into the bottom of one or
more coking drums where the first stages of thermal decomposition
reduce the hydrocarbons to a very heavy tar or pitch which further
decomposes into solid coke. Typically, the vapors formed during the
decomposition produce pores and channels in the coke through which
the incoming oil from the furnace may pass. This process may
continue usually until the drum is filled to a desired level with a
mass of coke. The vapors formed in the process can exit the top of
the coking drum and can be further processed. The resulting coke is
removed from the coking drum.
[0050] Slurry hydrocracking involves combining a catalyst with the
hydrocarbon stream. The slurry stream typically has a solids
content of about 0.01-about 10%, by weight.
[0051] The slurry stream and the recycle gas can enter a heater.
The recycle gas typically contains hydrogen, which can be
once-through hydrogen optionally with no significant amount of
recycled gases. Alternatively, the recycle gas can contain recycled
hydrogen gas optionally with added hydrogen as the hydrogen is
consumed during the one or more hydroprocessing reactions. The
recycle gas may be essentially pure hydrogen or may include
additives such as hydrogen sulfide or light hydrocarbons, e.g.,
methane and ethane. Reactive or non-reactive gases may be combined
with the hydrogen introduced into the upflow tubular reactor or
slurry hydrocracking reactor at the desired pressure to achieve the
desired product yields. Often, slurry hydroprocessing is carried
out using reactor conditions sufficient to crack at least a portion
of the hydrocarbon stream to lower boiling products, such as one or
more distillate hydrocarbons, naphtha, and/or C1-C4 products.
Conditions in the slurry hydrocracking reactor can include a
temperature of about 340.degree. C. to about 600.degree. C., a
hydrogen partial pressure of about 3.5-about 30 MPa and a space
velocity of about 0.1-about 30 volumes of the hydrocarbon stream
per hour per reactor or reaction zone volume.
[0052] Generally, the catalyst for the slurry hydrocracking reactor
provides a composition that is hydrophobic and resists clumping.
Typically, the slurry catalyst composition can include a
catalytically effective amount of one or more compounds having
iron. Particularly, the one or more compounds can include at least
one of an iron oxide, an iron sulfate, and an iron carbonate. Other
forms of iron can include at least one of an iron sulfide, a
pyrrhotite, and a pyrite. What is more, the catalyst can contain
materials other than an iron, such as at least one of molybdenum,
nickel, and manganese, and/or a salt, an oxide, and/or a mineral
thereof. Preferably, the one or more compounds includes an iron
sulfate, and more preferably, at least one of an iron sulfate
monohydrate and an iron sulfate heptahydrate. Alternatively, one or
more catalyst particles can include about 2-about 45%, by weight,
iron oxide and about 20-about 90%, by weight, alumina. In some
embodiments, the catalyst is supported. The support can be alumina,
silica, titania, one or more aluminosilicates, magnesia, bauxite,
coal and/or petroleum coke, for example. Such a supported catalyst
can include a catalytically active metal, such as at least one of
iron, molybdenum, nickel, and vanadium, as well as sulfides of one
or more of these metals. Generally, the catalyst can have about
0.01-about 30%, by weight, of the catalytic active metal based on
the total weight of the catalyst.
[0053] In some processes, all or a portion of the coal feed 10 is
mixed with oxygen 95 and steam 100 and reacted under heat and
pressure in the gasification zone 20 to form syngas 105, which is a
mixture of carbon monoxide and hydrogen. The syngas 105 can be
further processed using the Fischer-Tropsch reaction to produce
gasoline or using the water-gas shift reaction to produce more
hydrogen.
[0054] FIG. 2 shows an alternate mercury removal process 205. The
coal feed 210 is sent to the coking oven zone 215. A second portion
can be sent to the gasification zone (not shown), if desired.
Coking produces a coke stream 225 and a coal tar stream 230.
[0055] The coal tar stream 230 which comprises the volatile
components from the coking process is sent to fractionation zone
245 including a catalytic distillation zone 247. The use of a
catalyst in the catalytic distillation zone 247 allows simultaneous
distillation and catalytic reactions in a single contacting section
or the dual functions of distillation and catalytic reaction in
different sections of a common column.
[0056] The fractionation zone 245 and catalytic distillation zone
247 are operated at conditions effective to further react and
fractionate the coal tar stream 230. The catalytic distillation
zone 247 can operate at a wide variety of temperatures depending on
the catalyst type, the presence of hydrogen, and the location of
the catalytic distillation zone. For example, the temperatures can
range from about 35.degree. C. to about 320.degree. C. The pressure
can be low, for example, about 100 kPa (g) (1 bar (0) to about 300
kPa (g) (3 bar (g)).
[0057] The coal tar feed 230 is introduced to the fractionation
zone 245 in the catalytic distillation zone 247 at a point below
the draw for fraction 265 and above where pitch fraction 270 is
removed. The catalytic distillation zone 247 extends from the coal
tar feed inlet to a position below where the product draws are
taken. The location for the catalytic distillation zone will be a
function of the catalyst type and properties, and the presence or
absence of hydrogen. More active catalysts need a lower temperature
to be effective and will be located higher in the column. The
length of the catalytic distillation zone is a function of the
space velocity needed for complete conversion, with a more active
catalyst needing less volume. No particular apparatus or
arrangement is needed to retain the catalyst bed within the
distillation zone and a variety of methods can be used to
incorporate the bed or region of catalyst within the distillation
zone. For example, catalyst may be retained between suitable
packing materials or may be incorporated on to a distillation tray
itself.
[0058] In one example, the catalytic distillation zone 247 contains
a hydrogenation or hydrotreating catalyst, as described above.
During fractionation, the coal tar stream 230 contacts the catalyst
and at least a portion of the organic and ionic forms of mercury
react to form elemental mercury. The reactions can take place in
the liquid or vapor phase.
[0059] The elemental mercury and inorganic mercury compounds are
removed from one or more streams as described above, and further
treated and/or recovered, if desired. The mercury can be recovered
by vacuum distillation at high temperature (typically about
600.degree. C.), for example. The treaters can be operated in a
lead-lag mode in series. When the first one is spent, flow switches
to the second treater to allow for continuous protection.
[0060] As illustrated, the coal tar feed 230 is separated into gas
fraction 250, hydrocarbon fractions 255, 260, and 265 having
different boiling point ranges, and pitch fraction 270.
[0061] One or more of the fractions 250, 255, 260, 265, 270 can be
further processed, as desired. As illustrated, fraction 260 can be
sent to one or more hydrocarbon conversion zones 275, 280. Fraction
260 can be sent to hydrocarbon conversion zone 275 for
hydrotreating to remove sulfur and nitrogen. Effluent 285 is then
sent to hydrocarbon conversion zone 280 for hydrocracking, for
example, to produce product 290.
[0062] 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.
* * * * *