PATENT
Production of light olefins (Exxonmobil Chemical
Patents Inc.)
Publication
number
US8415518 B2
Application number
US 11/818,333
Publication date
Apr 9, 2013
Also published as
EP2054154A1, US20080033225, WO2008016423A1
Inventors
Richard B. Hall, 5 More »
Original Assignee
Exxonmobil Chemical Patents Inc.
US 8415518 B2
Abstract
This invention is directed to a process for
producing olefin product from an oxygenate feed that includes dimethyl ether
(DME). The process uses an olefin forming catalyst that contains a porous
crystalline material, preferably a porous crystalline aluminosilicate molecular
sieve material. The process produces high quantities of light olefin (i.e.,
ethylene, propylene, and mixtures thereof).
FIELD
OF THE INVENTION
This invention relates to the production of light olefins, such as ethylene and
propylene, from oxygenates. In particular, this invention relates to the
production of light olefins from an oxygenate feed-containing dimethyl ether
and using a catalyst containing a porous crystalline material.
BACKGROUND OF THE INVENTION
Oxygenate to olefins reaction systems typically convert oxygenates to olefin
products. In particular, methanol to olefins reaction systems utilize methanol
as the primary feed for the conversion process, and these processes typically
use molecular sieves as catalysts.
Silicoaluminophosphate (SAPO) molecular sieves have generally been considered
to be desirable catalytic materials in converting oxygenate feedstocks to
olefin compositions. These catalysts are particularly good catalysts for making
olefins such as ethylene and propylene from oxygenate compounds.
Alternative catalysts to the SAPO molecular sieves have also been sought.
Particularly desirable alternatives have included those catalysts that have a
high selectivity to ethylene and propylene, are highly attrition resistant and
are, of course, those that are more efficiently used in the overall oxygenate
to olefin production process.
U.S. Pat. No. 7,071,136 discloses molecular sieves containing [AlO4]
and [SiO4] tetrahedral units can be used as a catalyst to convert
methanol to olefins such as ethylene and propylene. The particular catalysts
are considered to be highly attrition resistant, which is a preferred
characteristic for the operation of the reaction system.
U.S. Pat. No. 6,844,291 B2 discloses a molecular sieve catalyst composition
that includes a metal oxide. Combining the metal oxide with the molecular sieve
was considered to enhance olefin yield and catalyst lifetime in the oxygenate
to olefin reaction process.
U.S. Patent Publ. No. 2003/0176751 describes a porous crystalline material that
has a chabazite framework type and involves the molar relationship: X2O3:(n)YO2,
where X is a trivalent element, such as aluminum, boron, iron, indium, and/or
gallium; Y is a tetravalent element such as silicon, tin, titanium and/or
germanium; and n is greater than 100. The material is synthesized in a fluoride
medium and exhibits activity and selectivity in the conversion of methanol to
lower olefins, especially ethylene and propylene.
U.S. Pat. No. 7,094,389 discloses a crystalline material substantially free of
framework phosphorus and comprising a CHA framework type molecular sieve with
stacking faults or at least one intergrown phase of a CHA framework type
molecular sieve and an AEI framework type molecular sieve. The material in its
calcined, anhydrous form, involves the molar relationship: (n)X2O3:YO2,
where X is a trivalent element; Y is a tetravalent element; and n is from 0 to
about 0.5. The material exhibits activity and selectivity in the conversion of
methanol to lower olefins, especially ethylene and propylene.
Various catalyst pretreatment methods are also used to increase the amount of
light or prime olefins (i.e., ethylene or propylene, or mixtures thereof)
produced in the methanol to olefins conversion processes. For example, U.S.
Pat. No. 7,045,672 is directed to processes for making olefin product from an
oxygenate feed that includes a step of pretreating a fresh or regenerated
metalloaluminophosphate molecular sieve, which is low in carbon content, with a
dimethyl ether composition. The dimethyl ether in the composition forms a
hydrocarbon co-catalyst within the pore structure of the molecular sieve, and
the pretreated molecular sieve containing the co-catalyst is used to convert
oxygenate to an olefin product, with high selectivity to light olefins.
Although advances have been made in increasing the amount of ethylene and
propylene produced in the oxygenate to olefins conversion reaction, further
increases in these amounts are sought. In certain cases, it is particularly
desirable to increase the amount of ethylene produced relative to the
propylene.
SUMMARY OF THE INVENTION
This invention provides a process for producing an olefin product that is high
in ethylene and propylene content. The process is particularly beneficial in
producing higher quantities of ethylene relative to that of propylene.
According to one aspect of the invention, there is provided a process for
producing an olefin product. The process comprises contacting an oxygenate feed
containing at least 15 wt % dimethyl ether, preferably at least 25 wt %, more
preferably at least 30 wt %, and still more preferably at least 50 wt %
dimethyl ether, based on total weight of the feed, with an olefin forming
catalyst to form the olefin product. Preferably, the catalyst contains a porous
crystalline material, preferably a porous crystalline aluminosilicate molecular
sieve material, having a chabazite or AEI framework, or a mixture or
intergrowth containing a chabazite and AEI framework with a molar relationship
of:
X2O3:(n)YO2,
wherein X is a trivalent element, Y is a tetravalent element and n is greater
than 20, preferably at least 30, more preferably at least 50, and still more
preferably at least 100.
According to another aspect of the invention, there is provided a process for
producing an olefin product in which an olefin forming catalyst is provided
that contains a porous crystalline material having a chabazite or AEI
framework, or a mixture or intergrowth containing a chabazite and AEI framework
with a molar relationship of:
X2O3:(n)YO2:(m)R:zH2O,
wherein X is a trivalent element, Y is a tetravalent element, n is greater than
20, preferably at least 30, more preferably at least 50, and still more
preferably at least 100, R is a directing agent, m ranges from 15 to 350, and z
ranges from 0 to 10. The directing agent is removed to form an active olefin
forming catalyst, and the active olefin forming catalyst is contacted with an
oxygenate feed containing at least 15 wt % dimethyl ether, based on total
weight of the feed, to form the olefin product.
In one embodiment, R comprises at least one cyclic amine or ammonium compound.
Alternatively, R comprises at least one multi-cyclic amine or ammonium
compound.
In another embodiment, m ranges from about 30 to about 50. In still another
embodiment, n is from about 200 to about 2000, preferably from about 200 to
about 1200.
In another embodiment, X is selected from aluminum, boron, iron, indium, and/or
gallium and Y is selected from silicon, tin, titanium and/or germanium.
Preferably, X is aluminum and Y includes silicon.
In another embodiment, the oxygenate feed is contacted with the olefin forming
catalyst at an average reactor temperature in the range of from 200° C. to
1000° C.
In another embodiment, the oxygenate feed is a mixed feed that contains not
greater than 40 wt % methanol and at least 40 wt % dimethyl ether, based on
total weight of the oxygenate feed. Preferably, the oxygenate feed is a mixed
feed that contains not greater than 35 wt % methanol and at least 50 wt %
dimethyl ether, based on total weight of the oxygenate feed.
In yet another embodiment, the olefin forming catalyst is contacted with a
second oxygenate feed containing at least 50 wt % methanol, based on total
weight of the second oxygenate feed.
In an alternative embodiment, the olefin forming catalyst is contacted with the
oxygenate feed until the olefin forming catalyst is deposited with a coke
deposit of 20% or more, based on percent of maximum coke content, and the coke
deposited catalyst is then contacted with a second oxygenate feed containing at
least 50 wt % methanol, based on total weight of the second oxygenate feed.
In another embodiment of the invention, olefin from the olefin product is
contacted with a polyolefin forming catalyst to form a polyolefin.
Free Full Text Source: http://www.google.com/patents/US8415518
Showing posts with label EXXONMOBIL. Show all posts
Showing posts with label EXXONMOBIL. Show all posts
Friday, November 15, 2013
Wednesday, October 2, 2013
Hydroprocessing Of Heavy Hydrocarbon Feeds Using Small Pore Catalysts (Exxonmobil Research And Engineering Company)
PATENT
Hydroprocessing Of Heavy Hydrocarbon Feeds Using Small Pore Catalysts (Exxonmobil Research And Engineering Company)
United States Patent Application 20130081977
Inventors:
Woo, Hyung Suk (Easton, PA, US)
Cheng, Jane Chi-ya (Bridgewater, NJ, US)
Ho, Teh C. (Bridgewater, NJ, US)
Brown, Stephen Harold (Annandale, NJ, US)
Application Number:
13/597523
Publication Date:
04/04/2013
Assignee:
Exxonmobil Research And Engineering Company (Annandale, NJ, US)
Abstract:
Heavy oil feeds are hydroprocessed in the presence of a solvent and in the presence of a catalyst with a median pore size of about 85 Å to about 120 Å under conditions that provide a variety of benefits. The solvent can be an added solvent or a portion of the liquid effluent from hydroprocessing. The processes allow for lower pressure processing of heavy oil feeds for extended processing times or extended catalyst lifetimes be reducing or mitigating the amount of coke formation on the hydroprocessing catalyst.
FIELD OF THE INVENTION
This invention is directed to a process for producing a hydroprocessed product from residua or heavy hydrocarbon feeds.
BACKGROUND
Crude oil is typically distilled to produce a variety of components that can be used directly as fuels or that are used as feedstocks for further processing or upgrading. In what is known as atmospheric distillation, a heavy residuum is produced typically that has an initial boiling point of about 650° F. (343° C.). This residuum is typically referred to as atmospheric residuum or as an atmospheric residuum fraction.
Atmospheric residuum fractions tend to collect a relatively high quantity of various metals, sulfur components and nitrogen components relative to the lighter distillation fractions as a result of the distillation process. Because these metal, sulfur and nitrogen components are relatively undesirable in various fuels, they are typically removed by various catalytic hydroprocessing techniques.
In some instances, the atmospheric residuum is further distilled under vacuum, i.e., at a pressure below atmospheric pressure, to recover additional distillation fractions. At vacuum conditions, additional lighter fractions can be recovered without adding to various problems encountered in atmospheric distillation such as coking of the heavy fraction components. The heavy residuum recovered in vacuum distillation of the atmospheric residuum is typically referred to as vacuum residuum or a vacuum residuum fraction, and typically has an initial boiling point of about 1050° F. (566° C.). This vacuum residuum is generally higher in metals, sulfur components and nitrogen components than atmospheric residuum, and as was the case with atmospheric residuum, removal of these components can be carried out by catalytic hydroprocessing.
Catalytic hydroprocessing of atmospheric and vacuum residua is carried out in the presence of hydrogen, using a hydroprocessing catalyst. In some processes, hydroprocessing of residua is carried out by adding a diluent or solvent.
U.S. Pat. No. 3,617,525 discloses a process for removing sulfur from a hydrocarbon fraction having a boiling point above about 650° F. (343° C.). In carrying out the process, the hydrocarbon fraction is separated into a gas oil fraction having a boiling point between about 650° F. (343° C.) and about 1050° F. (566° C.), and a heavy residuum fraction boiling above about 1050° F. (566° C.). The gas oil fraction is catalytically hydrodesulfurized until the gas oil fraction contains less than 1 percent sulfur. The hydrodesulfurized gas oil is then used to dilute the heavy residuum fraction, and the diluted heavy residuum fraction is catalytically hydrodesulfurized, producing fuels or fuel blending components reduced in sulfur content. The process is considered to provide an increased catalyst life and to use a smaller reactor volume compared to typical processes.
U.S. Pat. No. 4,302,323 discloses a process for upgrading a residual petroleum fraction in which the residual fraction is mixed with a light cycle oil and hydrogen and the mixture sent through a catalytic hydrotreating zone containing a hydrotreating catalyst and then a hydrocracking zone containing a hydrocracking catalyst. Upgraded products are then separated from the effluent of the hydrocracking zone. The light cycle oil boils in the range of from 400° F. (204° C.) to 700° F. (371° C.), has a high aromatic content, and is high in nitrogen. It is considered that the light cycle oil acts more as a diluent rather than as a hydrogen donor and that the addition of the light cycle oil resulted in a substantial increase in the yield of premium products such as distillate fuels.
U.S. Pat. No. 4,421,633 discloses a combination hydrodesulfurization and hydrocracking process. The feedstock can be atmospheric residuum or vacuum residuum, which is mixed with a solvent that is a recycled distillate boiling at about 400° F.-700° F. (204° C.-371° C.), considered to be equivalent to a FCC light cycle oil. The process uses a mixture of large pore and small pore catalysts such as large pore and small pore sulfided Ni—W catalysts. The large pore catalyst has a median pore diameter of 180 Å, while the small pore catalyst has a median pore diameter of about 60 Å with no pores larger than 80 Å. The process converts the higher boiling point residua to lower boiling point hydrocarbons by forming distillate and naphtha while removing heteroatoms, metals and carbon residuals from the higher boiling point residua. It is noted that the description also includes examples where no solvent is used. The desulfurization activity in examples without solvent appears to be comparable or superior to the desulfurization activity for the examples that include a solvent.
U.S. Pat. No. 4,585,546 describes a method for hydrotreating petroleum heavy ends in aromatic solvents with large pore size alumina. The methods include processing resids mixed with a solvent such as ortho-xylene or a light cycle oil at 1000 psig (5.5 MPag) and 350° C. The resids were hydroprocessed in the presence of either a commercial hydrodesulfurization catalyst with a median pore size of 70 Å to 80 Å or a hydrodesulfurization catalyst with an alumina support having a median pore size of about 220 Å. The larger pore catalyst was shown to have higher activity for metals removal and comparable activity for sulfur removal as compared to the smaller pore catalyst.
There is a need to further develop processes for hydroprocessing heavy hydrocarbon oils to produce fuel grade products. It is also particularly desirable to provide hydroprocessing processes with improved selectivity to desired products. For example, it is desirable to provide hydroprocessing processes that crack molecules boiling at or above 1050° F. (566° C.) (also referred to as a “1050° F.+ (566° C.+) fraction” herein) into molecules boiling below 1050° F. (566° C.) (also referred to as a “1050° F.− (566° C.−) fraction” herein), while minimizing the formation of “C4−” hydrocarbon compounds (i.e., hydrocarbon compounds having four carbons or less), and coke byproducts.
SUMMARY OF THE PREFERRED EMBODIMENTS OF THE INVENTION
In various embodiments, systems and methods are provided for hydroprocessing of heavy oil feeds. In one embodiment, a process for producing a hydroprocessed product includes exposing a combined feedstock comprising a heavy oil feed component and a solvent component to a hydroprocessing catalyst comprising a Group VIII non-noble metal and a Group VI metal and having a median pore size of about 85 Å to about 120 Å, such as 85 Å to about 100 Å, under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a total pressure of about 1500 psig (10.3 MPag) or less, such as a hydrogen partial pressure of about 1000 psia (6.9 MPa) or less, and a liquid hourly space velocity of the fraction of the combined feedstock boiling above 1050° F. of at least about 0.10 hr−1, such as at least about 0.12 hr−1; separating the hydroprocessing effluent to form at least a liquid effluent; and fractionating a first portion of the liquid effluent to form at least a distillate product and a bottoms product, the bottoms product having a T5 boiling point of about 600° F. The effective hydroprocessing conditions can also include a temperature of at least about 360° C. and/or less than about 510° C., such as about 380° C. to about 460° C.
The solvent can be in the form of an added solvent, in the form of a recycled portion of the liquid effluent from hydroprocessing, or a combination thereof. Optionally, a portion of the bottoms product, such as a second bottoms product from a reduced pressure distillation, can be processed via solvent deasphalting to form a deasphalted oil fraction and a deasphalting residue or asphalt fraction.
In some embodiments, hydroprocessing conditions effective for conversion of at least about 90% of the feedstock relative to a conversion temperature of 1050° F. (566° C.), including a hydroprocessing temperature of at least about 420° C., can be used to form a bottoms product with an increased amount of wax relative to the feedstock. In still other embodiments, hydroprocessing conditions effective for conversion of at least about 80% of the feedstock relative to a conversion temperature of 1050° F. and for 75% desulfurization of the feedstock can be used to form a bottoms product having a sulfur content of about 1 wt % or less.
In another embodiment, a process for producing a hydroprocessed product includes exposing a combined feedstock comprising a heavy oil feed component and a solvent component to a hydroprocessing catalyst under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a hydrogen partial pressure of about 1000 psia (6.9 MPa) or less, such as 800 psia (5.5 MPa) or less, a temperature of at least about 360° C., such as about 380° C. to 510°, and optionally at least about 420° C., and a liquid hourly space velocity of the fraction of the combined feedstock boiling above 1050° F. (566° C.) of at least about 0.10 hr−1, such as at least about 0.12 hr−1; separating the hydroprocessing effluent to form at least a liquid effluent; and fractionating a first portion of the liquid effluent to form at least a distillate product and a bottoms product, the bottoms product having the bottoms product having an ASTM D86 10% distillation point of at least about 600° F. (316° C.).
In various aspects where the solvent component includes a recycle component, the ratio of the heavy oil feed component and the recycle component can be from about 0.3 to about 6.0, such as from about 0.5 to about 5.0.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0081977.html
Hydroprocessing Of Heavy Hydrocarbon Feeds Using Small Pore Catalysts (Exxonmobil Research And Engineering Company)
United States Patent Application 20130081977
Inventors:
Woo, Hyung Suk (Easton, PA, US)
Cheng, Jane Chi-ya (Bridgewater, NJ, US)
Ho, Teh C. (Bridgewater, NJ, US)
Brown, Stephen Harold (Annandale, NJ, US)
Application Number:
13/597523
Publication Date:
04/04/2013
Assignee:
Exxonmobil Research And Engineering Company (Annandale, NJ, US)
Abstract:
Heavy oil feeds are hydroprocessed in the presence of a solvent and in the presence of a catalyst with a median pore size of about 85 Å to about 120 Å under conditions that provide a variety of benefits. The solvent can be an added solvent or a portion of the liquid effluent from hydroprocessing. The processes allow for lower pressure processing of heavy oil feeds for extended processing times or extended catalyst lifetimes be reducing or mitigating the amount of coke formation on the hydroprocessing catalyst.
FIELD OF THE INVENTION
This invention is directed to a process for producing a hydroprocessed product from residua or heavy hydrocarbon feeds.
BACKGROUND
Crude oil is typically distilled to produce a variety of components that can be used directly as fuels or that are used as feedstocks for further processing or upgrading. In what is known as atmospheric distillation, a heavy residuum is produced typically that has an initial boiling point of about 650° F. (343° C.). This residuum is typically referred to as atmospheric residuum or as an atmospheric residuum fraction.
Atmospheric residuum fractions tend to collect a relatively high quantity of various metals, sulfur components and nitrogen components relative to the lighter distillation fractions as a result of the distillation process. Because these metal, sulfur and nitrogen components are relatively undesirable in various fuels, they are typically removed by various catalytic hydroprocessing techniques.
In some instances, the atmospheric residuum is further distilled under vacuum, i.e., at a pressure below atmospheric pressure, to recover additional distillation fractions. At vacuum conditions, additional lighter fractions can be recovered without adding to various problems encountered in atmospheric distillation such as coking of the heavy fraction components. The heavy residuum recovered in vacuum distillation of the atmospheric residuum is typically referred to as vacuum residuum or a vacuum residuum fraction, and typically has an initial boiling point of about 1050° F. (566° C.). This vacuum residuum is generally higher in metals, sulfur components and nitrogen components than atmospheric residuum, and as was the case with atmospheric residuum, removal of these components can be carried out by catalytic hydroprocessing.
Catalytic hydroprocessing of atmospheric and vacuum residua is carried out in the presence of hydrogen, using a hydroprocessing catalyst. In some processes, hydroprocessing of residua is carried out by adding a diluent or solvent.
U.S. Pat. No. 3,617,525 discloses a process for removing sulfur from a hydrocarbon fraction having a boiling point above about 650° F. (343° C.). In carrying out the process, the hydrocarbon fraction is separated into a gas oil fraction having a boiling point between about 650° F. (343° C.) and about 1050° F. (566° C.), and a heavy residuum fraction boiling above about 1050° F. (566° C.). The gas oil fraction is catalytically hydrodesulfurized until the gas oil fraction contains less than 1 percent sulfur. The hydrodesulfurized gas oil is then used to dilute the heavy residuum fraction, and the diluted heavy residuum fraction is catalytically hydrodesulfurized, producing fuels or fuel blending components reduced in sulfur content. The process is considered to provide an increased catalyst life and to use a smaller reactor volume compared to typical processes.
U.S. Pat. No. 4,302,323 discloses a process for upgrading a residual petroleum fraction in which the residual fraction is mixed with a light cycle oil and hydrogen and the mixture sent through a catalytic hydrotreating zone containing a hydrotreating catalyst and then a hydrocracking zone containing a hydrocracking catalyst. Upgraded products are then separated from the effluent of the hydrocracking zone. The light cycle oil boils in the range of from 400° F. (204° C.) to 700° F. (371° C.), has a high aromatic content, and is high in nitrogen. It is considered that the light cycle oil acts more as a diluent rather than as a hydrogen donor and that the addition of the light cycle oil resulted in a substantial increase in the yield of premium products such as distillate fuels.
U.S. Pat. No. 4,421,633 discloses a combination hydrodesulfurization and hydrocracking process. The feedstock can be atmospheric residuum or vacuum residuum, which is mixed with a solvent that is a recycled distillate boiling at about 400° F.-700° F. (204° C.-371° C.), considered to be equivalent to a FCC light cycle oil. The process uses a mixture of large pore and small pore catalysts such as large pore and small pore sulfided Ni—W catalysts. The large pore catalyst has a median pore diameter of 180 Å, while the small pore catalyst has a median pore diameter of about 60 Å with no pores larger than 80 Å. The process converts the higher boiling point residua to lower boiling point hydrocarbons by forming distillate and naphtha while removing heteroatoms, metals and carbon residuals from the higher boiling point residua. It is noted that the description also includes examples where no solvent is used. The desulfurization activity in examples without solvent appears to be comparable or superior to the desulfurization activity for the examples that include a solvent.
U.S. Pat. No. 4,585,546 describes a method for hydrotreating petroleum heavy ends in aromatic solvents with large pore size alumina. The methods include processing resids mixed with a solvent such as ortho-xylene or a light cycle oil at 1000 psig (5.5 MPag) and 350° C. The resids were hydroprocessed in the presence of either a commercial hydrodesulfurization catalyst with a median pore size of 70 Å to 80 Å or a hydrodesulfurization catalyst with an alumina support having a median pore size of about 220 Å. The larger pore catalyst was shown to have higher activity for metals removal and comparable activity for sulfur removal as compared to the smaller pore catalyst.
There is a need to further develop processes for hydroprocessing heavy hydrocarbon oils to produce fuel grade products. It is also particularly desirable to provide hydroprocessing processes with improved selectivity to desired products. For example, it is desirable to provide hydroprocessing processes that crack molecules boiling at or above 1050° F. (566° C.) (also referred to as a “1050° F.+ (566° C.+) fraction” herein) into molecules boiling below 1050° F. (566° C.) (also referred to as a “1050° F.− (566° C.−) fraction” herein), while minimizing the formation of “C4−” hydrocarbon compounds (i.e., hydrocarbon compounds having four carbons or less), and coke byproducts.
SUMMARY OF THE PREFERRED EMBODIMENTS OF THE INVENTION
In various embodiments, systems and methods are provided for hydroprocessing of heavy oil feeds. In one embodiment, a process for producing a hydroprocessed product includes exposing a combined feedstock comprising a heavy oil feed component and a solvent component to a hydroprocessing catalyst comprising a Group VIII non-noble metal and a Group VI metal and having a median pore size of about 85 Å to about 120 Å, such as 85 Å to about 100 Å, under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a total pressure of about 1500 psig (10.3 MPag) or less, such as a hydrogen partial pressure of about 1000 psia (6.9 MPa) or less, and a liquid hourly space velocity of the fraction of the combined feedstock boiling above 1050° F. of at least about 0.10 hr−1, such as at least about 0.12 hr−1; separating the hydroprocessing effluent to form at least a liquid effluent; and fractionating a first portion of the liquid effluent to form at least a distillate product and a bottoms product, the bottoms product having a T5 boiling point of about 600° F. The effective hydroprocessing conditions can also include a temperature of at least about 360° C. and/or less than about 510° C., such as about 380° C. to about 460° C.
The solvent can be in the form of an added solvent, in the form of a recycled portion of the liquid effluent from hydroprocessing, or a combination thereof. Optionally, a portion of the bottoms product, such as a second bottoms product from a reduced pressure distillation, can be processed via solvent deasphalting to form a deasphalted oil fraction and a deasphalting residue or asphalt fraction.
In some embodiments, hydroprocessing conditions effective for conversion of at least about 90% of the feedstock relative to a conversion temperature of 1050° F. (566° C.), including a hydroprocessing temperature of at least about 420° C., can be used to form a bottoms product with an increased amount of wax relative to the feedstock. In still other embodiments, hydroprocessing conditions effective for conversion of at least about 80% of the feedstock relative to a conversion temperature of 1050° F. and for 75% desulfurization of the feedstock can be used to form a bottoms product having a sulfur content of about 1 wt % or less.
In another embodiment, a process for producing a hydroprocessed product includes exposing a combined feedstock comprising a heavy oil feed component and a solvent component to a hydroprocessing catalyst under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a hydrogen partial pressure of about 1000 psia (6.9 MPa) or less, such as 800 psia (5.5 MPa) or less, a temperature of at least about 360° C., such as about 380° C. to 510°, and optionally at least about 420° C., and a liquid hourly space velocity of the fraction of the combined feedstock boiling above 1050° F. (566° C.) of at least about 0.10 hr−1, such as at least about 0.12 hr−1; separating the hydroprocessing effluent to form at least a liquid effluent; and fractionating a first portion of the liquid effluent to form at least a distillate product and a bottoms product, the bottoms product having the bottoms product having an ASTM D86 10% distillation point of at least about 600° F. (316° C.).
In various aspects where the solvent component includes a recycle component, the ratio of the heavy oil feed component and the recycle component can be from about 0.3 to about 6.0, such as from about 0.5 to about 5.0.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0081977.html
Tuesday, October 1, 2013
Hydrocracking Catalysts Containing Stabilized Aggregates of Small Crystallites of Zeolite Y Associated Hydrocarbon Conversion Processes (ExxonMobil Research and Engineering Company)
CATEGORY: ZEOLITES
PATENT
Hydrocracking Catalysts Containing Stabilized Aggregates of Small Crystallites of Zeolite Y Associated Hydrocarbon Conversion Processes (ExxonMobil Research and Engineering Company)
United States Patent Application 20130026070
Abstract:
This invention relates to hydrocracking catalysts utilizing stabilized aggregates of small primary crystallites of zeolite Y that are clustered into larger secondary particles. At least 80% of the secondary particles may comprise at least 5 primary crystallites. The size of the primary crystallites may be at most about 0.5 micron, or at most about 0.3 micron, and the size of the secondary particles may be at least about 0.8 micron, or at least about 1.0 μm. The silica to alumina ratio of the resulting stabilized aggregated Y zeolite may be 4:1 or more. This invention also relates to the use of such catalysts in hydrocracking processes for the conversion of heavy oils into lighter fuel products. The invention is particularly suited for the selective production of diesel range products from gas oil range feedstock materials under hydrocracking conditions.
Inventors:
Oliveri, Christopher G. (Stewartsville, NJ, US)
Lai, Wenyih Frank (Bridgewater, NJ, US)
Dandekar, Ajit B. (Bridgewater, NJ, US)
Weigel, Scott J. (Allentown, PA, US)
Wu, Jason (Clinton, NJ, US)
Kay, Robert E. (Easton, PA, US)
Application Number:
13/412945
Publication Date:
01/31/2013
Assignee:
ExxonMobil Research and Engineering Company (Annandale, NJ, US)
FIELD
This invention relates to hydrocracking catalysts containing stabilized aggregates of small crystallites of zeolite Y and hydrocarbon conversion processes utilizing such catalysts. Small primary crystallites of zeolite Y can cluster into larger secondary particles, at least 80% of which may comprise at least 5 primary crystallites. When the outer surfaces of the secondary particles are viewed, e.g., in a SEM image, the average size (width/diameter) of the primary crystallites may be about 0.5 μm or less, or about 0.3 micron or less, though the average size of the secondary particles may be about 0.8 μm or more, or about 1.0 μm or more. The silica to alumina ratio of the resulting stabilize zeolite Y products may be 4:1 or more. Methods for stabilizing the aggregates of Y crystals as well as the catalyst synthesis using the aggregated stabilized Y crystals herein are also disclosed. Catalysts and the use of such catalysts in processes for hydrocracking of hydrocarbon feedstocks are also disclosed herein.
BACKGROUND
Zeolite Y, a member of the Faujasite family, is widely used in many catalytic processes such as fluid catalytic cracking (FCC), hydrocracking, aromatics alkylation, and aromatics transalkylation. A particular type of zeolite Y is known as ultra-stable Y zeolite (USY). Typical USY has crystal morphology of non-aggregated and submicrosized crystals and may contain intra-crystal mesopores after post-treatment involving high temperature steaming. The individual submicrosized crystals may have crystal defects which produce variously oriented crystal grains within an individual crystal particle. U.S. Pat. No. 6,284,218 states that such defects include stacking faults and screw defects.
When heavy molecules are catalytically processed, such as in catalytic cracking of heavy gas oil, transport properties (both intra-particle and inter-particle) of the catalyst are important, in order to operate outside of the diffusion limited regime that often leads to coking.
The article by K. Rajagopalan et al., “Influence of Zeolite Particle Size on Selectivity During Fluid Catalytic Cracking”, Applied Catalysis, 1986, 23, 69-80, reports that smaller particle size NaY zeolite fluid catalytic cracking (FCC) catalysts exhibited improved activity and selectivity to intermediate cracked products, such as gasoline and light cycle oil. Selectivity differences were said to be explained by considering the effect of diffusion resistance on the rate constants for cracking of gas oil and gasoline.
U.S. Pat. No. 5,620,590 reports that small crystal zeolite Y of less than 1 micron shows activity benefit in hydrocracking compared to larger crystals. However, small crystal zeolites often present problems in manufacturing (e.g., difficulties in filtration and formulation) due to their small particle sizes and low bulk density. Therefore, it is desirable to have zeolites that possess the performance advantages of small particles, while still maintaining the easy processability of large particles. Thus, one ideal zeolite morphology includes large secondary particles (often greater than 1 micron) formed by agglomeration of smaller primary crystallites (often less than, or even much less than, 1 micron). Furthermore, to improve mass transportation rates, zeolite crystals with small size or aggregated crystals containing inter-crystal mesopores can be desirable, e.g., for reducing diffusion limitations.
Conventional zeolite Y tends to have a crystal or primary crystallite size of much greater than 0.1 μm, even greater than 1 μm. Examples of such conventional forms of zeolite Y include U.S. Pat. Nos. 3,343,913, 3,690,823, and 3,808,326, for example. Small crystal size zeolite Y may be prepared by methods disclosed in U.S. Pat. Nos. 3,516,786 and 3,864,282.
Zeolite X, zeolite Y, and natural faujasite have identical structure types and differ only in the ratio of silica to alumina in the final crystal structure. For example, zeolite X is generally referred to as having a Si/Al2 molar ratio of 2-3, whereas zeolite Y is generally referred to as having a Si/Al2 molar ratio of 3-7.
U.S. Pat. Nos. 5,993,773 and 6,306,363 describe various forms of low-silica faujasite zeolite, referred to as LSX, having silica to alumina molar ratios of 1.9-2.1. These patents include SEM photographs showing LSX zeolite particle size and morphology.
In U.S. Pat. No. 6,306,363, it is stated that, when zeolites are observed by a SEM, they may be visible either (1) in the form of non-aggregated primary crystallites only, which are the smallest units of zeolite particles, or (2) in the form of secondary particles which are formed by agglomeration of a plurality of primary crystallites. Primary crystallites of zeolites may have their shapes predetermined, depending upon the type of zeolite. For example, A-type zeolite tends to have a cubic shape, and faujasite-type zeolite tends to have an octahedral shape or a polyhedral shape developed from a generally spherical shape with some angularity, as shown in FIG. 3 of this patent. However, it is possible for faujasite-type zeolites to have other shapes, such as elongated shapes (e.g., rod-like shapes).
Usually, particle sizes distributions of these particles are roughly symmetric about an average peak maximum. A method for obtaining an average particle size from particles having a distribution is described in detail, for example, at pages 1 to 31 of “Powder Engineering Theory”, Shigeo Miwa ed., 1981, Nikkan Kogyo Shinbun K. K. The primary crystallite size of the faujasite-type zeolite may be described as a number average particle size of the primary crystallite particle diameters (observed by SEM) as approximated to spheres, which is called the “projected area diameter” or “Heywood diameter”.
LSX in U.S. Pat. No. 6,306,363 is described as being of high purity and characterized in its primary crystallite size of at least 0.05 μm and less than 1 μm, which is said to be a fine (small) size, in comparison with previously known forms of LSX, e.g., where the primary crystallite size is from 3-5 μm, and even more generally where it is at least 1 μm. In this patent, it is stated that, when fine LSX of high purity is used, for example, as an adsorbent of various substances, diffusion into the interior will be facilitated, and improvement in various dynamic properties can be expected.
The LSX described in U.S. Pat. No. 5,993,773 is said to be characterized not only by high purity, but also a peculiar primary crystallite size distribution, wherein the primary crystallite size of a smaller set of particles is from 1-8 μm, the primary crystallite size of a larger set of particles is from 5-15 μm, and 90% or more of the particles are in the smaller set. The right hand portion of FIG. 2 of this patent illustrates a large single crystal or primary crystallite having a spherical polyhedral shape with angularity or edges developed.
SUMMARY
A stabilized aggregated form of zeolite Y utilized in the hydrocracking catalysts and associated hydrocarbon conversion processes disclosed herein comprises small primary crystallites and secondary particles of larger size. At least 80%, e.g., at least 90% or at least 95%, of the primary crystallites may be aggregated or clustered to form the secondary particles. The ratio of the average size (width/diameter) of the secondary particles to the average size (width/diameter) of the primary crystallites, when the outer (i.e., external) surfaces of the secondary particles are viewed, may be at least 3:1, for example at least 5:1 or at least 10:1. When the outer surfaces of the secondary particles are viewed, e.g., in an SEM image, the average size of the primary crystallites in a secondary particle may be about 0.5 μm or less, for example about 0.3 μm or less, about 0.2 μm or less, or about 0.1 μm or less, whereas the average size of the secondary particles may be about 0.8 μm or more, for example about 1.0 μm or more or about 2.0 μm or more. At least 80%, e.g., at least 90% or at least 95%, of the aggregated secondary particles may comprise at least 5, for example at least 10, primary crystallites. These primary crystallites and secondary particles as described herein may be observable, e.g., by an SEM under sufficient conditions including appropriate magnification and resolution.
The average sizes of the primary crystallites and secondary particles can be determined, for instance, by viewing one or more sufficient two-dimensional SEM images of the secondary particles and approximating the shape of the primary crystallites and secondary particles roughly as two-dimensional spherical projections (circles). When percentages (e.g., 80%, 90%, 95%, or the like) of primary crystallites and secondary particles are referred to herein, it should be understood that these percentages are based on numbers of these particles. Although SEM images referred to herein do not necessarily depict all of the particles in an entire batch of primary crystallites and secondary particles, it should also be understood that the SEM images referred to herein are viewed as representative of an entire batch of primary crystallites and secondary particles, including even those particles not specifically observed.
The aggregates of zeolite Y of the present invention can have enhanced stability, particularly enhanced thermal and/or hydrothermal stability, relative to the as-synthesized forms of these aggregates. The present stabilized aggregates of zeolite Y, which can advantageously have an alkali metal content less than 4 wt %, can further have different chemical compositions than the as-synthesized forms of these aggregates, which can typically comprise as much as 8 wt % or more alkali metal content.
Thus, without being bound by theory, it is believed that the chemical composition change may be a reason for the increased stability. As such, aggregates of zeolite Y may attain increased stability through one or more of the following treatments: by exchanging alkali metal (e.g., sodium) atoms from the as-synthesized form of the aggregates with an ammonium salt and by calcining the ammonium exchanged aggregates under conditions sufficient to decompose ammonium; by steaming the calcined, ammonium exchanged form of the aggregates under steaming conditions sufficient, e.g., to remove framework aluminum from the zeolite Y crystallites; and/or by contacting (washing) steamed aggregates with an aqueous acid, e.g., to remove non-framework aluminum from the zeolite Y aggregates.
In other preferred embodiments, the aggregates of zeolite Y herein are incorporated into a catalyst by the use of a suitable binder material or mixtures of suitable binder materials. Suitable binder materials include materials selected from metal oxides, zeolites, aluminum phosphates, polymers, carbons, and clays. Most preferable, the binder is comprised of at least one metal oxide, preferably selected from silica, alumina, silica-alumina, amorphous aluminosilicates, boron, titania, and zirconia. Preferably, the binder is selected from silica, alumina, and silica-alumina. In a preferred embodiment, the binder is comprised of pseudoboehmite alumina.
A significant advantage of the present invention over the prior art, is that in the prior art, the zeolite crystals typically require a significant amount of binder material in order to get obtain sufficient mesoporosity which is defined herein as pore diameters from 2 to 30 nm (20 to 300 angstroms, A) for optimum hydrocracking of hydrocarbon feedstocks. In the present invention, the zeolite is aggregated into a structure containing a high relative mesoporosity and as such, the hydrocracking catalyst can made with very low concentration levels of binders and still maintain the necessary overall mesoporosity of the hydrocracking catalyst. While the catalysts of invention can contain from 0 to 99 wt % binder materials, due to the high mesoporosity of the aggregate Y zeolite, in preferred embodiments, the binders levels can be about 0 to about 80 wt %, more preferably, from about 5 to 50 wt %, or even from about 5 to about 25 wt % of the overall final hydrocracking catalyst. In other preferred embodiments, the hydrocracking catalyst can be less than 50 wt %, more preferably less than 25 wt %, and most preferably less than 10 wt % binder materials. As noted, in embodiments, the aggregated Y zeolites of the present invention may be used as the final catalyst without any binder materials.
The high relative mesoporosity of the catalysts of invention are indicated by the high Relative External Surface Areas of the catalysts. The Relative External Surface Area is defined herein as:
RelativeExternalSurfaceArea=BETExternalSurfaceAreaBETTotalSurfaceArea[1]
In preferred embodiments of the hydrocracking catalysts of invention herein, the catalyst has a Relative External Surface Area of at least 0.35, more preferably at least 0.50. In preferred embodiments of the hydrocracking catalysts of invention herein, the catalyst has a low BET surface area of less than 600 m2/g; more preferably less than 500 m2/g, and most preferably less than 450 m2/g. In other preferred embodiments of the catalysts of invention herein, the average pore diameter of the catalyst is at least 7.0 nanometers (nm), preferably at least 7.5 nm, more preferably at least 8.0 nm, and most preferably at least 9.0 nm.
In other preferred embodiments, the catalyst may contain additional zeolites or molecular sieves. In a preferred embodiment, the catalyst further comprises at least one of the following molecular sieves: beta, ZSM-5, ZSM-11, ZSM-57, MCM-22, MCM-49, MCM-56, ITQ-7, ITQ-27, ZSM-48, mordenite, zeolite L, ferrierite, ZSM-23, MCM-68, SSZ-26/-33, CIT-1, SAPO-37, ZSM-12, ZSM-18, and EMT faujasites. In more preferred embodiments, the catalyst comprises at least one of the following molecular sieves: beta, ZSM-5, ZSM-48, mordenite, and zeolite L. The molecular sieves listed above can be present in the as-synthesized form, or alternatively, can be post-modified chemically, thermally, or mechanically to create a stabilized form of the material.
The aggregates of zeolite Y, binder and additional components may be extruded, spray dried, or otherwise shaped into a catalyst particle for use in hydroconversion processes described herein. In preferred embodiments of the hydrocracking catalysts herein, the final catalyst contains an active Group VIA and/or Group VIIIA metal. In a preferred embodiment, the hydrocracking catalyst is comprised of at least one Group VIA metal selected from Mo and W, and at least one Group VIIIA metal selected from Ni and Co. In another preferred embodiment, the hydrocracking catalyst is comprised at least one Group VIIIA metal selected from Pt, Pd, Rh and Ru. In another preferred embodiment, the hydrocracking catalyst is comprised at least one Group VIIIA metal selected from Pt and Pd. In a preferred embodiment, the Group VIA metal is Mo and the Group VIIIA metal is Co. In another preferred embodiment, the hydrocracking catalyst is comprised of Pt. The active Group VIA or Group VIIIA metals may be incorporated into the catalyst by any technique known in the art. A preferred technique for active metal incorporation into the catalyst herein is the incipient wetness technique.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0026070.html
PATENT
Hydrocracking Catalysts Containing Stabilized Aggregates of Small Crystallites of Zeolite Y Associated Hydrocarbon Conversion Processes (ExxonMobil Research and Engineering Company)
United States Patent Application 20130026070
Abstract:
This invention relates to hydrocracking catalysts utilizing stabilized aggregates of small primary crystallites of zeolite Y that are clustered into larger secondary particles. At least 80% of the secondary particles may comprise at least 5 primary crystallites. The size of the primary crystallites may be at most about 0.5 micron, or at most about 0.3 micron, and the size of the secondary particles may be at least about 0.8 micron, or at least about 1.0 μm. The silica to alumina ratio of the resulting stabilized aggregated Y zeolite may be 4:1 or more. This invention also relates to the use of such catalysts in hydrocracking processes for the conversion of heavy oils into lighter fuel products. The invention is particularly suited for the selective production of diesel range products from gas oil range feedstock materials under hydrocracking conditions.
Inventors:
Oliveri, Christopher G. (Stewartsville, NJ, US)
Lai, Wenyih Frank (Bridgewater, NJ, US)
Dandekar, Ajit B. (Bridgewater, NJ, US)
Weigel, Scott J. (Allentown, PA, US)
Wu, Jason (Clinton, NJ, US)
Kay, Robert E. (Easton, PA, US)
Application Number:
13/412945
Publication Date:
01/31/2013
Assignee:
ExxonMobil Research and Engineering Company (Annandale, NJ, US)
FIELD
This invention relates to hydrocracking catalysts containing stabilized aggregates of small crystallites of zeolite Y and hydrocarbon conversion processes utilizing such catalysts. Small primary crystallites of zeolite Y can cluster into larger secondary particles, at least 80% of which may comprise at least 5 primary crystallites. When the outer surfaces of the secondary particles are viewed, e.g., in a SEM image, the average size (width/diameter) of the primary crystallites may be about 0.5 μm or less, or about 0.3 micron or less, though the average size of the secondary particles may be about 0.8 μm or more, or about 1.0 μm or more. The silica to alumina ratio of the resulting stabilize zeolite Y products may be 4:1 or more. Methods for stabilizing the aggregates of Y crystals as well as the catalyst synthesis using the aggregated stabilized Y crystals herein are also disclosed. Catalysts and the use of such catalysts in processes for hydrocracking of hydrocarbon feedstocks are also disclosed herein.
BACKGROUND
Zeolite Y, a member of the Faujasite family, is widely used in many catalytic processes such as fluid catalytic cracking (FCC), hydrocracking, aromatics alkylation, and aromatics transalkylation. A particular type of zeolite Y is known as ultra-stable Y zeolite (USY). Typical USY has crystal morphology of non-aggregated and submicrosized crystals and may contain intra-crystal mesopores after post-treatment involving high temperature steaming. The individual submicrosized crystals may have crystal defects which produce variously oriented crystal grains within an individual crystal particle. U.S. Pat. No. 6,284,218 states that such defects include stacking faults and screw defects.
When heavy molecules are catalytically processed, such as in catalytic cracking of heavy gas oil, transport properties (both intra-particle and inter-particle) of the catalyst are important, in order to operate outside of the diffusion limited regime that often leads to coking.
The article by K. Rajagopalan et al., “Influence of Zeolite Particle Size on Selectivity During Fluid Catalytic Cracking”, Applied Catalysis, 1986, 23, 69-80, reports that smaller particle size NaY zeolite fluid catalytic cracking (FCC) catalysts exhibited improved activity and selectivity to intermediate cracked products, such as gasoline and light cycle oil. Selectivity differences were said to be explained by considering the effect of diffusion resistance on the rate constants for cracking of gas oil and gasoline.
U.S. Pat. No. 5,620,590 reports that small crystal zeolite Y of less than 1 micron shows activity benefit in hydrocracking compared to larger crystals. However, small crystal zeolites often present problems in manufacturing (e.g., difficulties in filtration and formulation) due to their small particle sizes and low bulk density. Therefore, it is desirable to have zeolites that possess the performance advantages of small particles, while still maintaining the easy processability of large particles. Thus, one ideal zeolite morphology includes large secondary particles (often greater than 1 micron) formed by agglomeration of smaller primary crystallites (often less than, or even much less than, 1 micron). Furthermore, to improve mass transportation rates, zeolite crystals with small size or aggregated crystals containing inter-crystal mesopores can be desirable, e.g., for reducing diffusion limitations.
Conventional zeolite Y tends to have a crystal or primary crystallite size of much greater than 0.1 μm, even greater than 1 μm. Examples of such conventional forms of zeolite Y include U.S. Pat. Nos. 3,343,913, 3,690,823, and 3,808,326, for example. Small crystal size zeolite Y may be prepared by methods disclosed in U.S. Pat. Nos. 3,516,786 and 3,864,282.
Zeolite X, zeolite Y, and natural faujasite have identical structure types and differ only in the ratio of silica to alumina in the final crystal structure. For example, zeolite X is generally referred to as having a Si/Al2 molar ratio of 2-3, whereas zeolite Y is generally referred to as having a Si/Al2 molar ratio of 3-7.
U.S. Pat. Nos. 5,993,773 and 6,306,363 describe various forms of low-silica faujasite zeolite, referred to as LSX, having silica to alumina molar ratios of 1.9-2.1. These patents include SEM photographs showing LSX zeolite particle size and morphology.
In U.S. Pat. No. 6,306,363, it is stated that, when zeolites are observed by a SEM, they may be visible either (1) in the form of non-aggregated primary crystallites only, which are the smallest units of zeolite particles, or (2) in the form of secondary particles which are formed by agglomeration of a plurality of primary crystallites. Primary crystallites of zeolites may have their shapes predetermined, depending upon the type of zeolite. For example, A-type zeolite tends to have a cubic shape, and faujasite-type zeolite tends to have an octahedral shape or a polyhedral shape developed from a generally spherical shape with some angularity, as shown in FIG. 3 of this patent. However, it is possible for faujasite-type zeolites to have other shapes, such as elongated shapes (e.g., rod-like shapes).
Usually, particle sizes distributions of these particles are roughly symmetric about an average peak maximum. A method for obtaining an average particle size from particles having a distribution is described in detail, for example, at pages 1 to 31 of “Powder Engineering Theory”, Shigeo Miwa ed., 1981, Nikkan Kogyo Shinbun K. K. The primary crystallite size of the faujasite-type zeolite may be described as a number average particle size of the primary crystallite particle diameters (observed by SEM) as approximated to spheres, which is called the “projected area diameter” or “Heywood diameter”.
LSX in U.S. Pat. No. 6,306,363 is described as being of high purity and characterized in its primary crystallite size of at least 0.05 μm and less than 1 μm, which is said to be a fine (small) size, in comparison with previously known forms of LSX, e.g., where the primary crystallite size is from 3-5 μm, and even more generally where it is at least 1 μm. In this patent, it is stated that, when fine LSX of high purity is used, for example, as an adsorbent of various substances, diffusion into the interior will be facilitated, and improvement in various dynamic properties can be expected.
The LSX described in U.S. Pat. No. 5,993,773 is said to be characterized not only by high purity, but also a peculiar primary crystallite size distribution, wherein the primary crystallite size of a smaller set of particles is from 1-8 μm, the primary crystallite size of a larger set of particles is from 5-15 μm, and 90% or more of the particles are in the smaller set. The right hand portion of FIG. 2 of this patent illustrates a large single crystal or primary crystallite having a spherical polyhedral shape with angularity or edges developed.
SUMMARY
A stabilized aggregated form of zeolite Y utilized in the hydrocracking catalysts and associated hydrocarbon conversion processes disclosed herein comprises small primary crystallites and secondary particles of larger size. At least 80%, e.g., at least 90% or at least 95%, of the primary crystallites may be aggregated or clustered to form the secondary particles. The ratio of the average size (width/diameter) of the secondary particles to the average size (width/diameter) of the primary crystallites, when the outer (i.e., external) surfaces of the secondary particles are viewed, may be at least 3:1, for example at least 5:1 or at least 10:1. When the outer surfaces of the secondary particles are viewed, e.g., in an SEM image, the average size of the primary crystallites in a secondary particle may be about 0.5 μm or less, for example about 0.3 μm or less, about 0.2 μm or less, or about 0.1 μm or less, whereas the average size of the secondary particles may be about 0.8 μm or more, for example about 1.0 μm or more or about 2.0 μm or more. At least 80%, e.g., at least 90% or at least 95%, of the aggregated secondary particles may comprise at least 5, for example at least 10, primary crystallites. These primary crystallites and secondary particles as described herein may be observable, e.g., by an SEM under sufficient conditions including appropriate magnification and resolution.
The average sizes of the primary crystallites and secondary particles can be determined, for instance, by viewing one or more sufficient two-dimensional SEM images of the secondary particles and approximating the shape of the primary crystallites and secondary particles roughly as two-dimensional spherical projections (circles). When percentages (e.g., 80%, 90%, 95%, or the like) of primary crystallites and secondary particles are referred to herein, it should be understood that these percentages are based on numbers of these particles. Although SEM images referred to herein do not necessarily depict all of the particles in an entire batch of primary crystallites and secondary particles, it should also be understood that the SEM images referred to herein are viewed as representative of an entire batch of primary crystallites and secondary particles, including even those particles not specifically observed.
The aggregates of zeolite Y of the present invention can have enhanced stability, particularly enhanced thermal and/or hydrothermal stability, relative to the as-synthesized forms of these aggregates. The present stabilized aggregates of zeolite Y, which can advantageously have an alkali metal content less than 4 wt %, can further have different chemical compositions than the as-synthesized forms of these aggregates, which can typically comprise as much as 8 wt % or more alkali metal content.
Thus, without being bound by theory, it is believed that the chemical composition change may be a reason for the increased stability. As such, aggregates of zeolite Y may attain increased stability through one or more of the following treatments: by exchanging alkali metal (e.g., sodium) atoms from the as-synthesized form of the aggregates with an ammonium salt and by calcining the ammonium exchanged aggregates under conditions sufficient to decompose ammonium; by steaming the calcined, ammonium exchanged form of the aggregates under steaming conditions sufficient, e.g., to remove framework aluminum from the zeolite Y crystallites; and/or by contacting (washing) steamed aggregates with an aqueous acid, e.g., to remove non-framework aluminum from the zeolite Y aggregates.
In other preferred embodiments, the aggregates of zeolite Y herein are incorporated into a catalyst by the use of a suitable binder material or mixtures of suitable binder materials. Suitable binder materials include materials selected from metal oxides, zeolites, aluminum phosphates, polymers, carbons, and clays. Most preferable, the binder is comprised of at least one metal oxide, preferably selected from silica, alumina, silica-alumina, amorphous aluminosilicates, boron, titania, and zirconia. Preferably, the binder is selected from silica, alumina, and silica-alumina. In a preferred embodiment, the binder is comprised of pseudoboehmite alumina.
A significant advantage of the present invention over the prior art, is that in the prior art, the zeolite crystals typically require a significant amount of binder material in order to get obtain sufficient mesoporosity which is defined herein as pore diameters from 2 to 30 nm (20 to 300 angstroms, A) for optimum hydrocracking of hydrocarbon feedstocks. In the present invention, the zeolite is aggregated into a structure containing a high relative mesoporosity and as such, the hydrocracking catalyst can made with very low concentration levels of binders and still maintain the necessary overall mesoporosity of the hydrocracking catalyst. While the catalysts of invention can contain from 0 to 99 wt % binder materials, due to the high mesoporosity of the aggregate Y zeolite, in preferred embodiments, the binders levels can be about 0 to about 80 wt %, more preferably, from about 5 to 50 wt %, or even from about 5 to about 25 wt % of the overall final hydrocracking catalyst. In other preferred embodiments, the hydrocracking catalyst can be less than 50 wt %, more preferably less than 25 wt %, and most preferably less than 10 wt % binder materials. As noted, in embodiments, the aggregated Y zeolites of the present invention may be used as the final catalyst without any binder materials.
The high relative mesoporosity of the catalysts of invention are indicated by the high Relative External Surface Areas of the catalysts. The Relative External Surface Area is defined herein as:
RelativeExternalSurfaceArea=BETExternalSurfaceAreaBETTotalSurfaceArea[1]
In preferred embodiments of the hydrocracking catalysts of invention herein, the catalyst has a Relative External Surface Area of at least 0.35, more preferably at least 0.50. In preferred embodiments of the hydrocracking catalysts of invention herein, the catalyst has a low BET surface area of less than 600 m2/g; more preferably less than 500 m2/g, and most preferably less than 450 m2/g. In other preferred embodiments of the catalysts of invention herein, the average pore diameter of the catalyst is at least 7.0 nanometers (nm), preferably at least 7.5 nm, more preferably at least 8.0 nm, and most preferably at least 9.0 nm.
In other preferred embodiments, the catalyst may contain additional zeolites or molecular sieves. In a preferred embodiment, the catalyst further comprises at least one of the following molecular sieves: beta, ZSM-5, ZSM-11, ZSM-57, MCM-22, MCM-49, MCM-56, ITQ-7, ITQ-27, ZSM-48, mordenite, zeolite L, ferrierite, ZSM-23, MCM-68, SSZ-26/-33, CIT-1, SAPO-37, ZSM-12, ZSM-18, and EMT faujasites. In more preferred embodiments, the catalyst comprises at least one of the following molecular sieves: beta, ZSM-5, ZSM-48, mordenite, and zeolite L. The molecular sieves listed above can be present in the as-synthesized form, or alternatively, can be post-modified chemically, thermally, or mechanically to create a stabilized form of the material.
The aggregates of zeolite Y, binder and additional components may be extruded, spray dried, or otherwise shaped into a catalyst particle for use in hydroconversion processes described herein. In preferred embodiments of the hydrocracking catalysts herein, the final catalyst contains an active Group VIA and/or Group VIIIA metal. In a preferred embodiment, the hydrocracking catalyst is comprised of at least one Group VIA metal selected from Mo and W, and at least one Group VIIIA metal selected from Ni and Co. In another preferred embodiment, the hydrocracking catalyst is comprised at least one Group VIIIA metal selected from Pt, Pd, Rh and Ru. In another preferred embodiment, the hydrocracking catalyst is comprised at least one Group VIIIA metal selected from Pt and Pd. In a preferred embodiment, the Group VIA metal is Mo and the Group VIIIA metal is Co. In another preferred embodiment, the hydrocracking catalyst is comprised of Pt. The active Group VIA or Group VIIIA metals may be incorporated into the catalyst by any technique known in the art. A preferred technique for active metal incorporation into the catalyst herein is the incipient wetness technique.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0026070.html
An improved hydrotreating process for lube oil boiling range feedstreams (Exxonmobil Research And Engineering Company)
CATEGORY: LUBRICATING OILS
PATENT
An improved hydrotreating process for lube oil boiling range feedstreams (Exxonmobil Research And Engineering Company)
Publication number
CA2578416 C
Publication type
Grant
PCT number
PCT/US2005/031067
Publication date
Jul 23, 2013
Inventors
Stephen J. Mccarthy, 4 More »
Applicant
Exxonmobil Research And Engineering Company
Abstract
An improved hydrotreating process for use with lube oil boiling range feedstreams utilizing a catalyst comprising a hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof, a mesoporous support, and a binder.
FIELD OF THE INVENTION
[0001] This invention relates to a hydrotreating process for lube oil boiling range feedstreams. More particularly, the present invention is directed at a hydrotreating process for lube oil boiling range feedstreams utilizing a catalyst comprising a hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof, a mesoporous support, and a binder.
BACKGROUND OF THE INVENTION
[0002] Historically, lubricating oil products for use in applications such as automotive engine oils have used additives to improve specific properties of the basestocks used to prepare the finished products. With the advent of increased environmental concerns, the performance requirements for the basestocks themselves have increased. For example, American Petroleum Institute (API) requirements for Group II basestocks include a saturates content of at least 90%, a sulfur content of 0.03 wt.% or less and a viscosity index (VI) between 80 and 120.
Currently, there is a trend in the lube oil market to use higher quality basestocks in order to meet the demand for higher quality products that provide for increased fuel economy, reduced emissions, etc.
[0003] Conventional techniques for preparing basestocks such as hydrocracking or solvent extraction require severe operating conditions such as high pressure and temperature or high solvent:oil ratios and high extraction temperatures to reach these higher basestock qualities. Either alternative involves expensive operating conditions and low yields.
[0004] Hydrocracking has been combined with hydrotreating as a preliminary step. However, this combination also results in decreased yields of lubricating oils due to the conversion to distillates that typically accompany the hydrocracking process.
[0005] In United States Patent Number 5,573,657, a hydrogenation catalyst, and process using the same, is described wherein a mineral oil based lubricant is passed over a mesoporous crystalline material, preferably with a support, containing a hydrogenation metal function. The supported mesoporous material has pore diameters greater than 200A. The hydrogenation process is operated such that the product produced therein has a low degree of unstaturation.
[0006] However, there is still a need in the art for an effective process to prepare quality lubricating oil basestocks.
SUMMARY OF THE INVENTION
[0007] The present invention is directed at a process used to hydrotreat lube oil boiling range feedstreams. The process comprises:
a) contacting a lube oil boiling range feedstreams containing aromatics and nitrogen and organically bound sulfur contaminants with a hydrotreating catalyst in the presence of a hydrogen-containing treat gas in a reaction stage operated under effective hydrotreating conditions, wherein said hydrotreating catalyst comprises:
i) 40 wt.% to less then 60 wt.% of an inorganic, porous, non-layered, crystalline, mesoporous support material;
ii) 40 to 60 wt.% of a binder material; and iii) at least one hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof.
[0008] In one embodiment of the instant invention, the inorganic, porous, non-layered, crystalline, mesoporous support material of the hydrotreating catalyst is characterized as exhibiting an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18A. The support material is further characterized as having a benzene absorption capacity greater than 15 grams benzene per 100 grams of the material at 50 torr (6.67 kPa) and 25 C.
[0009] In a preferred form, the support material of the hydrotreating catalyst is characterized by a substantially uniform hexagonal honeycomb microstructure with uniform pores having a d100 value greater than 18A.
[0010] In another preferred form, the support material of the hydrotreating catalyst is MCM-41.
[0011] In yet another embodiment of the instant invention, the lube oil boiling range feedstream is hydrotreated in a two stage hydrotreating process. The first stage contains a conventional hydrotreating catalyst, and the second reaction stage contains a hydrotreating catalyst comprising a mesoporous support, a binder material, and a hydrogenation-dehydrogenation metal. This embodiment of the instant invention comprises:
a) contacting a lube oil boiling range feedstream containing aromatics, nitrogen and organically bound sulfur contaminants in a first reaction stage operated under effective hydrotreating conditions and in the presence of hydrogen-containing treat gas with a hydrotreating =
catalyst comprising at least one Group VIII metal oxide and at least one Group VI metal oxide thereby producing a reaction product comprising at least a vapor product and a liquid lube oil boiling range product; and b) contacting said reaction product with a hydrotreating catalyst in the presence of a hydrogen-containing treat gas in a second reaction stage operated under effective hydrotreating conditions, wherein said hydrotreating catalyst comprises:
i) 40 wt.% to less then 60 wt.% of an inorganic, porous, non-layered, crystalline, mesoporous support material;
ii) 40 to 60 wt.% of a binder material; and iii) at least one hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof [0012] In another embodiment of the instant invention, the process further comprises:
a) separating said vapor product from said liquid lube oil boiling range product; and b) conducting said liquid lube oil boiling range boiling range product to the second reaction stage containing said hydrogenation catalyst.
Free Full Text Source: http://www.google.com/patents/CA2578416C
PATENT
An improved hydrotreating process for lube oil boiling range feedstreams (Exxonmobil Research And Engineering Company)
Publication number
CA2578416 C
Publication type
Grant
PCT number
PCT/US2005/031067
Publication date
Jul 23, 2013
Inventors
Stephen J. Mccarthy, 4 More »
Applicant
Exxonmobil Research And Engineering Company
Abstract
An improved hydrotreating process for use with lube oil boiling range feedstreams utilizing a catalyst comprising a hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof, a mesoporous support, and a binder.
FIELD OF THE INVENTION
[0001] This invention relates to a hydrotreating process for lube oil boiling range feedstreams. More particularly, the present invention is directed at a hydrotreating process for lube oil boiling range feedstreams utilizing a catalyst comprising a hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof, a mesoporous support, and a binder.
BACKGROUND OF THE INVENTION
[0002] Historically, lubricating oil products for use in applications such as automotive engine oils have used additives to improve specific properties of the basestocks used to prepare the finished products. With the advent of increased environmental concerns, the performance requirements for the basestocks themselves have increased. For example, American Petroleum Institute (API) requirements for Group II basestocks include a saturates content of at least 90%, a sulfur content of 0.03 wt.% or less and a viscosity index (VI) between 80 and 120.
Currently, there is a trend in the lube oil market to use higher quality basestocks in order to meet the demand for higher quality products that provide for increased fuel economy, reduced emissions, etc.
[0003] Conventional techniques for preparing basestocks such as hydrocracking or solvent extraction require severe operating conditions such as high pressure and temperature or high solvent:oil ratios and high extraction temperatures to reach these higher basestock qualities. Either alternative involves expensive operating conditions and low yields.
[0004] Hydrocracking has been combined with hydrotreating as a preliminary step. However, this combination also results in decreased yields of lubricating oils due to the conversion to distillates that typically accompany the hydrocracking process.
[0005] In United States Patent Number 5,573,657, a hydrogenation catalyst, and process using the same, is described wherein a mineral oil based lubricant is passed over a mesoporous crystalline material, preferably with a support, containing a hydrogenation metal function. The supported mesoporous material has pore diameters greater than 200A. The hydrogenation process is operated such that the product produced therein has a low degree of unstaturation.
[0006] However, there is still a need in the art for an effective process to prepare quality lubricating oil basestocks.
SUMMARY OF THE INVENTION
[0007] The present invention is directed at a process used to hydrotreat lube oil boiling range feedstreams. The process comprises:
a) contacting a lube oil boiling range feedstreams containing aromatics and nitrogen and organically bound sulfur contaminants with a hydrotreating catalyst in the presence of a hydrogen-containing treat gas in a reaction stage operated under effective hydrotreating conditions, wherein said hydrotreating catalyst comprises:
i) 40 wt.% to less then 60 wt.% of an inorganic, porous, non-layered, crystalline, mesoporous support material;
ii) 40 to 60 wt.% of a binder material; and iii) at least one hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof.
[0008] In one embodiment of the instant invention, the inorganic, porous, non-layered, crystalline, mesoporous support material of the hydrotreating catalyst is characterized as exhibiting an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18A. The support material is further characterized as having a benzene absorption capacity greater than 15 grams benzene per 100 grams of the material at 50 torr (6.67 kPa) and 25 C.
[0009] In a preferred form, the support material of the hydrotreating catalyst is characterized by a substantially uniform hexagonal honeycomb microstructure with uniform pores having a d100 value greater than 18A.
[0010] In another preferred form, the support material of the hydrotreating catalyst is MCM-41.
[0011] In yet another embodiment of the instant invention, the lube oil boiling range feedstream is hydrotreated in a two stage hydrotreating process. The first stage contains a conventional hydrotreating catalyst, and the second reaction stage contains a hydrotreating catalyst comprising a mesoporous support, a binder material, and a hydrogenation-dehydrogenation metal. This embodiment of the instant invention comprises:
a) contacting a lube oil boiling range feedstream containing aromatics, nitrogen and organically bound sulfur contaminants in a first reaction stage operated under effective hydrotreating conditions and in the presence of hydrogen-containing treat gas with a hydrotreating =
catalyst comprising at least one Group VIII metal oxide and at least one Group VI metal oxide thereby producing a reaction product comprising at least a vapor product and a liquid lube oil boiling range product; and b) contacting said reaction product with a hydrotreating catalyst in the presence of a hydrogen-containing treat gas in a second reaction stage operated under effective hydrotreating conditions, wherein said hydrotreating catalyst comprises:
i) 40 wt.% to less then 60 wt.% of an inorganic, porous, non-layered, crystalline, mesoporous support material;
ii) 40 to 60 wt.% of a binder material; and iii) at least one hydrogenation-dehydrogenation component selected from the Group VIII noble metals and mixtures thereof [0012] In another embodiment of the instant invention, the process further comprises:
a) separating said vapor product from said liquid lube oil boiling range product; and b) conducting said liquid lube oil boiling range boiling range product to the second reaction stage containing said hydrogenation catalyst.
Free Full Text Source: http://www.google.com/patents/CA2578416C
Hydrotreating Process (Exxonmobil Research And Engineeringcompany)
CATEGORY: HYDROTREATING
PATENT
Hydrotreating Process (Exxonmobil Research And Engineeringcompany)
United States Patent Application 20130006029
Inventors:
Kiss, Gabor (Hampton, NJ, US)
Nistor, Iulian (Center Valley, PA, US)
Zengel, John (Clinton, NJ, US)
Miseo, Sabato (Pittstown, NJ, US)
Krycak, Roman (Annandale, NJ, US)
Ho, Teh C. (Bridgewater, NJ, US)
Application Number:
13/575849
Publication Date:
01/03/2013
Assignee:
Exxonmobil Research And Engineeringcompany (Annandale, NJ, US)
FIELD OF THE INVENTION
This invention relates to hydrotreating processes for reducing the level of sulfur in diesel fuels and other sulfur-containing hydrocarbon feeds.
BACKGROUND OF THE INVENTION
Supported CoMo catalysts have been used for decades in the fixed bed hydrotreatment of diesel fuels. These catalysts have been proven to be very effective for removing the bulk of the sulfur content from diesel fuels at relatively low cost. Moreover, until the 2006 U.S. regulatory changes reduced the maximum sulfur levels in diesel fuels from 500 ppm by weight (S500) to 15 ppm by weight (S15), these catalysts were also typically very robust, generally lasting for years before replacements were necessary, and thereby typically affording very low catalyst cost.
However, delivering S15 generally requires an increase of the severity of the hydrotreating conditions when using the same catalyst, which in turn leads to faster catalyst deactivation, particularly in relatively low-pressure units that have to rely more on increased temperature to produce S15. The catalyst deactivation often accelerates so much that it significantly affects the cost of refining diesel fuel. There is, therefore, a need for process and/or catalyst solutions to mitigate the accelerated catalyst deactivation involved in hydrotreating diesel fuels to sulfur levels below 15 wppm.
According to the present invention, it has now been found that the impact of catalyst deactivation, particularly during the start up, can be reduced by using a start-up feed with reduced aromatic content as compared with that of the feed to be hydrotreated.
U.S. Pat. No. 3,436,338 discloses that hydrocracking catalysts which have been partially deactivated by polycyclic aromatic hydrocarbons present in the charge stock are reactivated by introducing a feed having a lower polycyclic aromatic content. This patent is, however, silent as to the effect of lowering the overall aromatic content of the deactivation rate of a fresh, undeactivated catalyst.
SUMMARY OF THE INVENTION
One aspect of the invention relates to a process for hydrotreating, or alternately starting up a hydrotreating process involving, a first aromatics- and sulfur-containing hydrocarbon feed, preferably a diesel fuel (for example having an aromatic content of at least 20 wt %), using a fresh supported CoMo catalyst, the process including, or consisting essentially of, treating the fresh catalyst under first hydrotreating conditions with a second hydrocarbon feed having a lower aromatics content than the first feed, and then, optionally but preferably, also hydrotreating the first feed. Advantageously, the first hydrotreating conditions can include a temperature of about 300° C. to about 350° C., a pressure of about 1.5 MPag to about 3.5 MPag, and an LHSV of about 0.3 hr−1 to about 1.0 hr−1. In one embodiment, the treating is conducted from 3 days to 10 days.
In one embodiment, the process further comprises contacting the treated catalyst with the first aromatics- and sulfur-containing hydrocarbon feed under second hydrotreating conditions to reduce the sulfur content of the first feed to 15 wppm or less. Conveniently, the second hydrotreating conditions include a temperature of about 300° C. to about 380° C., a pressure of about 1.5 MPag to about 3.5 MPag, and an LHSV of about 0.2 hr−1 to about 0.8 hr−1.
In one embodiment, the first and second hydrotreating conditions can be substantially the same.
Conveniently, the second feed can be produced by adding aliphatic hydrocarbons to the first feed. In one such embodiment, the process can further comprise adding the aliphatic hydrocarbons to the first feed so as to reduce the aromatics content thereof by at least 50%.
Another aspect of the invention relates to a method for selectively treating hindered sulfur species from a sulfur-containing hydrocarbon feed, the method comprising: providing a multimetallic amine oxide catalyst having the formula (T1)x(T2)(1-x)(am)a(M6)Ob, where T1 is a first row transition metal from Group VIII of the Periodic Table of Elements, where T2 is a first row transition metal from Group VIIB and/or Group VIII of the Periodic Table of Elements that is different from T1, where M6 is molybdenum and/or tungsten, where “am” is an organic amine ligand such as ethylenediamine, where “x” is a relative molar amount of cobalt such that 0≦x≦1, where “a” is a relative molar amount of the organic amine ligand such that 1≦a≦6, and where “b” is a relative molar amount of the oxygen and 3≦b≦5; sulfiding the multimetallic amine oxide catalyst using a sulfiding composition and sulfiding conditions in the liquid phase in order to activate the catalyst for selective hydrodesulfurization; contacting the activated catalyst with a hydrocarbon feed having at least 25 wppm of hindered sulfur species and/or having a ratio of hindered sulfur species to unhindered sulfur species of at least 0.4:1, in the presence of hydrogen, under conditions sufficient to selectively hydrodesulfurize the hindered sulfur species in the feed, so as to attain a treated hydrocarbon feed having no more than 10 wppm of hindered sulfur species and having 30 wppm or less total sulfur content.
In some embodiments, the hydrocarbon feed (optionally having a total sulfur content of at least 2000 wppm), prior to being contacted with the activated catalyst, can first be placed in the presence of a hydrotreating catalyst and hydrogen, under similar or different effective hydrotreating conditions (which can optionally but advantageously reduce the total sulfur content to 500 wppm or less) to cause said resultant pre-treated feed to have at least 25 wppm of hindered sulfur species and/or to have a ratio of hindered sulfur species to unhindered sulfur species of at least 0.4:1 upon being contacted with the activated catalyst.
Additionally or alternately, the multimetallic amine oxide catalyst can be a cobalt-amine molybdate catalyst having the formula Cox(T2)(1-x)(am)aMoOb, where T2 is a first row transition metal from Group VIIB and/or Group VIII of the Periodic Table of Elements other than cobalt, where “am” is an organic amine ligand, where “x” is a relative molar amount of cobalt such that 0.33≦x≦1, where “a” is a relative molar amount of the organic amine ligand such that 1≦a≦6, and where “b” is a relative molar amount of the oxygen and 3≦b≦5. In some preferred embodiments, the cobalt-amine molybdate catalyst has the formula Co(en)3MoO4.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0006029.html
PATENT
Hydrotreating Process (Exxonmobil Research And Engineeringcompany)
United States Patent Application 20130006029
Inventors:
Kiss, Gabor (Hampton, NJ, US)
Nistor, Iulian (Center Valley, PA, US)
Zengel, John (Clinton, NJ, US)
Miseo, Sabato (Pittstown, NJ, US)
Krycak, Roman (Annandale, NJ, US)
Ho, Teh C. (Bridgewater, NJ, US)
Application Number:
13/575849
Publication Date:
01/03/2013
Assignee:
Exxonmobil Research And Engineeringcompany (Annandale, NJ, US)
FIELD OF THE INVENTION
This invention relates to hydrotreating processes for reducing the level of sulfur in diesel fuels and other sulfur-containing hydrocarbon feeds.
BACKGROUND OF THE INVENTION
Supported CoMo catalysts have been used for decades in the fixed bed hydrotreatment of diesel fuels. These catalysts have been proven to be very effective for removing the bulk of the sulfur content from diesel fuels at relatively low cost. Moreover, until the 2006 U.S. regulatory changes reduced the maximum sulfur levels in diesel fuels from 500 ppm by weight (S500) to 15 ppm by weight (S15), these catalysts were also typically very robust, generally lasting for years before replacements were necessary, and thereby typically affording very low catalyst cost.
However, delivering S15 generally requires an increase of the severity of the hydrotreating conditions when using the same catalyst, which in turn leads to faster catalyst deactivation, particularly in relatively low-pressure units that have to rely more on increased temperature to produce S15. The catalyst deactivation often accelerates so much that it significantly affects the cost of refining diesel fuel. There is, therefore, a need for process and/or catalyst solutions to mitigate the accelerated catalyst deactivation involved in hydrotreating diesel fuels to sulfur levels below 15 wppm.
According to the present invention, it has now been found that the impact of catalyst deactivation, particularly during the start up, can be reduced by using a start-up feed with reduced aromatic content as compared with that of the feed to be hydrotreated.
U.S. Pat. No. 3,436,338 discloses that hydrocracking catalysts which have been partially deactivated by polycyclic aromatic hydrocarbons present in the charge stock are reactivated by introducing a feed having a lower polycyclic aromatic content. This patent is, however, silent as to the effect of lowering the overall aromatic content of the deactivation rate of a fresh, undeactivated catalyst.
SUMMARY OF THE INVENTION
One aspect of the invention relates to a process for hydrotreating, or alternately starting up a hydrotreating process involving, a first aromatics- and sulfur-containing hydrocarbon feed, preferably a diesel fuel (for example having an aromatic content of at least 20 wt %), using a fresh supported CoMo catalyst, the process including, or consisting essentially of, treating the fresh catalyst under first hydrotreating conditions with a second hydrocarbon feed having a lower aromatics content than the first feed, and then, optionally but preferably, also hydrotreating the first feed. Advantageously, the first hydrotreating conditions can include a temperature of about 300° C. to about 350° C., a pressure of about 1.5 MPag to about 3.5 MPag, and an LHSV of about 0.3 hr−1 to about 1.0 hr−1. In one embodiment, the treating is conducted from 3 days to 10 days.
In one embodiment, the process further comprises contacting the treated catalyst with the first aromatics- and sulfur-containing hydrocarbon feed under second hydrotreating conditions to reduce the sulfur content of the first feed to 15 wppm or less. Conveniently, the second hydrotreating conditions include a temperature of about 300° C. to about 380° C., a pressure of about 1.5 MPag to about 3.5 MPag, and an LHSV of about 0.2 hr−1 to about 0.8 hr−1.
In one embodiment, the first and second hydrotreating conditions can be substantially the same.
Conveniently, the second feed can be produced by adding aliphatic hydrocarbons to the first feed. In one such embodiment, the process can further comprise adding the aliphatic hydrocarbons to the first feed so as to reduce the aromatics content thereof by at least 50%.
Another aspect of the invention relates to a method for selectively treating hindered sulfur species from a sulfur-containing hydrocarbon feed, the method comprising: providing a multimetallic amine oxide catalyst having the formula (T1)x(T2)(1-x)(am)a(M6)Ob, where T1 is a first row transition metal from Group VIII of the Periodic Table of Elements, where T2 is a first row transition metal from Group VIIB and/or Group VIII of the Periodic Table of Elements that is different from T1, where M6 is molybdenum and/or tungsten, where “am” is an organic amine ligand such as ethylenediamine, where “x” is a relative molar amount of cobalt such that 0≦x≦1, where “a” is a relative molar amount of the organic amine ligand such that 1≦a≦6, and where “b” is a relative molar amount of the oxygen and 3≦b≦5; sulfiding the multimetallic amine oxide catalyst using a sulfiding composition and sulfiding conditions in the liquid phase in order to activate the catalyst for selective hydrodesulfurization; contacting the activated catalyst with a hydrocarbon feed having at least 25 wppm of hindered sulfur species and/or having a ratio of hindered sulfur species to unhindered sulfur species of at least 0.4:1, in the presence of hydrogen, under conditions sufficient to selectively hydrodesulfurize the hindered sulfur species in the feed, so as to attain a treated hydrocarbon feed having no more than 10 wppm of hindered sulfur species and having 30 wppm or less total sulfur content.
In some embodiments, the hydrocarbon feed (optionally having a total sulfur content of at least 2000 wppm), prior to being contacted with the activated catalyst, can first be placed in the presence of a hydrotreating catalyst and hydrogen, under similar or different effective hydrotreating conditions (which can optionally but advantageously reduce the total sulfur content to 500 wppm or less) to cause said resultant pre-treated feed to have at least 25 wppm of hindered sulfur species and/or to have a ratio of hindered sulfur species to unhindered sulfur species of at least 0.4:1 upon being contacted with the activated catalyst.
Additionally or alternately, the multimetallic amine oxide catalyst can be a cobalt-amine molybdate catalyst having the formula Cox(T2)(1-x)(am)aMoOb, where T2 is a first row transition metal from Group VIIB and/or Group VIII of the Periodic Table of Elements other than cobalt, where “am” is an organic amine ligand, where “x” is a relative molar amount of cobalt such that 0.33≦x≦1, where “a” is a relative molar amount of the organic amine ligand such that 1≦a≦6, and where “b” is a relative molar amount of the oxygen and 3≦b≦5. In some preferred embodiments, the cobalt-amine molybdate catalyst has the formula Co(en)3MoO4.
Free Full Text Source: http://www.freepatentsonline.com/y2013/0006029.html
Subscribe to:
Posts (Atom)