(12) United States Patent
`Ellis et al.
`
`I 1111111111111111 11111 111111111111111 lllll 111111111111111 1111111111 11111111
`US006893475Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,893,475 Bl
`May 17, 2005
`
`(54) LOW SULFUR DISTILLATE FUELS
`
`(75)
`
`Inventors: Edward S. Ellis, Basking Ridge, NJ
`(US); Lynne Gillespie, Oxfordshire
`(GB); Michele S. Touvelle, Baton
`Rouge, LA (US); William E. Lewis,
`Baton Rouge, LA (US); Gordon F.
`Stuntz, Baton Rouge, LA (US); Lisa I.
`Yeh, Marlton, NJ (US)
`
`(73) Assignee: ExxonMobil Research and
`Engineering Company, Annandale, NJ
`(US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 09/553,108
`
`(22)
`
`Filed:
`
`Apr. 20, 2000
`
`Related U.S. Application Data
`
`(63)
`
`(60)
`
`Continuation-in-part of application No. 09/457,434, filed on
`Dec. 7, 1999.
`Provisional application No. 60/111,346, filed on Dec. 8,
`1998.
`Int. Cl.7 .................................................. ClOL 1/08
`(51)
`(52) U.S. Cl. .............................. 44/300; 208/15; 585/14
`
`(58) Field of Search ............................. 44/300; 208/15;
`585/14
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`5,389,111 A * 2/1995 Nikanjam et al.
`5,389,112 A * 2/1995 Nikanjam et al.
`5,792,339 A * 8/1998 Russell
`5,976,201 A * 11/1999 Barry et al.
`6,004,361 A * 12/1999 Barry et al.
`6,150,575 A * 11/2000 Angevine et al.
`
`* cited by examiner
`
`Primary Examiner-Jerry D. Johnson
`(74) Attorney, Agent, or Firm-Gerard J. Hughes; Jeremy J.
`Kliebert
`
`(57)
`
`ABSTRACT
`
`A distillate fuel composition boiling in the range of about
`190° C. to 400° C. with a TlO point greater than 205° C., and
`having a sulfur level of less than about 100 wppm, a total
`aromatics content of about 15 to 35 wt. %, a polynuclear
`aromatics content of less than about 3 wt. %, wherein the
`ratio of total aromatics to polynuclear aromatics is greater
`than about 11.
`
`23 Claims, 2 Drawing Sheets
`
`1 of 13
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`REFINED TECHNOLOGIES, INC.
`EXHIBIT 2002
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`

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`U.S. Patent
`
`May 17, 2005
`
`Sheet 1 of 2
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`US 6,893,475 Bl
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`FIGURE 1
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`::,;_
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`J
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`U.S. Patent
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`May 17, 2005
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`Sheet 2 of 2
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`US 6,893,475 Bl
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`FIGURE 2
`
`100
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`90
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`80
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`70
`
`-
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`-
`
`• Examples 1-5
`
`o Comparative
`Examples A-F
`
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`
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`
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`
`fr
`
`0
`
`.....
`.
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`
`E
`C.
`C.
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`
`60
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`50
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`40
`
`30
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`20
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`10
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`0
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`0
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`A
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`- - -
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`0
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`2
`
`10
`14
`16
`12
`8
`4
`6
`Total Aromatics (wto/o) / Polynuclear Aromatics (wt%)
`
`18
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`20
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`US 6,893,475 Bl
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`1
`LOW SULFUR DISTILLATE FUELS
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`This is a Continuation-in-Part of U.S. Ser. No. 09/457,434
`filed Dec. 7, 1999, which claims priority from U.S. Provi(cid:173)
`sional Patent Application No. 60/111,346, filed Dec. 8, 1998.
`
`FIELD OF THE INVENTION
`
`10
`
`2
`ASTM D2887 providing the temperature at which 10% of
`the fuel was recovered (TlO) and the temperature at which
`95% of the fuel was recovered (T95).
`Hydrodesulfurization processes that reduce PNAs typi-
`5 cally reduce monocyclic aromatics as well as resulting in
`higher than desired hydrogen consumption. Legislation
`requiring reduced sulfur content is also anticipated. For
`example, proposed sulfur limits for distillate fuels to be
`marketed in the European Union for the year 2005 is 50
`wppm or less. Further, the maximum allowable total aro-
`matics level for California Air Resources Board (CARE)
`reference diesel and Swedish Class I diesel are 10 and 5 vol.
`%, respectively. Further, the CARE reference fuels allows
`no more than 1.4 vol. % polyaromatics (PNAs). In Europe,
`from the year 2000, a limit of polynuclear aromatic content
`in diesel fuel has been set at 11 % by weight but no limit has
`been set for the total aromatic content (including monocyclic
`aromatics) of the fuel. Consequently, much work is presently
`20 being done in the hydrotreating art because of these pro(cid:173)
`posed regulations.
`Hydrotreating, or in the case of sulfur removal,
`hydrodesulfurization, is well known in the art and typically
`requires treating the petroleum streams with hydrogen in the
`presence of a supported catalyst at hydrotreating conditions.
`The catalyst is usually comprised of a Group VI metal with
`one or more Group VIII metals as promoters on a refractory
`support. Hydrotreating catalysts that are particularly suitable
`for hydrodesulfurization, as well as hydrodenitrogenation,
`generally contain molybdenum or tungsten as the Group VI
`metal on alumina support promoted with cobalt, nickel, iron,
`or a combination thereof as the Group VIII metal. Cobalt
`promoted molybdenum on alumina catalysts are most
`widely used when the limiting specifications are
`hydrodesulfurization, while nickel promoted molybdenum
`on alumina catalysts are the most widely used for
`hydrodenitrogenation, partial aromatic saturation, as well as
`hydrodesulfurization.
`Much work is also being done to develop more active
`catalysts and to improve reaction vessel designs in order to
`meet the demand for more effective hydroprocessing pro(cid:173)
`cesses. Various improved hardware configurations have
`been suggested. One such configuration is a co-current
`design where feedstock flows downwardly through succes(cid:173)
`sive catalyst beds and treat gas, which is typically a
`hydrogen-containing treat gas, also flows downwardly,
`50 co-current with the feedstock. Another configuration is a
`countercurrent design wherein the feedstock flows down(cid:173)
`wardly through successive catalyst beds counter to upflow(cid:173)
`ing treat gas, which is typically a hydrogen-containing
`55 treat-gas. The downstream catalyst beds, relative to the flow
`of feed, can contain high performance, but otherwise more
`sulfur sensitive catalysts because the upflowing treat gas
`carries away heteroatom components, such as H2 S and NH3 ,
`that are deleterious to sulfur and nitrogen sensitive catalysts.
`Other process configurations include the use of multiple
`reaction stages, either in a single reaction vessel, or in
`separate reaction vessels. More sulfur sensitive catalysts can
`be used in the downstream stages as the level of heteroatom
`components becomes successively lower. European Patent
`Application 93200165.4 teaches such a two-stage
`hydrotreating process performed in a single reaction vessel.
`
`The present invention relates to a distillate fuel compo(cid:173)
`sition boiling in the range of about 190° C. to 400° C. with
`a TlO point greater than 205° C., and having a sulfur level
`of less than about 100 wppm, a total aromatics content of 15
`about 15 to 35 wt. %, a polynuclear aromatics content of less
`than about 3 wt. %, wherein the ratio of total aromatics to
`polynuclear aromatics is greater than about 11.
`
`BACKGROUND OF THE INVENTION
`
`Diesel fuels are used widely in automotive transport
`largely due to their high fuel economy. However, one of the
`problems when such fuels are burned in internal combustion
`engines is the pollutants in the exhaust gases that are emitted 25
`into the environment. For instance, some of the most com(cid:173)
`mon pollutants in diesel exhausts are oxides of nitrogen
`(hereafter abbreviated as "NOx"), particulate matter
`(including inter alia soot, adsorbed hydrocarbons and
`sulfates), unburned hydrocarbons, and to a lesser extent 30
`carbon monoxide. Also, sulfur dioxide emissions from die-
`sel fuel exhaust gases are becoming increasingly a problem
`due to their affinity with after-treatment devices designed to
`reduce NOx and particulate emissions, thereby adversely 35
`affecting the functioning efficiency. The oxides of sulfur
`have been reduced considerably by reducing the sulfur
`levels in the diesel itself through refining operations such as
`by hydrodesulfurization. However, further advances are
`required to meet increasingly demanding worldwide legis- 40
`lation for progressively lower diesel powered vehicle
`exhaust emissions, especially NOx and particulate matter.
`An established trade-off exists between the two pollutants,
`i.e. NOx and particulate matter, whereby an increase in one 45
`leads to a decrease in the other, for a given engine and
`operating conditions.
`A typical example of such a scenario is U.S. Pat. No.
`5,792,339 in which a diesel oil composition comprising
`250---495 wppm sulfur, 5-8.6 wt. % of polynuclear aromatics
`(PNAs) and 10-23.9 wt. % total aromatics is disclosed. At
`the same time, further advances in sulfur-sensitive after(cid:173)
`treatment technology have led to increasing demand for
`lower levels of sulfur in diesel fuels.
`There are a variety of analytical techniques that have been
`reported for measurement of total aromatics and polynuclear
`aromatics. In the discussion and claims that follow, aromat-
`ics and PNAs are measured by high performance liquid
`chromatography (HPLC) as defined by test number IP 60
`391/95, unless otherwise indicated. IP391/95 is described in
`"IP Standard Methods for Analysis and Testing of Petroleum
`& Related Products, and British Standard 2000 Parts, 58th
`edition, February, 1999. This publication is incorporated 65
`herein by reference. Boiling range distillation determina(cid:173)
`tions were performed via gas chromatography according to
`
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`3
`Distillate fuel compositions are taught that meet some of
`the low emissions requirements. For example, U.S. Pat. No.
`5,389,111 teaches a diesel fuel composition having an aro(cid:173)
`matics content in the range from about 13 to 20 wt. %, a
`cetane number from about 54 to 60, which cetane number
`and aromatics content being within a certain area defined in
`FIG. 1 of that patent. U.S. Pat. No. 5,389,112 teaches a low
`emissions diesel fuel composition having an aromatics con(cid:173)
`tent in the range of about 14.3 to 19.7 wt. %, a cetane 10
`number from about 53.4 to 60.8, which cetane number and
`aromatics content falls within a certain area ofFIG. l of their
`patent.
`While distillate fuel compositions exist that produce
`lower levels of emissions than years past, there is still a need
`in the art for fuels with ever lower emissions levels that are
`needed to meet the ever stricter environmental regulations.
`It has now been found that by controlling the amount of
`sulfur, PNAs and total aromatics in the diesel fuel within
`specific limits, the amount of NOx and particulates emitted
`from exhausts can be synergistically reduced.
`
`20
`
`SUMMARY OF THE INVENTION
`In accordance with the present invention there is provided 25
`a distillate fuel composition boiling in the range of about
`190° C. to 400° C. with a TlO point greater than 205° C., and
`having a sulfur level of less than about 100 wppm, a total
`aromatics content of about 15 to 35 wt. %, a polynuclear
`aromatics content of less than about 3 wt. %, wherein the
`ratio of total aromatics to polynuclear aromatics is greater
`than about 11.
`In a preferred embodiment of the present invention the
`sulfur level is less than about 50 wppm.
`In another preferred embodiment of the present invention
`the total aromatics content is from about 20 to 35 wt. %.
`In still another preferred embodiment of the present
`invention the ratio of total aromatics to polynuclear aromat- 40
`ics is at least 15.
`In yet another embodiment, the invention is a fuel com-
`position comprising
`a distillate boiling in the range of about 190° C. to 400° 45
`C. with a TlO point greater than 205° C., and having a
`sulfur level of less than about 100 wppm, a total
`aromatics content of about 15 to 35 wt. %, a poly(cid:173)
`nuclear aromatics content of less than about 3 wt. %,
`wherein the ratio of total aromatics to polynuclear 50
`aromatics is greater than about 11, to which is added at
`least one of (i) one or more lubricity aid, (ii) one or
`more viscosity modifier, (iii) one or more antioxidant,
`(iv) one or more cetane improver, (v) one or more
`dispersant, (vi) one or more cold flow improver, (vii) 55
`one or more metals deactivator, (viii) one or more
`corrosion inhibitor, (ix) one or more detergent, and (x)
`one or more distillate or upgraded distillate.
`In still another preferred embodiment, the fuel is
`employed in a compression ignition (e.g. diesel) engine, 60
`preferably in order to abate NOx and particulate emissions
`therefrom. More preferably, the fuel is employed in an
`automotive diesel engine.
`
`BRIEF DESCRIPTION OF THE FIGURE
`FIG. 1 hereof shows one preferred process scheme used
`to prepare distillate fuel compositions of present invention.
`
`US 6,893,475 Bl
`
`4
`This process scheme includes two co-current hydrodesulfu(cid:173)
`rization stages with once through hydrogen-containing treat
`gas in the second hydrodesulfurization stage.
`FIG. 2 hereof shows a plot that defines the composition of
`distillate products of the present invention where the sulfur
`content is less than 100 ppm and the ratio of total aromatics
`to polynuclear aromatics is greater than about 11.
`
`5
`
`30
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`Feedstreams suitable for producing the low emissions
`distillate fuel compositions of this invention are those petro(cid:173)
`leum based feedstreams boiling in the distillate range and
`15 above. Such feedstreams typically have a boiling range from
`about 190 to about 400° C., preferably from about 200 to
`about 370° C. These feedstreams typically contain greater
`than about 3,000 wppm sulfur. Non-limiting examples of
`such feedstreams include virgin distillates, light cat cycle
`oils, light coker oils, etc. It is highly desirable for the refiner
`to upgrade these types of feedstreams by removing as much
`of the sulfur as possible, as well as to saturate aromatic
`compounds.
`It is not critical how the distillate fuel compositions are
`produced. One preferred process for producing the fuel
`products of the present invention is illustrated in FIG. 1
`hereof. The preferred process uses once-through hydrogen
`treat gas in a second hydrodesulfurization stage and option(cid:173)
`ally in a first hydrodesulfurization stage as well. Relatively
`low amounts of hydrogen are utilized in the second
`hydrodesulfurization stage in such a way that very low
`levels of sulfur in the liquid product can be achieved while
`35 minimizing the amount of hydrogen consumed via satura(cid:173)
`tion of the aromatics. The first hydrodesulfurization stage
`will reduce the levels of both sulfur and nitrogen, with sulfur
`levels being less than about 1,000 wppm, preferably less
`than about 500 wppm. The second hydrodesulfurization
`stage will reduce sulfur levels to less than about 100 wppm,
`preferably to less than about 50 wppm. In the practice of this
`invention the hydrogen in the treat gas reacts with impurities
`to convert them to H2S, NH3 , and water vapor, which are
`removed as part of the vapor effluent, and it also saturates
`olefins and aromatics.
`Miscellaneous reaction vessel internals, valves, pumps,
`thermocouples, and heat transfer devices etc. are not shown
`for simplicity. FIG. 1 shows hydrodesulfurization reaction
`vessel Rl which contains reaction zones 12a and 12b, each
`of which is comprised of a bed of hydrodesulfurization
`catalyst. It will be understood that this reaction stage can
`contain only one reaction zone or two or more reaction
`zones. It is preferred that the catalyst be in the reactor as a
`fixed bed, although other types of catalyst arrangements can
`be used, such as slurry or ebullating beds. Downstream of
`each reaction zone is a non-reaction zone, 14a and 14b. The
`non-reaction zone is typically void of catalyst, that is, it will
`be an empty section in the vessel with respect to catalyst.
`Although not shown, there may also be provided a liquid
`distribution means upstream of each reaction stage or cata(cid:173)
`lyst bed. The type of liquid distribution means is believed
`65 not to limit the practice of the present invention, but a tray
`arrangement is preferred, such as sieve trays, bubble cap
`trays, or trays with spray nozzles, chimneys, tubes, etc. A
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`5
`vapor-liquid m1xmg device (not shown) can also be
`employed in non-reaction zone 14a for the purpose of
`introducing a quench fluid (liquid or vapor) for temperature
`control.
`The feedstream is fed to reaction vessel Rl via line 10 5
`along with a hydrogen-containing treat gas via line 18,
`which treat gas will typically be from another refinery
`process unit, such as a naphtha hydrofiner. It is within the
`scope of this invention that treat gas can also be recycled via
`lines 20, 22, and 16 from separation zone Sl. The term
`"recycled" when used herein regarding hydrogen treat gas is
`meant to indicate a stream of hydrogen-containing treat gas
`separated as a vapor effluent from one stage that passes
`through a gas compressor 23 to increase its pressure prior to
`being sent to the inlet of a reaction stage. It should be noted
`that the compressor will also generally include a scrubber to
`remove undesirable species such as H2S from the hydrogen
`recycle stream. The feedstock and hydrogen-containing treat
`gas pass, co-currently, through the one or more reaction
`zones of hydrodesulfurization stage Rl to remove a sub(cid:173)
`stantial amount of the heteroatoms, preferably sulfur, from
`the feedstream. It is preferred that the first hydrodesulfur-
`ization stage contain a catalyst comprised of Co-Mo, or 25
`Ni-Mo on a refractory support.
`The term "hydrodesulfurization" as used herein refers to
`processes wherein a hydrogen-containing treat gas is used in
`the presence of a suitable catalyst which is primarily active
`for the removal of heteroatoms, preferably sulfur, and
`nitrogen, and for some hydrogenation of aromatics. Suitable
`hydrodesulfurization catalysts for use in the reaction vessel
`Rl of the present invention include conventional hydrodes(cid:173)
`ulfurization catalyst such as those that are comprised of at
`least one Group VIII metal, preferably Fe, Co or Ni, more
`preferably Co and/or Ni, and most preferably Co; and at
`least one Group VI metal, preferably Mo or W, more
`preferably Mo, on a relatively high surface area refractory
`support material, preferably alumina. Other suitable
`hydrodesulfurization catalyst supports include refractory
`oxides such as silica, zeolites, amorphous silica-alumina,
`and titania-alumina. Additives such as P can also be present.
`It is within the scope of the present invention that more than 45
`one type of hydrodesulfurization catalyst be used in the
`same reaction vessel and in the same reaction zone. The
`Group VIII metal is typically present in an amount ranging
`from about 2 to 20 wt. %, preferably from about 4 to 15%.
`The Group VI metal will typically be present in an amount 50
`ranging from about 5 to 50 wt. %, preferably from about 10
`to 40 wt. %, and more preferably from about 20 to 30 wt. %.
`All metals weight percents are based on the weight of the
`catalyst. Typical hydrodesulfurization temperatures range 55
`from about 200° C. to about 400° C. with a total pressures
`of about 50 psig to about 3,000 psig, preferably from about
`100 psig to about 2,500 psig, and more preferably from
`about 150 to 500 psig. More preferred hydrogen partial
`pressures will be from about 50 to 2,000 psig, most prefer- 60
`ably from about 75 to 800 psig.
`A combined liquid phase/vapor phase product stream
`exits hydrodesulfurization stage Rl via line 24 and passes to
`separation zone Sl wherein a liquid phase product stream is
`separated from a vapor phase product stream. The liquid
`phase product stream will typically be one that has compo-
`
`6
`nents boiling in the range from about 190° C. to about 400°
`C., but will not have an upper boiling range greater than the
`feedstream. The vapor phase product stream is collected
`overhead via line 20. The liquid reaction product from
`separation zone Sl is passed to hydrodesulfurization stage
`R2 via line 26 and is passed downwardly through the
`reaction zones 28a and 28b. Non-reaction zones are repre(cid:173)
`sented by 29a and 29b.
`Hydrogen-containing treat gas is introduced into reaction
`stage R2 via line 30 which may be cascaded or otherwise
`obtained from a refinery process unit such as a naphtha
`hydrofiner. Although this figure shows the treat gas flowing
`co-current with the liquid feedstream, it is also within the
`15 scope of this invention that the treat gas can be introduced
`into the bottom section of reactor R2 and flowed counter-
`current to the downward flowing liquid feedstream. It is
`preferred that the rate of introduction of hydrogen contained
`in the treat gas be less than or equal to 3 times the chemical
`hydrogen consumption of this stage, more preferably less
`than about 2 times, and most preferably less than about 1.5
`times. The feedstream and hydrogen-containing treat gas
`pass, preferably cocurrently, through the one or more reac(cid:173)
`tion zones of hydrodesulfurization stage R2 to remove a
`substantial amount of remaining sulfur, preferably to a level
`wherein the feedstream now has less than about 100 wppm
`sulfur, preferably less than about 50 wppm sulfur, and more
`preferably less than 10 wppm sulfur. Suitable hydrodesulfu-
`rization catalysts for use in the reaction vessel R2 in the
`present invention include conventional hydrodesulfurization
`catalyst, such as those previously described for use in Rl.
`Noble metal catalysts may also be employed, preferably the
`35 noble metal is selected from Pt and Pd or a combination
`thereof. Pt, Pd or the combination thereof is typically present
`in an amount ranging from about 0.5 to 5 wt. %, preferably
`from about 0.6 to 1 wt. %. Typical hydrodesulfurization
`temperatures range from about 200° C. to about 400° C. with
`a total pressures of about 50 psig to about 3,000 psig,
`preferably from about 100 psig to about 2,500 psig, and
`more preferably from about 150 to 1,500 psig. More pre(cid:173)
`ferred hydrogen partial pressures will be from about 50 to
`2,000 psig, most preferably from about 75 to 1,000 psig. In
`one embodiment, R2 outlet pressure ranges from about 500
`to about 1000 psig.
`It is within the scope of this invention that second reaction
`stage R2 can be run in two or more temperature zones and
`in either cocurrent or countercurrent mode. By two or more
`temperature zones we mean that reaction stage R2 will
`contain two or more separate beds of catalyst wherein at
`least one such bed is operated at a temperature of at least 25°
`C. lower than the other catalyst beds comprising the reaction
`stage. It is preferred that the lower temperature zone(s) be
`operated at a temperature of at least about 50° C. lower than
`the higher temperature zone(s). It is also preferred that the
`lower temperature zone be the last downstream zone(s) with
`respect to the flow of feedstock. It is also within the scope
`of this invention that the second reaction stage be operated
`in either co-current or countercurrent mode. By countercur(cid:173)
`rent mode we mean that the treat gas will flow upwardly,
`65 counter to the downflowing feedstock.
`The reaction product from second hydrodesulfurization
`stage R2 is passed via line 35 to a second separation zone S2
`
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`US 6,893,475 Bl
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`10
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`20
`
`7
`wherein a vapor product, containing hydrogen, is preferably
`recovered overhead via line 32 and may be removed from
`the process via line 36. When either (i) all hydrogen(cid:173)
`containing treat gas introduced into a reactor is consumed
`therein or (ii) unreacted hydrogen-containing treat gas 5
`present in a reactor's vapor phase effluent and is conducted
`away from the reactor, then the treat gas is referred to as a
`"once-through" treat gas. Alternatively, all or a portion of the
`vapor product may be cascaded to hydrodesulfurization
`stage Rl via lines 34 and 16. The term "cascaded", when
`used in conjunction with treat gas is meant to indicate a
`stream of hydrogen-containing treat gas separated as a vapor
`effluent from one stage that is sent to the inlet of a reaction
`stage without passing through a gas compressor. That is, the 1s
`treat gas flows from a downstream reaction stage to an
`upstream stage that is at the same or lower pressure, and thus
`there is no need for the gas to be compressed.
`FIG. 1 also shows several optional process schemes. For
`example, line 38 can carry a quench fluid that may be either
`a liquid or a gas. Hydrogen is a preferred gas quench fluid
`and kerosene is a preferred liquid quench fluid.
`The reaction stages used in the practice of the present
`invention are operated at suitable temperatures and pressures
`for the desired reaction. For example, typical hydroprocess(cid:173)
`ing temperatures will range from about 200° C. to about
`400° C. at pressures from about 50 psig to about 3,000 psig,
`preferably 50 to 2,500 psig, and more preferably about 150
`to 1,500 psig. Furthermore, reaction stage R2 can be oper(cid:173)
`ated in two or more temperature zones wherein the most
`downstream temperature zone is at least about 25° C.,
`preferably about 35° C., cooler than the upstream tempera(cid:173)
`ture zone(s).
`For purposes of hydroprocessing and in the context of the
`present invention, the terms "hydrogen" and "hydrogen(cid:173)
`containing treat gas" are synonymous and may be either
`pure hydrogen or a hydrogen-containing treat gas which is
`a treat gas stream containing hydrogen in an amount at least
`sufficient for the intended reaction, plus other gas or gasses
`(e.g., nitrogen and light hydrocarbons such as methane)
`which will not adversely interfere with or affect either the
`reactions or the products. Impurities, such as H2 S and NH3
`are undesirable and, if present in significant amounts, will
`normally be removed from the treat gas, before it is fed into
`the Rl reactor. The treat gas stream introduced into a
`reaction stage will preferably contain at least about 50 vol.
`% hydrogen, more preferably at least about 75 vol. %
`hydrogen, and most preferably at least 95 vol. % hydrogen.
`In operations in which unreacted hydrogen in the vapor
`effluent of any particular stage is used for hydroprocessing
`in any stage, there must be sufficient hydrogen present in the
`fresh treat gas introduced into that stage, for the vapor
`effluent of that stage to contain sufficient hydrogen for the
`subsequent stage or stages. It is preferred in the practice of
`the invention, that all or a portion of the hydrogen required
`for the first stage hydroprocessing be contained in the
`second stage vapor effluent fed up into the first stage. The
`first stage vapor effluent will be cooled to condense and
`recover the hydrotreated and relatively clean, heavier ( e.g.,
`C4+) hydrocarbons.
`The liquid phase in the reaction vessels used in the present
`invention will typically be comprised of primarily the higher
`
`8
`boiling point components of the feed. The vapor phase will
`typically be a mixture of hydrogen-containing treat gas,
`heteroatom impurities like H2 S and NH3 , and vaporized
`lower-boiling components in the fresh feed, as well as light
`products of hydroprocessing reactions. If the vapor phase
`effluent still requires further hydroprocessing, it can be
`passed to a vapor phase reaction stage containing additional
`hydroprocessing catalyst and subjected to suitable hydro(cid:173)
`processing conditions for further reaction. Alternatively, the
`hydrocarbons in the vapor phase products can be condensed
`via cooling of the vapors, with the resulting condensate
`liquid being recycled to either of the reaction stages, if
`necessary.
`As discussed, the preferred process may be used to form
`the fuel products of the invention. Such distillate fuel
`products are characterized as having relatively low sulfur
`and polynuclear aromatics (PNAs) levels and a relatively
`high ratio of total aromatics to polynuclear aromatics. Such
`distillate fuels may be employed in compression-ignition
`engines such as diesel engines, particularly so-call "lean(cid:173)
`burn" diesel engines. Such fuels are compatible with:
`compression-ignition engine systems such as automotive
`25 diesel systems utilizing (i) sulfur-sensitive NOx conversion
`exhaust catalysts, (ii) engine-exhaust particulate emission
`reduction technology, including particulate traps, and (iii)
`combinations of (i) and (ii). Such distillate fuels have
`moderate levels of total aromatics, reducing the cost of
`30 producing cleaner-burning diesel fuel and also reducing CO 2
`emissions by minimizing the amount of hydrogen consumed
`in the process.
`The preferred fuels may be combined with other distillate
`35 or upgraded distillate. As discussed, the products are com(cid:173)
`patible with effective amounts of fuel additives such as
`lubricity aids, cetane improvers, and the like. While a major
`amount of the product is preferably combined with a minor
`amount of the additive, the fuel additive may be employed
`40 to an extent not impairing the performance of the fuel. While
`the specific amount(s) of any additive employed will vary
`depending on the use of the product, the amounts may
`generally range from 0.05 to 2.0 wt % based on the weight
`45 of the product and additive(s), although not limited to this
`range. The additives can be used either singly or in combi(cid:173)
`nation as desired.
`In one embodiment, the distillate compositions of the
`present invention contain less than about 100 wppm, pref-
`erably less than about 50 wppm, more preferably less than
`about 10 wppm sulfur. They will also have a total aromatics
`content from about 15 to 35 wt. %, preferably from about 20
`to 35 wt. %, and most preferably from about 25 to 35 wt. %.
`ss The PNA content of the distillate product compositions
`obtained by the practice of the present invention will be less
`than about 3 wt. %, preferably less than about 2 wt. %, and
`more preferably less than about 1 wt. %. The aromatics to
`PNAratio will be at least about 11, preferably at least about
`60 13, and more preferably at least about 15. Further, the
`distillate fuels of the present invention have relatively low
`amounts of low boiling material with a TlO distillation point
`of at least about 205° C. In one embodiment, the aromatics
`65 to PNA ratio will be at least about 11, preferably at least
`about 13, and more preferably at least about 15. In another
`embodiment, the aromatics to PNA ratio ranges from 11 to
`
`so
`
`7 of 13
`
`REFINED TECHNOLOGIES, INC.
`EXHIBIT 2002
`
`

`

`US 6,893,475 Bl
`
`9
`about 50, preferably from 11 to about 30, and more prefer(cid:173)
`ably from 11 to about 20.
`The term PNA is meant to refer to polynuclear aromatics
`that are defined as aromatic species having two or more
`aromatic rings, including alkyl and olefin-substituted deriva(cid:173)
`tives thereof. Naphthalene and phenanthrene are examples
`of PNAs. The term aromatics is meant to refer species
`containing one or more aromatic ring, including alkyl and
`olefin-substituted derivatives thereof. Thus, naphthalene and
`phenanthrene are also considered aromatics along with
`benzene, toluene and tetrahydronaphthalene. It is desirable
`to reduce PNA content of the liquid product stream since
`PNAs contribute significantly to emissions in diesel engines.
`However, it is also desirable to minimize hydrogen con(cid:173)
`sumption for economic reasons and to minimize CO 2 emis(cid:173)
`sions associated with the manufacture of hydrogen via steam
`reforming. Thus, the current invention achieves both of
`these by obtaining a high aromatics to PNA ratio in the
`liquid product.
`The following examples are presented to illustrate the
`present invention and not to be taken as limiting the scope
`of the invention in any way.
`
`EXAMPLES 1-5
`
`A virgin distillate feed containing from about 10,000 to
`12,000 wppm sulfur was processed in a commercial
`hydrodesulfurization unit (first hydrodesulfurization stage)
`using a reactor containing both conventional commercial
`NiMo/Al2 0 3 (Akzo-Nobel KF842/840) and CoMo/Al2 0 3
`(Akzo-Nobel KF-752) catalyst under the following typical
`conditions: 300---350 psig; 150-180 psig outlet H 2 ; 75% H 2
`treat gas; 500-700 SCF/B treat gas rate; 0.3-0.45 LHSV;
`330-350 C. The liquid product stream from this first
`hydrodesulfurization stage was used as feedstream to the
`second hydrodesulfurization stage, which product stream is
`described under the feed properties heading in Tab