EP0931123A1 - Procede d'alkylation pour desulfurer l'essence - Google Patents

Procede d'alkylation pour desulfurer l'essence

Info

Publication number
EP0931123A1
EP0931123A1 EP96933971A EP96933971A EP0931123A1 EP 0931123 A1 EP0931123 A1 EP 0931123A1 EP 96933971 A EP96933971 A EP 96933971A EP 96933971 A EP96933971 A EP 96933971A EP 0931123 A1 EP0931123 A1 EP 0931123A1
Authority
EP
European Patent Office
Prior art keywords
naphtha
process according
sulfur
boiling range
range
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96933971A
Other languages
German (de)
English (en)
Inventor
Nick Allen Collins
Jeffrey C. Trewella
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Oil Corp
Original Assignee
Mobil Oil Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mobil Oil Corp filed Critical Mobil Oil Corp
Priority claimed from PCT/US1996/015689 external-priority patent/WO1998014535A1/fr
Publication of EP0931123A1 publication Critical patent/EP0931123A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G31/00—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G29/00—Refining of hydrocarbon oils, in the absence of hydrogen, with other chemicals
    • C10G29/20—Organic compounds not containing metal atoms
    • C10G29/205—Organic compounds not containing metal atoms by reaction with hydrocarbons added to the hydrocarbon oil
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G29/00—Refining of hydrocarbon oils, in the absence of hydrogen, with other chemicals
    • C10G29/20—Organic compounds not containing metal atoms

Definitions

  • This invention relates to a process for the upgrading of hydrocarbon streams.
  • the invention more particularly relates to a process for upgrading gasoline boiling range petroleum fractions containing olefins and substantial proportions of sulfur impurities.
  • Heavy petroleum fractions such as vacuum gas oil, or even resids such as atmospheric resid, may be catalytically cracked to lighter and more valuable products, especially gasoline.
  • the product of catalytic cracking is conventionally recovered and the products fractionated into various fractions such as light gases; naphtha, including light and heavy gasoline; distillate fractions, such as heating oil and Diesel fuel; lube oil base fractions; and heavier fractions.
  • Sulfur in various forms is commonly found in petroleum and petroleum products either as dissolved free sulfur, hydrogen sulfide, or as organic compounds, such as thiophenes, sulfonic acids, mercaptans, alkylsulfates, and alkyl sulfides.
  • the products of catalytic cracking usually contain sulfur impurities which normally require removal, usually by hydrotreating, in order to comply with the relevant product specifications.
  • hydrotreating can be done either before or after catalytic cracking. Because naphtha streams from both catalytic, e.g., FCC, and thermal, e.g., coking, cracking processes contribute most of the sulfur present in the gasoline pool, reducing the sulfur content of cracked naphthas will be important in order to meet liquid transportation sulfur specifications and emission standards.
  • cracked naphtha as it comes from the catalytic cracker and without any further treatments such as purifying operations, has a relatively high octane number as a result of the presence of olefinic components. It also has an excellent volumetric yield. As such, cracked gasoline is an excellent contributor to the gasoline pool. It contributes a large quantity of product at a high blending octane number. In some cases, this fraction may contribute as much as up to half the gasoline in the refinery pool. Therefore, it is one of the most desirable components of the gasoline pool.
  • pyrolysis gasoline This is a fraction which is often produced as a by-product in the cracking of petroleum fractions to produce light unsaturates, such as ethylene and propylene.
  • Pyrolysis gasoline may have a very high octane number but is quite unstable in the absence of hydrotreating because, in addition to the desirable olefins boiling in the gasoline boiling range, it also contains a substantial proportion of diolefins, which tend to form gums upon storage or standing. Cracking of naphtha is a highly useful process to increase the yield of gasoline.
  • the cracking process also effects sulfur containing materials and results in a reduction in their molecular weight from a range that is greater than the average molecular weight of the gasoline boiling range fraction into a range that is within the molecular weight range of the gasoline fraction.
  • Much of this gasoline boiling range sulfur is contained in aromatic compounds and, consequently, needs to removed by hydrotreating.
  • hydrotreating of any of the sulfur containing cracked fractions which boil in the gasoline boiling range e.g., FCC, pyrolysis and coker naphtha, causes a reduction in the olefin content, and consequently a reduction in the octane number.
  • the degree of desulfurization increases, the octane number of the normally liquid gasoline boiling range product decreases.
  • An objective of the present invention is to provide a process for reducing the sulfur level in naphtha streams especially the sulfur in naphtha attributable to thiophene or thiophenic compounds, while minimizing product losses in volume and octane number.
  • Sulfur species present in cracked naphthas may be converted and removed by first passing the naphtha over an acid catalyst to alkylate the thiophenic compounds in the naphtha using the indigenous olefins and diolefins present in the naphtha as alkylating agent.
  • alkylation reactions provide alkylated thiophenes that concentrate the sulfur species in the heavy portion of the naphtha, greatly reducing the amount of naphtha that needs to be hydrodesulfurized.
  • the invention comprises a process for upgrading a sulfur-containing feedstream comprising olefinic gasoline boiling range hydrocarbons rich in thiophenic sulfur compounds.
  • the process is carried out by contacting the feedstream with acidic alkylation catalyst particles under alkylation conditions in an alkylation zone to provide an effluent stream comprising hydrocarbons containing alkylated thiophenic sulfur compounds.
  • the alkylated thiophenic compounds are separated from the effluent stream by fractional distillation to provide a heavy naphtha of higher boiling point rich in alkylated thiophenic compounds and a light naphtha portion.
  • the light naphtha portion is recovered to provide gasoline boiling range hydrocarbons containing a reduced amount of thiophe- nic sulfur compounds.
  • the heavy naphtha portion may be desulfurized using conventional hydrotreating or other desulfurization processes.
  • a process according to the invention specifically achieves the intended benefit of a lowering of the sulfur content of the naphtha feedstream, there are corollary benefits. It is to be expected that A process according to the invention will also lower the amount of aromatic nitrogen compounds in the naphtha as well as the amount of diolefins.
  • the Figure is a schematic drawing of one embodiment of a process according to the invention.
  • the feed to the process comprises a sulfur-containing petroleum fraction, generally olefinic, which boils in the gasoline boiling range.
  • Feeds of this type include olefinic light naphthas typically having a boiling range of about C 6 to 165 °C, full range naphthas typically having a boiling range of about C 5 to 215 °C, heavier naphtha fractions boiling in the range of about 127 ° to 210EC, or heavy gasoline fractions boiling at, or at least within, the range of about 165E to 260°, preferably about 165E to 210EC.
  • the preferred feed is a light naphtha or full range naphtha .
  • the feedstream to the process preferably comprises a sulfur-containing olefinic petroleum fraction which boils in the gasoline boiling range in which indigenous olefins are used to carry out the alkylation reaction
  • an additional or cofeed olefin feedstream to the process to provide or supplement alkylating agents for the process.
  • This optional variation of the process could be elected depending on conditions extant in the refinery, including an abundant supply of light olefins or a sulfur-rich gasoline boiling range stream that is not sufficiently rich in indigenous olefins.
  • the process may be operated with the entire gasoline fraction obtained from the catalytic cracking step or, alternatively, with part of it.
  • the cut point between the treated and untreated fractions may vary according to the sulfur compounds present but usually, a cut point in the range of from about 100°F (38°C) to about 300°F (150°C), more usually in the range of about 200°F(93°C) to about 300°F(150°C) will be suitable.
  • the exact cut point selected will depend on the sulfur specification for the gasoline product as well as on the type of sulfur compounds present: lower cut points will typically be necessary for lower product sulfur specifications.
  • Sulfur which is present in components boiling below about 150°F(65°C) is mostly in the form of mercaptans which may be removed by extractive type processes such as Merox. Removal of thiophenic compounds and present in higher boiling components, e.g., component fractions boiling above about 180°F(82°C) , is carried out according to a process according to the instant invention.
  • the sulfur content of these catalytically cracked fractions will depend on the sulfur content of the feed to the cracker as well as on the boiling range of the selected fraction used as the feed in the process. Lighter fractions, for example, will tend to have lower sulfur contents than the higher boiling fractions. As a practical matter, the sulfur content will exceed 50 ppmw and usually will be in excess of 100 ppmw, and in most cases in excess of about 500 ppmw. For the fractions which have 95 percent points over about 380 °F (193 °C) , the sulfur content may exceed about 1,000 ppmw and may be as high as 4,000 or 5,000 ppmw or even higher.
  • the nitrogen content of cracked naphtha is not as characteristic of the feed as is the sulfur content and is preferably not greater than about 20 ppmw although higher nitrogen levels typically up to about 50 ppmw may be found in certain higher boiling feeds with 95 percent points in excess of about 380 °F (193 °C) .
  • the nitrogen level will, however, usually not be greater than 250 or 300 ppmw.
  • the feed to A process according to the invention will be olefinic, with an olefin content of at least 3 and more typically in the range of 10 to 20, e.g. 15 - 20, weight percent.
  • Lewis acids include those derived from A1C1 3 , FeCl 3 , SbCl 3 , BF 3 , ZnCl 2 , TiCl 4 and P 2 0 5 ; but particularly, Lewis acids such as AlCl 3 /silica, AlCl 2 /silica, BF 3 /silica, Co/Mo/alumina, Mo/- alu ina, MoS 2 are useful for A process according to the invention.
  • Typical Bronsted acids include HF, H 2 S0 4 , metallosilicates, silica-alumina, sulfonic acid resins, and the like.
  • Well-known methods of maintaining or recovering catalyst activity such as promoter cofeed or hydrogenative or oxidative regeneration, may also be employed.
  • the useful catalysts include the crystalline aluminosilicate zeolites especially the medim pore size zeolites having a silica: alumina ratio of at least 12, and constraint index of about 1 to 12.
  • these zeolites are ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, MCM-22, MCM-36, MCM-49, MCM-49 and ZSM-48.
  • the larger pore size zeolites may also be used as catalysts in the present process, i.e., those zeolites having a Constraint Index of no greater than about 2.
  • Representative of these zeolites are zeolite Beta, TEA mordenite, faujasites, USY and ZSM- 12.
  • One group of preferred catalysts for use in the present invention are the members of the MCM-22 group which includes MCM-22, MCM-36, MCM-49 and MCM-56.
  • MCM-22 is described in U. S. patent 4,954,325.
  • MCM-36 is described in U. S. patent 5,250,277 and MCM-36 (bound) is described in U. S. patent 5,292,698.
  • MCM-49 is described in U. S. patent 5,236,575 and MCM-56 is described in U. S. patent 5,362,697.
  • a process according to the invention reduces the sulfur level in naphtha streams while minimizing volume and octane loss.
  • Olefins either present in cracked naphthas or fed to virgin naphtha, are used to convert sulfur species to higher molecular weight compounds thereby concentrating the sulfur in the "back-end" of the naphtha.
  • this redistribution of the sulfur in the naphtha leads to a relatively sulfur-free light naphtha and a sulfur-rich heavy naphtha which may be desulfurized via conventional hydrotreating.
  • Conversion of the sulfur in the heavy fraction of naphtha reduces the amount of naphtha that must be hydrodesulfurized which, in the case of cracked naphthas, leads to lower hydrogen consumption and greater octane-barrels.
  • the conversion carried out in the process is one of alkylation of aromatic heterocyclic sulfur compounds, i.e., thiophene and related thiophenic compounds, in contact with acidic alkylation catalyst.
  • the process is carried out on a cracked naphtha feedsteam at temperatures between 100°F (38°C) and 700°F (371°C) and pressure between atmospheric or autogenous pressure and 7000 kPa.
  • the preferred temperature is 300-400°F (149-204°C).
  • reactor configurations can be employed to carry out the alkylation step of A process according to the invention. These include a down-flow, liquid phase, fixed bed process; an up-flow, fixed bed, trickle phase process; an ebulating, fluidized bed process; or a transport, fluidized bed process.
  • the fixed bed arrangements are preferred for simplicity of operation.
  • a preferred implementation of the proposed concept is shown schematically in the Figure.
  • Cracked naphtha (1) possibly prefractionated (2) to obtain a light fraction (3) , is fed to a condensation or alkylation reactor (4) containing acid catalyst where naphtha-range olefins alkylate sulfur species producing heavier sulfur compounds.
  • the reactor effluent (5) is distilled (6) to obtain low- sulfur light naphtha (7) and a heavy naphtha (8) enriched in sulfur.
  • This high-sulfur heavy naphtha may be combined with heavy naphtha (9) from the prefractionator and hydrodesulfurized in reactor (10) using conventional hydrotreating processes or alternatively sent to the distillate pool.
  • the low-sulfur light naphtha (7) may be optionally etherified (11) in etherification reactor (13) or optionally recycled (12) to the sulfur conversion reactor depending on overall desulfurization targets.
  • the naphtha splitter may also have utility in meeting T 90 distillation targets.
  • Feedstocks included both light (C 5 -100°C, 230 ppmw S) and full-range (C 5 + , 0.14 wt%S) FCC naphthas. These batch runs were conducted at 350 °F (177C) for three hours at autogenous pressure with loadings of 10 grams of light naphtha per gram of catalyst and 11.6 grams of full-range naphtha per grams of catalyst. Results for the light FCC are shown in Table 1 and for the full-range FCC in Table 2.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

On convertit et élimine les espèces soufrées présentes dans le naphta de craquage (1) en faisant d'abord passer le naphta (1) sur un catalyseur acide dans un réacteur d'alkylation (4), de façon à alkyler les composés thiophéniques présents dans le naphta en utilisant comme agent alkylant les oléfines, c'est-à-dire les mono-oléfines et les dioléfines, présentes dans le naphta (1). On concentre les thiophènes alkylés dans la partie lourde du naphta (8) par distillation, ce qui réduit la quantité de naphta ayant besoin d'être hydrodésulfurée dans le réacteur 810). On concentre les oléfines du naphta de craquage dans la partie légère du naphta (7), qui n'est pas hydrotraitée ensuite. Ceci permet de minimiser les inconvénients liés à la consommation d'octane et d'hydrogène associée à l'hydrotraitement.
EP96933971A 1996-09-30 1996-09-30 Procede d'alkylation pour desulfurer l'essence Withdrawn EP0931123A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1996/015689 WO1998014535A1 (fr) 1996-09-30 1996-09-30 Procede d'alkylation pour desulfurer l'essence

Publications (1)

Publication Number Publication Date
EP0931123A1 true EP0931123A1 (fr) 1999-07-28

Family

ID=22255887

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96933971A Withdrawn EP0931123A1 (fr) 1996-09-30 1996-09-30 Procede d'alkylation pour desulfurer l'essence

Country Status (4)

Country Link
EP (1) EP0931123A1 (fr)
JP (1) JP3635496B2 (fr)
KR (1) KR19990028199A (fr)
AU (1) AU750118B2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9150467B2 (en) 2013-07-23 2015-10-06 Uop Llc Processes and apparatuses for preparing aromatic compounds

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1948528A (en) * 1930-12-13 1934-02-27 Atlantic Refining Co Purification of hydrocarbon oils
US3642927A (en) * 1968-02-07 1972-02-15 Ashland Oil Inc Process for desulfurization of aromatics

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9814535A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9150467B2 (en) 2013-07-23 2015-10-06 Uop Llc Processes and apparatuses for preparing aromatic compounds

Also Published As

Publication number Publication date
JP2001500535A (ja) 2001-01-16
AU7250196A (en) 1998-04-24
JP3635496B2 (ja) 2005-04-06
KR19990028199A (ko) 1999-04-15
AU750118B2 (en) 2002-07-11

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