US3449460A - Upgrading of coke oven light oils - Google Patents

Upgrading of coke oven light oils Download PDF

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US3449460A
US3449460A US735131A US3449460DA US3449460A US 3449460 A US3449460 A US 3449460A US 735131 A US735131 A US 735131A US 3449460D A US3449460D A US 3449460DA US 3449460 A US3449460 A US 3449460A
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upgrading
hydro
fraction
benzene
compounds
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Mehmet Orhan Tarhan
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Bethlehem Steel Corp
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Bethlehem Steel Corp
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    • 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
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only

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  • the BT fraction is vaporized with hot hydrogen witho-ut polymer formation, further heated and hydrodealkylated in a hydro-upgrading zone in the presence of a chromiaalumina catalyst.
  • the C8 to ⁇ Cm fraction including the xylenes is vaporized and hydrotreated in the presence of a hydrotreating catalyst such as cobaltor nickel-molybdate on alumina to a polymer-free and oxygen-free aromatic stream, and the thus treated fraction, free of water is further heated and refined by hydrodealkylating in the later stages of the hydro-upgrading zone. From both treated fractions a product is obtained comprising benzene, toluene and xylenes, and any non-converted C9 and C10 aromatics lmay be recycled.
  • This invention relates to an improvement in the upgrading lof aromatic hydrocarbons, and pertains particularly to the hydrogenation of crude light oil obtained by the carbonization of coal.
  • Crude light oils obtained during the carbonization of coal contain principally ⁇ one-ring aromatics which are associated with numerous impurities.
  • the aromatics include benzene, toluene, xylenes, ethylbenzene and trimethylbenzenes.
  • the impurities include parafns, naphthenes, oleins, carbon disulfide, phenol, heterocyclic compounds such as thiophenes, pyridines and coumarone, and certain unsaturated derivatives such as styrene and indene.
  • a method increasingly used to refine crude light oil is that by which crude feedstock is vaporized and treated with hydrogen, or hydrogen mixed with other gases, in the presence of a catalyst at elevated pressure and temperature.
  • This type of treatment is known variously as hydrogenation, hydrodesulfurization, hydrodenitrogenation, hydroefracking, hydrofining or hydrodealkylation.
  • hydro-upgrading processes impurities are converted into compounds which can be separated readily from benzene, toluene and xylene by subsequent operations such as condensation, stripping, fractional distillation, azeotropic distillation, solvent extraction or combinations 3,449,460 Patented June 10, 1969 thereof.
  • Hydro-upgrading processes are usually performed at temperatures which may range from 190 C. to 680 C.
  • the polymerization reaction also occurs in vapor phase when the vapors of an aromatic feedstock containing polymerizable impurities are exposed to hot surfaces, resulting in the fouling of these surfaces.
  • polymerized impurities of the feedstock form excessive coke on many hydro-upgrading catalysts.
  • the rate of polymer formation is considerably greater in liquid phase or in mixed phase, than in dry gas phase.
  • Certain hydro-upgrading processes have considered the use of a preliminary catalytic reactor, usually referred to as a treater, pretreater or guard case, ahead of the main catalytic reactor in order to selectively convert polymer-formers to non-polymerizable compounds at a relatively low temperature.
  • a preliminary catalytic reactor usually referred to as a treater, pretreater or guard case
  • the feed vapors can be heated with safety to the higher temperature of the main hydro-upgrading reactor.
  • the total feedstock is pretreated and hydroupgraded in one stream.
  • the regeneration cycle of the pretreat catalyst is in the order of from one to two months, while some hydro-upgrading processes require regeneration of the catalyst about once a year.
  • the entire upgrading system must be shut down during regeneration of the catalyst when the complete process is performed in a single stream. This practice reduces the overall capacity of an installation. It would, of course, be possible to use two parallel pretreat reactors, each capable of treating the total feed, and to regenerate the catalyst in one, while the other is on stream. However, such a system involves considerably higher capital expenditure, and therefore is not a desirable solution.
  • a further object is to produce a refined aromatic product with a minimum of dealkylation of the xylenes, while maintaining a maximum of toluene dealkylation.
  • the low-boiling fraction boiling below about 120 C., is vaporized in the presence of hydrogen and heated to the temperature required in the subsequent hydro-upgrading step, this portion of the feedstock then being fed to the hydro-upgrading zone comprising a first and second stage in series, where it is reacted in both stages in the presence of a chromia-alumina catalyst to hydrocrack olefins, parafiins and naphthalene to C1 to C4 aliphatics, to hydrogenate sulfur compounds such as thiophenes, and to hydro-dealkylate toluene to benzene.
  • the higher boiling fraction is sent to a pretreat reactor, where it is reacted with hydrogen in the presence of a hydrogenation catalyst.
  • polymer-formers are converted to non-polymerizable matter, and oxygen-containing compounds are converted to hydrocarbons and water.
  • the efliuent from the pretreater after removal of water therefrom, is introduced into the second stage of the hydro-upgrading zone, where it is reacted to hydrocrack paraflins and naphthenes, to desulfurize sulfur compounds, and to hydro-dealkylate the C9 and C10 compounds.
  • Some xylene is also dealkylated.
  • the efiiuent of the hydro-upgrading Zone is liquefied and separated from gases.
  • Trace impurities are removed from the liquid product, and said product is fractionated to benzene, toluene and xylenes, and the residue containing any C9 and C10 compounds iS recycled to the second stage of the hydro-upgrading zone.
  • FIGURE 1 is a schematic representation of ⁇ a preferred mode of hydro-upgrading separate fractions of a crude light oil.
  • FIGURE 2 is a modification of FIGURE 1.
  • crude light oil obtained from coal carbonization, enters rectification tower 12 by way of line 11.
  • the oil is separated into two fractions, one fraction boiling above 120 C. and the other boiling below 120 C.
  • the lower boiling fraction enters, by way of line 13, forerun removal still 14.
  • Foreruns, making up the portion in the still boiling below 80 C., are removed overhead at line 15. This portion may be burned as waste or disposed of in some other manner.
  • the bottoms, boiling between and 120 C. contain benzene, toluene, a certain amount of sulfur in the form of thiophenes, and non-aromatic impurities usually associated with this fraction.
  • reactors 21 and 22 contain ⁇ a fixed-bed of chromia-alumina catalyst.
  • the feed in the reactors is maintained at a temperature between 600 and 640 C. and a pressure of about 800 to 840 p.s.i.g. A hydrogen to aromatics ratio of 4:1 to 7:1 is maintained.
  • Liquid product containing a mixture of benzene, toluene and, usually, as will be explained, xylenes, is withdrawn from separator 27 by way of line 29. Further refining steps, not shown, of this liquid product include further separation of small amounts of gaseous impurities in a stripping tower, clay treating to remove residual olefins, and fractionating to separate the purified product into its saleable components of benzene and toluene, and xylene if present.
  • liquid bottoms are withdrawn from the tower at line 31. These bottoms represent the crude light oil boiling above C., and they are introduced into fractionation tower 32, where that fraction boiling between 120 C. and 200 C. is led off overhead by way of line 33 to a pretreating reactor, or pretreater, 34.
  • the residue from tower 32 comprising components of the crude light oil which boil above 200 C., such as naphthalene, is withdrawn at line 37. This residue may be utilized as fuel, or the naphthalene may be recovered.
  • the liquid feed from tower 32 is mixed, at 39, with hot hydrogen from line 38 bringing the incoming feed to a temperature of about 325 C. This mixing insures complete vaporization of the feed as it enters reactor 34.
  • the feed contains a mixture of xylenes, ethyl benzene, trimethyl benzene and other alkyl benzenes.
  • the feed also contans numerous alkylated thiophenes. More serious is the fact that the feed contains polymer-forming materials such as styrene, indene and coumarone.
  • This invention overcomes the formation of objectionable gummy material anywhere in the system by dividing the crude light oil stream at the rectification tower as described.
  • the rectification tower must be designed to produce an overhead fraction which contains no gumforming material. This fraction, boiling below 120 C., can therefore be sent to the main reactors 21 and 22 without pretreatment.
  • the portion of the light oil boiling above 120 C. contains the gum-formers, and steps must be taken to eliminate gum formation therefrom.
  • coumarone along with any phenol present in the higher boiling crude light oil portion, contains oxygen.
  • both the polymer-formers and the oxygen-containing compounds are rendered innocuous by hydrogenation in the pretreater 34 and a subsequent water elimination step.
  • pretreater 34 which contains a fixed bed catalyst of pre-sulfided nickel-molybdate on alumina
  • vaporized feed is hydrogenated in the presence of the catalyst, and the polymerizable compounds are rendered non-polymerforming.
  • styrene is converted to ethyl benzene, and indene to indan.
  • Coumarone under these conditions is completely converted to ethyl benzene, ethyl cyclohexane and water, the water containing al1 of the oxygen from these compounds.
  • the reactions are performed at a temperature of 350 C., a hydrogen-to-feed mol ration of 5:1, a hydrogen partial pressure of 625 p.s.i.g., and at 2 LHSV.
  • the treated feed free of all polymer-forming components, but containing the converted forms of these components for further upgrading, is withdrawn from pretreater 34 as gaseous efliuent at line 35.
  • the efiiuent is cooled in cooler 41 to condense pretreated C9 to C10 vapors and the water vapor resulting from the reaction of the oxygen-containing compounds with hydrogen, and is transferred by line 42 to liquid-gas separator 43, where water is withdrawn at line 44.
  • Effluent from the pretreater, on entering the hydroupgrading zone may be utilized as a quench of the main stream to maintain proper temperature in the second stage of the hydro-upgrading zone.
  • Liquid product, Withdrawn at line 29, is further refined in a series of steps, not shown, Which include sending the product to a stripping tower for further separation of gases from the product, to a clay treater for removal of residual olefins and then to a fractionator, where the refined aromatic product is separated into benzene, toluene and xylene, and residual C9 and C19 aromatics. The residuals are recycled to the second hydro-upgrading stage.
  • pyridines are hydrogenated to nitrogen-free aliphatic compounds which are readily separated from benzene.
  • the separation of crude light oil into the desired fractions can be performed in any manner known in the art, provided the fractionation is sufficiently effective to leave no polymer formers in the lower-boiling fraction C.) and polymer formation is avoided lby not allowing the feedstock extended residence time at elevated temperature anywhere in the fractionation system. It is preferable to use an overhead product for the 120-200 C. fraction and to process this fraction without delay in the pretreater.
  • the 120-200 C. fraction by blending the unpreheated feedstock with hot hydrogen prior to the inlet to the pretreat reactor. It is also preferable to vaporize this fraction by blending the unpreheated feedstock with the hot hydrogen in a pipe-T, in order to speed up the vaporization to a dry vapor.
  • these operations may be performed by alternate means known to the art, provided such means does not lead to polymer formation.
  • the temperature in the pretreater may range from about 250 to 375 C., preferably 300 to 350 C., and the pressure should be maintained between 300 and 1500 p.s.i.g.
  • the LHSV may be Within the range of 0.5 to 4.0, and preferably 'between from l to 2. Hydrogen to aromatics mol ratio may range between 2.5 :l and 10:1.
  • a presulfided nickel-molybdate on alumina catalyst has been found to be the most satisfactory catalyst for use in the pretreater for converting polymerizable components to a non-polymerizable form and for de-oxygenating the oxygen-containing compounds.
  • other catalysts have been used which give a satisfactory performance, chief of which is presulfided cobalt-molybdlate on alumina.
  • the temperature and pressure in the hydro-upgrading reactors may range from 550 C. to 675 C. and from 500 to 1500 p.s.i.g. respectively.
  • the preferred temperature range is from 600 to 640 C.
  • a hydro-upgrading zone comprising two stages, each stage represented by a reactor.
  • the relative severities of each hydro-upgrading stage, in terms of residence times may be varied as desired, provided the pretreated C8 to C10 stream can be sufficiently refined. Also, more than two stages may be used.
  • the condenser and liquidgas separator following the pretreater may be omitted.
  • the feedstock in the example is a crude light oil from coke manufacture
  • the invention can be applied to other aromatic feedstock containing styrene, indene, coumarone, conjugated diolefins such as cyclopentadienes and/ or phenol.
  • Unsaturated Gumformers and Oxygenated Aromatic Compounds Compounds Sulfur Compounds Nitrogen Compounds Selected Fraction Forerunnings Cyolopentadicne 42 Carbon bisulfide, 1, discarded.
  • o, 1n and p xylenes styrene 145 Other methyl thio- 3, to pretreater then 133l44. ethyl phenes 136-146. to hydro-upgrading benzene 136. reactor.
  • Dividing the feedstock into two streams, as has been described in the foregoing example, and introducing the higher boiling stream into the pretreater as shown, provides the several advantages of preventing formation of any gummy residue in the system, use of a small pretreater to handle only that fraction which contains gumformers and oxygen-containing compounds (less than 6% of the total feed) and permitting refining operations to proceed on the benzene-toluene fraction (selected fraction 2 of table) while the pretreater catalyst is being regenerated.
  • storage tanks may be supplied as temporary reservoirs in order to accumulate the C8 to C10 fraction during the start-ups and catalyst regeneration of the pretreating and of the hydro-upgrading unit.
  • the hydro-upgrading unit can continue operation during the shutdown of the pretreater and presulfiding and regeneration of the pretreated cat-a-lyst.
  • FIGURE 2 A modification of the process of FIGURE 1 is shown in FIGURE 2, wherein the hydro-upgrading zone consists of three stages, or reactors, to provide greater flexibility in hydrodealkylating Cg-Clo aromatics selectively to the C8 level.
  • the lower-boiling 80-120 C. fraction containing mainly benzene and toluene, is withdrawn from forerun removal still 14, and mixed with hot hydrogen gas from line 17 at line 16.
  • This portion of the feed is heated to approximately 600 C. in heater 18, and passed, by way of lines 19, 20 and 20 to reactors 21, 22 and 23 respectively, in series.
  • Reactors 21, 22 and 23 each contain a fixed bed of chromia-alumina catalyst, and they operate under the same conditions as described in the previous example, except that the total amount of catalyst is distributed througout a total of three reactors instead of two.
  • separator 27 the condensed liquid product still retains some hydrogen, hydrogen sulfide and C1C4 hydrocarbons in dissolved state, corresponding to the absorption equilibria of these gases between gas and liquid phases 4at the temperature and pressure existing in the liquid-gas separator.
  • These dissolved gases are stripped from the liquid product in a stripper 61.
  • the bottoms from the stripper are sent through line 63 to a clay treater 64, and through successive fractionation columns 66, 67, 68 and 69.
  • Waste gas containing hydrogen sulfide and C1-C4 aliphatics, is exhausted overhead from stripper 61 at line 62.
  • the products removed overhead from columns 66 through 69 are pure benzene, pure toluene, pure Imixed Xylenes and refined C9 aromatics, and
  • the fractionation of the hydro-upgrading product is performed in this example in four continuous columns, however, the same fractionation can be performed by any other method known to the art, provided the products of fractionation are of the desired purity.
  • polymerizable components and oxygen-containing compounds contained in aromatic feedstocks boiling up to 200 C. are quantitatively converted into nonpolymerizable and oxygen-free compounds, and are recovered as saleable products, such as benzene, toluene, xylene, and ethylbenzene.
  • Aromatic feedstocks containing oxygen-containing compounds, such as coumarone and phenol, are rendered usable in light oil refining processes with a water-sensive chromia-alumina catalyst. Due to the treatment of the lower boiling fraction in the entire hydro-upgrading zone, maximum conversion of toluene to benzene is maintained, while at the same time conversion ofthe CB-Cw fraction below the C8 level is effectively decreased.
  • any unconverted C9 and C10 aromatics can be fractionally separated and recycled to the proper hydro-upgrading stages.
  • a method of upgrading aromatic feedstock boiling up to 200 C. and containing polymerizable compounds, oxygen-containing compounds, non-aromatics and sulfur compounds which comprises separating said feedstock into ⁇ a first fraction boiling between 80 C. and 120 C. and a second fraction boiling betwen C. and 200 C., vaporizing and heating said first fraction to the reaction temperature of a hydro-upgrading zone and introducing the fraction into the first and subsequent stage or stages of a hydro-upgrading zone and therein reacting said first fraction with hydrogen in the presence of a chromiaalumina catalyst at a temperature between 550 C. and 675 C.
  • a method according to claim 9 in which the efiluent from the hydro-upgrading zone is condensed, separated from gases and fractionally separated into pure benzene, toluene, xylenes and several Cg-Cw fractions, the Cg-Cm fractions being recycled to selected upgrading .stages subsequent to the rst stage for conversion to xylenes.
  • thermo-upgrading zone is between 600 and 640 C.

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  • Engineering & Computer Science (AREA)
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  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US735131A 1968-06-06 1968-06-06 Upgrading of coke oven light oils Expired - Lifetime US3449460A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3717570A (en) * 1971-02-05 1973-02-20 J Hochman Simultaneous hydrofining of coker gas oil, vacuum gas oils and virgin kerosene
EP0582723A1 (de) * 1992-08-04 1994-02-16 NEUMANN + STALLHERM GmbH Verfahren zur Aufbereitung von Rohbenzol
US5767332A (en) * 1994-10-22 1998-06-16 Krupp Koppers Gmbh Process and apparatus for producing aromatic hydrocarbon composition
CN100448957C (zh) * 2006-01-19 2009-01-07 中国石油化工股份有限公司 一种焦化全馏分油的加工方法
CN100457861C (zh) * 2006-01-19 2009-02-04 中国石油化工股份有限公司 焦化全馏分油生产优质柴油的方法
WO2015000848A1 (en) * 2013-07-02 2015-01-08 Saudi Basic Industries Corporation Process and installation for the conversion of crude oil to petrochemicals having an improved carbon-efficiency

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081259A (en) * 1963-03-12 Coke oven light oil purification
US3094481A (en) * 1960-09-09 1963-06-18 Exxon Research Engineering Co Hydrofining process with temperature control
US3207802A (en) * 1960-12-14 1965-09-21 Air Prod & Chem Purification of coke-oven light oil
US3260765A (en) * 1965-05-25 1966-07-12 Universal Oil Prod Co Treatment of alkyl-substituted aromatic compounds
US3267021A (en) * 1964-03-30 1966-08-16 Chevron Res Multi-stage hydrocracking process

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081259A (en) * 1963-03-12 Coke oven light oil purification
US3094481A (en) * 1960-09-09 1963-06-18 Exxon Research Engineering Co Hydrofining process with temperature control
US3207802A (en) * 1960-12-14 1965-09-21 Air Prod & Chem Purification of coke-oven light oil
US3267021A (en) * 1964-03-30 1966-08-16 Chevron Res Multi-stage hydrocracking process
US3260765A (en) * 1965-05-25 1966-07-12 Universal Oil Prod Co Treatment of alkyl-substituted aromatic compounds

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3717570A (en) * 1971-02-05 1973-02-20 J Hochman Simultaneous hydrofining of coker gas oil, vacuum gas oils and virgin kerosene
EP0582723A1 (de) * 1992-08-04 1994-02-16 NEUMANN + STALLHERM GmbH Verfahren zur Aufbereitung von Rohbenzol
US5767332A (en) * 1994-10-22 1998-06-16 Krupp Koppers Gmbh Process and apparatus for producing aromatic hydrocarbon composition
CN100448957C (zh) * 2006-01-19 2009-01-07 中国石油化工股份有限公司 一种焦化全馏分油的加工方法
CN100457861C (zh) * 2006-01-19 2009-02-04 中国石油化工股份有限公司 焦化全馏分油生产优质柴油的方法
WO2015000848A1 (en) * 2013-07-02 2015-01-08 Saudi Basic Industries Corporation Process and installation for the conversion of crude oil to petrochemicals having an improved carbon-efficiency
CN105473690A (zh) * 2013-07-02 2016-04-06 沙特基础工业公司 用于将原油转化成具有改进的碳效率的石化品的方法和设施
CN105473690B (zh) * 2013-07-02 2018-01-09 沙特基础工业公司 用于将原油转化成具有改进的碳效率的石化品的方法和设施
EP3460026A1 (en) 2013-07-02 2019-03-27 Saudi Basic Industries Corporation Process and installation for the conversion of crude oil to petrochemicals having an improved carbon-efficiency
EA033477B1 (ru) * 2013-07-02 2019-10-31 Saudi Basic Ind Corp Способ и установка для конверсии сырой нефти в нефтехимические продукты с повышенной эффективностью по углероду
US10676681B2 (en) 2013-07-02 2020-06-09 Saudi Basic Industries Corporation Process and installation for the conversion of crude oil to petrochemicals having an improved carbon-efficiency
EA038963B1 (ru) * 2013-07-02 2021-11-16 Сауди Бейсик Индастриз Корпорейшн Способ переработки сырой нефти

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GB1264373A (nl) 1972-02-23
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