US3558729A - Dealkylation of alkylaromatic hydrocarbons - Google Patents

Dealkylation of alkylaromatic hydrocarbons Download PDF

Info

Publication number
US3558729A
US3558729A US729719A US3558729DA US3558729A US 3558729 A US3558729 A US 3558729A US 729719 A US729719 A US 729719A US 3558729D A US3558729D A US 3558729DA US 3558729 A US3558729 A US 3558729A
Authority
US
United States
Prior art keywords
toluene
benzene
stream
zone
dealkylation
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.)
Expired - Lifetime
Application number
US729719A
Other languages
English (en)
Inventor
Richard R De Graff
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.)
Universal Oil Products Co
Original Assignee
Universal Oil Products Co
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 Universal Oil Products Co filed Critical Universal Oil Products Co
Application granted granted Critical
Publication of US3558729A publication Critical patent/US3558729A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
    • C07C15/02—Monocyclic hydrocarbons
    • C07C15/04—Benzene
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S203/00—Distillation: processes, separatory
    • Y10S203/11—Batch distillation

Definitions

  • This application relates to a method for the dealkylation of alkyl-substituted aromatic hydrocarbons. More particularly, the invention relates to a method for hydrodealkylating alkyl-substituted aromatic hydrocarbons, such as toluene, in the presence of a catalytic composition of matter.
  • aromatic hydrocarbons such as benzene
  • benzene of a high-grade purity is used as an intermediate in the preparation of styrene monomer which may be polymerized to form a type of rubber.
  • benzene is used as an intermediate in the preparation of phenol, aniline, maleic anhydride, insecticides such as DDT and benzene hexachloride,and as intermediates in the preparation of synthetic fibers, such as some types of nylon.
  • benzene is as an intermediate in the preparation of detergents, such as alkylaromatic sulfonates.
  • detergents such as alkylaromatic sulfonates.
  • alkylaromatic sulfonates These latter compounds are prepared by alkylating benzene with a long chain polymer containing from about 12 to 15 carbon atoms or more in the chain. Following the alkylation of benzene, these long chain alkylbenzenes are then sulfonated by any method well known in the art to produce the corresponding sulfonic acid. The acid may then be neutralized to form the corresponding sulfonate, such as the sodium or potassium salt of the sulfonic alkylaromatic acid.
  • the dealkylation of alkylaromatic hydrocarbon is, generally, well known in the art and may be performed either thermally or catalytically.
  • the reaction is exothermic in nature and must be carefully controlled in order to prevent a runaway reaction, i.e. the reaction temperature increases beyond acceptable and desirable limits.
  • the most efficient dealkylation reaction to produce benzene would be to supply as feed relatively high purity toluene so that a minimum of side products, such as gaseous hydrocarbons and polymers, will be formed.
  • a method for producing benzene via dealkylation of toluene which comprises the steps of: (a) introducing a feed stream comprising toluene into a fractionation zone maintained under fractionation conditions at a locus intermediate the ends of said zone; (b) introducing a hereinafter specified benzene-containing stream into said fractionation zone at a locus above said feed locus; (c) supplying heat for fractionation in said fractionation zone through first reboiler means spaced below said feed locus; (d) supplying heat for fractionation in said fractionation zone through second reboiler means spaced below said rst reboiler means; (e) withdrawing from said fractionation zone an overhead distilalte product stream, a first side-cut benzene stream, a second side-cut toluene stream, and a bottom stream comprising higher-boiling aromatic hydrocarbons; (f) passing at least a portion of said second side-cut
  • Another embodiment of this invention includes the method hereinabove wherein said second side-cut fraction of step (e) is withdrawn from a locus between said first and second reboiler means.
  • the present invention provides improvement in the simultaneous processing of the efuent from the reaction zone and a relatively impure feed stream utilizing a single fractionation zone.
  • a relatively low concentration toluene feed stream may be processed through the system, in such a manner that the actual feed to the dealkylation reaction zone is relatively concentrated thereby providing economy of operation and economy of capital investment in terms of reactor size, pump size, ⁇ etc.
  • the single fractionation zone is operated by having at least two (2) reboiler systems, preferably, each located internally to the fractionation column.
  • the benets to be gained from the present invention reside in this dual reboiler feature and the withdrawal of the relatively concentrated toluene stream from a location within the fractionation zone between the two (2) reboiler means.
  • the upper reboiler means utilizes relatively low pressure steam as the external heat media while the lower reboiler means utilizes relatively high pressure steam as the external heating media.
  • the method of this invention utilizes the hydro-dealkylation reaction for removing the alkyl side chains from the benzene neucleus. Therefore, the feedstock to the reaction zone should be a concentrate of toluene; although, to some extent, the xylenes may also be converted to benzene via dealkylation.
  • the dealkylation reaction is not always selective in that xylenes frequently are only reduced to toluene and/or the severity of the reaction is such that the benzene ring is opened or cracked thereby decreasing the aromatic hydrocarbon yield from the overall reaction.
  • the feed stream comprise relatively low concentration toluene, e.g.
  • the feed stream to the present invention will comprise from 70% to 80% toluene and, generally, will be obtained from a catalytic reforming operation.
  • the dealkylation reaction of the present invention is performed in the presence of a catalyst which may comprise a soluble salt of a metal of Group IV of the Periodic Table, such as, for example, tin chloride, titanium chloride, zirconium oxychloride, tin nitrate, tin sulfate, titanium nitrate, titanium sulfate, zirconium oxybromide, zirconium oxyiodide, etc., is coprecipitated with an alumina sol.
  • a catalyst which may comprise a soluble salt of a metal of Group IV of the Periodic Table, such as, for example, tin chloride, titanium chloride, zirconium oxychloride, tin nitrate, tin sulfate, titanium nitrate, titanium sulfate, zirconium oxybromide, zirconium oxyiodide, etc.
  • dealkylation reaction be etfectuated thermally, i.e., in the substantial absence of catalytic materials.
  • Those skilled in the art are familiar with the details of dealkylation; therefore, additional description of this well known reaction need not be presented herein.
  • Suitable dealkylation reaction conditions utilizing the catalytic composite referred to hereinabove will include a temperature from 1,000 F. to 1,500 F. and a pressure from 300 p.s.i.g. to 1,000 p.s.i.g. Desirably, a molar excess of hydrogen is also maintained in the reaction zone in order to reduce the possibility of catalyst deactivation due to deposition of coke or other heavy carbonaceous material upon the catalytically active centers and surfaces of the catalyst.
  • the liquid hourly space velocity through the catalyst bed may range from 0.5 to and the hydrogen to hydrocarbon mol ratio may range from 3:1 to 15:1. Additionally, while the method of this invention may be effected in either a batch type or continuous type operation, it is distinctly preferred that a continuous operation be utilized.
  • the fractionation zone of the present invention involves, preferably, a single distillation column having a feed inlet for the dealkylated product stream, a feed inlet for the relatively low concentration toluene stream, a side-cut stream for withdrawing high purity benzene, and a side-cut stream for withdrawing a relatively high purity toluene.
  • side reboilers or external reboilers may be used in combination With or instead of the internal reboilers where desired within the scope of this invention.
  • various forms or designs of liquid wells to accommodate the nternal reboiler means may be utilized as long as there is proper weir means to effect a liquid overow from each zone containing a reboiler and a substantially constant liquid level in such zone to permit uniform heating over the reboiler tubes.
  • another embodiment of this invention includes the broad method hereinabove wherein said first and second reboiler means are internal and a portion of said bottoms stream of step (e) is returned to said fractionation zone to provide a liquid seal over said second reboiler means.
  • this concentrate of toluene is passed into the dealkylation reaction zone operating, preferably, in the presence of a molar excess of hydrogen and a preferred catalytic composite of the type described herein.
  • the eluent from the reaction zone is then, typically, passed through heat exchange means into a separation zone wherein hydrogen gas for recycle purposes is obtained and returned to the reaction zone.
  • the remaining liquid from the separation zone is then passed into stripping and/or absorption means wherein normally gaseous hydrocarbons are obtained and separated from the benzene-containing dealkylated product stream.
  • This benzene-containing stream is withdrawn from the stripping and/or absorption zone and passed into a treating zone, such as with clay, wherein impurities which might impair the acid-wash color test for benzene are removed.
  • the clay treated product containing benzene is passed into the fractionation zone at a locus generally intermediate the ends of the fractionation zone and above the inlet locus for the relatively low concentration toluene feed stream which had previously been introduced into such zone.
  • the ultimate benzene product is of relatively high purity in that, typically, it may have a 5.5 C. freeze point. Also, practice of the present invention will typically handle a toluene feed stream containing about 70% toluene and produce a reaction zone feed stream containing at least on a mol basis toluene.
  • a relatively low concentration toluene stream diluted with other aromatic hydrocarbons and obtained as a by-product oil from a coke oven operation or from a catalytic reforimng operation is introduced into the system via line 10 and passed into fractionation column 11 at a locus intermediate the ends of fractionation column 11.
  • a typical toluene-containing stream may comprise on a commercial scale 154 mols per hour of toluene, 48 mols per hour of benzene, and 12 mols per hour of xylenes.
  • This feed stream enters fractionator 11 at a temperature of about 250 F. and a pressure of about 9 p.s.i.g.
  • fractionator 11 Suitable fractionation conditions are maintained in fractionator 11 whereby a light hydrocarbon stream comprising, for example, cyclohexane, is withdrawn as an overhead distillate fraction via line I13 at a temperature of about F. and a pressure of about 5 p.s.i.g.
  • a hereinafter described benzene-containing stream comprising the hydrocarbon efiuent from the reaction zone is also introduced into fractianator 11 via line 12 at a locus above said feed locus for line 10.
  • This benzenecontaining stream on a commercial scale may comprise 159 mols per hour of benzene, 70 mols per hour of toluene, 1.2 mols per hour of Xylene, 2.9 mols per hour of CNHI@ (diphenyl), 3.2 mols per hour of CloHg (naphthalene), and 3.8 mols per hour of CmHm (anthracene) and enters fractionator 11 at a temperature of 220 F. and a pressure of about 8 p.s.i.g.
  • An upper side-cut fraction comprising high purity Ibenzene is withdrawn via line 14 at a temperature of 195 F. and a pressure of about p.s.i.g. Typically, this upper side-cut stream will comprise about 207 mols per hour of 5 C. freeze point benzene.
  • a lower side-cut stream comprising relatively concentration toluene is withdrawn via line 16 at a temperature of about 275 F. and a pressure of about 12 p.s.i.g.
  • This lower side-cut stream on a commercial basis may comprise 223 mols per hour of toluene, 14 mols per hour of xylene, 2.8 mols per hour of ClgHm, 3 mols per hour of ClOHg, and 3.6 mols per hour of CMHm. It should be noted at this point that the material in line 16 comprises about 90% on a mol basis toluene whereas the feed material entering via line 10 comprised only about 72% toluene on a mol basis.
  • a bottoms stream comprising higher-boiling heavy hydrocarbons is withdrawn from fractionator 11 via line 15 at a temperature of 405 F. and a pressure of about 12 p.s.i.g.
  • the net amount of material in line 15 is withdrawn via line 17 and sent to storage for use as fuel. If necessary or desirable, a portion of the material in line :15 may be passed via line 18 into line 16 for further processing as more fully described hereinbelow.
  • fractionator 411 comprises at least two (2) internal reboiler means 23 and 24, respectively.
  • reboiler means 23 is heated by relatively low pressure steam (eg. 150 p.s.i.g.) which passes through reboiler 23 via lines 21.
  • relatively low pressure steam eg. 150 p.s.i.g.
  • Suitable well means 25 having associated therewith a weir is also utilized in the column in order to maintain a liquid seal over the tubes of reboiler 23.
  • reboiler 24- is heated by relatively high pressure steam (eg. 600 p.s.i.g.) which passes through reboiler 24 via lines 22.
  • relatively high pressure steam eg. 600 p.s.i.g.
  • Well 26 having associated therewith suitable Weir means is also a desirable part of fractionator 11 in order to maintain a liquid seal over the tubes of lower reboiler means 24.
  • two of the essential features of the preferred embodiment of this invention includes the withdrawal of the toluene concentrate stream via line 16 at a locus between internal reboiler means 23 and 24.
  • the higher-boiling heavy aromatic hydrocarbons are rejected from the bottom of the column via line 15 and any toluene constituents therein are stripped out by the added heat which is introduced into the column via internal reboiler 24.
  • any benzene which has passed down the column into the vapor-liquid contacting means or trays normally associated with fractionating columns is also stripped out by the heat which is introduced into the column via internal reboiler 23.
  • this material is now passed via line 19 wherein it is mixed with a hydrogen-containing gas stream from line 27 and passed via line 28 into hydrodealkylation reaction zone 29 which contains, preferably, a dealkylation catalyst.
  • the total reactor hydrocarbon charge may comprise 224 mols per hour of toluene, 13 mols per hour of xylene, 2.8 mols per hour of CmHlo, 3.1 mols per hours of CIOHB, and 3.6 mols per hour of CMHIU.
  • the combined feed to the reactor in line 28 may comprise 1,776.14 mols per hour of hydrogen, 1,053.53 mols per hour of methane, 80.12 mols per hour of ethane, 19.45 mols per hour of benzene, 226.68 mols per hour of toluene, 13.71 mols per hour of Xylene, 2.84 mols per hour of C12H10, 3.07 mols per hour of C10H8, and 3.55 mols per hour of CMH, and enters reactor 29 at a temperature of 1,275 F. and a pressure of about 570 p.s.1.g.
  • the effluent is withdrawn from reactor 29 via line 30 at a temperature of about l,340 F. and is immediately quenched by a recycle stream from line 33 to a temperature of about 1,000 F.
  • the quenching zone is located internal the reactor shell.
  • the quenched etiiuent is then passed via line 30 into separator 31 which may comprise one or more separation vessels which are lmaintained under conditions sufficient to separate a hydrogencontaining gas via line 27 which is returned to the reaction zone as previously discussed.
  • separator 31 may comprise one or more separation vessels which are lmaintained under conditions sufficient to separate a hydrogencontaining gas via line 27 which is returned to the reaction zone as previously discussed.
  • separator 31 may comprise one or more separation vessels which are lmaintained under conditions sufficient to separate a hydrogencontaining gas via line 27 which is returned to the reaction zone as previously discussed.
  • separator liquid is withdrawn via line 32 and a portion thereof returned via line 33 as quench to reactor 29 in the manner previously discussed.
  • the net a-mount of separator liquid in line 32 is passed into stripping zone 34 wherein suitable conditions are maintained to produce overhead the normally gaseous materials which are sent via line 35, generally, to a refinery fuel system.
  • the composition of the material in line 35 on a commercial basis may comprise 1.6 mols per hour of hydrogen, 8.2 mols per hours of methane, 2.8 mols per hour of ethane, and .3 mol per hour of benzene.
  • Operating conditions in stripper 34 include an overhead temperature of about F. and an overhead pressure of about 218 p.s.i.g. with a bottoms temperature of about 430 F. and a bottoms pressure of about 220 p.s.1.g.
  • the stripper bottoms material comprising a benzene concentrate is withdrawn via line 36 and passed into conventional clay treating means 37 for the re-moval therein of certain impurities which might impair the acid-wash color test of the ultimate benzene which is recovered in ractionator 11 previously discussed.
  • the clay treated benzene-containing stream is withdrawn via line 12 and passed into fractionator 11 in the manner previously discussed.
  • another embodiment of this invention includes the method for producing benzene via hydrodealkylation of toluene which comprises the steps of: (a) introducing a feed stream comprising relatively low concentration toluene diluted with other aromatic hydrocarbons into a fractionation zone maintained under fractionation conditions at a locus intermediate the ends of said zone; (b) introducing a hereinafter specified benzenecontaining stream into said fractionation zone at a locus above said feed locus; (c) withdrawing from said fractionation Zone an overhead distillate product stream comprising relatively light hydrocarbons, an upper side-cut stream comprising high purity benzene, a lower side-cut stream comprising relatively concentration toluene, and a bottoms stream comprising higher-boiling heavy hydrocarbons; (d) passing said lower side-cut stream into a hydrodealkylation reaction zone maintained under conditions including the presence of hydrogen gas sufficient to dealkylate toluene to benzene; (e) separating a
  • Method for producing benzene via dealkylation of toluene which comprises the steps of:
  • step (f) passing at least a portion of said second side-cut stream of step (e) into a dealkylation reaction zone maintained under dealkylation conditions;
  • step (h) passing said benzene stream of step (g) into said fractionation zone as specified in step (b); and,
  • step (e) is withdrawn from a locus between said first and second reboiler means.
  • Method for producing benzene via hydrodealkylation of toluene which comprises the steps of (a) introducing a feed stream comprising from about 50 to 80 mol percent toluene diluted with other aromatic hydrocarbons including benzene into a unitary fractionation zone maintained under fractionation conditions at a locus intermediate the ends of said zone;
  • step (f) passing said benzene containing stream into said fractionation zone as specified in step (b).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
US729719A 1968-05-16 1968-05-16 Dealkylation of alkylaromatic hydrocarbons Expired - Lifetime US3558729A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US72971968A 1968-05-16 1968-05-16

Publications (1)

Publication Number Publication Date
US3558729A true US3558729A (en) 1971-01-26

Family

ID=24932297

Family Applications (1)

Application Number Title Priority Date Filing Date
US729719A Expired - Lifetime US3558729A (en) 1968-05-16 1968-05-16 Dealkylation of alkylaromatic hydrocarbons

Country Status (7)

Country Link
US (1) US3558729A (enrdf_load_stackoverflow)
JP (1) JPS518928B1 (enrdf_load_stackoverflow)
BR (1) BR6908912D0 (enrdf_load_stackoverflow)
DE (1) DE1923564B2 (enrdf_load_stackoverflow)
ES (1) ES367247A1 (enrdf_load_stackoverflow)
FR (1) FR2011841A1 (enrdf_load_stackoverflow)
GB (1) GB1214955A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014098816A1 (en) * 2012-12-19 2014-06-26 Stone & Webster Process Technology, Inc. Method for reducing energy consumption in a process to purify styrene monomer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5843860B2 (ja) 2010-08-10 2016-01-13 アーエスエス・アインリヒトゥングスシステム・ゲーエムベーハー 座席家具の品物

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3193594A (en) * 1961-09-29 1965-07-06 Union Oil Co Manufacture of naphthalene
US3310593A (en) * 1965-06-23 1967-03-21 Gulf Research Development Co Method for improving the quality of dealkylated aromatic compounds

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014098816A1 (en) * 2012-12-19 2014-06-26 Stone & Webster Process Technology, Inc. Method for reducing energy consumption in a process to purify styrene monomer
US9902667B2 (en) 2012-12-19 2018-02-27 Technip Process Technology, Inc. Method for reducing energy consumption in a process to purify styrene monomer

Also Published As

Publication number Publication date
ES367247A1 (es) 1972-01-16
FR2011841A1 (enrdf_load_stackoverflow) 1970-03-13
BR6908912D0 (pt) 1973-02-15
JPS518928B1 (enrdf_load_stackoverflow) 1976-03-22
DE1923564B2 (de) 1973-05-24
GB1214955A (en) 1970-12-09
DE1923564C3 (enrdf_load_stackoverflow) 1973-12-20
DE1923564A1 (de) 1970-12-03

Similar Documents

Publication Publication Date Title
US2697684A (en) Reforming of naphthas
US3996305A (en) Fractionation of aromatic streams
US4041091A (en) Fractionation of aromatic streams
US2335596A (en) Refining of refractory hydrocarbons
US3623973A (en) Process for producing one- and two-ring aromatics from polynuclear aromatic feedstocks
US3204007A (en) Dealkylation of alkyl aromatic compounds
US3835037A (en) Purification of aromatic hydrocarbons
US3291850A (en) Hydrodealkylation of alkyl aromatic hydrocarbons
US3145238A (en) Hydrodealkylation of special feed stocks
US4070408A (en) Aromatics extraction and distillation process
US3055956A (en) Process for the separation of naphthalene
US3304340A (en) Aromatics production
US4203826A (en) Process for producing high purity aromatic compounds
US3193595A (en) Hydrocarbon conversion
US2380853A (en) Method of producing aromatic hydrocarbons
US3607960A (en) Thermal hydrodealkylation process
US3558729A (en) Dealkylation of alkylaromatic hydrocarbons
US4144280A (en) Vapor circulation in hydrocarbon conversion processes
US3449460A (en) Upgrading of coke oven light oils
US3197523A (en) Dealkylation of alkylaromatic compounds
US3222410A (en) Dealkylation of unsaturated sulfur-containing alkylaromatic hydrocarbons
US3591651A (en) Combination thermal hydrodealkylation diphenyl hydrogenation process
US3448039A (en) Vaporizing and pretreating aromatic hydrocarbon feed stock without polymerization
US3310593A (en) Method for improving the quality of dealkylated aromatic compounds
US4338476A (en) Alkylaromatic hydrocarbon dehydrogenation process