US2859170A

US2859170A - Method of treating hydrocarbons

Info

Publication number: US2859170A
Application number: US493096A
Authority: US
Inventors: Samuel P Dickens; Benjamin F Smith; Wiley P Ballard
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1955-03-09
Filing date: 1955-03-09
Publication date: 1958-11-04
Anticipated expiration: 1975-11-04

Description

Nov. 4, 1958 2 Sheets-Sheet l Filed March 9, 1955 QMR KWSN 593025 Nov. 4, 1958 s. P. DlcKENS ETAL 2,859,170

METHOD oF TREATING HYDRocARBoNs l Patented Nov .:4, 1958.

2,859,170 Mnrnon or TREA'HNG nYDnocARBoNs Application March 9, 1955, Serial No. 493,096

9 Claims. (Cl. 208-85) This invention relates to a method of treating hydrocarbon fractions, such as petroleum fractions and hydrocarbon synthesis (Fischer-Tropsch) fractions. In ac cordance with one embodiment this invention relates to the treatment of hydrocarbon fractions in the naphtha, or gasoline boiling range, said fractions containing straight chain and non-straight chain hydrocarbons, in order to improve their quality. In accordance with stillf. another embodiment this invention relates to an improvedv hydrocarbon conversion process. Generally this invention is directed to the upgrading of petroleum fractions containing straight chain and non-straight chain hydro-v carbons, especially naphtha stocks wherein the amounty of straight chain hydrocarbons is substantial, e. g. in the, range 240% by volume and higher. v

Accordingly, it is an object of this invention to providef an improved process for treating hydrocarbon fractions.V containing straight chain hydrocarbons and non-straight` chain hydrocarbons. I

It is another object of this invention to provide a; flexible hydrocarbon converting process which is capable of handling a wide variety of hydrocarbon fractions containing straight chain hydrocarbons and non-straight chain hydrocarbons.

Another object of this invention is to provide a com? bination hydrocarbon treating process for treating ai, hydrocarbon fraction containing straight chain hydro-l carbons and non-straight chain hydrocarbons wherein the straight chain hydrocarbons are selectively adsorbed by.. means of a Vsolid selective adsorbent, followed by desorption of the straight chain hydrocarbons in a special manner in accordance with. this invention.

Still another object of this invention is to provide a; combination hydrocarbon treating process wherein a hy'V drocarbon'fraction containing `straight chain hydrocar-` bons and non-straight chain hydrocarbons can eventually. be converted substantially entirely to non-straight chain hydrocarbons.

In at least one embodiment of this invention at least one of the foregoing objects will be achieved.

How these and other objects of this invention-are achieved will become apparent with reference to the accompanying disclosure and drawings wherein:

Fig. 1 schematically illustrates one embodiment of the y.

I United States Patent ()flice practice of this invention employing a desorption zone ,60

containing iluidized solids, and

Fig. 2 schematically illustrates another embodiment of the practice of this invention employing in combination an adsorption operation followed by a substantially simultaneous desorption and catalytic reforming of the components adsorbed during the adsorption operation.

In accordance with our invention We haveV provided an improved process for treating or converting a hydrocarbon fraction containing straight chain hydrocarbons and non-straight chain hydrocarbons whichcomprises' subjecting the hydrocarbon fraction to be treated to con- A tact with a selective adsorbent which selectively adsorbs v straight chain hydrocarbons tothe substantial exclusion of non-straight chain hydrocarbons to adsorb straight chain hydrocarbons from said fraction, separating froml the aforesaid adsorption operation a treatedeiuent hav-- ing a ,reduced straight. chain hydrocarbon content and said solid adsorbentcontaining straight chain hydrocarbons adsorbed therein-and entraining the resulting separated solid adsorbent in a .gaseous or vaporous desorbing medium whereby said entrainedadsorbent is carried into contactvwith a mass o'f solid particle-,form

contact material l'under conditions of temperature andV flow such that the straight chain hydrocarbons are desorbed fromv the solid adsorbent while at'thesame time the solid adsorbent is elutriated through the jmassk ofl solid contact material. FollowingY desorption and elutria-y tion of the solid adsorbent there is separatelyk recovered a gas-solids phase comprising the gaseous desorbingmef dium, the resulting gaseous desorbed straight chain hy drocarbons together with the regenerated solid adsorbent entrained therein, thereby eiectingja separation betweenthe solid adsorbent and the solid particle form contact material.- At this point it is mentioned that the separation of the solid adsorbent from the solid particle-form contact material byv elutriation is; due l,primarily to the. substantial diiference in average particle sizebetweenthe solid adsorbent, which is relatively small, and the `solid particle-form contact material, which is relatively large.

By straight chain hydrocarbonsis meant anytaliphaticl or acyclic or open chain hydrocarbon whichdoes ynoty possess side chain branching. Representative straight; chain hydrocarbons are the normal parans and the normal oleiins, monoor polyolens, including theystraightchain acetylenic hydrocarbons. The non-straightvchain hydrocarbons comprise the aromatic and naphthenic hydrocarbons as well as the isoparainic Vand isooleiinic` hydrocarbons and the like. Straight chain hydrocarbon-V containing mixtures which are suitably treated in taccordance with this invention include the varlouspetroleum fractions, such as a naphtha 'action, aA gasoline` fraction, a diesel oil fraction, akerosenefraction,i a gas oil fraction and the like. Particularly suitable for` treatment in accordance with this invention are straight chain hydrocarbon-containing fractions having a boiling 'point or a boiling range in the range 40-600 F, and higher'- and containing a substantial amount of straight chain hydrocarbons, e. g. 2-35% by volume. More'particularly, a petroleum fraction suitable for use in the practice of this invention might have an `initial boiling point in` the range 40-300 F. and an end point inthe range 15G-600 F. Furthermore a petroleum fraction suitf able for use inthe practice of this invention must `contain both straight chain and non-straight `chain hydro-j carbone and might have the following composition:

y Hydrocarbon Type Percent by -l olume Nanhthenps 0-75 A rnmatins f 0-50 Acyclic Saturates (including normal parans and isopar.

adins Y 2-90 Acyelic Unsaturates (including normal olefns and isoolefns) 0-50 Typical refinery stocks or fractions which are applicable A' to the .practice of this inventionare a Wide boilingu straight run naphtha, a light straight run naphtha, a 'f heavy straight run naphtha,` a catalytic cracked naphtha, a thermally cracked or thermally reformed naphtha, a

catalyticreformed naphtha and the like.

Anysolid selective adsorbent which selectively Vad-l i sorbs f straight chain hydrocarbons nto the substantial f exclusion of `non-straight chain hydrocarbons lcan be employed inthe practice of' this invention. It is precarbs, asfthenotijils'parains and normal olens, tray-theA fsrubstantial "j 'c'lusionoffthe "non-straight chain naphthenicgaroniatic, lspa'rainicfandsoolenic hydroselective -'a'dso'rbe'1"at,""Type D5A*4 Molecular Sieve, "is availablepasa" finely'fdivide'dpowder `lvravin'g a vparticle size infime-'range f 5'-f5-;0fnerons,"exhibitin'g 'a bulk Vdensity in'lbsfperf'cubicfotwf 33,"an`d Vaparticle vdensity in grainspercc; (if 315.6; v

1@thersuitable solid selective adsorbents linclude the d neutral l'-'zeolites yzhich, when "dehydrated, may be fdesfcrlbed fas-l crystallinev'zeolites having a rigid the Jdim ina'lnionic 'network' and'having interstitial sufficiently large toadsorb straight chain dimens'lo s'traight cli n hydrocarbons'possessinglarger -rnolecular eiiturally'occrring 4z'eolites, chabazite,

y base ,exchangeV yields a' material Vwhich Vrna'y b'efre esentedbythefoi-mula '(Ca, Naz) AlgSnOlZHG and lwhich,""atte'r suitable conditioning, will adsorb straight hainjhydrocarbons'tothe substantial exclusion o'ffnonstrightichainfhydrocarbons. Naturally occurring o'rfsyiitheticallyprepared;phacolite, gmelinite, harmotome and thelikeA k'or *suitable* base exchange modifications of .-'thfese'i zelitls are-I n so rsuitable.

(Dtler"l Ys'lidl inorganic -`o'rjrnineral selective adsorments are Yk'l'lcvvn dfmayibe' employed inthe lpractice of vthis invention, lItis contemplated that's'elective Vadsorbents having th'e property 'fof "selectively adsorbin'g Vstraight chain ydrocar'bos Ato thesubst'antial'exclusionof Vnonstraight chain: hydrocarbons in5 the manner of a :molecular sieve `may `be obtainedbyfsuit'able,treatment of various oxidegels,fespecially metaloxide gels of the polyvalent amphoterid'metal 'Xides.

The adsorptive Avseparation of 'the lstraig'ht lchain hydroearbons 5f from the hydrocarbon fractionv `undergoing treatne'nt-"niayfbe `T:':arried i outY1 in V"the `liquid or gaseous vphase and Vat any suitable temperature and 'pressure ef ective'inthe adsorptive separation operation. It is desirable,'of course, to coordinate the adsorptive separation conditions, e. g. such as temperature and pressure with 4. by simply slurrying the solid adsorbent with the liquid "hydrocarbon fraction to be treated, followed by separation or decantation of the nreated hydrocarbon eluent now substantially free of or having a reduced straight chain hydrocarbon content. Liquid phase adsorption may also be carried out by percolating the liquid hydrocarbon fraction to be treated through a bed of solid adsorbent ymaterial. It is preferred, however, in the practice of this 4invention to carry out the adsorptive the desorptivefsepr'ati'on 'c'nditinsfde'scibed herein'- Y after so as to effect 'fa most' economical -use*of"the `ma-v terials employed and fors'eofc'nt'l.

The adsorptive Yseparationwofwthe -straight -chain hy'- drocarbons by the solid selective 'adsorbent'may be carried out Jatany suitabletemperature such as a temperature in theerange 50,-1000" FLyandfat;anysuitable 'pressure such asapressure in the-range 0-10,000p. s. i. g. 'and highenthe temperature and pressure being adjusted withy respectwto the hydrocarbon lfractionundergoing treatment depending upon -whether;-ornot `iteiswdesiredfto maintain4 f the (hydrocarbon fraction :in ,-th'e liquid phase or inA the vapo;y phase during-the-jadsorptive separation operation. Liquidfphase adsorption'may be carried-Out Y Iinthe Arange' lil-'22000 p. s. i. g. 'is suitable.

times *desirable-to* 'carry -out the desorption operation at'y a pressure VVsubstantially lower 'than thek adsorption 'pres-1 In general, the pressure employed during Ythe'- higher or lower, may be employed.

however, lto carry out the ndesorption operation at an' elevated temperature `such as a temperature in the'range" separation operation in the gaseous phase, that is 'to' maintain the hydrocarbon fraction undergoing treatment in the vapor phase during the adsorptive separation operation. Any suitable methodl for effecting gas-solid contact maybe employed, for example a fixed bed, amoving Y bed or a fluidized bed of selective adsorbent may be lt Vis employed during gas phase fadsorp'tive separation. preferred in the practice of this invention to employ a nely divided solid selective adsorbent such as a sodium calcium alumina-'silicate as *exemplied'bythe Linde Type 5A 1'lvlolecula'r VSieve, having `a particle size distribution inthe lrange 0.5-5.0 microns vand'v to Ventrain the adsorbent' t`o the "gaseous hydrocarbonfraction undergoing treat-` `After a*su'icient.contact4 time, the entrained solidadsorbent'is.separatedffromfthe gaseous treated ei'lluent ment.

now having -a reduced `amount of straight Vchain hydro-A carbons. Theseparated `solid adsorbent is then subsequently treated Vto ydesorb the lstraight chain hydroarbons therefrom.

The desorption of straight "chain hydrocarbons from the solid 'adsorbentmaterial-canbe'made'at any suitable temperature orf'pres'sure. AFor example, the desorption operation maybe carried out at 'apressure in the rangev 0-10,000 p. s. i. g. `Generally a desorption lpressure sure. ads'rptive separation "operation 'is` not vdeterminative of the-desorption `pressure and any :suitable desorption pres'- sure may be employed. Substantially thesame'com-i ments may AYbe'made with respect tofthe desorption tem` perature.

A`Generally any suitable 'desorptive temperaturernaybe employed in the practice of this invention. It is some-` times'desirable, howeverfto carry out'substantially iso` thermal adsorption-desorption"operations l desorption' temperature in the 'range 400;'1100" "FQ,

700 F.-1l00 It is realized, of courseyth'at 'the desorption temperature should not be excessively high,KV

for examplejnot greater than about 110Gl300 YF.,`in

'the c'aseof Linde lTypeSA Molecular Sieve, "which excessive temperatures would lead 'to destruction of the adsorbent material, presumably by collapse of the crystal structure, with resultant' loss'of its selective adsorption.A properties.

Although 'it is 'possible to effect desorption of the V straight chain hydrocarbons from the solid adsorbent by the application Yof heat alone, for `example by 'radianti` heating or by indirectheat exchange, it is a feature of` this 'invention that the Vdesorption operation is carried out in the presence of a gaseous desorbing'medium Within which the 'selective adsorbentl undergoingdesorptio'n or regeneration'isfentrained. Generally any suitable gaseous desorbinglmedium may be employed vin the practice 'of this invention. As a general rule, however, it is preferred to employ a gaseous desorbing medium the molecules' of 'which are su'ici'entlysmall so th'at'penetration of the pores of theiadsorbent may be effected. The'vfollowingvmaterials ymay fbe femployed'las the gaseous desorbing medium: nitrogen, methane,hydrogen, carbonvdioxide, carbon'monox-ide,}.lue;gas, substantially dry vnatural :gas f (mixture of-methanefand ethane) andthe=like including:

Any suitable It` is preferred, V

assedio,

5.. airunderjcontrolled temperature conditions, and steam, preferably superheated steam. In general, any vaporizable material which possesses a high heat capacity,v is thermally stable and which is readily separable, as by distillation or condensation, from the desorbed straight chain hydrocarbons may be used.

During the desorption of the straight chain hydrocarbons from the entrained powdery solid adsorbent the adsorbent is at the same time elutriated through a mass of solid contact material under conditions such that the desorbing medium together with the desorbed straight chain hydrocarbons and the entrained solid adsorbent pass through the interstices of themass of solidcontact material and are separated therefrom. The mass of solid contact material may comprise a xed bed, a moving or falling bed or a luidized bed of solid particle-form contact material. This solid particle form contact material serves to maintain the desorption operation at the desired desorption temperature. v Additionally, besides serving as a means to control the desorption temperature, the solid contact material also tends toaid the desorption of the straight chain hydrocarbons from the adsorbent by provmoting contact between the adsorbent and desorbing medium, such as by increasing residence time and the like. The solid contact material may serve as a means for effecting desorption temperature control in the following manner. For example, in the instancewhen the gaseous desorbing medium, also employed to ventrain the solid adsorbent, is initially ata relatively high temperature, e. g. 700 F. or'above about 700 F., upon introduction of the desorbing medium together with* treated solid adsorbent into the desorption zone which contains solid particle-form contact material the desorption operation can be conveniently carried out at a temperature lower than about 700 F. by supplying and maintaining in the desorption zone relatively cool solid particle-form contact material.' Alternatively, vshould it be desired to maintain the desorption operation, i. e. the desorption zone, at a relatively elevated temperature, e., g. above about 700 F., while at the same time introducing into the desorption zone the gaseous desorbing medium together with the entrained adsorbent at a ternperature below 700 F., e. g. 500 F., the solid contact material is maintained or introduced into the desorption zone at a relatively elevatedtemperature, such as above about 700 F. vAccordingly in view of the foregoing it is apparent that, depending upon the temperature of the desorbing medium together with entrained adsorbent with respect to the solid particle-form contact material, the solid particle-form contact material may serve as a means for cooling or heating the desorbing medium. If desired the solid contact material may be maintained at a rather high temperature during the desorption operation,-

suciently high, preferably not higher than 1300 F., to effect tnermal cracking of the desorbed straight chain hydrocarbons. In the instance where the solid particleform contact material is introduced or maintained in the desorption zone at substantially the same temperature as the gaseous desorbing medium the solid contact material serves substantially only to provide a more eicient desorption operation by promoting more intimate and vigorous contact between the desorbing medium and the solid contact material being elutriated therethrough.

The solid particle-form contact material provided in the desorption zone may comprise any substantially inert, solid thermophore such as a non-metal or metal or their oxides, or refractory ceramic material, in the form of granular particles, pellets, balls, etc. When the contact material is in the form of a porous xed bed the mass of contact material should be sufficiently permeable so that the powdery adsorbent material can be readily elutriated therethrough. If desired, the solid contact material may be in the form of a uidized bed, iiuidization of the solid contact material conveniently being Veffected by the,

desorbing medium flowing therethrough.. .Y

Inaccordance with one embodiment of the -practice of this invention the solid. contact material possessescracking activity with respect to straight.chain hydrocarbons, that is, it comprises a cracking catalyst such as a silica-alumina cracking catalyst. When a .cracking catalyst is employed as Vthe solid contact material or as a component thereof'and when the desorption operation is carried out at a suitable elevated temperature, e. g. above 800 F., not only are the straight chain hydrocarbons desorbed but substantially simultaneously with the desorp tion operation the straight chain hydrocarbons are cracked to form corresponding low molecular weight hydrocarbons and corresponding olefinic or unsaturated hydrocarbons. Suitable cracking catalysts are wellA known to those skilled in the art and generally comprise aluminosilicates. Cracking catalysts are available` in various forms and sizes, e. g. pellets, beads, microspheres and the like. In the practice ofV this invention the cracking catalyst employedy should have an average particle size? substantially greater than the average particle size of thel adsorbent material, so that the adsorbent material can be readily elutriated through the mass of cracking catalyst when .the cracking catalyst is maintained in a fixed bed,` a moving or falling bed or a uidized bed. In the uidthat is a reforming or isomerization catalyst. Reforming-i catalysts are well known and comprise such materials asA a platinum-containing catalyst, a cobalt molybdate cata` lyst, socalled Hyperforming catalyst, chromia-aluminaV catalyst which may be identified as a Sovaforming or Thermofor catalytic reforming catalyst, a molybdenaalumina catalyst sometimes referred to as a Hydroforming or Orthoforming catalyst and the like.

dergo. substantially simultaneously a number of reactions vincluding isomerization, dehydrogenation, aromatizationV or dehydrocyclization, cracking, disproportionation, and the like depending upon the severity of the desorbingreforming conditions and the composition of the desorbed straight chain hydrocarbons. It is apparent in view of the foregoing that when the solid contact material comprises a reforming or isomerizing catalyst simultaneous desorption and reforming or isomerization of the straight chain hydrocarbons is accomplished.

.Generally straight chain hydrocarbon reforming or isomerization operations are carried out at a temperatureV in the range 750-1100 F. and at a pressure in the range l0-1,000 p. s. i. g., more or less, desirably in the presence of hydrogen. The severity of the reforming or isomerization'operation is dependent to some extent upon vthe I composition of the desorbed straight chain hydrocarbons and the quality or composition of the catalytic reformate' desired. Uusually during the reforming operation there is a net production of hydrogen (due to dehydrogenation of the hydrocarbons) which advantageously is subsequently separated from the resulting eluent and employed as a desorbing medium as Well as the means for elutriating the powdery adsorbent through the reforming catalyst.

Referring now to the drawing and in particular to Fig. 1 thereof which schematically illustrates one embodiment of the practice of this invention as applied to A the treatment of a hydrocarbon naphtha fraction, a light straight run naphtha having a boiling range in the range e 45-250 F. and containing straight chain hydrocarbons and non-straight chain hydrocarbons is supplied in vapor# ized form via line 11 into conduit 12 which is supplied Molecular Seive, from hopper 13.

During re` forming the desorbed straight chain hydrocarbons un-' Vstraight chain hydrocarbon. content.

phase in line -1'5 isintroduced into va :gas-solids separator 16 whereinY the `solid eadsorbent separated. from the resulting 4treatedygaseous :efuent which is removed Vvia line .19. The `gas-:solids separator y1.6 may 'comprise' va cyclone, Va Cottrell precipitator, ceramic lter, bag lter or .combinations'fof'theaboveto Leiect substantially complete fseparationrofI-the rsolid adsorbentffrom the gas stream. The separated solid' adsorbent is `removed from theiga's-.solids Vseparatoralt via line 20. If desired, depending upon foperating conditions within the adsorber, a portion of this removed-adsorbent may be recycled to adsorber 14 via line 2.1 toY effect a substantially complete separation `of the straightfchain hydrocarbons from the naphtha fraction Vintroduced into adsorber 14. The above-described adsorption operations are carried out at substantially atmospheric pressure and `at a temperature in the range 50550 F.

- When lthe powdered adsorbentl is made up of finely divided sparticles, as zin the case rof Linde Type 5A Molecular Sieve which has 'a particle size in the range 0545.0 microns, allof the adsorbent sometimes will not be recovered ,by the ,gras-solids separator 16 alone. In order to recover the more iinelydivided `adsorbent which remains-ehtrained in the treated `elluent or naphtha leaving separator v16 via line 19, the treated euentis passed via line `17-thoughcondenser18 :to cool and condense the treatedl naphtha and then through line 27 into liquidsolids separator 28 from i which the liquid treated naphtha, Vsubstantially free of adsorbent, isfremoved via line 37. The-separated adsorbent, wetted by the treated naphtha is removed from liquid-solids separator `28 via lnef38 for recycle to adsorber 14 or for introduction via line 47 into relatively hot, dry adsorbent in line 20. Liquid-solids separator 28 may comprise a battled tower orhold-up settling tank, alone or in combination with a liquid-solids lter, suitable .to eifect separation of solids from liquid.

The solid adsorbent material, containing straight chainl hydrocarbons adsorbed therein removed from separator 16 via line 20 is contacted in line 22 with a gaseous desorbing medium comprised predominantly of' methane introduced into line 22 by means of line 23. The gaseous desorbing medium, methane, entrains the solidadsorbent material within line 22 Vand introduces the same into a fluidized solids desorber or desorption zone 24 which also contains a uidizedmass ofrelatively inert solid particle-V form contact material, such as solid metal particles or balls or abrasion-resistantrefractory pebbles, the gaseous A desorbing medium serving to elutriate Athe .entrained adsorbent'material through the uidized bed'of contact:-ma` terial and at the same time'serving toifluidize said'co'ntact Because of the great difference infparticle-s'i'ze material. between'the adsorbent material, iwhich possess a particle size in the range 0.5-5.0 microns, and the contact'material which has a particle -size5greater-.than 200Ym`esh,the solid adsorbent material, after intimate Contact: with the desorbing medium and Asolid contact material within desorption zone 24 is elutriated therethrough and removed as va relatively dilute 'gas-solids phase from the top of desorber 24 via line 25. Desorber 24 is maintained at an effective desorption temperature in the range 700-800 vF. by introducing the desorbing medium, methane, at substantially that temperature. The desorption operation vis endothermic and accordingly the heat of desorption must be supplied.v The heat-of desorption xiapparatus and conduits.

is advantageously supplied rin. accordance 'wi'thlthi'sf in-l ventionv by.:continuous1y withdrawing Aa portion of r`the uidized solid.contact material from withinvdesorber 24 by means /of lin'e226 passing-.the `same to heatl eX- changer 29y wherein.its.1temperature is increased fsuiciently so that when it is.:returned to desorber24 via .line 30;su1cient heatlisravailable therein to maintainthe -de sorption-operation-r Idesorberr24iat the .desired desorptiontemperature.I Aslindicated-.in Fig. 1 la portion of the desorbing mediumfis desirably introduced into ydesorber 24 by meansot' line1'3v1to aid inuidization ofthe solid .contact .materialitherein and `another portion .is desirablyintroducedvbymeans of :line 32 into line 26 in` order toiecttmovement ofthe :solid Contact material i througllline` 26, s heateris29z'and `line 30 .back .into-deorder to betterz-eiect controlof the desorption operation.l

The whole relatively. 'dilute gas-solids phase is withdrawn from Vline l2'5-via:1ine.36.and introduced into gas-solids separator lt9itoeiect separation ofthe 'desorbed-regenerated adsorbenthfrom the gasstream which is withdrawn via line 40 and .passedzto a straight chain hydrocarbon recoveryplant forseparationof the'straight chain hydrocarbons `fromthe methane desorbing medium. The separation of fthevdesorbed straightchain hydrocarbons from' thefmethane desorbingimediurn may be `elected by charcoal-.adsorptionand .ther like, the methane desorbing medium .being separately Vrecoveredand recycled to de sorber .24.

f As previouslyzindicated with respect to the operation of gas-solidsfseparator 16, if -a substantial amount of adsorbent-,remainsentrained in the `gas phase issuing'via line 40 from gas-solids separator 39, the gas streamis introduced via line 49`into cooler-condenser 50 for condensation of lthe 'normally' `liquid desorbed hydrocarbons and then via line 151 intoliquid-solids separator 52. A

liquid stream comprising substantially only straight chain.

hydrocarbons is recovered from separator 52 via line 56, provisionalso being made for the recovery of the gaseous desorbing medium via line'SS and for the withdrawal'of liquid water (condensed lstearn) via line 5@ in the event steam is employed as the desorbingV medium. The solid' adsorbent, -separated in liquid-solids separator 5 2, now wetted Aby the liquefied straight chain hydrocarbons and/ or water, is Withdrawn via line 53 for admixing with the previously separated dry adsorbent in line 41 or, if def line 42. As indicated fresh naphtha feed is injected into line 4i by means of line '43 in order to effect movement or transfer of the desorbed-regenerated adsorbent -eveny tually to adsorber 14.

Referring now inV detail to Fig. 2 of the drawing which .schematically illustrates another feature of the practice of this invention wherein a reforming catalyst is em ployed as said solid particle-form Contact material such that 'the desorption and reforming operations are carried out substantially simultaneously, that is catalytically reas they are desorbed from the solid adsorbent.

reference numerals employed with respect to Fig. l are alsousedin Fig. v2 to identify substantially vrthe sam essaim Il 3riefly1,l Fig. 2 schematicallyillustrates an operation 'wherein Ystraight chain hydrocarbons-are adsorbed from a naphtha `fraction in a gaspha/se adsorption system, .followed by separation of the adsorbent containing straight chain hydrocarbons adsorbed therein, thereby yielding a naphtha eluent having a reduced straight chain hydrocarbon content or substantially free. of straight chain hydrocarbons. The resulting adsorbent material is con- -tacted with a gaseous desorbing medium, hydrogen,'and -entrained therein and introduced into a desorption zone 'which is provided with a uidized bed of reforming catfalyst, e. g. a so-calledHydroforming or Orthoforming catalyst, wherein Vthe straight chain, hydrocarbons are ldesorbed from the adsorbent and reformed in the pres- -ence of the reforming catalyst. A stream of spent reforming catalyst is withdrawn Yfrom the combination de- .sorber-reformer and introduced into a catalyst regeneration zone wherein any carbon deposited upon there- :forming catalyst is burned oi by contact with air. The resulting hot regenerated reforming catalyst is returned to the combination desorber-reformer.V At the same time there is produced overhead from the combination delsorber-reformer a relatively dilute gas-solids phase comprising the stripping medium, hydrogen, gaseous catalytic reformate comprising straight chain-and non-straight chain hydrocarbons, and the desorbed-regenerated adsorbent which is eventually recycled into the aforementioned adsorption zone. The desorbed-regenerated adsorbent is separately recovered and recycled to the adsorber, the resulting catalytic reformate being separately recovered from the hydrogen desorbing medium. If desired a portion of the recovered catalytic reformate may be recycled to the adsorption zone -for the removal of straight chain hydrocarbons therefrom.

Referring now in greater detail to Fig. 2 a naphtha fraction which may be higher boiling than or substantially the same as disclosedwith respect to Fig. 1, is introducedv via line 11 Vinto conduit 12 wherein it contacts and entrains powdered solid adsorbent, e. g. Linde Type A Molecular Sieve, supplied to conduit 12 via hopper 13. The gaseous naphtha fraction containing entrained solid adsorbent enters adsorber or adsorption zone 14 wherein atleast a substantial amount of straight chain hydrocar bons originally present in the naphtha fraction are adsorbed by the adsorbent. There issues from adsorber 14 via line 15 a gas-solids phase containing resulting treated lnaphtha fraction now having a reduced straight chain hydrocarbon content and containing entrained solid adsorbent. This gas-solids phase enters gas-solids separator 16 wherein substantially all or a substantial amount of r the adsorbent is separated via line 20. The ramaining treated naphtha eluent may be separately withdrawn via line 19 or introduced by means of line 17 into cooler or condenser 18 to liquefy the treated naphtha fraction which is transferred via line 27 into a liquid-solids separator 28 for the removal of any remaining solid adsorbent. A liquid treated naphtha efuent substantially free of adsorbent is removed via line 37. This treated effluent is substantially free of straight chain hydrocarbons. Any solid adsorbent removed in liquid-solids separator 28 is recycled to adsorber 14 via line 38 and/or introduced into line 20 via line 47.

The separated solid adsorbent removed from separator 16 via line 20 is introduced into line 22 wherein it is contacted by gaseous desorbing medium, hydrogen, introduced thereinto via line 23. The resulting entrained adsorbent together with the hydrogen is introduced into combination desorber-reformer 24 wherein is maintained a liuidized bed of hydroforming catalyst such as a socalled Orthoforming catalyst comprising a molybdenaalumina catalyst maintaining a minor amount, e. g. 9l1% by weight, M003. This reforming catalyst is maintained as fluidized bed within desorber-reformer 24 by the injection thereinto of gaseous hydrogen via lineA 31. Because of the great difference in average particle Asizey between the entrained solid adsorbent introduced into the combination adsorber-reformer via line 22 and the iluidized reforming catalyst therein, the solid adsorbent is elutriated through the mass of fluidized reforming catalyst and there issues overhead from adsorber-reformer 24 via line 25 a relatively dilute gas-solids phase containing gaseous hydrogen and gaseous :catalytic reformate containing entrained solid adsorbent. If desired a portion of this whole gas-solids phase may be recycled to absorber-reformer 24 via line 33.

The whole gas-solids phase issuing from adsorberreformer 24 via line 25 is introduced via line 36 into gas-solids separator 39 wherein a substantial portion of the desorbed-regenerated entrained adsorbent is separated and removed via line 41. The gas phase separated from gas-solids separator 39 is introduced via line 49 in cooler or condenser 50. The resulting cooled mixture now containing gaseous hydrogen, liquefied catalytic reformate and any entrained solid adsorbent is introduced via line 51 into vliquid-solids separator 52 wherein the entrained solid adsorbent material is removed via line 53. This removed solid adsorbent may be directly introduced into desorber-reformer 24 via line 54 or into line 41 which contains desorbed-regenerated adsorbent separated from gas-solids separator 39.

Gaseous hydrogen is removed from separator 52 via line 55 and desirably it is recycled to desorber-reformer 24 as the desorbing medium. Liquid reformate is removed from separator 52 via line 56. If desired this liquid reformate, containing straight chain and non-straight chain hydrocarbons is .recycled to adsorber 14 in order to remove the straight chain hydrocarbons therefrom.

Provision is made for the separate Withdawal from separator 52 by means of line 59 of liquid water in the event that steam or superheated steam is employed together with hydrogen as the desorbing medium.

As is apparent in Fig. 2 provision has been made for the regeneration of spent reforming catalyst. In accordance with this embodiment a stream of spent reform-V ing catalyst is withdrawn from adsorber-reformer 24 by means of line 26 and introduced into catalyst regenerator 60 wherein it is contacted and iluidized by means of incoming oxygen-containing stream such as air introduced into regenerator 60 via line 67. Within catalyst regenerator which is operated at a suitable catalyst regeneration temperature such as a temperature in the range G-120()c F. substantially all of the carbon'which may have been deposited upon the reforming catalyst is burned. The resulting regenerated reforming catalyst.

is removed from catalyst regenerator 60 and introduced into adsorber-reformer 24 via line 61. Provision is made for the recovery of any catalyst iines entrained in the regenerated off-gas or flue gas by means of line 62, gassolids separator 63 and recycle line 64.

It has been observed in actual practice that after the solid absorbent material has undergone a number of adsorption-desorption operations, particularly when rela-A tively high desorption temperatures are employed (desorption temperatures in the range 600ll00 F.), carbon is deposited upon the solid adsorbent material with the result that its adsorptive capacity is adversely affected. in accordance with this invention provision is made for the intermittent or continuous regeneration of the desorbed adsorbent issuing from adsorber-reformerk 24 by the withdrawal of a side stream of a solid adsorbent of 24 via line 65 and introducing the same into regenerator 60 wherein carbon is burned therefrom. The regenerated adsorbent is removed from regenerator 60 via line 62 and separated in gas-solids separator 63 and returned via

lines

64 and 66 to line 41 for eventual introduction into adsorber 14.

In accordance with still another feature of this yinvention the reforming catalyst regeneration and the re` generation of the spent adsorbent may be carried out substantially simultaneously within regeneratorV 60 by 11 elutriating 'thesolid adsorbent through l the L-'fii1`i 'i.ized 'mass of-J catalystundergoing regeneration `-in regenerator' `60, in :almanner similar to the operation :adsorberi-re'former 2'4, the small amount of catalyst nes 'which may be taining straight chain hydrocarbons and non-straight chain lectively Vadsorbs "straight `'chain Yhydrocarbonstothe sub- Y introduced intothe -vregenerator adsorberitestre'am issu- 5 stantialexclusionof non-'straight chainhydro'carbonsito in'glirom fregenerat'or "60 `-via line "62 being `considered adsorb straightchainjhydrocarbons therefrom, 'thereby negligible. Y t producing-atreatedieuent havinga reduced amount of Although,-w1th respectJtoF1g.- 2,1thepractice fofthis straight chainhydrocarbons, Vseparating s'aidisolid vjadi'nvention lhasibeen'illustrated `whereinfa-'so=ca1ledrortho sorbentf-now-"containing straight chain 'hydrocarbons adforming or hydroi'o'rming molybdena-alumina catalyst iS 10 sorbedtherein, from'said'treated euent,.contactingsaid employed, `1tis pointed 'out that any suitable catalyst separated solid "adsorbentwith a 4gaseous"'desorbinglme.- whicheffects the desired conversionI or treatment of the dium in the*'presence'ofaporous'xed massof particle# desorbed/'straight chain hydrocarbons, lfor example, a formcatalyticmaterial'under conditions.. to e'iect desorp- Pl'al'IlUITl-COIIHDDg Vfefrnl'lg 01" SOmel'Zillg Catalyst tionfof said straight' chain hydrocarbons from` saidadsuch'as the platforming catalyst or ultraforming cata- 15 sorbentfandcatalytic conversioniofntbe,resultingdesoibed lysty maybe employed. Also'a cracking catalyst 0r a straight'chain*hydrocarhonswherebylhe resulting regendeh'ydroge'nation-aromatization vcatalyst such as afcatamated-adsorbentv together the converted'desdrbed IYS COIltaining chromia, alumina and magnesstraight chain hydrocarbons'rand gaseous desorbing me` 'Further illustrative ofthe practice -of this invention dium pass"through"the-interstices of saidxe'd bed fof a mX'fUre 0f Straight Chainhydl'ocarbon Comparable t0 20 catalyst, recovering from the aforementioned desorptionthe mlxture, or stralght cham hydroearborrs released r conversion -`'operation a relatively dilute gas-solids phase desorbed 'within 'desorber 24 and comprislng 23% by comprising converted hydI-Oc-bons wgaseousdes'obillg Volume IPPSHHIIS, 55% by Volume 1141321116 and 2 170 medium and said 'regenerated adsorbent substantially'free by Volume D'heptme Was C Ont'fered Wrrh a Parrrele of said catalystyandrseparating said adsorbent fromsaid form dehydrogenation-aromatization catalyst comprising dute'gaySHdS-phaS-e. Cr2O3`-Mg( )*-A12O3 ai Various temperatures and at a `2. Arnethod in vaccordance with claim '1 wherein a space Veloclty er about 0-4 V-/hrJ V- at a Pressure ef portion of. said converted. hydrocarbons, after separation about 49 P' s- 1- gand at a H2 recycle rate O f 1200 of `the regenerated adsorbenttherefrom, is recycledfto cu. ft./ bbl. of feed. The properties of the resulting up- Contact Sadrst memiohedhydrocarbon *stream -forfthe4 graded Product are Set frthim Table NO- L removal of straight chain hydrocarbons therefrom.

Table Na I 3.'A method offtreating @gaseous Stream-containing sttaglitV chain' hydrocarbons and non-straight chai'rihydr TempvoF A n Y n ,920 943 carbons which comprises'contacting Vsaid"stream with a.

particle-form selective.. adsorbent whlch sellecttve'lyad- Wt. percent recovery 93:8 81.3 sol-b s "Stralgh-t chaln hyd1ocabonsl to the srubstantrsll B X' Bwinine No y2o 22 clusion' of non-straight chain hydrocarbons toy Vadsorb Xgl'ii/ir; lrlltlra'f mig 511g straight chainhydroc'arbons therefrom, 'thereby pr't'iduei V+3 cc.TEL/sa1 80.4 80.2 ing a gaseous treated efuent and having a reduced 40 amountofjstraight chain Vhydrocarbons and containing Likewise, the same mixture of straight chain hydro saidadsorbent entrained"therein, separating said solid carbons was contacted with a number of platinumcon adsorbent from said .treated eluent, entrainng said septaining reforming or predominantly isomerizing catalysts arated adsorbent inagaseous.desorbingvmedum and' passat apressure of about G p. s. i. g., a H2 recycle rate ing'the same into contact with a u'idized mass of'reform-f of about 4000 cu. ft./bbl. charge. The results are set ing catalyst under conditionssuch that the straightchain forthin Table No. II. j hydrocarbons Vare 'des'orb'etlV from said slid adsorbent Table N0. II

Temp., F 800 850 900 Catalyst A B C A B C A B C 1 .D.GasMake 0.209 0.173 0.150 0.414 0.338 0.299 2.567 2.609 0.715 Liq. Rec.,Wt. Percent 95.9 99.8 90.1 95.0 99.0 88.2 67.7 :70,1 72.7 Isomate ASTM Res., Clear 60.0 51. 0 54. 0 75. 4 74. 0 77. l 89, 6 70.0 .78. 9 Finished ASTM Res., Clear. 78.0 61.0 72.0 84.0 82.0 82.6 80.3 Finished, +3 cc. TEL/gal 86.0

A-Platiorming catalyst. B-Sinelair-Baker Rd 150 catalyst. C-Ultraforming catalyst.

vFor purposes of simplicity and clarity, conventional and are catalytically reforrnedby'contact'withsaidfluid-i control equipment, valves, pumps, compressors, heaters, ized catalyst, elutriating the resulting regenerated adsorb coolers and supplementary gas-liquid gas-solids and ent from said fluidized massof'catalysttogetherwithsaidV liquid-solids separators, fractionators, etc. have for the gaseous desorbing'medium andthejresulting reformed` most part not been illustrated in the drawings. The straightchain hydrocarbons, V'separately"withdrawing"a location and employment of these auxiliary pieces of portionof the catalyst from-said`-uidized bed, regeneratV` equipment such as may be necessary in the practice of ing kthe same and returning 'the'fresulting regenerated this invention are well known to those skilled in the catalyst to'said'uidized bed. art. 4. Afmethod in-,accordancewithclaim 3- wherein said vAs is evident to those skilled in the art many modigaseous desorbing medium comprises-predominantlythy# fications, substitutions and changes are possible 1n tne drogen. practice of this invention without departing from the 5.-'A1nethod 'or treating a hydrocarbon stream `con'- spirit or scope thereof. taining straight chain hydrocarbons and non-straight We claim: chain hydrocarbons which fcomprises'- Vcontacting:said vl. Arnethod of treating alhydrocarbon'streamcon- `751st'1'eamwith a solid particle-form V4selective adsorbent which selectively adsorbs straight chain hydrocarbons to the substantial exclusion of non-straight chain hydrocarbons to adsorb straight chain hydrocarbons therefrom, thereby producing a treated eihnent having a reduced amount of straight chain hydrocarbons and containing said solid adsorbent entrained therein, separating said solid adsorbent from said treated efuent, contacting said separated solid adsorbent with a gaseous desorbing medium in the presence of a uidized mass of reforming catalyst under conditions to effect desorption of said straight chain hydrocarbons from said adsorbent and catalytic reforming of the resulting desorbed straight chain hydrocarbons whereby the resulting regenerated adsorbent together with the reformed desorbed straight chain hydrocarbons and gaseous desorbing medium pass through said uidzed bed of reforming catalyst, recovering from the aforementioned desorption-reforming operation a dilute gas-solids phase comprising reformed hydrocarbons, gaseous desorbing medium and said regenerated adsorbent and substantially free of said reforming catalyst, separating said adsorbent from said dilute gas-solids phase, recycling at least a portion of said separated regenerated adsorbent to contact said first-mentioned hydrocarbon stream, recovering said reformed straight chain hydrocarbons, separately withdrawing spent reforming catalyst from said uidized bed to a catalyst regeneration zone wherein it is contacted with an oxygen-containing stream to regenerate said withdrawn catalyst and recycling the resulting regenerated catalyst to said uidized bed,

6. A method of treating a gaseous hydrocarbon stream containing straight chain hydrocarbons and non-straight chain hydrocarbons which comprises contacting said gaseous stream with a particle-form selective adsorbent which selectively adsorbs straight chain hydrocarbons to the substantial exclusion of non-straight chain hydrocarbons to adsorb straight chain hydrocarbons therefrom under conditions whereby said particle-form adsorbent is entrained in said gaseous hydrocarbon stream, separating said solid adsorbent now containing straight chain hydrocarbons adsorbed therein from the resulting gaseous eu- 14 ent now having a reduced amount of straight chain hydrocarbons therein, contacting and entraining said solid adsorbent in a gaseous desorbing medium and passing the resulting relatively dilute gas-solids phase into contact with a relatively dense gas-solids phase containing a uidized mass of solid particle-form reforming catalyst maintained as a uidized bed by said gaseous desorbing medium, the desorption contacting operation being carried out under conditions to effect desorption of said straight chain hydrocarbons from said adsorbent and catalytic reforming of the resulting desorbed straight chain hydrocarbons by said reforming catalyst, elutriating the resulting regenerated adsorbent from said uidized mass of reforming catalyst by means of said gaseous desorbed medium together with the gaseous resulting reformed hydrocarbons, separately recovering said regenerated adsorbent from said gaseous reformed hydrocarbons and said gaseous desorbing medium and recyclingthe separated adsorbent to the aforesaid adsorption contacting operation.

7. A method in accordance with claim 6 wherein said reforming catalyst is a chromia-alumina reforming catalyst.

8. A method in accordance with claim 6 wherein said reforming catalyst is a molybdena-alumina reforming catalyst.

9. A method in accordance with claim 6 wherein said catalyst is a platinum-containing reforming catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 2,380,853 Linn et al. July 31, 1945 2,393,636 Johnson Jan. 29, 1946 2,425,535 Hibshman Aug. 12, 1947 2,446,247 Scheineman Aug. 3, 1948 2,522,426 Black Sept. 12, 1950 2,539,005 Berg Ian. 23, 1951 2,620,363 Hibshman Dec. 2, 1952 2,636,574 Widdowson et al Apr. 28, 1953 2,651,597 Corner et al. Sept. 8, 1953 2,666,733 Scorill Jan. 19, 1954 2,793,713 Fritz et al. May 28, 1957

Claims

1. A METHOD OF TREATING A HYDROCARBON STREAM CONTAINING STRAIGHT CHAIN HYDROCARBONS AND NON-STRAIGTH CHAIN HYDROCARBONS WHICH COMPRISES CONTACTING SAID STREAM WITH A SOLID PARTICEL-FORM SELECTIVE ADSORBENT WHICH SELECTIVELY ADSORBS STRAIGHT CHAIN HYDROCARBONS TO THE SUBSTANTIAL EXCLUSION OF NON-STRAIGHT CHAIN HYDROCARBONS TO ADSORB STRAIGHT CHAIN HYDROCARBONS THEREFROM, THEREBY PRODUCING A TREATED EFFUENT HAVING A REDUCED AMOUNT OF STRAIGHT CHAIN HYDROCARBONS, SEPARATING SAID SOLID ADSORBENT, NOW CONTAINING STRAIGHT CHAIN HYDROCARBONS ADSORBED THEREIN, FROM SAID TREATED EFFUENT, CONTACTING SAID SEPARATED SOLID ADSORBENT WITH A GASEOUS DESORBING MEDIUM IN THE PRESENCE OF A POROUS FIXED MASS OF PARTICLEFORM CATALYTIC MATERIAL UNDER CONDITIONS TO EFFECT DESORPTION OF SAID STRAIGHT CHAIN HYDROCARBONS FROM SAID ADSORBENT AND CATALYTIC CONVERSION OF THE RESULTING DESORBED STRAIGHT CHAIN HYDROCARBONS WHEREBY THE RESULTING REGENERATED ADSORBENT TOGETHER WITH THE CONVERTED DESORBED STRAIGHT CHAIN HYDROCARBONS AND GASEOUS DESORBING MEDIUM PASS THROUGH THE INTERSTICES OF SAID FIXED BED OF CATALYST, RECOVERING FROM THE AFOREMENTIONED DESORPTIONCONVERSION OPERATION A RELATIVELY DILUTE GAS-SOLIDS PHASE COMPRISING CONVERTED HYDROCARBONS, GASEOUS DESORBING MEDIUM AND SAID REGENERATED ADSORBENT SUBSTANTIALLY FREE OF SAID CATALYST, AND SEPARATING SAID ADSORBENT FROM SAID DILUTE GAS-SOLIDS PHASE.