US2881128A

US2881128A - Hydrocarbon conversion system

Info

Publication number: US2881128A
Application number: US453888A
Authority: US
Inventors: Bednars Charles; Martin R Smith; George W Stanford
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1954-09-02
Filing date: 1954-09-02
Publication date: 1959-04-07
Anticipated expiration: 1976-04-07

Description

APIil 7, 1959 c. BEDNARs ETA.

HYDROCARBON cNvERsIoN SYSTEM Filed Sept; 2, 1954 kondom u United States Patent HYDROCARBON CONVERSION SYSTEM Charles Bednars, Port Washington, N.Y., and Martin R. Smith, Glen Ridge, andGeorge W. Stanford, Linden, NJ., assignors to The M. W. Kellogg Company, Jersey City, NJ., a corporation of Delaware Application September 2, 1954, Serial No. 453,888

9 Claims. (Cl. 208-93) This invention relates to an improved hydroforming process for light hydrocarbon oils and, more particularly, it pertains to an improved method for the preparation of feed material to a hydroforming unit and the recovery of product material therefrom.

In the design of hydroforming units, it is important that there be a minimum loss of valuable gasoline components and further, that the process streams be interrelated in such a manner that there is little or no need for extraneous means in the recovery of product material and for the preparation of the feed stock to be hydroformed. With regard to the feed stock in the case of platinum hydroforming, it is found that a high end point can result in a more rapid deactivation rate than is desired. Accordingly, it is necessary to subject the feed material to a separation treatment for this purpose. On the other hand, the recovery of product materials ,is effected with as little loss of valuable gasoline components as possible. Pursuant to this purpose, the normally gaseous material is subjected to a suitable vtreatment for the recovery of` hydrocarbons containing at least four vcarbon atoms.v

Therefore, it can be seen that in the method of processing the various materials for either feed `preparation or product recovery, it is important that the, process streams bey interrelated such that the process canbe operated as cheaply as possible. The present invention is concerned with a method by which such advantages can be attained.-v

An object of this invention is to provide an improved hydroforming process. v j v Another yobject of this invention is to provide an economical and etlicient method of-preparing feed material` andrecovering product in ahydroforming process.

Other objects and advantages will become apparent from the following description and explanation thereof.

By means of the present invention, it iscontemplated improvinga reforming process in lwhichga naphtha iscontacted Withva reformingcatalysttoproduce ra reaction` product including normally gaseous and normallyliquid,l

materials bythe method which comprises subjectingy the naphtha feed material ,to av separation treatment for` thev recovery of a heavy or high boiling naphthay fraction therefrom, separating normally gaseous product material from normally liquid product materiaLand contactingthe nor- 2,881,128 Patented Apr. 7, 1959 ICC materials such as, for example, alumina, silica, silicaalumina, activated charcoal, zinc aluminate, pumice,

kieselguhr, magnesia, alumina-magnesia, etc. The catalyticy element comprises about 0.01 to about 50% by weight of the total catalytic material. Among the various catalysts which are useful for the reforming reaction, the noble metals supported on alumina with or without a small amount of silica included therewith are particularly suitable for the present invention.

The feed material to be used in the present invention is a light hydrocarbon oil, e.g., naphtha. This feed material can be a straight run fraction, a cracked stock, or a mixture of the two. In regard to catalysts which are sulfur sensitive such as, for example, platinum catalysts, it is preferred that the sulfur concentration be not greater than about 0.03%, preferably about 0.01 Vor less percent, by weight. the naphtha contains a higher sulfur concentration, it is desirable to subject the same to a desulfurization treatment by any of the conventional methods in order to reduce the sulfur concentration to the desired range. vFor this purpose, the feed material can be subjected to a desulfurization treatment either before it is subjected to a separation treatment for the removal of the heavy naph-` For this purpose, in the case that tha fraction therefrom or following said separation treatment. f

vFrom the standpoint of long catalyst life, infthecase of the noble metalsit is desirable thatthe feed mate-'- rial have an end point of about 325 to about 400 F.

y in the4 case of expensive catalytic materials it:beco`mes important from an economical standpoint toremove the higher boiling hydrocarbons from the-feed stock. prior; to subjecting the same to a hydroformingtreatment. i' With regard to the initialboiling point ofthe feedmai terial, it is preferred that the initial boilingpoint lie in;` the range of about 150 to about 300 F.'byfvirtue:thatl.1 lighter boiling materials may'not ybe affected appreciably."

by the hydroforming treatment. ,Thefeed materialhas, usually, a low anti-knock quality, in the.order of/atfleast` about 20 CFRR clear,'a1though-the octanewquality of -.f the feed material can be as high as 75 CFRR clear. lThe'.y

mally gaseous product material with the heavy naphtha l fraction in an absorption zone for `the recovery of Valu-` able gasoline components therefrom.

The present invention is concernedwith a reforming process in which a light hydrocarbon oil is contacted with a suitable reforming catalyst, namely, oneA which has` hy drogenation-dehydrogenation properties ory the ,catalytic property of aromatizing hydrocarbonmaterials.y A large` variety of catalytic materials can be used for this purpose including thenoble metals, eg., platinum, palladium, etc.;

the oxides and/or suldes ofy metals in groupstIV, V and VI of the periodic table, e.g., molybdenum trioxide, chromia, tungsten oxide, etc.; the heteropoly acids in which the central acid forming element is, for example, phosphorus, germanium, aluminum,l silicon,platinum, etc.,'

measure of the paraitnicity `of the `feed ymaterial-isthe' Watson characterization factorand in the,present,case,:1 they Watson factor can vary.'y from'vabout 11.5 to-:about:y

- 12.2. The olen concentration can/varyjfrorn about 0f to-about 30` mol; percent, although it*is'preferredthat the olenicconcentration be kept to a,minimurrr,wheny using a `platinum ycatalyst for `the hydroformingrprocessa;

The hydroforming reaction is conducted at a4 temper-y ature ofaboutr 750ov to about` 1075 F., more usually,

about `850 to about 975l F. The reaction vs carriedout. at. a total pressure of aboutZS to about 1000 p.s.i.g.,-`l more usually, about 50 toabout 750 p.s.i.g. `Thef.quan-,.;

tity of oil which is processed relative to the catalyst.- present in the reactionl zone is measured as weight space vef.

l, i 10. The hydroformingmeaction is conducted inthel pres-.

ence of added hydrogen. The conditions .of .thefreac-v is recycledfor furtherputilizationjinbthe processagluTliemlocity, that is, the pounds ofoil `charged to lthe reactiomg zoney per hourvpergpound of catalyst whicll'isl present therein.. Generally, the. weight `spacevelocitygisabout 0.05 to about20, more usua1lyabouty 0.25. to` about.

tion-are selected to produceanet productionof hydrogen, consequently, lthe normally gaseous,productzmate-Q rial contains an appreciable, amount of hydrogen which.;

hydrogencontaining gas .orrecycle gas contains about 50 to about 98% by volume of hydrogen. The hydrogen rate to the reforming process is about 500 to about 15,000.1:standard cubicfeet, measured at 60 F. and 760 mm. Hg, :per barrel .of oil feed, vabbreviated as s.c.f.b. More usually, the hydrogen rate 4is about 1500 to `about 7500' s.c.f:b.

:Asprcviously indicated, it is important from an economcal standpoint to preparean optimum feed stock for the` hydroforming operation and recover the product materialswith as littleA economicalloss as possible. Accordingly, the vfeed material is :subjected to a separation treatment for ythe removaltherefrom of a heavy naphtha fraction. This heavy naphtha fraction may have an initial boiling .pointlwhich is-.equivalent to the end point of the desired-naphthafraction to behydroformed. The initial boiling point can also be higher or lower than the end point. of the naphtha to be hydroformed, and generally, it canbe about 330 to about 420 F. The end point of the heavy naphtha fraction can vary over an appreciable range such as, for example, in the order of about 400 to'about.55 0-F. :In the practice of this invention, the heavy naphtha fraction is employed as an absorption medium for the recovery of valuable gasoline components from the normally gaseous product material. The enriched heavy naphtha is then charged to a feed prefractionator for the removal of absorbed hydrocarbons. The conditions in the feed prefractionator are favorable for appreciable overhead carry-over of the absorbed gasoline components and subsequent inclusion in the feed material. The gasoline components contact a feed material which has a low concentration of such materials, consequcntly, there `is appreciable absorption thereof. The feed prefractionator also serves to separate from the naphtha feed a heavy naphthafraction which is essentially of the'same composition as the heavy naphtha used in the recovery of gasoline components `and a lighter naphtha ywhich is used as feed in the hydroforming operation.

In another'aspect of the invention, the light naphtha fraction is also used as an absorption medium for the recoveryof gasoline components from the normally gaseous product material. In this connection, the lighter naphtha fraction is used as a preliminary absorption medium and then it is followed by a treatment of the gaseous material with a heavy naphtha fraction. In this manner, any light naphtha which is vaporized and becomes part of the normally gaseous material can be recoveredby means of the heavy naphtha. Any hydrocarbon or mixtures `thereof in the naphtha boiling range and having va lower boiling range than the heavy naphtha can be used for this purpose. This light naphtha has an initial boiling point of about 100 to 225 F., and an end point of 'about 325 to 400 F. The light naphtha which is^used 'as the Aabsorbing medium can also be the feed material Yfor the hydroforming operation. Consequently, in addition to the process advantage of using feed material `as the absorbent for -gasoline components, any Water `and/o1' oxygen which is dissolved in the feed is stripped therefrom by means of the normally gaseous product. Water has an adverse effect upon platinum catalyst life, whereas oxygen is undesirable because it can cause fouling of feed preheaters due to high boiling material formation, e.g., polymers, etc.

In order to provide a better understanding of the present invention, `reference will 'be had'to the accompanying drawing which Iserves as a specific illustration thereof.

In the drawing, a petroleum naphtha fraction having an initial boiling point of 205 F., an end point of 425 F. and an API gravity of 49.0, is supplied by means of line 5 at the rate of 22,300 barrels per day. The fresh naphtha feed owing in line 5 is `first combined with an enriched heavy naphtha flowing from line 7 and then as a combined stream, the material passes to prefractionator 8 by means of line 10. The feed prefractionator is operated vwith a top temperature of 349 F., a bottom temperature of 460 F. and a pressure in the bottom of the tower of 10 p.s.i.g. An overhead fraction comprising light naphtha, having an initial boiling point of 200 F., and an end point of 400 F., is discharged from the top of tower 8 by means of line 11. Vaporous overhead fraction is cooled to a temperature of F. by means of condenser 12 and then it is passed to a separating drum 14 by means vof line 15. 'Separating drum 14 is kmaintained at essentially atmosphericpressure and 100 F. When it isrequired, normally gaseous material can be discharged from the top of separating drum 14 by means of a valved line l16. The ycondensed light naphtha is discharged from the separator 14 by means of line 18 and it is divided to provide a recycle stream of 3650 barrels per day through line 20 and an overhead yield of 21,420 barrels per day through line 21. The recycle stream is transported to the top of tower 8 by means of pump 23 and line 24. The net yield of light naphtha fraction is transported vby means of pumpf25 and line 26 to the top of an absorption section 27 of the absorption column. The heavy naphtha fraction is discharged from the bottom of prefractionator 8 by means of line 30 and itis Vconveyed at the rate of 3100 barrels per day by means 'of pump 31. This -heavy naphtha has an initial boiling point of 390 F. and an end point of 475 F. The heavy naphtha is cooled from a temperature of 360 F. to 100 F. by means of a cooler 32 which is connected tothe discharge end of. pump 31 by means of line 33. The cooled heavy naphtha is discharged from cooler 32 by meansof line 35, and thereafter, a net yield of heavy naphtha, A1100 barrels per day, is discharged from line 36; whereas the remaining portion of 2000 barrels per day is passed by means of line 38 to the top of absorption section 39 of the absorption column.

Absorption section 39 `is superimposed on absorption section 27 and it is separated therefrom by means of a partition 41. The 4top'fof t absorption section 39 is maintained at a temperature of l05 F. and a pressure of 230 p.s.i.g. The bottom of absorption section 39 is maintained at a temperature of 125 F. and a pressure of 230 p.s.i.g. The gaseous feed materialffor the absorption tower having a molecular weight of f1l.6 is fed to the bottom of section 27 of the absorption tower by means of line 43 at a temperature of approximately F. and at a rate of 51,171 pounds per hour. The gaseous material flows upwardly in countercurrent relation to the downowing light naphtha, consequently, aportion of hydrocarbons containingat least four 'carbon atoms are absorbed therefrom. After Vthe gaseous material has contacted the light naphtha, it flows Vthrough .line 44 which interconnects the top oftsection 27 with the bottom of section 39. In section 39 the gaseous materials flow incountercurrent relation with the downowing heavy naphtha and thereby any -gasoline components whichwe're originally present'in the gaseous material fed to the absorption column and any vaporized light Anaphtha is're'covered substantially in section 39. It is toV be understood for the purposes 'of this specification and the appended claims that `by the expression gasoline components, it is intended to include hydrocarbons containing at least four carbon atoms. The enriched heavy naphtha is discharged from the bottom of section 39 yby means of line 7, and thence, it is combined with the fresh naphtha feed being supplied to the' prefractionator 8 by means of line 5. On the other hand, the-'enriched light-naphtha is discharged from the bottom of section 27 by `means of line 47 and it passes to a surge drum 48. Surge drum 48 is maintained under the same temperature and v'pressure as the bottom of section 27of the absorption column. To avoid developing a different pressure in surge drum 48 than exists in the bottom of absorption column 27, pressure balancingrline 49 interconnects` the top thereof with the gaseous feed line 43.

The enrichedV lightnaphtha having an API gravity of 56.4 is discharged from the bottom of surge drurh 48 by means of line 51 at the rate of 24,486 barrels per day. The light naphtha has an API gravity of 49.8 prior to being used as an absorption medium. The enriched light naphtha is transported by means of pump 53 and line 54 to a hydroforming unit shown schematically as 55. In the hydroforming unit, the enriched light naptha is contacted with a platinum catalyst containing 0.6% by weight of platinum supported on alumina at a weight space velocity of 1.1. The hydroforming reaction is effected at an average temperature of 905 F. and an average total pressure of 335 p.s.i.g. This reaction is effected in the presence of hydrogen-rich gas which is added in an amount of 5000 s.c.f.b. The reaction product is discharged from the hydroforming unit by means of line 57 and then it is cooled to a temperature of 105 F. at a pressure of 230 p.s.i.g. by means of condenser 59. The cooled reaction product is passed from condenser 59 to a separating drum 61 by means of line 62. The normally gaseous product material containing 80% by volume of hydrogen is discharged from the top of drum 61 by means of line 64. A portion of the normally gaseous material is recycled to the hydroforming unit by rst passing it through line 65, compressing it to a pressure of about 425 p.s.i.g. by means of compressor 66 and then passing it through line 67. The net yield of normally gaseous material having a molecular weight of 10.6 and in the amount of 45,662 pounds per hour is passed through line 70, which, in turn, is connected to feed line 43 of the absorption column.

The normally liquid product having an API gravity of 49.4 is discharged from the bottom of drum 61 at the rate of 19,489 barrels per day by means of line 72. The liquid product is passed from line 72 to a heater 73 wherein the temperature is'raised to 378 F. The heated liquid product passes from heater 73 to a line 74, and then it passes to the middle section of a debutanizer 76.

The top of debutanizer column 76 is maintained at a temperature of 150 F.; Whereas the bottom of the column is at a temperature of 459 F. and a pressure of 150 p.s.i.g. TheA vaporous overhead butane fraction is discharged from the top of debutanizer column 76 by means of line 77 and thence vit is cooled to a temperature of 110 F. by means of condenser 79. The cooled overhead product is passed from condenser 79 to separating drum 81 by means of line 82. The total pressure in separating drum 81 is 140 p.s.i.g. o The gaseous material in sepa- \rating drum 81 is discharged from' the top thereof by 'by means of line 83 and it 'is passed to a trap-out drum 85 wherein any liquid material is removed therefrom. The gaseous material is discharged from the top of trapout drum 85 by means of line 86, and thence, it is compressed by means of compressor 87 to a pressure of 23S p.s.i.g. The compressed normally gaseous material is discharged from compressor 87 by means of line y88, which, in turn, is connected to feed line 43 of the absorption column. The normally gaseous material from the debutanizer column having a molecular weight of 41.8 is yielded at a rate of 5509 pounds per'hour. The liquid material in separating drum 81 of debutanizer column 76 is discharged from thebottom thereof by means of line 90. A portion of the overhead product having a molecular weight of 53.1 passes from line 90 to line 91 aty the trate of 11,750 `barrels per day. This stream is used as recycle to the top of the debutanizer column and it is transported thereto by means of pump '92 and line 93. The other portion of the liquid-'product from separating drum 81 is passed from line 90 to line 94 at the'rate of 1634 barrels per day. This overhead product is charged to a depropanizercolumn 95.

A debutanized liquid product is fed to the middle section of a polymer stripping tower 98. In the polymer stripper, the overhead temperature is maintained at 340 F.; whereas the bottom of the tower is at500 F. and a pressure of 8 p.s.i.g. It can be seen that the pressure in the bottom of the debutanizer is 150 p.s.i.g. and the pressure inthe polymer tower is 9 p.s.i.g. Stripping action is obtained by reason ofthe reduced pressure in addition to reboiling means (not shown). Further, the stripping action is enhanced by reason of steam which is introduced into the bottom of the polymer stripper 98 by means of line 99. In this connection, steam is fed to the tower by means of line 99 at the rate of 6200 pounds per hour. The debutanized gasoline fraction is yielded overhead from the polymer tower 98 by means of line 101. This vaporous gasoline fraction is cooled to a temperature of 100 F. by means of condenser 103. The cooled overhead from the condenser is fed to a separating drum 104 by means of line 105. Water is discharged from drum 1104 at the rate of 6200 pounds per hour by means of line 106. The separating drum is provided with a vent line 107. The pressure in drum 104 is maintained at essentially atmospheric level. The debutanized gasoline is discharged from drum 104 by means of line 108, and it is pumped by means of pump 109. The debutanized gasoline tirst passes from pump 109 to line 110 and then it is divided such that the net yield of 16,420 barrels per day, having an API gravity of 43.6, is discharged from the system by means of line 111 and the remaining portion of 4300 barrels per day is recycled Atothe topof the polymer stripper 98 by means of line 112. A polymer product having an API gravity of 11 is discharged from the bottom of tower 98 by means of line 114 at the rate of 700 barrels per day. This polymer product is cooled to a temperature of 100 F. by means of a cooler 115 and it is discharged therefrom by means of line 116.

The raw butane product from the debutanizer 76 fhaving a molecular weight of 53.1 is fed to a depropanizer column 95 at the rate of 1634 barrels per day. In the depropanizer column, the overhead temperature is maintained at F.; whereas the bottomrtemperature of the tower is maintainedat 220 F. and 260 p.s.i.g.v The overhead yfraction is discharged from the top of'the tower by vmeansof; line 1.21v and it is first cooled toa temperature of 117 F. by, means of 'condenser 122 before it is passed to a separating drum 123 by means of line 124. Normally gaseous material'having a molecular weight of 42.1 is discharged from the top of drum 123 by means of'valved` line v125 atV the rate of 2981pounds per hour. The' separating dru'mi123 is at .117 Fjand 256 p.s.i.g. The liquid in separating drum 123'having a molecular weight' of 43.8 is discharged from the 'bottom thereof by means of line 127 at the rate of` 2370 vbar relsv per day. This liquid is recycled to the topof depropanizer column by means of pump 128 'and line 129. The butane product is 'discharged' from the bottom of depropanizer column 95,"by means of line 131, and' it Lis,l cooled to a temperature of 100 F.' by means of cooler 132 and thence, it is discharged from the system by means of line 133;

y In regard to the operation of

towers

8, 76, 95 and 98 it should be understood 'that heatI is'supplied' by suitablel reboiling'means in the vbottom section such as by withdrawing a liquid stream, heating .the vsame and recycling it to the tower. The reboiling means 'are' not yshown in the drawing.

Having thus provided av written description of'they presentinvention, it should. bev understood that no yundue limitations or restrictions areI to jbe imposed by reason thereof, but that the, scopev of the. present invention yis` defined by the vappended clairr'xsy y 'Weclaimz 1. In a reforming process whereina naphtha fraction is contacted with a` reforming catalyst vto produce ay reformed product including normally liquid'an'd normallyl gaseous materials, the yimprovement'which comprises i subjecting a naphtha feed material to a separation treatment forv the Arecovery of a heavy naphtha stream from4 alight naphtha stream, passing a stream comprising a portion of'the light naphtha `to said reforming Zone,

separating gaseous product material containing gasoline componentsfrom said"refor`med product, contacting'a strea'incoiriprising aportion ofthe `gaseous product .materials separated from -the reformed product with heavy naphtha recovered from said naphtha feed in an absorption zone for the recovery of valuable gasoline components vtherefrom and passing enriched heavy naphtha to said feed separation step.

2. In a reforming process wherein a naphtha fraction is contacted with a reforming catalyst to produce a reformed product including normally liquid and normally gaseous materials, the improvement which comprises passing a naphtha feed material to a feed separation zone wherein a heavy naphtha fraction is separated from a light naphtha fraction, separating-normally gaseous product material containing gasoline components from said reformed product, contacting a stream comprising a portion of the separated normally gaseous product material with heavy naphtha separated vfrom said naphtha feed in an absorption zone thereby enriching the heavy naphtha with gasoline components and passing heavy naphtha enriched with gasoline components to the aforesaid feed separation zone.

3. In a reforming process wherein a naphtha fraction is contacted with a reforming catalyst to produce a re- A formed product including normally liquid and normally gaseous materials, the improvement which comprises subjecting a naphtha feed -material to a separation treatment for the recovery of a heavy naphtha fraction from a naphtha feed suitable for said catalytic reforming step, separating normally gaseous product material containing gasoline components from said reformed product, first contacting a portion of the normally gaseous product material with a portion of'said naphtha lsuitable for said reforming step which is lower in boiling pointthan the aforesaid heavy naphtha fraction in a first absorption zone for the recovery of valuable gasoline components therefrom, thereby enriching said low-boiling naphtha, passing said enriched low-boiling naphtha to said reforming zone and contacting gaseous product material separated from the first absorption zone with a portion of the heavy naphtha separated from said naphtha feed in a second absorption zone for recovery of valuable gasoline components from said gaseous product and recycling enriched heavy naphtha to said naphtha separation step.

4. In a reforming zone wherein a naphtha fraction is contacted with a reforming catalyst to produce a reformed product including normally liquid and normally gaseous materials, the improvement which comprises passing a naphtha feedmaterialto a separation zone for the separation of a heavy naphtha fraction from a lower boiling naphtha fraction, vseparating hydrogen-rich gaseous material containing gasoline components from said reformed product, contacting a portion of the separated hydrogen-rich gaseous product material with the naphtha which is lower boiling than theaforesaid heavy naphtha fraction in a first absorption zone for the recovery of gasoline components therefrom, passing enriched lowboiling naphtha from said firstabs'orption zone to said reforming zone, separating gaseous product material from the first absorption zone and passing the same to a second absorption zone wherein it is contacted with heavy naphtha for therecovery of additional low-boiling hydrocarbons from said gaseous material, 'and passing the heavy naphtha enriched with low-boiling hydrocarbons from the second absorption'zone to the naphtha feed separation zone.

5. In a reforming process wherein a naphtha'fraction is contacted with a reforming catalyst in va reforming zone to produce a reformed product including normally liquid and normally gaseous materials, the improvement which comprises subjecting a naphtha feed material to a separation treatment forthe recovery of a light naphtha fraction from-a heavy naphtha fraction, separating normally gaseous product material containing gasoline components from said reformed product, contacting a portion Vof the thus separated`normallygaseous product material with a portion of the separated light naphtha in a first absorption'zone for the recovery of gasoline components from said gaseous product material, separating gaseous product material from said first absorption zone and contacting the same with a portion of the separated heavy naphtha fraction in a second absorption zone for the recovery of additional gasoline components and passing the enriched light naphtha fraction from said first absorption zone to the reforming zone.

6. In a reforming process wherein a naphtha fraction is contacted with a noble metal reforming catalyst under conditions to produce a reformed product including gasoline, polymer and normally hydrogen rich gaseous materials, the improvement which comprises subjecting a naphtha feed material to a separation treatment for the separation of a heavy naphtha fraction from a light naphtha fraction, separating under pressure a first hydrogen rich gaseous product lfraction containing gasoline components from said reformed product, passing the remainder of said reformed product from said pressure separation step to further separation to recover a polymer fraction, a gasoline fraction and a second gaseous fraction, combining a portion of the first gaseous product fraction with the second gaseous fraction, contacting the combined gaseous fraction with light naphtha in a first absorption zone, recovering enriched light naphtha 'absorbent from said first absorption zone and passing the same to said reforming step, recovering a gaseous fraction from said first absorption zone and passing the same in contact with a portion of the separated heavy naphtha fraction in a second absorption zone and recycling enriched heavy naphtha from said's'econd'absorption zone to said naphtha feed separation step. t

7. In a reforming process wherein a naphtha fraction is contacted with a reforming catalyst in a reforming zone to produce a reformed product including gasoline, polymer and normally gaseous materials, the improvement which comprises subjecting a naphtha feed material to a separation treatment for the recovery of a light naphtha fraction from a heavy naphtha fraction, separating a first hydrogen rich gaseous product fraction from said reformed product containing gasoline, polymer and normally gaseous product in a first separation zone, passing the remainder of said reformed product to further separation for the recovery of a gasoline fraction, a polymer fraction and a second fraction of normally gaseous product, passing a portion of the first gaseous product combined with the second fraction of normally gaseous product to a first absorption zone vin contact with a portion of the separated light naphtha fraction for the recovery of gasoline components from the gaseous product, separating a gaseous product material from the first absorption zone and passing the same to a second absorption zone in contact with a portion of the separated heavy naphtha fraction for the recovery of additional gasoline components from said gaseous material and passing enriched light naphtha from the first absorption zone to the reforming zone.

8. In a reforming process wherein a naphtha fraction is contacted with a reforming catalyst to produce a reformed product including normally liquid and normally gaseous materials, the improvement which comprises subjecting a naphtha feed material to a separation treatment for the recovery of a light naphtha fraction therefrom, separating normally gaseous product material containing gasoline components from said reformed product, con- -tacting a portion of the thus separated normally gaseous product material with a portion of the light naphtha fraction recovered from said naphtha feed in an absorption zone for the recovery of valuable gasoline cornponents therefrom and passing the enriched light naphtha to said reforming step.

9. In a reforming process wherein a naphtha fraction is passed in Contact with a noble metal reforming catalyst under conditions to produce a reformed product containing normally liquid and normally gaseous material, the improved method of operation which comprises fractionating a naphtha fraction to recover a low-boiling naphtha feed stream suitable for said reforming step from a heavy naphtha stream, passing a stream comprising a portion of said low-boiling naphtha to said reforming step, separating under pressure a hydrogen-rich gaseous product stream containing low-boiling gasoline components from said reformed product, recycling a portion of 10 2,719,816

said separated hydrogen-rich gaseous product stream to said reforming Zone, passing another portion of the separated gaseous lstream containing hydrogen and gasoline components to an absorption zone in countercurrent contact with a portion of the separated heavy naphtha stream to recover additional gasoline components by absorption, recovering enriched heavy naphtha absorbent from said absorption zone and passing the enriched heavy naphtha to said naphtha fractionating step.

10 References Cited in the le of this patent UNITED STATES PATENTS 2,358,149 Cooke Sept. 12, 1944 2,358,183 Ostergaard Sept. 12, 1944 2,404,050 Gilbert July 16, 1946 2,485,073 Shifer et al Oct. 18, 1949 2,653,175 Davis Sept. 22, 1953 Rich Oct. 4, 1955 OTHER REFERENCES Fulton: Petroleum Engineer, vol. 29 (1950), pp. 109-112.

Progress in Petroleum Technology (No. 5 of Advarices in Chemistry Series), pages 6065. Published by the American Chemical Society, Washington, D.C., 1951.

Claims

1. IN A REFORMING PROCESS WHEREIN A NAPHTHA FRACTION IS CONTACTED WITH A REFORMING CATALYST TO PRODUCE A REFORMED PRODUCT INCLUDING NORTMALLY LIQUID AND NORMALLY GASEOUS MATERIALS, THE IMPROVEMENT WHICH COMPRISES SUBJECTING A NAPHTHA FEED MATERIAL TO A SEPARATION TREATMENT FOR THE RECOVERY OF A HEAVY NAPHTHA STREAM FROM A LIGHT NAPHTHA STREAM, PASSING A STREAM COMPRISING A PORTION OF THE LIGHT NAPHTHA TO SAID REFORMING ZONE, SEPARATING GASEOUS PRODUCT MATERIAL CONTAINING GASOLINE COMPONENTS FROM SAID REFORMED PRODUCT, CONTACTING A STREAM COMPRISING A PORTION OF THE GASEOUS PRODUCT MATERIALS SEPARATED FROM THE REFORMED PRODUCT WITH HEAVY NAPHTHA RECOVVERED FROM SAID NAPHTHA FEED IN AN ABSORPTION ZONE FOR THE RECOVERY OF VALUABLE GASOLINE COMPONENTS THEREFROM AND PASSING ENRICHED HEAVY NAPHTHA TO SAID FEED SEPARATION STEP.