US3751361A

US3751361A - Process for upgrading dripolene

Info

Publication number: US3751361A
Application number: US00187691A
Authority: US
Inventors: E Caflisch; K Williamson; R Keister; D Reed
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1971-10-08
Filing date: 1971-10-08
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07

Abstract

A PROCESS FOR PROVIDING A HIGH OCTANE BLENDING COMPONENT FOR GASOLINE FROM DRIPOLENE FEEDSTOCK, CONTAINING AT LEAST FIVE PERCENT BY WEIGHT OF AT LEAST ONE DIMER OF THE GROUP CONSISTING OF DICYCLOPENTADIENE AND THE METHYL DERIVATIVES THEREOF, ONE CODIMER FORMED FROM MEMBERS OF THE GROUP CONSISTING OF CYCLOPHENTADIENE AND THE METHYL DERIVATIVES THEREOF, OR ONE CODIMER OF THE GROUP CONSISTING OF CYCLOPHENTADIENE AND THE METHYL DERIVATIVES THEREOF WITH CONJUGATED DIENES HAVING 4 TO 10 CARBON ATOMS COMPRISING THE FOLLOWING STEPS: (A) INTRODUCING THE FEEDSTOCK INTO A DISTILLATION ZONE WHEREIN THE TEMPERATURE AT THE BOTTOM OF THE ZONE IS IN THE RANGE OF ABOUT 120*C. TO ABOUT 300*C.; (B) PASSING THE BOTTOMS FROM THE DISTILLATION ZONE THROUGH A SEPARATE HEATING ZONE ASSOCIATED THEREWITH HAVING A TEMPERATURE IN THE RANGE OF ABOUT 120*C. TO ABOUT 400*C. AT A VELOCITY OF ABOUT FIVE TO ABOUT FIFTEEN FEET PER SECOND TO PROVIDE A LIQUID PHASE AND A VAPOR PHASE; WHEREIN, IN STEP (A) AND (B), THE DIMERS OR CODIMERS DEFINED ABOVE AND PRESENT IN THE PROCESS ARE SUBSTANTIALLY CRACKED TO THE CORRESPONDING MONOMERS THEREOF; (C) INTRODUCING THE PHASES OF STEP (B) INTO THE DISTILLATION ZONE WHEREIN SAID VAPOR PHASE BECOMES PART OF THE OVERHEAD DISTILLATE AND SAID LIQUID PHASE BECOMES PART OF THE BOTTOMS; (D) INTRODUCING THE OVERHEAD DISTILLATE INTO A HYDROGENERATION ZONE UNDER HYDROGENATING CONDITIONS, SAID CONDITIONS BEING SUCH THAT THE ZONE IS ESSENTIALLY INCAPABLE OF HYDROGENATING AROMATIC HYDROCARBONS, AND HYDROGENATING SAID OVERHEAD DISTILLATE TO PROVIDE A HIGH OCTANE BLENDING COMPONENT RICH IN CYCLIC HYDROCARBONS HAVING ONE FIVEMEMBERED RING AND NO MORE THAN ONE DOUBLE BOND; PROVIDING THAT (I) EACH OF THE AFOREMENTIONED ZONES IS ESSENTIALY OXYGEN-FREE; AND (II) THE RESIDENCE TIME OF THE FEEDSTOCK AND ITS DERIVATIVES IN THE PROCESS PRIOR TO STEP (D) IS LIMITED TO THE TIME IN WHICH NO MORE THAN FIFTY PERCENT BY WEIGHT OF THE TOTAL CYCLOPENTADIENE AND METHYL DERIVATIVES THEREOF PRODUCED IN THE PROCESS DIMERIZES; AND (E) RECOVERING THE HIGH OCTANE BLENDING COMPONENT.

Description

Aug. 7, 1973 G, AFUSCH ETAL 3,751,361

PROCESS FOR UPGRADING DRIPOLENE Filed Oct. 8, 1971 United States Patent Office 3,751,361 Patented Aug. 7, 1973 US. Cl. 208-255 SS 10 Claims ABSTRACT OF THE DISCLOSURE A process for providing a high octane blending component for gasoline from dripolene feedstocks containing at least five percent by weight of at least one dimer of the group consisting of dicyclopentadiene and the methyl derivatives thereof, one codimer formed from members of the group consisting of cyclopentadiene and the methyl derivatives thereof, or one codimer of the group consisting of cyclopentadiene and the methyl derivatives thereof with conjugated dienes having 4 to 10 carbon atoms comprising the following steps:

(a) Introducing the feedstock into a distillation zone wherein the temperature at the bottom of the zone is in the range of about 120 C. to about 300 C.;

(b) Passing the bottoms from the distillation zone through a separate heating zone associated therewith having a temperature in the range of about 120 C. to about 400 C. at a velocity of about five to about fifteen feet per second to provide a liquid phase and a vapor phase;

Wherein, in steps (a) and (b), the dimers or codimers defined above and present in the process are substantially cracked to the corresponding monomers thereof;

(c) Introducing the phases of step (b) into the distillation zone wherein said vapor phase becomes part of the overhead distillate and said liquid phase becomes part of the bottoms;

((1) Introducing the overhead distillate into a hydrogenation zone under hydrogenating conditions, said conditions being such that the zone is essentially incapable of hydrogenating aromatic hydrocarbons, and hydrogenating said overhead distillate to provide a high octane blending component rich in cyclic hydrocarbons having one fivemembered ring and no more than one double bond;

Providing that (i) each of the aforementioned zones is essentially oxygen-free; and (ii) the residence time of the feedstock and its derivatives in the process prior to step (d) is limited to the time in which no more than fifty percent by weight of the total cyclopentadiene and methyl derivatives thereof produced in the process dimerizes; and

(e) Recovering the high octane blending component.

FIELD OF THE INVENTION This invention relates to a process for upgrading dripolene feedstocks to provide high octane blending components for gasoline.

DESCRIPTION OF THE PRIOR ART In view of the increased demand for high octane gasoline arising out of the current feeling that lead, which has been under fire as a pollutant, be reduced in amount or completely eliminated as a gasoline additive, the art has turned to the problem of upgrading various feedstocks which have high octane blending potential in the gasoline field. One such feedstock is dripolene, a liquid by-product of a hydrocarbon cracking process for the production of ethylene. For many years the C to C fraction of dripolene has been distilled olf and used as a blending component in the gasoline market, but the C fraction, which makes up about 10 percent to about percent by weight of the dripolene has proved to be of comparatively little commercial value in view of its high gum content after distillation, 1000 to 5000 milligrams per milliliters, and poor stability, both of which cause malfunction in gasoline engines.

What is known as the C fraction (or C dripolene) has potential in gasoline blending because of its make-up, which varies over a Wide range, but generally comprises styrenes; indenes; naphthalenes; alkylbenzenes having one or more alkyl side chains each having one to six carbon atoms; a small amount, if any, of cyclopentadiene and its methyl derivatives; dicyclopentadiene and its methyl derivatives; and, on occasion, some C compounds. In terms of boiling points, the components have ranged upwards from as low as about 30 C.

A chromatographic analyses of several specific C fractions shows the following compounds to be present in all or some of the fractions: ethynylbenzene, ethylbenzene, m-xylene, o-xylene, p-xylene, styrene, mand pethyltoluene, o-ethyltoluene, mesitylene, psuedocumene, omethylstyrene, mand p-methylstyrene, beta-methylstyrene, indan, indene, C benzenes, Tetralin, naphthalene, methylindenes, methylnaphthalenes, n-octane, n-nonane, n-decane, cyclopentadiene, methylcyclopentadiene, bicyclononadiene, isopropenylbicycloheptene, dicyclopentadiene, methyldicyclopentadiene, vinylbicycloheptene, dimethyldicyclopentadiene, and allylbenzene.

In spite of the high octane blending potential of the C fraction, its disadvantages, i.e., high gum content and polymer formation on distillation, the attendant fouling of processing apparatus, poor stability, low overall octane values, persistent foul odors, low volatilities, and propensity for shortening of catalyst life when hydrogenated, have been difiicult, if not impossible to overcome, using known methods for dealing with same. For example, one method proposed to reduce gum formation in the C fraction was hydrotreatment which is a process for reacting hydrogen with some of the known gum formers, conjugated diolefins and styrenes, but this process did not succeed in eliminating the stated disadvantages appreciably and the C fraction remained in the category of a heavy fuel oil.

SUMMARY OF THE INVENTION An object of this invention, therefore, is to provide a process for upgrading dripolene to the point where not only the C to C fraction is useful in high octane gasoline blending, but where a high proportion of the C fraction is useful as well by essentially eliminating the heretofore mentioned disadvantages.

Other objects and advantages will become apparent hereinafter.

According to the present invention, gum formation and fouling of hydrogenation apparatus are essentially eliminated, stability is achieved, and useful high octane gasoline blending components are obtained from dripolene feedstocks containing at least five percent by Weight of at least one dimer of the group consisting of dicyclopentadiene and the methyl derivatives thereof, one codimer formed from members of the group consisting of cyclopentadiene and the methyl derivatives thereof, or one codimer of the group consisting of cyclopentadiene and the methyl derivatives thereof with conjugated dienes having 4 to 10 carbon atoms by a process comprising the following steps:

(a) Introducing the feedstock into a distillation zone wherein the temperature at the bottom of the zone is in the range of about C. to about 300 C.;

Wherein, in steps (a) and (b), the dimers and codimers defined above and present in the process are cracked to the corresponding monomers thereof;

Introducing the phases of step (b) into the distillation zone wherein said vapor phase becomes a part of the overhead distillate and said liquid phase becomes a part of the bottoms;

(d) Introducing the overhead distillate into a hydrogenation zone under hydrogenating conditions, said conditions being such that the zone is essentially incapable of hydrogenating aromatic hydrocarbons, and hydrogenating said overhead distillate to provide a high octane blending component rich in cyclic hydrocarbons having one five-membered ring and no more than one double bond;

(e) Recovering the high octane blending component.

BRIEF DESCRIPTION OF THE DRAWING The sole figure of the drawing is a schematic flow dia gram of an illustrative embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The feedstock used in the process of this invention can either be the whole dripolene fraction which includes both the C to C fraction and the C fraction, the 0 fraction itself, or a portion of each fraction. The feedstock can also be any one of the components of these fractions, e.g., dicyclopentadiene, or a mixture of two or more components, providing the following process requirement is met, although, in some cases, the commercial objective may change in that all of the components are not useful as high octane gasoline blending components.

It has been found that the only process requirement for the feedstock is that it contain at least five percent of at least one dimer of the group consisting of dicyclopentadiene or its methyl derivatives, a codimer formed from cyclopenadiene and its methyl derivatives, or a codimer of cyclopentadiene and its methyl derivatives with conjugated dienes having 4 to 10 carbon atoms. Whole dripolene generally contains at least five percent by weight of the dimer, dicyclopentadiene, together with the codimer, methyldicyclopentadiene, whereas the Q9 fraction generally contains at least 25 percent by weight of the dimer and codimer.

The codimer formed from cyclopentadiene and its methyl derivatives is a combination of two different monomers in one molecule, e.g., methyldicyclopentadiene is a combination of cyclopentadiene and methylcyclopentadiene.

The codimer of the group consisting of cyclopentadiene and its methyl derivatives with conjugated dienes having 4 to 10 carbon atoms is also a combination of two different monomers in one molecule, one of the monomers having a cyclopentadiene nucleus and the other monomer being a conjugated diene exemplified by isoprene, piperylene, butadiene, styrene, and indene.

Endoand exoisomers are considered to be included within the above definitions. The methyl derivatives mentioned can have 1 to 5 methyl groups on each ring. For the sake of brevity, the term cyclopentadiene and dicyclopentadiene may be used herein to include their methyl derivatives and dicyclopentadiene to include the codimers since all are similarly affected by the described process conditions.

A further process requirement is the use of an essentially oxygen-free environment. The process, i.e., the distilling and cracking portions thereof, can either be conducted in the absence of air, e.g., under vacuum, or in the presence of an inert gas. Air leaks should be guarded against. The hydrogenation portion, of course, is conducted in a hydrogen atmosphere and so provides the necessary oxygen-free environment.

The distillation zone can be provided for by a conventional distillation column. Columns having from five to 20 theoretical stages have been found suitable. Packed or bubble plate fractionating columns are most commonly used.

The heating zone is generally provided for by what might be termed as a high velocity heat exchanger. The diameter or length of the tubes are not important, but rather the length of time the material resides on the surface at any one point along the tube. The velocity with which the materials pass along the tube, therefore, becomes critical to the process. To obtain this velocity the pump speed has to be regulated as well as the diameter of the tube in relationship to the amount of material passing through. The heat exchanger can be of the shell and tube type (with forced circulation) or any other similar conventional heat exchanger.

The apparatus used in the hydrogenation, other heat exchangers, reflux condensers, pumps and various controls are also conventional.

In the distillation zone, the bottom temperature can be in the range of about C. to about 300 C. and is preferably about C. to about 200 C. The pressure can be in the range of about 0.25 atmosphere to about the pressure required to accommodate the maximum temperature employed and is preferably in the range of about one atmosphere to about three atmospheres. Both temperature and pressure vary throughout the zone. The head temperature is not controlled and is dependent on the feed and the bottoms temperature. Under usual operating conditions, it can vary from about 20 C. to about 200 C. or higher.

The heating zone is also controlled to provide a temperature in the range of about 120 C. to about 400 C. and preferably about 150 C. to about 350 C. The pressure is maintained in about the same range as the distillation zone.

Referring to the drawing:

The feedstock is introduced through line 1 into distillation column 2 at about the middle tray thereof. The temperature of the column is such that the light components are vaporized and pass up the column where they become overhead distillate and are taken off through line 3. The distillate is condensed in condenser 4 and continues along line 3. A portion of the distillate is returned along line 5 to distillation column 2 above the top plate as reflux and the balance of the overhead distillate, which may be called distillate make or make, continues along line 3, through pump 6, to join line 13 and enter hydrogenator 14. The ratio of reflux to make in the distillation zone is maintained in the range of about 0.1 to about 10 parts by weight of reflux to one part by weight of make and preferably about 0.2 to about 4 parts by weight of reflux to one part by weight of make. The particular ratio is generally selected by the technician running the process based on the particular feedstock and the technicians experience with same.

Returning to distillation column 2, the heavy components of the feedstock, including the dicyclopentadiene, pass down the column and become bottoms. The portion below the bottom plate in column 2 acts as a kettle (not delineated) and the bottoms passes through line 7 and is pumped by pump 8 at the required velocity along line 7. At a point along line 7 a portion of the bottoms is removed along line 9. The amount removed is simply that amount which will maintain a constant level of the bottoms below the bottom plate. The bottoms removed along line 9 contains some dicyclopentadiene, which is removed "by this method of operation, but the expense of its retrieval does not justify using more sophisticated methods.

The balance of the bottoms including the bulk of the dicyclopentadiene is pumped into the tube side of heat exchanger 12 at a high velocity, in the range of about five to fifteen feet per second and preferably ten to fifteen feet per second. The heating fluid passes through the shell side of the heat exchanger and can be steam at a pressure in the range of about 2 atmospheres to about 40 atmospheres or other suitable heating fluid at a temperature in the range of about 120 C. to about 400 C. and preferably 150 C. to about 350 C. The average residence time for a unit of bottoms in the heat exchanger is estimated to be about 0.1 to about 1 second, but this is not considered to be too meaningful.

It is theorized that the contact time of any one unit of fluid bottoms with any point along the heat exchanger tube must be kept to a minimum and this is accomplished by the high velocity. This also keeps the rise in average bulk temperature to a minimum and provides a washing action to keep the tube surfaces free of polymer. It is believed that although cracking of the dicyclopentadiene and polymerization are accelerated by the contact with the hot tube surface, the short contact time minimizes polymer formation. In any case, the heat exchanger tubes are not essentially fouled during this procedure.

The bottoms which is now a mixture of vapor and liquid continues along line 7 and enters into column 2 below the bottom plate and into what may be called a vaporliquid disengagement section (not shown). Here, the vapor which contains cyclopentadiene flashes up the column to join the overhead distillate and the balance of the bottoms which includes naphthalene, polymers and gum passes as a liquid into the kettle portion of column 2 (also called the collection 'vessel) where it joins the process bottoms passing down from the feedstock and the same procedure continues with this composite mixture. It is found that, in addition to essentially polymer-free tube walls in the heat exchanger, the walls of the kettle are also maintained in an essentially polymer-free state by following this procedure.

The temperature in the kettle (or the bottom of the distillation column) is as noted above.

The average residence time of the feedstock components, subject to the dimerization limitation stated heretofore, in distillation column 2 can be for about 10 to about 90 minutes and preferably about 10 to about 30 minutes to achieve maximum cracking of dicyclopentadiene and minimum polymer and gum formation. These times are not critical to the process, but the faster and more interruption-free the process the higher its efficiency providing there is adequate cracking time, which cracking, it is believed, takes place in heat exchanger 12 and the kettle.

One more function of heat exchanger 12 can be mentioned, however, that is, the heat exchanger provides heat via the recycle bottoms for the kettle, which not only supplies the heat for the distillation, but facilitates the escape of any cyclopentadiene that may be present in the bottoms by virtue of cracking.

The condensed make, essentially depleted of dicyclopentadiene, proceeds, as noted, along line 3 to join line 13 into which hydrogen gas has been introduced from a source, which is not shown. The hydrogen under a partial pressure, sufiicient to provide the hydrogen required to accomplish the desired reduction in unsaturation, typically in the range of about 10 atmospheres to about 75 atmospheres mixes with the make in line 13 and enters hydrogenator 14.

The make provides a liquid phase containing some dissolved hydrogen. The balance of the hydrogen remains in the gas phase so that both a liquid phase and a gas phase enter hydrogenator 14.

The hydrogenator apparatus is conventional and contains a conventional hydrogenation catalyst such as palladium on an alumina support, e.g., 0.3 percent by weight palladium based on the weight of the alumina support. An example of the hydrogenator is a well-insulated steel tube containing a single bed of the aforementioned catalyst. The temperature of the bed is measured by a concentric thermowell. The length to diameter ratio of the tube is about 2 to 1 to about 30 to 1.

The amount of hydrogen fed is, typically, for a 0 fraction, about 600 to 800 standard cubic feet per barrel of make (based on pure hydrogen). Excess hydrogen of up to about 20 percent or even more can easily be tolerated, but must be vented.

The hydrogen, make, and recycle (discussed below) are fed into the top of the hydrogenator as shown in the drawing and the make and recycle trickle down over the catalyst.

Another hydrogenation catalyst which can be used is a mixture of 0.5 percent by weight palladium and 0.5 percent by weight chromium on an alumina support (percentages based on weight of support).

The temperature in the hydrogenator is in the range of about 40 C. to about 250 C. and preferably about 50 C. to about 150 C. depending on the activity of the catalyst. These ranges include a temperature gradient of about 25 C. to about 75 C. A preferred mode of operation is to increase the inlet temperature to maintain an efiluent diene value of about 1 to about 2 (diene value is determined by ASTM method D1961-64).

The hydrogen used in the hydrogenator does not have to be pure or essentially pure thus the hydrogen gas can range from percent hydrogen down to a mixture of about 30 percent hydrogen and up to 70% other gases which will not detract from the hydrogenation such as methane. A mixture containing about 70 percent hydrogen and about 30 percent methane (by volume) is a good example of a mixture of gases which can be used. Again venting is important.

The total pressure in the hydrogenator is about 10 atmospheres to about 75 atmospheres and is preferably about 20 atmospheres to about 60 atmospheres.

The feed rate of the make is about one to about ten liquid hourly space velocity (LHSV) and is preferably about 2 to about 6 LHSV.

The hydrogen can be fed cocurrent to the liquid flow as shown above and preferred, or it can be fed countercurrent thereto.

As stated heretofore, the hydrogenation conditions must be such as to avoid hydrogenation of the aromatic rings, which are so important in high octane blending. Since the hydrogenation reaction is highly exothermic, some means of temperature control is used to prevent reaching a temperature of greater than 250 C. to 300 C. in which range aromatic rings might be hydrogenated. Two optional means are shown in the drawing. One means is the introduction of a diluent (source not shown) along line 19 to join line 13, i.e., the mixture of make and hydrogen. The diluent can be a hydrocarbon mixture free of active olefins such as reformate or trimethylcyclohexane. The other and preferred means is the use of a cooled recycle of a portion of the hydrogenated product, which is pumped along line 18 to join line 13. The recycle to make ratio can be in the range of about 2 parts to about 10 parts by weight of recycle per part by weight of make fed into the hydrogenator and is preferably in the range of about 4 parts to about 6 parts by weight of recycle per part by weight of make. Each of the mentioned cooling means can be used alone or together and other conventional means of temperature control in hydrogenator 14 can be availed of where desired.

The desired product passes from hydrogenator 14 as bottoms through line 15 and into heat exchanger 16 where it is cooled. Other cooling means can, of course, be used here. The product then continues along line 15 to pump 17 Where the product is pumped to a still or storage (not shown) and a portion may be pumped as recycle through line 18 as previously described.

Where it is desired at any point of the process to measure the amount of conjugated dienes including cyclopentadiene present, the diene value measurement can be used. Measurement is best achieved for both monomer and dimer by analysis with a high-resolution gas chromatograph.

The residence time of the feedstock and its derivatives resulting from cracking in the process prior to hydrogenation must be limited if polymer and gum formation are to be avoided. The use of a continuous process with no delays en route is the preferred way of maintaining low residence times; however, the definition stated heretofore provides the maximum time permissible, i.e., limiting the residence time to that in which no more than fifty percent by weight of the total cyclopentadiene and its methyl derivatives produced in the process dimerizes after being cracked from dicyclopentadiene and its methyl derivatives. A preferred dimerization percentage would be no more than about 10 percent by Weight. This definition allows for various delays which might occur in the process. One way to extend the process time is to bring the distillate down to a temperature of about C. to about minus C., which avoids dimerization beyond the defined limits for an extended period of time. Dimerization percentages are best determined by analysis and maintained by adjustment of process time.

As long as the process requirements discussed above are followed, many variations of the process can be used especially depending upon the apparatus available, e.g., a distillation column prior to that described may be used to initially remove some of the lights or two or more hydrogenators can be used in parallel.

The following example illustrates the invention.

Example The equipment, steps, and conditions described in the preferred embodiment and the drawing are used in this example.

Specific conditions are as follows:

Distillation column; 16 trays. Feed to 6th tray from bottom.

Bottom temperature in distillation column: 162 C. i Temperature in reflux condenser: 20 C. Pressure in distillation column: 0.6 atmosphere i Reflux ratio: 0.5:1

Overhead temperature in distillation column: 34 C. Composition of whole dripolene feed to distillation column:

Feed to distillation column: 171,000 pounds per hour Velocity through heat exchanger: 12 feet per second Temperature in heat exchanger: 196 C.

Heat supplied to heat exchanger: 200 p.s.i.g. steam Cit 8 Make: 150,000 pounds per hour Composition of make fed to hydrogenator:

Component: Percent by weight (1) Benzene 55 Toluene 14. Cyclopentadiene 5 Methylcyclopentadiene 2 Styrene 3 Cyclopentene and cyclopentane 2 Methylcyclopentene and methylcyclopentane Other components 18 Total feed Dimerization in feed to hydrogenator: less than 10 percent by Weight of cyclopentadiene produced.

Hydrogenator-inlet temperature: 89 C. (-1-) Catalyst: 0.3 percent by weight (based on weight of support) of palladium on an alumina support.

Hydrogen feed: a mixture of 60 percent by volume hydrogen and 40 percent by volume methane at a total pressure of 52 atmospheres.

Hydrogenator-outlet temperature: 139 C. (-3) Temperature dilferential in hydrogenator: 50 C. (1)

Liquid hourly space velocity of make to hydrogenator:

Recycle to make ratio: 3.2:1

Diene value of hydrogenated product: 1.4

Composition of hydrogenated product:

Component: Percent by weight (i) Benzene 55 Toluene 14 Cyclopentene and cyclopentane 7 Ethylbenzene 4 Methylcyclopentene and methylcyclopentane 3 Other components 17 Total product 100 In this example the benzene and toluene are separated by conventional fractional distillation as well as the C s and ethylbenzene. The C s and ethylbenzene are used as blending component for automotive gasoline.

It is found that essentially all of the cyclopentadiene and its methyl derivatives are hydrogenated to corresponding cyclopentenes and cyclopentanes; hydrogenation of aromatic rings is negligible; the gum content of the blending component after distillation is less than 10 milligrams per 100 milliliters (as determined by ASTM D 381 64). Essentially no fouling of the apparatus or catalyst, or fuel odor is observed, and good stability and high volatilities are achieved.

What is claimed is: 1. A process for producing a high octane blending component for gasoline from feedstocks containing at least five percent by weight of at least one dimer of the group consisting of dicyclopentadiene and the methyl derivatives thereof, one codimer formed from members of the group consisting of cyclopentadiene and the methyl derivatives thereof, or one codimer of the group consisting of cyclopentadiene and the methyl derivatives thereof with conjugated dienes having 4 to 10 carbon atoms comprising the following steps:

wherein, in steps (a) and (b), the dimers or codimers present in the process are cracked to the corresponding monomers thereof;

(c) introducing the phases of step (b) into the distillation zone wherein said vapor phase becomes a part of the overhead distillate and said liquid phase be comes a part of the bottoms;

wherein each of the aforementioned zones is essentially oxygen-free; and the residence time of the feedstock and its derivatives in the process prior to step (d) is limited to the time in which no more than fifty percent by weight of the total cyclopentadiene and methyl derivative thereof produced in the process dimerizes; and

(e) recovering the high octane blending component.

2. The process of claim 1 wherein:

the temperature at the bottom of the distillation zone is in the range of about 150 C. to about 200 C.;

the temperature in the heating zone is in the range of about 150 C. to about 350 C.;

the velocity in the heating zone is about to about feet per second; and

the residence time is limited to the time in which no more than ten percent by weight of the total cyclopentadiene and methyl derivatives thereof produced in the process dimerizes.

3. The process of claim 2 wherein said process is carried out in a continuous manner.

4. The process of claim 3 wherein the amount of dimer or codimer present in the feedstock is at least 25 percent by weight thereof.

5. The process of claim 1 comprising the following additional step:

(f) recycling a portion of overhead distillate to the distillation zone as reflux at a ratio of about 0.1 to about 10 parts by weight of reflux per part by weight of the unrecycled portion of the overhead distillate.

6. The process of claim 3 comprising the following additional step:

(f) recycling a portion of overhead distillate to the distillate to the distillation zone as reflux at a ratio of about 0.2 to about 4 parts by weight of reflux per part by weight of the unrecycled portion of the overhead distillate.

7. The process of claim 5 wherein at least one of the dimers defined above is present in the feedstock.

8. The process of claim 6 wherein at least one of the dimers defined above is present in the feedstock.

9. The process of claim 7 wherein the feedstock is a whole dripolene or a C fraction thereof.

10. The process of claim 8 wherein the feedstock is a whole dripolene or a (3 fraction thereof.

References Cited UNITED STATES PATENTS 3,537,982 11/ 1970 Parker 208255 3,457,163 7/1969 Parker 208255 3,544,644 12/1970 Robota 260666 3,493,492 2/1970 Sze 208255 3,296,120 1/1967 Doelp 20848 R 3,448,039 6/1969 Tarhan 208255 DELBERT E. GANTZ, Primary Examiner J. M. NELSON, Assistant Examiner US. Cl. X.R.