US3788979A

US3788979A - Process for upgrading dripolene

Info

Publication number: US3788979A
Application number: US00187690A
Authority: US
Inventors: E Caflisch; D Reed; K Williamson
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1971-10-08
Filing date: 1971-10-08
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29

Abstract

A PROCESS FOR PROVIDING A HIGH OCTANE BLENDING COMPONENT FOR GASOLINE FROM DRIPOLENE FEEDSTOCKS CONTAINING DIMERS AND CODIMERS OF CYCLOPENTADIENE AND VARIOUS METHYL DERIVATIVES THEREOF BY DISTILLING, CRACKING , AND HYDROGENATING UNDER DEFINED CONDITIONS INCLUDING THE USE OF AN OXYGEN-FREE ATMOSPHERE AND LIMITED RESIDENCE TIMES OF THE DISTILLING AND CRACKING STEPS WHEREBY HYDROGENATED MONOMERS OF THE DIMERS AND CODIMERS ARE OBTAINED IN THE DRIPOLENE THUS UPGRADING IT.

Description

Jan. 29, 1974 E. CAFLISCH ETAL 3,788,979

PROCESS. FOR UPGRADING DRIPOLENE Filed Oct. 8, 1971 United States Patent 3,788,979 Patented Jan. 29., 1974 US. Cl. 208-255 10 Claims ABSTRACT OF THE DISCLOSURE A process for providing a high octane blending component for gasoline from dripolene feedstocks containing dimers and codimers of cyclopentadiene and various methyl derivatives thereof by distilling, cracking, and hydrogenating under defined conditions including the use of an oxygen-free atmosphere and limited residence times in the distilling and cracking steps whereby hydrogenated monomers of the dimers and codimers are obtained in the dripolene thus upgrading it.

FIELD OF THE INVENTION This invention relates to a process for upgrading dripolene feedstocks to provide high octane blending compoents 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 dripoline, liquid by-product of a hydrocarbon cracking process for the production of ethylene. For many years the C to C fraction of dripoline has been distilled off and used as a blending component in the gasoline market, but the C fraction, which makes up about 10 percent to about 20 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 100 milliliters, and poor stability, both of which cause malfunction in gasoline engines.

What is known as the 0 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; a'lkylenbenzenes 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 0, 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 p-ethyltoluene, o-ethyltoluene, mesitylene, psuedocumene, o-methylstyrene, mand p-methylstyrene, beta-methylstyrene, indan, indene, C benzenes, tetralin, napthalene, 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) (i) introducing the feedstock into a distillation zone wherein the temperature at the bottom of the zone is in the range of about 40 C. to about C. to provide an overhead distillate which includes essentially all of the dimers and codimers defined above and present in the feedstock; or

(ii) introducing the feedstock into a cracking zone wherein the temperature in the zone is in the range of about 150 C. to about 500 C. to providean efliuent which includes, as a result of cracking, monomers corresponding to the dimers and codimers defined above and present in the feedstock;

(b) (i) where step (a) (i) is effected, introducing the overhead distillate therefrom into a cracking zone wherein the temperature in the zone is in the range of about 150 C. to about 500 C. to provide an effluent which includes, as a result of cracking, monomers corresponding to the dimers and codimers provided in step (a) (i);

(ii) where step (a) (ii) is elfected, introducing the effluent therefrom into a distillation zone wherein the temperature at the bottom of the zone is in the range of about 40 C. to about 300 C. to provide an overhead distillate which includes monomers produced in step (a) (ii),

(c) introducing the efiluent from step (b) (i) or the overhead distillate from step (b)(ii) into a hydrogenation zone under hydrogenating conditions, said conditions being such that the zone is essentially incapable of hydrogenating aromatic hydrocarbons, and hydrogenating said effluent or 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;

wherein 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 (c) 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 (d) recovering the high octane blending component.

BRIEF DESCRIPTION OF THE DRAWING The sole figure in the drawing is a schematic flow diagram 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 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 cyclopentadiene 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 C 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 andmethyl cyclopentadiene.

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 exo-isomers are considered to be included within the above definitions. The methyl derivatives mentioned can have 1 to 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 disfilling 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 a conventional distillation column. Columns having from five to twenty theoretical stages have been found suitable. Packed or bubble plate fractionating columns are most commonly used.

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 40 C. to about 150 C. and is preferably about 80 C. to about 140 C. The pressure can be in the range of about 0.01 atmosphere to about the pressure required to accommodate the maximum temperature employed, e.g., one atmosphere, and is preferably in the range of about 0.1 atmosphere to about 0.2 atmosphere. Both temperature and pressure vary throughout the zone. The head temperature can be controlled, if desired; however, it is dependent on the feed and the bottoms temperature. Under usual operating conditions, it can vary from about 40 C. to about 150 C. or higher.

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 the overhead distillate and are taken off through line 3. A portion of the distillate is returned along line 5 to distillate column 2 above the top plate as reflux. The balance of the overhead distillate which may -be called distillate make or make, continues along line 3 and enters cracker 6. A pump may optionally be inserted in line 3 between the inlet to line 5 and cracker 6. 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 0.1 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 compo nents of the feedstock 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. At a point along line 7 a portion of the bottoms is removed from the system along line 9. The amount removed is simply that amount which will maintain a constant level of the bottoms below the bottom plate.

The balance of the bottoms passes into the tube side of heat exchanger 12 which acts as a reboiler. The heating fluid passes through the shell side of the heat exchanger and can be steam at a pressure in the range of about one atmosphere to about ten atmospheres or other suitable heating fluid at a temperature in the range of about 50 C. to about 160 C. and preferably about C. to about C. The bottoms recycle provides the heat for the distillation column, but this recycle can be omitted if desired and other conventional heating devices used. A pump can also be inserted in line 7 to increase the velocity of the recycle and assist in avoiding fouling in the heat exchanger and kettle. The recycle keeps the rise in average bulk temperature to a minimum and provides a washing action to keep the tube and kettle surfaces free from polymer. The bottoms return to distillation column 2 along line 7 at a point below the bottom plate. Essentially any lights which had remained in the bottoms are separated at this point which may be called a vapor-liquid disengagement section (not shown). Here, any vapor or residual lights flash 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 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 (which is the same as the bottom of the distillation column) is as noted heretofore.

The balance of the condensed make proceeds, as noted, along line 3 into the cracking zone identified as cracker 6. Cracker 6 can be any conventional cracking device, such as a steel tube with temperature and pressure controls, heated by steam or other medium. The tempera ture in the cracking zone can be about 150 C. to about 500 C. and is preferably about 350 C. to about 450 C. Cracking can be carried out in the liquid phase, e.g., in a heavy mineral oil or uncracked polymer formed, in. th:

process, or in the vapor phase, the latter being preferred. The preferred liquid phase temperature range is about 275 C. to 350 C., and the residence time can be from one to sixty minutes and is preferably from two to thirty minutes. The pressure in the vapor phase cracking zone can be about 0.5 to about 2 atmospheres and is preferably about 0.7 to about 1 atmosphere. Residence time in the vapor phase is in the range of about 0.1 to about 30 seconds and is preferably about 0.1 to about 6 seconds. The conditions can be adjusted as that essentially all of the dicyclopentadiene is cracked to cyclopentadiene. Residence time is limited to avoid dimerization beyond the defined limits.

The efiiuent from cracker 6, essentially depleted of dicyclopentadiene, is cooled (all or part) to a liquid in a conventional cooling device (not shown) and then proceeds, as noted, along line 8 through a pump (not shown) 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 acomplish the desired reduction in unsaturation, typically in the range of about 10 atmospheres to about 7 5 atmospheres mixes with the effiuent in line 13 and enters hydrogenator 14.

The effiuent provides a liquid phase containing some dissolved hydrogen. The balance of the hydrogen and possibly some effluent 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 l to about 30 to l.

The amount of hydrogen fed is, typically, fora C 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, efiluent, and recycle (discussed below) are fed into the top of the hydrogenator as shown in the drawing and the liquid effluent 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 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 100 C. A preferred mode of operation is to increase the inlet temperature to maintain an effluent diene value of about 1 to about 2 (diene value is determined by ASTM method Dl961-64).

The hydrogen used in the hydrogenator does not have to be pure or essentially pure thus the hydrogen gas can range from 100 percent hydrogen down to a mixture of about 30 percent hydrogen and up to 70 percent 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 two to about six 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 effluent and hydrogen. The diluent can be a hydrogcarbon 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 line 13. The recycle to efiluent ratio can be in the range of about 2 parts to about 10 parts by weight of recycle per part by weight of efiiuent 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 effluent. 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 meas ure 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 enroute 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 the defined dimers and codimers. 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 0 C. to about minus 10 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: 120 C: Temperature in reflux condenser: 10 Cd:

Pressure in distillation column: 0.1 to 0.2 atmosphere i Reflux ratio: 2:1

Overhead temperature in distillation column: 100 C.:':

Composition of whole dripolene feed to distillation column:

Component: Percent by weight (i): Naphthalene 7 Dicyclopentadiene 40 Methyldicyclopentadiene 9 Other components 44 Total feed 100 Feed to distillation column: 29,000 pounds per hour Make: 65 percent by weight of feed.

Feed to cracker same as overhead distillate.

Cracker temperature: 420 c.1-

Cracker pressure: 1 atmosphere Cracker residence time: seconds Feed to Hydrogenator (efliuent): 16,000 pounds per hour Component: Percent by weight (:t) Cyclopentadiene 55 Dicyclopentadiene 2 Naphthalene Methylcyclopentadiene 12 Other components 29 Dimerization in feed to hydrogenator: less than ten percent by weight.

Hydrogenator-inlet temperature: 40 Ci- Catalyst: 0.3 percent by weight (based on weight of support) of palladium on an alumina support.

Hydrogen: essentially pure at 400 p.s.i.g.

Hydrogenator-outlet temperature: 130 C.J:

Temperature differential in hydrogenator: 90 C:

Liquid hourly space velocity of feed to hydrogenator;

1.5 Recycle to feed ratio: 5 :1 Diene value: 1.5

Results: Composition of hydrogenated product:

Component: Percent by weight (i) Cyclopentene and cyclopentane 57 Methylcyclopentene and methylcyclopentane 12 Naphthalene 2 Other components 29 Total product 100 As stated heretofore in the definition of invention, cracking can precede distillation rather than following distillation as described previously herein and in the drawing. The same apparatus is used and the same procedure is followed for both modes of operation with minor variation as follows:

The initial feed is introduced into the cracking zone which is operated in the same temperature and pressure range as cracker 6. The effluent is cooled at least partially to condense it to a liquid and then passes into a distillation column in the same manner as the feed through line 1. Since the effluent contains cyclopentadiene instead of dicyclopentadiene, the bottom temperature range of the distillation column can differ from the previously described distillation zone. The temperature range can be about 40 C. to about 300 C. and is preferably about 80 C. to about 200 C. The overhead distillate proceeds as previously described, but the cracking zone following the distillation column is now omitted and the distillate goes directly to a line previously described as line 13 (optionally, a pump may be inserted along this line) and into the hydrogenator where again the same conditions prevail. The results are similar for both modes of operation.

In the above example the C s are separated by conventional fractional distillation and 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 milliliters (as determined by -ASTM D381-64). Essentially no fouling of the apparatus or catalyst, or foul 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:

(a) introducing the feedstock into a distillation zone wherein the temperature at the bottom of the zone is in the range of about 40 C. to about 150 C. to provide an overhead distillate which includes essentially all of the dimers and codimers defined above and present in the feedstock;

(b) introducing the overhead distillate therefrom into a cracking zone wherein the temperature in the zone is in the range of about 150 C. to about 500 C. to provide an efiluent which includes, as a result of cracking, monomers corresponding to the dimers and codimers provided in step (a);

(c) introducing the efiiuent from step (b) into a hydrogenation Zone under hydrogenating conditions, said conditions being such that the zone is essentially incapable of hydrogenating aromatic hydrocarbons, and hydrogenating said effluent or 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;

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 (c) 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 dimerize; and

(d) 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 80 C. to about C.;

the temperature in the cracking zone is in the range of about 350 C. to about 450 C.; 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 dicyclopentadiene present in the feedstock is at least 25 percent by weight thereof.

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

(g) recycling a portion of the 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. 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:

(a) introducing the feedstock into a cracking zone wherein the temperature in the zone is in the range of about 150 C. to about 500 C. to provide an effluent which includes, as a result of cracking, monomers corresponding to the dimers and codimers defined above and present in the feedstock;

(b) introducing the efliuent therefrom into a distillation zone wherein the temperature at the bottom of the zone is in the range of about 40 C. to about 300 C. to provide an overhead distillate which includes monomers provided in step (a);

(c) introducing the overhead distillate from step (b) into a hydrogenation zone under hydrogenating conditions, said conditions being such that the zone is essentially incapable of hydrogenating aromatic hydrocarbons, and hydrogenating said effiuent or 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;

(d) recovering the high octane blending component.

7. The process of claim 6 wherein the temperature in the bottom of the distillation zone about 350 C. to about 450 C.;

the tempenature in the bottom of the distillation zone is in the range of about C. to about 200 C.; and

8. The process of claim 7 wherein said process is carried out in a continuous manner.

9. The process of claim 8 wherein the amount of dicyclopentadiene present in the feedstock is at least 25 percent by weight thereof.

10. The process of claim 8 comprising the following additional step:

References Cited UNITED STATES PATENTS 3,457,163 7/1969 Parker 208-255 3,537,982 11/ 1970 Parker 208-255 3,493,492 2/ 1970 Sze 208--255 3,215,618 11/1965 Watkins 208255 X 3,544,644 12/1970 Robota 260-666 A 2,352,025 6/1944 Seguy 208-68 2,431,243 11/1947 Greensfelder et a1. 208-68 2,953,513 9/1960 Langer, Jr 208-68 X DELBERT E. GANTZ, Primary Examiner I. M. NELSON, Assistant Examiner US. Cl. X.R.

v UNITED STATES PATENT @FFECE (IERTIFHCATE @i QURRECTWN Patent No. 3 ,788,979 Dated January 29, 1974 fl Edward G. Ceflisch, Denvil kirReed & Kenneth D.Williamson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as show-n below:

Column 8 line 43, Claim 1 delete "or overhead distillate".

Column 8, line 7]., Claim 5 change "(g)" to (e);

I Column 9, line 25, Claim 6 delete "effluent or". Column 10, line 2; Claim 7, change bottom of the distiiiation zone" to cracking zone is in the range of".

\ Column 10, line 17, Claim 10, change Mg)" to --(e)--.

Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JRo C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM P (10-59) uscoMM 0c 60376 P69 0.5. GOVERNMENT PRINTING OFFICE: 196. 0-366-334.