US3590089A

US3590089A - Cracking dicyclopentadiene to monomer

Info

Publication number: US3590089A
Application number: US767761A
Authority: US
Inventors: Stephen Robota
Original assignee: Hooker Chemical Corp
Current assignee: Occidental Chemical Corp
Priority date: 1968-10-15
Filing date: 1968-10-15
Publication date: 1971-06-29
Anticipated expiration: 1988-06-29
Also published as: GB1261565A

Abstract

IN THE LIQUID PHASE CRACKING OF DICYCLOPENTADIENE, A PARAFFINIC HYDROCARBON OIL IS EMPLOYED WHICH HAS THE FOLLOWING CHARACTERISTICS: (A) AN INITIAL BOILING POINT OF ABOUT 270* C. TO ABOUT 277* C. (B) A LOW BOILING FRACTION WHEREIN ABOUT 10 TO ABOUT 20% TO THE OIL WILL BOIL OFF WHEN THE TEMPERATURE IS ABOUT 295* TO ABOUT 310* C. (C) A WIDE BOILING FRACTION WHEREIN ABOUT 75% TO ABOUT 85% OF THE OIL BOILS OFF WHEN THE TEMPERATURE IS ABOUT 337* TO ABOUT 357* C.

Description

United States Patent 3,590,089 CRACKING DICYCLOPENTADIENE T0 MONOMER Stephen Robota, North Tonawanda, N.Y., assignor to Hooker'Chemical Corporation, Niagara Falls, N.Y. Filed Oct. 15, 1968, Ser. No. 767,761 Int. Cl. C07c 3/26 US. Cl. 260-666 6 Claims ABSTRACT OF THE DISCLOSURE In the liquid phase cracking of dicyclopentadiene, a parafiinic hydrocarbon oil is employed which has the following characteristics:

(a) an initial boiling point of about 270 C. to about (b) a low boiling fraction wherein about 10 to about to the oil will boil off when the temperature is about 295 to about 310 C.

(c) a wide boiling fraction wherein about 75% to about 85% of the oil boils oil? when the temperature is about 337 to about 357 C.

BACKGROUND OF THE INVENTION The invention relates to the liquid phase cracking of dicyclopentadiene to monocyclopentadiene, and the employment of a parafiinic hydrocarbon oil as a solvent.

The formation of cyclopentadiene from dicyclopentadiene by means of hydrocarbon cracking in liquid phase systems is known. There has been difficulty experienced in the amount of resins which accumulate in the fractionating column and in other pieces of equipment as the cracked gas proceeds from the cracking chamber to the fractionating column. It has been found that the use of a parafiinic hydrocarbon oil with a low boiling fraction and a wide boiling fraction decreases the resin buildup and facilitates the overall operating system.

In US. Pat. 2,831,904 there is described a liquid phase cracking of dicyclopentadiene. The improvement described in this patent is the use of an auxiliary liquid, which has a parafiinic hydrocarbon fraction having an initial boiling point above 250 degrees centigrade and of which at least 80 percent boils within a range of no greater than about 50 degrees centigrade, lying within the range between 250 degrees centigrade and about 350 degrees centigrade, and which permits a decrease in resin buildup and the plugging of mechanical systems.

Another method for cracking cyclopentadiene is the hot tube process wherein dicyclopentadiene is funneled through a heated tube to obtain a pure product. An example of such a process is U.S. Pat. 2,582,920. However, the hot tube process is used mainly in the laboratory and is not readily amenable to commercial operations primarily because of plugging of the tube after continuous processing.

It is an object of this invention to obtain an improved yield in the cracking of dicyclopentadiene and to obtain a pure product. It is also an object to obtain a continuous process for the cracking of dicyclopentadiene. These and other objects of this invention will become evident as the invention is further described below.

*SUMMARY OF THE INVENTION Dicyclopentadiene may be cracked to relatively pure monomer in a paraflinic hydrocarbon oil, which has the following characteristics: (a) an initial boiling point of about 270 to about 277 C.; (b) a low boiling fraction wherein about 10 to about 20% to the oil will boil off when the temperature is about 295 to about 310 C.; (c) a wide boiling fraction wherein about 75% to about 3,590,089 Patented June 29, 1971 PREFERRED EMBODIMENTS OF THE INVENTION Crude dicyclopentadiene may be employed. However, it is preferred to use relatively pure dicyclopentadiene. The resulting monomer from the process of this invention is pure monocyclopentadieue. A lower limit of crude dicyclopentadiene would be one that contains approximately percent dicyclopentadiene, with percent purity preferred.

Various paraflinic hydrocarbon oils may be employed as solvents. It is preferred that the oil not be reactive at the operating temperatures and further that it be stable to dicyclo and monocyclopentadiene. The paraffinic oils that may be employed are those that have the following characteristics: (a) an initial boiling point of about 270 to about 277 C.; (b) a low boiling fraction wherein about 10 to about 20% to the oil will boil off when the temperature is about 295 to about 310 C.; (c) a wide boiling fraction wherein about 75 to about 85% of the oil boils off when the temperature is about 337 to about 357 C. The characteristics of an oil can be tested according to ASTM D8661. It is also desirable to have a paratfinic hydrocarbon oil that will be stable to continuous procesing. This can be determined by periodically testing the pour point of the oil as it is recycled. Pour points of about 30 degrees centigrade to about 15 degrees centigrade may be employed. preferably about 20 degrees centirgrade to about 10 degrees centigrade.

The cracking temperatures may range from approximately 270 degrees centigrade to about 325 degrees centigrade, preferably 280 degrees centigrade to about 320 degrees centigrade. As the gaseous mixture leaves the cracking chamber, it enters the partial condenser which may be maintained at approximately 45 degrees centigrade to about degrees centigrade, preferably approximately 45 degrees to about 70 degrees centigrade. The inlet to the fractionation apparatus should be maintained at a high enough temperature to keep the monocyclopentadiene in the vapor state and low enough to remove the high boiling impurities, such as, dicyclopentadiene or other polymers of cyclopentadiene.

The inlet to the fractionation apparatus may be maintained at about 45 degrees centigrade to about 70 degrees centigrade, preferably about 45 degrees centigrade to about 65 degrees centigrade. The fractionation apparatus may be maintained at about 40 degrees centigrade.

The cracked gases referred to in this invention are those gases leaving the cracking chamber. They are generally comprised of cyclopentadiene, hydrocarbon oil and a small amount, if any of dicyclopentadiene. The function of the partial condensor is to condense the hydrocarbon oil, which oil will then run down the inside of the condenser back to the-cracking chamber. Since the partial condenser is kept relatively cool, high boiling polymers of cyclopentadiene will also be condensed and returned to the cracking chamber.

The cracking chamber for commercial operation may employ a stainless steel vessel, a glass lined vessel or some other ceramic vessel.

The partial condenser may be made of carbon steel, a glass lined vessel or other materials obvious to one of skill in the art.

The residence time in the partial condenser should be short about 1 to about 20 seconds, preferably 1 to about 8 seconds or 5 to about 7 seconds and more preferably about 6.6 seconds. Residence times of less than about 5 seconds are not preferred for they may require expensive refrigeration equipment.

The fractionation column is usually packed with ceramic packing while the column itself may use glass-lined or nickel walls. The column may also be packed with ceramic berl saddles of varying length, such as inch or glass helices of varying lengths such as inch or 1 inch.

In order to obtain improved yields of cyclopentadiene, it is desirable that the condensed vapors be cooled as quickly as possible. Cyclopentadiene has a tendency to repolymerize which is an exothermic reaction. The purified monocyclopentadiene should be cooled rapidly in a zone having a temperature from degrees centigrade to -40 degrees centigrade. The formation of dimer can also be prevented by immediately reacting monocyclopentadiene. An example of such a process is described in Bel- .gium Pat. 498,176 wherein monocyclopentadiene is reacted with acetylene to form bicyclo-(2.2.1)-2,5-heptadiene. Also cyclopentadiene is a highly useful intermediate which can be employed to produce such compounds as chlorinated cyclopentadiene, such as chlorendic acid.

This process can be further described by an analysis of the schematic diagram attached. Dicyclopentadiene from dicyclopentadiene reserve 1 directed to the cracking chamber 7 through line 5. The auxiliary liquid is also directed from auxiliary liquid reserve 2 to the cracking chamber through line 6.

Metering pumps

3 and 4 are employed in order to maintain a constant level of material in the cracking chamber. The materials may be preheated prior to being added to the cracking chamber. They may also be merged together before being added to the cracking chamber. To insure further a constant amount of material in the cracking chamber an overflow vessel 8 is employed. Material from this overflow vessel may be directed back to the cracking chamber. During the cracking process, the auxiliary liquid will reflux to coat the partial condenser thereby preventing repolymerization of the cyclopentadiene. The gaseous mixture that leaves the cracking chamber is directed to partial condenser 9 wherein it has a short retention time as it continues to the fractionation column 13. In order to cool and condense the gases in the partial condenser, liquid from cooling liquid reserve 11 pass into the condenser through line 12 and exit back to the reserve through line 10. The cyclopentadiene gas is directed to the fractionation column 13 from the partial condenser and as it exits in the liquid form it can either be stored or passed on for further processing.

The use of a liquid phase cracking system lends itself to the continuous process of cracking dicyclopentadiene. As the pure product is removed from the auxiliary liquid, said liquid can be recycled and used again. The limiting factors are the amount of resin buildup and the point at which the auxiliary liquid becomes clogged with impurities. A quick test for determining the adequacy of the liquid is by measuring the pour point as has been described above.

Varying weight ratios of dicyclopentadiene to paraffinic oil may be used from about 1:1 to 15:1, preferably 4:1 to :1 and even more preferably 10:1 (dicyclopentadiene2oil).

From an economic point of view it is preferred to operate the above described process at atmospheric pressure. To increase product produced per period of time, pressure may be applied. Further during normal processing some pressure may buildup in the equipment. It is within the scope of this invention to operate at such minimal pressures.

Parafiinic hydrocarbon oils with the Wider boiling range of the invention are desirable because less oil will reflux in the partial condenser thereby preventing clogging and consequently increasing the yields of cyclopentadiene. Further, the oil will be more stable during the cracking process and there will be decreased losses of solvent.

Paraffinic hydrocarbon oils with the lower boiling fraction of said wider boiling range oils are desirable. The function of this low boiling fraction is to boil off and coat the partial condenser. The oil will continue to reflux 4 in the condenser, thereby prevent the repolymerization of cyclopentadiene.

The parafiinic hydrocarbon oils of this invention are generally prepared by cracking petroleum. From the cracking of petroleum there are produced several fractions. The paraffinic hydrocarbon oils of this invention are the lighter fractions resulting from the petroleum cracking.

Having described in general the novel points of the invention below are several examples indicating preferred operations. These examples are in no way a limitation on the scope of the invention as described above.

EXAMPLE 1 A paraflinic oil having an initial boiling point of about 272 degrees centigrade 10 percent of which boiled over at 298 degrees centigrade; 20 percent of which boiled over when the temperature is about 307 degrees centigrade and percent of which boiled over at about 345 degrees centigrade was employed. Charged to a 1000 ml. flask is 400 ml. (334 grams) of the oil. The oil was agitated and heated whereby it expanded to 500 ml. Heated dicyclopentadiene of percent purity was fed to the cracker at various rates up to 3.43 grams per minute. The feed is a dicyclopentadiene oil mixture in a weight ratio of 10 to 1 (dicyclozoil). The spent oil was continuously discharged by an overflow line to maintain a 500 ml. oil volume in the cracker. This experiment was run continuously. Three sample runs are indicated in Table I. The percent take off of product is 90 percent.

The dicyclopentadiene feed rate was decreased from 3.43 grams/minute to a low of 1.4 grams per minute to determine if the liquid temperature in the cracking chamber could be increased. The results indicate that the rise in temperature was negligible, reaching 287 degrees centigrade maximum. The pour point of the discharged oil from the cracking chamber remained constant at about ---7 degrees centigrade; the resin buildup in the partial condenser, in connecting lines and in the fractionating column was negligible. The overall average product recovery based on feed was 96.6 percent. The partial condenser volume is about ml.

TABLE I.CRACKING OF DIOYCLOPENTADIENE USING A PARAFFINIC OIL Run No 1 2 3 Dicyclopentadiene teed:

Grams, as dicyclopentadiene 384 258 463 Grams/minute, as dieyc1opentadiene.- 1. 67 1. 845 1. 685 Cracker liquid volume, ml 500 500 500 Cracker vapor volume, ml 500 500 500 Cracker temperatures:

Oil (liquid), average C 280 280 285 (Vapor), Average C 295 286 Fractionation system temperature:

Inlet to fractionation column, average, C. 59 60 60 Reflux, average, C 40 40 40 Oil discharged from cracker, grams". 80. 0 65. 2 30. 9 Pour point of sample, 0. (initial 1 C.) -7 Product collected:

Specific gravity at 20 C 0.8019 0.8017 0. 8014 Percent cyclopentadiene 100. 00 100. 0 100. 0 Grams 367. 5 253. 5 450. 1 Recozery (product/feedXlOO), per- 95. 8 97. 5 97. 2

cen Duration of run, minutes 230 140 What is claimed is:

1. A method for cracking dicyclopentadiene to monocyclopentadiene which comprises heating dicyclopentadiene in a liquid paraffinic hydrocarbon solvent having the following characteristics: (a) an initial boiling point of about 270 to about 277 C.; (b) a low boiling fraction wherein about 10 to about 20% to the oil will boil off when the temperature is about 295 to about 310 C.; (c) a Wide boiling fraction wherein about 75% to about 85% of the oil boils off when the temperature is about 337 to about 357 C. and recovering the substantially pure monocyclopentadiene by distillation.

2. A method of claim 1 wherein the cracking is performed at a temperature in the range of about 270 to about 325 degrees centigrade.

3. A method of claim 2 wherein the cracking temperature is about 280 to about 320 degrees centigrade.

4. The method of claim 1 wherein the liquid hydro carbon parafiinic solvent has an initial boiling point of about 272 to 277 degrees centigrade; 20 percent of which boils over when the temperature is about 307 degrees centigrade and 80 percent of which boils over when the temperature is about 345 degrees centigrade.

5. The method of claim 1 wherein after cracking, the

gaseous mixture is partially condensed at a temperature 10 References Cited UNITED STATES PATENTS 1/1952 Busiuger et a1. 260-666A 4/1958 Kreps 260-666A PAUL M. COUGHLAN, 111., Primary Examiner V. OKEEFE, Assistant Examiner