CA1117554A - Process for isomerization of tetrahydrodimethyldicyclopentadiene - Google Patents
Process for isomerization of tetrahydrodimethyldicyclopentadieneInfo
- Publication number
- CA1117554A CA1117554A CA000340087A CA340087A CA1117554A CA 1117554 A CA1117554 A CA 1117554A CA 000340087 A CA000340087 A CA 000340087A CA 340087 A CA340087 A CA 340087A CA 1117554 A CA1117554 A CA 1117554A
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- endo
- mixture
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- alumina
- Prior art date
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/2206—Catalytic processes not covered by C07C5/23 - C07C5/31
- C07C5/226—Catalytic processes not covered by C07C5/23 - C07C5/31 with metals
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
- C07C2521/14—Silica and magnesia
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
- C07C2521/16—Clays or other mineral silicates
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
- C07C2521/18—Carbon
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
- C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
- C07C2523/44—Palladium
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
- C07C2523/74—Iron group metals
- C07C2523/755—Nickel
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
- C07C2523/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with noble metals
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2603/00—Systems containing at least three condensed rings
- C07C2603/56—Ring systems containing bridged rings
- C07C2603/58—Ring systems containing bridged rings containing three rings
- C07C2603/60—Ring systems containing bridged rings containing three rings containing at least one ring with less than six members
- C07C2603/66—Ring systems containing bridged rings containing three rings containing at least one ring with less than six members containing five-membered rings
- C07C2603/68—Dicyclopentadienes; Hydrogenated dicyclopentadienes
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Tetrahydrodimethyldicyclopentadiene is catalytically isomerized to a liquid isomeric mixture having a suitable low temperature viscosity making it suitable as a missile fuel. A
catalyst is selected from the group consisting of nickel on silica-alumina, palladium on alumina, a mixture of palladium on carbon and nickel on silica-alumina, a mixture of palladium on carbon and acid clay. The temperature of isomerization is in the range from between about 100°C to about 350°C. Hydrogen is also present at a pressure of above about 200 psig.
Tetrahydrodimethyldicyclopentadiene is catalytically isomerized to a liquid isomeric mixture having a suitable low temperature viscosity making it suitable as a missile fuel. A
catalyst is selected from the group consisting of nickel on silica-alumina, palladium on alumina, a mixture of palladium on carbon and nickel on silica-alumina, a mixture of palladium on carbon and acid clay. The temperature of isomerization is in the range from between about 100°C to about 350°C. Hydrogen is also present at a pressure of above about 200 psig.
Description
~ACKGROUND OF TH~ INVENTION
The invention herein described ~as made in the course of or under a contract thereunder with the United States Air Force Systems Con~and.
This invention relates to the isomerization of tetrahydrodimethyldicyclopentadiene, hereinafter referred to as THDMDCP. More particularly, the invention relates to the preparation of an isomeric liquid mixture from THDMDCP. Still more particularly, ~he invention rela~es to the catalytic isomerization of THDMDCP to an isomeric liquid mixture.
Generally the invention relates to the isomerization of endo-THDMDCP to exo-THDMDCP.
The aforementioned isomeric liquid mixture can be used as high energy missile fuel. Such fuels can be used in either jet or rocket propulsion. Jet propulsi~n includes a jet engine which can be used ~or a missile, a~ aircraft and others ~nd includes the three basic types, i.e., ramjet, turbojet and pulse jet. The term rocket genera~ly refers to a device containing its own oxygen or oxidizing agent. An article in A~iation Week and Space Technology~ January 26, 1976, pages 111-113, discloses some of the high density hydrocarbon fuels that are under consideration as missile fuels.
A precursor, dimethyldicyclopentadiene, hereinafter referred to as DMDCP, is prepared by dimerizing methylcyclo-pentadiene. The resulting ~imethyl dimer mixture contains many isomers some of which can be represented by the following structures:
CH3 CH~ CH3 CH3 ~5~
The foregoing structures are predomlnately of endo stereo chemical configuration.
DMDCP can be hydrogenatecl to l~IDMDCP using hydrogen and a hydrogenation catalyst such as nickel on silica-alumina, Raney Ni, palladium on carbon or palladium on alumina and the like. The hydrogenation proceeds smoothly at a temperature of about 100-400C and with a hydrogen pressure of about 200-5000 psig.
Thus, in accordance with the present teachings, a process is provided for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene which comprises contacting endo tetrahydrodimethyldicyclopentadiene with a catalytic amount of a catalyst from the group consisting of a mixture of palladium on carbon and an acid clay, a mixture of palladium on carbon and nickel on silica-alumina, and palladium on alumina. The tempera-ture of contact occurs in the range of from about 100C to about 400C in the presence of hydrogen and at a pressure of at least about 30 psig. The contacting is continued until at least a portion of the endo diene is converted to the exo isomer.
Some of the isomers are known to have substantially different melting points. For example the following two isomers are a clear liquid at ambient temperature, C~ ~ 3 CH3 ~ ~ CH3 3a S~
whereas the following two isomers are solid a~ room temperature and therefore have an adverse effect on the freezing point of the mixture.
~ ~ ~ i ~ CH ~ CH3 This problem is how ~o isomeri~e the isomeric mixture from one which is not suitable as a missile fuel to an isomeric liquid mixture that is suitable.
U.S. Patent 3~381,046 discloseæ the isomerization of dimethyltetrahydrodicyclopentadienes using a liquid acidic catalys~ such as sulfuric acid. It also discloses thermal isomerization. In contrast, applicant uses a solid catalyst and hydrogen. The solid catalyst permits ea~e of separation of the resulting isomeric mixture from the used catalyst while the hydrogen facilitates the iaomerization.
-3a-5~
~UMMA~Y OF THE IN~7IION
THDMDCP is isomerized using ~ catalyst selected from the group consisting of nickel on silica-alumina, a mixture of palladium on carbon and nickel on silica alumina, palladium on alumina, or a mixture of palladium on carbon and an acid clay. ~he isomerization temperature is in the range between from about 100C to abou~ 400C. The pressure of the hydrogen present is at least about 200 psig. The resulting liquid isomeric mixture of tetrahydxodimethyldicyclopen~adiene has a high density and a suitable low temperature viscosity.
~hus, the mixture can be used as a missile fuel.
DESCRIPTION
The isomerization of one of the THDMDCP's via present invention can be represented by the following formula reaction: C
3 ~ CH~
It can also be represented by the following formula reaction:
~ ~ Catalys~ ~ ~ JCH'3 The exo compounds shown are but two of many possible isomers of THDMDCP that result via the isomerization.
While the THDMDCP feed can contain other similar hydrocarbons, such hydrocarbons should not adversely affect the isomerization or the catalyst. Further, the similax hydrocarbons should not adversely influence the desired resulting properties of the isomeriz~d mixture. Thus, ~or optimum results, the feed consists essentially of THDMDCP
which itself can he a mixture of THDMDCP isomers.
The cat~yst used ~ isan~rize the THDMDCP is sel~ted frcm the group consisting of nickel on silica-alumina, a mixture of palladium on carbon and an acid clay, palladium on alumina, or a mixture of p~lladium on carbon and nickel on silica-alumina. The amount of catalyst present is a catalytic amount. Thus, the amount of the catalyst present is sufficient to direct, for exam~le, reactions A and B, and the reaction rate depends in part upon the amount of THDMDCP present~ The preferred catalyst concentration can range between from about one-half part by weight of catalyst per hundred parts by weight of the TH~MDCP to abou~ a one to one ratio while a more preferred range is between from about 1:20 to about 1 10.
The amount of the nickel on silica~alumina can vary substantially; e.g., from about 0.5 wt~ % to about 90 wt. ~, while a preferred range is between from about 40 wt % to about 90 wt. %. The silica-alumina weight ratio can also vary substantially; e.g. t in the range bétween from ahout 1:30 to about 30:70. The amount of palladium on carbon or alumi~
can vary in the range between from about 0.25 wt % to about 20 wt. %. When a catalyst mixture is used the weight ratio of acid clay or nickel on silica-alumina to the palladium on carbon can range between from about 1:50 to about 50:1.
In the catalyst mixture the acid clay; e.g., firebrick, or the silica-alumina, or alumina, supplies the acidic sites to cause the desired reaction to occur.
The isomerization temperature needs to be controlled between a narrow range. The lower limit can be determined by the rate of the reaction; i.e., if the temperature is too low the reaction rate is slow, and such a slow rate makes the ~ process uneconomical. Thus, generally the lower temperature limi~ is about 100C with about 125~C preferred. ~he upper -limit is controlled by the forma~ion o~ undesirable products which adversely affect the properties of thè resultiny missile fuel~ Thus, generally the upper temperature limit is about 400C with about 350C preferred.
Hydrogen needs to be present. It keeps the acti~e sites of the catalyst clean and by doing so minimizes carbonization and polymerization. Generally a wide range of hydrogen pressure can be used, however, economic considerations favor using as low a pressure as possible. As discussed in the Examples, a minimum hydrogen pressure of at least about 200 psig is necessary for an economic isomerization rate.
The properties of the resulting isomerized liquid mixture can vary substantially depending upon the amount of isomerization that occurs. It can dep~nd, in addition to the composition of the initial mixture, on ho~ much of each of the particular isomer of THDMDCP is present. Typically, the xesulting isomerized THDMDCP mixture will have a density (204 ) in the range between from about 0.911 to about 0.918.
The desired density of a missile fuel will depend, in part, on the particular missile design and such factors as the distance the missile is expected to travel.
As to viscosity, the isomeric mixture will typically have a kinematic viscosity @100F in the range between from about 2 cst to about 3 cst. The desired viscosity of a missile fuel will depend in part, on the particular missile design and whether the fuel will be heated during the flight and such factors as the altitude at which the missile will fly.
The desired freezing point of the isomeric fuel mixture depends, in part, in the design of the missile operating conditions.
~ -6-To obtain an isomerized mixture having a density and viscosity which rnake it useful as an additi~e ~or a high density fuel for an air-breathing missile, the reac~ion time or contacting time should be sufficient ~o obtain ~he desired properties. Sufficient time depends in part on the amount of the diene isomerized, the amount of stirring, the amount of catalyst used, the configuration of the vessel containing the reaction or contacting mixture, and other variables. The amount of isomerization c~n be monitored during the process by measuring, for example, the viscosity, thus when the desired amount of isomerization has been obtained, the reaction can be stopped.
The following examples illustrate embodiments of the present invention. Also shown are c~mparative runs.
EXAMPLES
Accompanying Table I summarizes the operating conditions, runs 1-4, during the isomerization of THDMDCP.
Also shown are the properties, i.e., density and viscosity of the resulting product. The products appear to have satisfactory freezing points. Also shown for comparative purposes is an unisomerized T~DMDP mixture having an unsatisfactory viscoity.
Runs 1, 3 and 4 indicated that the operating conditions used will result in an isomeric mixture of THDMDCP having densities and vis~osities suitable for missile fuels. The resulting isomeric mixtures of runs 1-4 and the comparative run were analyzed by vapor phase chromatography (vpc). These results are shown in accompanying Table II.
In accompanying Table II comparison of the vpc peaks indicates that peaks I and II represent the more desirable form of the THDMDCP isomers. While the isomexic product iq~ .
s~
from run 3 does have more of the peak three material, it is believed that this could have resulted from less than optimal contacting time. By comparis~n the product o~ run 4, which was two hours longer than run 3, contains only a small amount of peak III. Also shown in Table II, for comparative purposes, is the aforementioned non-treated THDMDCP mixture. The vpc data shows that the non-treated mix~cure contains only small amounts of peaks I and II compared to the treated (isomerized) mixture of Runs 1-4.
The THDMDCP used in Runs 1-4 was prepared in the ollowing manner. 95.5 grams of DMDCP and S grams of nickel (60~) on silica~alumina catalyst were placed in a 300 ml, autoclave (r~cking type) reactor. The reactor was purged with nitrogen which in turn was purged with hydrogen. Then the reactor contents were pressured with hydrogen to 1480 psig at 23C
and then heated to 275C with agitation. ~he reactor was maintained at 275C for ten hours. Makeup hydrogen was added during the ten hours to keep the reactor pressure at about 2000-2300 psig. Afterwards the reactor cooled and the hydrocarbon product was separated from the catalyst. The hydrocarbon product was analyzed by vpc and found to be completely saturated and primarily r~HDMDCP.
The isomerization (Run 1) was performed using the following procedure. 68.4 grams of THDMDCP and S grams of nickel (60%) on silica alumina catalyst were placed in a 300 ml. autoclave (rocking type) reactor. The reactor was pur~ed with nitrogen and then with hydrogen. After purging the reactor was pressured to 1400 psig with hydrogen and then heated to 235C at which temperature the pressure was about 2350 psig. ~he reactor was maintained at 235C and 2350 psig for ~wenty hours. Af~erwards the reactor and its 7S~
contents were cooled and the reaction product was separated from the catalyst. The reaction product was a clear colorless liquid.
Run 3 was performed using the ~ollowing procedure.
142 grams of DMDCP, 1.5 grams of palladium (10%) on carbon were placed in a 300 ml. autoclave (rocking type) reactor.
The reactor was purged with ni~rogen and then with hydrogen.
Then reactor was pressured with hydrogen to 140 psig and then the temperature raised to~50-60C and maintained at the aforementioned conditions for 5 hours. Vpc analysis indicated that complete hydrogenation has occurred, but that essentially no isomerization has occur~ed. The reactor and its contents were ~hen cooled to room temperature and treated as follows.
At room temperature the cooled reactor was opened and 1.5 grams of firebrick were added to the contents of the reactor. The reactor was purged and repressured with hydrogen and then heated to 235C at which temperature the pressure was 187 psig. After 17 hours at the aforementioned condition the pressure was lowered to 30 psig and the temperature increased to 240-245~C. During the last 3 hours vpc analysis indicated that th0 isomerization rate was increasing. A~ter a total of 6 hours at the higher temperature the reactor was cooled and the hydrocarbon contents separated from the catalyst.
Runs 2 and 4 were conducted in a manner similar to those described for run 3 and the results were as reported in the acoompanying Tables.
The example which indicates the advantage of at least a minimum hydrogen pressure was as follows A reactor was charged with 2800` mls. of feed and 63 grams of nickel on silica-alumina as catalyst. Only a small amount of _g_ '7~5~
isomerization was observed after about 20 hours at 460F with a hydrogen pressure of about 200 psig. However, increasing the hydrogen pressure of the reactor to about 450 psig and using a slightly higher temperature of about 460-470F, the isomerization was found to be complete after 14 additional hours.
` ~
~ ~ ~ t.~ S 4 M
~'1 O ~ o~
.
r-(~ t~
U :~
H El E'- H
E~ ~ D N
Z u~ o t~
H H ~1 .I
The invention herein described ~as made in the course of or under a contract thereunder with the United States Air Force Systems Con~and.
This invention relates to the isomerization of tetrahydrodimethyldicyclopentadiene, hereinafter referred to as THDMDCP. More particularly, the invention relates to the preparation of an isomeric liquid mixture from THDMDCP. Still more particularly, ~he invention rela~es to the catalytic isomerization of THDMDCP to an isomeric liquid mixture.
Generally the invention relates to the isomerization of endo-THDMDCP to exo-THDMDCP.
The aforementioned isomeric liquid mixture can be used as high energy missile fuel. Such fuels can be used in either jet or rocket propulsion. Jet propulsi~n includes a jet engine which can be used ~or a missile, a~ aircraft and others ~nd includes the three basic types, i.e., ramjet, turbojet and pulse jet. The term rocket genera~ly refers to a device containing its own oxygen or oxidizing agent. An article in A~iation Week and Space Technology~ January 26, 1976, pages 111-113, discloses some of the high density hydrocarbon fuels that are under consideration as missile fuels.
A precursor, dimethyldicyclopentadiene, hereinafter referred to as DMDCP, is prepared by dimerizing methylcyclo-pentadiene. The resulting ~imethyl dimer mixture contains many isomers some of which can be represented by the following structures:
CH3 CH~ CH3 CH3 ~5~
The foregoing structures are predomlnately of endo stereo chemical configuration.
DMDCP can be hydrogenatecl to l~IDMDCP using hydrogen and a hydrogenation catalyst such as nickel on silica-alumina, Raney Ni, palladium on carbon or palladium on alumina and the like. The hydrogenation proceeds smoothly at a temperature of about 100-400C and with a hydrogen pressure of about 200-5000 psig.
Thus, in accordance with the present teachings, a process is provided for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene which comprises contacting endo tetrahydrodimethyldicyclopentadiene with a catalytic amount of a catalyst from the group consisting of a mixture of palladium on carbon and an acid clay, a mixture of palladium on carbon and nickel on silica-alumina, and palladium on alumina. The tempera-ture of contact occurs in the range of from about 100C to about 400C in the presence of hydrogen and at a pressure of at least about 30 psig. The contacting is continued until at least a portion of the endo diene is converted to the exo isomer.
Some of the isomers are known to have substantially different melting points. For example the following two isomers are a clear liquid at ambient temperature, C~ ~ 3 CH3 ~ ~ CH3 3a S~
whereas the following two isomers are solid a~ room temperature and therefore have an adverse effect on the freezing point of the mixture.
~ ~ ~ i ~ CH ~ CH3 This problem is how ~o isomeri~e the isomeric mixture from one which is not suitable as a missile fuel to an isomeric liquid mixture that is suitable.
U.S. Patent 3~381,046 discloseæ the isomerization of dimethyltetrahydrodicyclopentadienes using a liquid acidic catalys~ such as sulfuric acid. It also discloses thermal isomerization. In contrast, applicant uses a solid catalyst and hydrogen. The solid catalyst permits ea~e of separation of the resulting isomeric mixture from the used catalyst while the hydrogen facilitates the iaomerization.
-3a-5~
~UMMA~Y OF THE IN~7IION
THDMDCP is isomerized using ~ catalyst selected from the group consisting of nickel on silica-alumina, a mixture of palladium on carbon and nickel on silica alumina, palladium on alumina, or a mixture of palladium on carbon and an acid clay. ~he isomerization temperature is in the range between from about 100C to abou~ 400C. The pressure of the hydrogen present is at least about 200 psig. The resulting liquid isomeric mixture of tetrahydxodimethyldicyclopen~adiene has a high density and a suitable low temperature viscosity.
~hus, the mixture can be used as a missile fuel.
DESCRIPTION
The isomerization of one of the THDMDCP's via present invention can be represented by the following formula reaction: C
3 ~ CH~
It can also be represented by the following formula reaction:
~ ~ Catalys~ ~ ~ JCH'3 The exo compounds shown are but two of many possible isomers of THDMDCP that result via the isomerization.
While the THDMDCP feed can contain other similar hydrocarbons, such hydrocarbons should not adversely affect the isomerization or the catalyst. Further, the similax hydrocarbons should not adversely influence the desired resulting properties of the isomeriz~d mixture. Thus, ~or optimum results, the feed consists essentially of THDMDCP
which itself can he a mixture of THDMDCP isomers.
The cat~yst used ~ isan~rize the THDMDCP is sel~ted frcm the group consisting of nickel on silica-alumina, a mixture of palladium on carbon and an acid clay, palladium on alumina, or a mixture of p~lladium on carbon and nickel on silica-alumina. The amount of catalyst present is a catalytic amount. Thus, the amount of the catalyst present is sufficient to direct, for exam~le, reactions A and B, and the reaction rate depends in part upon the amount of THDMDCP present~ The preferred catalyst concentration can range between from about one-half part by weight of catalyst per hundred parts by weight of the TH~MDCP to abou~ a one to one ratio while a more preferred range is between from about 1:20 to about 1 10.
The amount of the nickel on silica~alumina can vary substantially; e.g., from about 0.5 wt~ % to about 90 wt. ~, while a preferred range is between from about 40 wt % to about 90 wt. %. The silica-alumina weight ratio can also vary substantially; e.g. t in the range bétween from ahout 1:30 to about 30:70. The amount of palladium on carbon or alumi~
can vary in the range between from about 0.25 wt % to about 20 wt. %. When a catalyst mixture is used the weight ratio of acid clay or nickel on silica-alumina to the palladium on carbon can range between from about 1:50 to about 50:1.
In the catalyst mixture the acid clay; e.g., firebrick, or the silica-alumina, or alumina, supplies the acidic sites to cause the desired reaction to occur.
The isomerization temperature needs to be controlled between a narrow range. The lower limit can be determined by the rate of the reaction; i.e., if the temperature is too low the reaction rate is slow, and such a slow rate makes the ~ process uneconomical. Thus, generally the lower temperature limi~ is about 100C with about 125~C preferred. ~he upper -limit is controlled by the forma~ion o~ undesirable products which adversely affect the properties of thè resultiny missile fuel~ Thus, generally the upper temperature limit is about 400C with about 350C preferred.
Hydrogen needs to be present. It keeps the acti~e sites of the catalyst clean and by doing so minimizes carbonization and polymerization. Generally a wide range of hydrogen pressure can be used, however, economic considerations favor using as low a pressure as possible. As discussed in the Examples, a minimum hydrogen pressure of at least about 200 psig is necessary for an economic isomerization rate.
The properties of the resulting isomerized liquid mixture can vary substantially depending upon the amount of isomerization that occurs. It can dep~nd, in addition to the composition of the initial mixture, on ho~ much of each of the particular isomer of THDMDCP is present. Typically, the xesulting isomerized THDMDCP mixture will have a density (204 ) in the range between from about 0.911 to about 0.918.
The desired density of a missile fuel will depend, in part, on the particular missile design and such factors as the distance the missile is expected to travel.
As to viscosity, the isomeric mixture will typically have a kinematic viscosity @100F in the range between from about 2 cst to about 3 cst. The desired viscosity of a missile fuel will depend in part, on the particular missile design and whether the fuel will be heated during the flight and such factors as the altitude at which the missile will fly.
The desired freezing point of the isomeric fuel mixture depends, in part, in the design of the missile operating conditions.
~ -6-To obtain an isomerized mixture having a density and viscosity which rnake it useful as an additi~e ~or a high density fuel for an air-breathing missile, the reac~ion time or contacting time should be sufficient ~o obtain ~he desired properties. Sufficient time depends in part on the amount of the diene isomerized, the amount of stirring, the amount of catalyst used, the configuration of the vessel containing the reaction or contacting mixture, and other variables. The amount of isomerization c~n be monitored during the process by measuring, for example, the viscosity, thus when the desired amount of isomerization has been obtained, the reaction can be stopped.
The following examples illustrate embodiments of the present invention. Also shown are c~mparative runs.
EXAMPLES
Accompanying Table I summarizes the operating conditions, runs 1-4, during the isomerization of THDMDCP.
Also shown are the properties, i.e., density and viscosity of the resulting product. The products appear to have satisfactory freezing points. Also shown for comparative purposes is an unisomerized T~DMDP mixture having an unsatisfactory viscoity.
Runs 1, 3 and 4 indicated that the operating conditions used will result in an isomeric mixture of THDMDCP having densities and vis~osities suitable for missile fuels. The resulting isomeric mixtures of runs 1-4 and the comparative run were analyzed by vapor phase chromatography (vpc). These results are shown in accompanying Table II.
In accompanying Table II comparison of the vpc peaks indicates that peaks I and II represent the more desirable form of the THDMDCP isomers. While the isomexic product iq~ .
s~
from run 3 does have more of the peak three material, it is believed that this could have resulted from less than optimal contacting time. By comparis~n the product o~ run 4, which was two hours longer than run 3, contains only a small amount of peak III. Also shown in Table II, for comparative purposes, is the aforementioned non-treated THDMDCP mixture. The vpc data shows that the non-treated mix~cure contains only small amounts of peaks I and II compared to the treated (isomerized) mixture of Runs 1-4.
The THDMDCP used in Runs 1-4 was prepared in the ollowing manner. 95.5 grams of DMDCP and S grams of nickel (60~) on silica~alumina catalyst were placed in a 300 ml, autoclave (r~cking type) reactor. The reactor was purged with nitrogen which in turn was purged with hydrogen. Then the reactor contents were pressured with hydrogen to 1480 psig at 23C
and then heated to 275C with agitation. ~he reactor was maintained at 275C for ten hours. Makeup hydrogen was added during the ten hours to keep the reactor pressure at about 2000-2300 psig. Afterwards the reactor cooled and the hydrocarbon product was separated from the catalyst. The hydrocarbon product was analyzed by vpc and found to be completely saturated and primarily r~HDMDCP.
The isomerization (Run 1) was performed using the following procedure. 68.4 grams of THDMDCP and S grams of nickel (60%) on silica alumina catalyst were placed in a 300 ml. autoclave (rocking type) reactor. The reactor was pur~ed with nitrogen and then with hydrogen. After purging the reactor was pressured to 1400 psig with hydrogen and then heated to 235C at which temperature the pressure was about 2350 psig. ~he reactor was maintained at 235C and 2350 psig for ~wenty hours. Af~erwards the reactor and its 7S~
contents were cooled and the reaction product was separated from the catalyst. The reaction product was a clear colorless liquid.
Run 3 was performed using the ~ollowing procedure.
142 grams of DMDCP, 1.5 grams of palladium (10%) on carbon were placed in a 300 ml. autoclave (rocking type) reactor.
The reactor was purged with ni~rogen and then with hydrogen.
Then reactor was pressured with hydrogen to 140 psig and then the temperature raised to~50-60C and maintained at the aforementioned conditions for 5 hours. Vpc analysis indicated that complete hydrogenation has occurred, but that essentially no isomerization has occur~ed. The reactor and its contents were ~hen cooled to room temperature and treated as follows.
At room temperature the cooled reactor was opened and 1.5 grams of firebrick were added to the contents of the reactor. The reactor was purged and repressured with hydrogen and then heated to 235C at which temperature the pressure was 187 psig. After 17 hours at the aforementioned condition the pressure was lowered to 30 psig and the temperature increased to 240-245~C. During the last 3 hours vpc analysis indicated that th0 isomerization rate was increasing. A~ter a total of 6 hours at the higher temperature the reactor was cooled and the hydrocarbon contents separated from the catalyst.
Runs 2 and 4 were conducted in a manner similar to those described for run 3 and the results were as reported in the acoompanying Tables.
The example which indicates the advantage of at least a minimum hydrogen pressure was as follows A reactor was charged with 2800` mls. of feed and 63 grams of nickel on silica-alumina as catalyst. Only a small amount of _g_ '7~5~
isomerization was observed after about 20 hours at 460F with a hydrogen pressure of about 200 psig. However, increasing the hydrogen pressure of the reactor to about 450 psig and using a slightly higher temperature of about 460-470F, the isomerization was found to be complete after 14 additional hours.
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VPC ANALYSIS OF ISOMERIC PRODUCTS
AREP.S UNDE~ VPC PEAKS
PEAK BELGW I I I III I
RUNS
1.3 33.347.113.6 4.7 2 5.2 41.752.3 0.8
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VPC ANALYSIS OF ISOMERIC PRODUCTS
AREP.S UNDE~ VPC PEAKS
PEAK BELGW I I I III I
RUNS
1.3 33.347.113.6 4.7 2 5.2 41.752.3 0.8
3 - 4D~.622.427.3 5.7
4 - 51.144.7 4.1 0.1 Unisomerized - 9 4 46 40 Mixture r ~
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Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene comprising:
(a) contacting endo tetrahydrodimethyldicyclopentadiene with a catalytic amount of a catalyst selected from the group consisting of a mixture of palladium on carbon and an acid clay; a mixture of palladium on carbon and nickel on silica-alumina; and palladium on alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen; having a pressure of at least about 30 psig and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
(a) contacting endo tetrahydrodimethyldicyclopentadiene with a catalytic amount of a catalyst selected from the group consisting of a mixture of palladium on carbon and an acid clay; a mixture of palladium on carbon and nickel on silica-alumina; and palladium on alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen; having a pressure of at least about 30 psig and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
2. Process according to Claim 1 wherein the catalyst to the diene ratio ranges between from about one-half part by weight of catalyst per hundred parts by weight of the diene to about one to one.
3. Process according to Claim 2 wherein the hydrogen pressure is in the range from about 200 psig to about 5000 psig.
4. Process according to Claim 3 wherein the resulting isomer mixture has a density in the range between from about 0.911 to about 0.918.
5. Process according to Claim 3 wherein the resulting isomer mixture has a kinematic viscosity @100°F
in the range between from about 2 cst to about 3 cst.
in the range between from about 2 cst to about 3 cst.
6. Process according to Claim 5 wherein the temperature range is between from about 125° to about 350°C.
7. Process according to Claim 6 wherein the amount of nickel on silica-alumina range is between from about 0.5 wt. % to about 90 wt. %.
8. Process for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene comprising:
(a) contacting endo tetrahydrodimethyldicyclopen-tadiene with a catalytic amount of a mixture of palladium on carbon and firebrick;
(b) having the contacting occur at a temperature in he range from about 100°C to about 400°C and in the presence of hydrogen having a pressure of at least about 30 psig; and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
(a) contacting endo tetrahydrodimethyldicyclopen-tadiene with a catalytic amount of a mixture of palladium on carbon and firebrick;
(b) having the contacting occur at a temperature in he range from about 100°C to about 400°C and in the presence of hydrogen having a pressure of at least about 30 psig; and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
9. Process for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene comprising:
(a) contacting endo tetrahydrodimethyldicyclopenta-diene with a catalytic amount of a mixture of palladium on carbon and nickel on silica alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen having a pressure of at least about 105 psig; and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
(a) contacting endo tetrahydrodimethyldicyclopenta-diene with a catalytic amount of a mixture of palladium on carbon and nickel on silica alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen having a pressure of at least about 105 psig; and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
10. Process for the catalytic isomerization of endo tetrahydrodimethyldicyclopentadiene comprising:
(a) contacting endo tetrahydrodimethyldicyclo-pentadiene with a catalytic amount of nickel on silica-alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen having a pressure above about 200 psig;
and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
(a) contacting endo tetrahydrodimethyldicyclo-pentadiene with a catalytic amount of nickel on silica-alumina;
(b) having the contacting occur at a temperature in the range from about 100°C to about 400°C and in the presence of hydrogen having a pressure above about 200 psig;
and (c) continuing the contacting until at least a portion of the endo diene is converted to its exo isomer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96191178A | 1978-11-20 | 1978-11-20 | |
| US961,911 | 1978-11-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1117554A true CA1117554A (en) | 1982-02-02 |
Family
ID=25505173
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000340087A Expired CA1117554A (en) | 1978-11-20 | 1979-11-19 | Process for isomerization of tetrahydrodimethyldicyclopentadiene |
Country Status (9)
| Country | Link |
|---|---|
| BE (1) | BE880114A (en) |
| CA (1) | CA1117554A (en) |
| DE (1) | DE2946802A1 (en) |
| DK (1) | DK491379A (en) |
| FR (1) | FR2441600A1 (en) |
| GB (1) | GB2037314B (en) |
| IT (1) | IT1126330B (en) |
| NL (1) | NL7908450A (en) |
| NO (1) | NO793741L (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2918509A (en) * | 1957-10-31 | 1959-12-22 | Pure Oil Co | Process and catalyst for the isomerization of hydrocarbons |
| US3381046A (en) * | 1966-08-15 | 1968-04-30 | Exxon Research Engineering Co | Jet and rocket fuel |
| FR1537241A (en) * | 1966-08-15 | 1968-08-23 | Exxon Research Engineering Co | Preparation of fuels with high energy potential |
| US4051017A (en) * | 1973-05-14 | 1977-09-27 | Continental Oil Company | Catalytic hydrocarbon reforming process and catalyst |
| JPS5522452B2 (en) * | 1973-06-27 | 1980-06-17 |
-
1979
- 1979-11-16 FR FR7928349A patent/FR2441600A1/en active Granted
- 1979-11-19 BE BE0/198172A patent/BE880114A/en not_active IP Right Cessation
- 1979-11-19 NO NO793741A patent/NO793741L/en unknown
- 1979-11-19 DK DK491379A patent/DK491379A/en not_active Application Discontinuation
- 1979-11-19 IT IT27409/79A patent/IT1126330B/en active
- 1979-11-19 CA CA000340087A patent/CA1117554A/en not_active Expired
- 1979-11-20 NL NL7908450A patent/NL7908450A/en not_active Application Discontinuation
- 1979-11-20 DE DE19792946802 patent/DE2946802A1/en not_active Withdrawn
- 1979-11-20 GB GB7940049A patent/GB2037314B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2946802A1 (en) | 1980-05-29 |
| GB2037314A (en) | 1980-07-09 |
| DK491379A (en) | 1980-05-21 |
| IT1126330B (en) | 1986-05-21 |
| BE880114A (en) | 1980-05-19 |
| IT7927409A0 (en) | 1979-11-19 |
| FR2441600B1 (en) | 1982-12-31 |
| FR2441600A1 (en) | 1980-06-13 |
| NO793741L (en) | 1980-05-21 |
| NL7908450A (en) | 1980-05-22 |
| GB2037314B (en) | 1983-01-19 |
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