# US 4,398,978 A · High density, low viscosity airbreather fuel (RJ-4-I)

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- Number: US 4,398,978 A
- Document ID: US4398978A
- Status: Granted
- Kind: A
- Application number: 06/371,869
- Filed: 1982-04-26
- Granted: 1983-08-16
- Earliest claimed: 1982-04-26
- Assignees: The United States of America as represented by the Secretary of the Navy
- Inventors: George W. Burdette; Abraham I. Schneider
- Web page: https://patentgrep.com/patent/US4398978A

## CPC

- C10L 1/04: essentially based on blends of hydrocarbons
- C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS

## Abstract

A method for preparation of high density, high energy, low viscosity liquid ydrocarbon fuel by catalytic treatment of tetrahydrodimethyldicyclopentadiene (RJ-4) synthetic fuel. Endo-isomers within the fuel stock are isomerized to exo-isomers by treatment of the fuel stock with catalysts such as aluminum chloride, nickel, or pulverized, acid treated firebrick resulting in a fuel having a lower viscosity than the original RJ-4.

## Claims

### Claim 1

A process for making a high density, low viscosity liquid airbreather fuel, isomerized RJ-4, comprising the steps of:
(a) contacting RJ-4, comprising both endo-tetrahydrodimethylidicylopentadiene and exo-tetrahydrodimethyldicyclopentadiene isomers, with a catalyst consisting essentially of an AlCl.sub.3 -olefin complex; and
(b) treating for a sufficient time to obtain isomerized RJ-4 consisting essentially of the exo-tetrahydrodimethyldicyclopentadiene isomer.

### Claim 2 (depends on 1)

The process of claim 1 wherein the mole ratio of AlCl.sub.3 -olefin complex to RJ-4 is in the range of about 0.002 to 1 to about 0.5 to 1 based upon AlCl.sub.3.

### Claim 3 (depends on 1)

The process of claim 1 wherein the mole ratio of AlCl.sub.3 -olefin complex to RJ-4 is in the range of about 0.01 to 1 to about 0.02 to 1.

### Claim 4 (depends on 1)

The process of claim 1 wherein said treatment step is carried out at temperatures within the range of about 0.degree. C. and about 200.degree. C.

### Claim 5 (depends on 1)

The process of claim 1 wherein said treatment step is carried out at temperatures within the range of about 85.degree. C. and about 95.degree. C.

### Claim 6 (depends on 1)

The process of claim 1 wherein treatment is carried out for a time period within the range of about 30 minutes to about 15 hours.

### Claim 7 (depends on 1)

The process of claim 1 wherein treatment is carried out for a time period which is terminated upon measurement of a predetermined reactant viscosity below that of the RJ-4 feed, said measured viscosity being that of the desired isomerized RJ-4.