NZ198995A - Fuels containing a fatty acid ester of a monohydric alcohol and a fatty acid - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number 1 98995 198995 p«:~r,, r >■- If ■ 80 L L » O u L 1. ^ W W. -1^5^ Oy . v..

CcmpSste Specification Fil Ctass: cJP.h!t°J Puis:icrilcn Date: .. Q 6 dOI-" ,1984 3 IAS? :"V Journal fcSo: »» jfs £?) R j No.: Date: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION FUELS ¥/We, MASSEY-FERGUSON-PERKINS LIMITED, a British Company, of 33 Davies Street, London WlY 2EA, England hereby declare the invention for which ^ / we pray that a patent may be granted to $B6/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) 198995 la This invention relates to fuels suitable for use in diesel engines.

Alcohol and vegetable oil have each been considered as alternatives to conventional liquid hydrocarbon fuels. However, the low cetane number and high latent heat of vapourisation of alcohols make them generally unsuitable. in diesel engines except as an additive to diesel fuel. Further, although vegetable oils can be used neat in diesel engines they have a low cetane number, a very high viscosity and leave heavy carbon deposits. An object of the present invention is to provide an alternative fuel that avoids the above disadvantages of alcohol and vegetable oil and which is miscible.

According to the present invention a fuel suitable for a diesel engine comprises a fatty acid ester formed between mpnohydric "and a..fatty afcid.-: The monohydric alcohol may be a low molecular weight alcohol such as ethanol or methanol. The fatty acid may be lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, palmitoleic acid or others, either alone or in admixture with other fatty acids.

These esters are miscible with alcohol, have long straight chain molecules similar in structure to the para-finic type of hydrocarbons and have similar good auto-ignition characteristics when used in diesel engines.

Their cetane number is high and their viscosity is slightly higher than diesel fuel but because these esters are miscible with alcohol their viscosity can be reduced by blending with alcohol whilst still retaining an acceptably high cetane number. Thus a fuel is produced having low viscosity, and low molecular weight as compared with vegeta^<|, oils, C- *l10 FEB 1984 2 1 989 and carbon deposit problems are reduced.

The said ester fuel may be produced by the transest-erification of the esters of polyhydric alcohol and fatty acids present in animal and vegetable oils and fats so that the polyhydric alcohol part of the molecule is replaced by monohydric alcohol.

All vegetable oils and animal fats are mainly composed of esters of the trihydric alcohol, glycerol, and various fatty acids, having approximately 12 to 20 carbon atoms the principle acids being myristic acid, palmitic acid, stearic acid, oleic acid, palmitoleic acid and linoleic acid. For example, sunflower oil has typical acid contents comprising 7% palmitic, 5% stearic, 19% oleic, 69% linoleic. The esters are in fact present as tri-esters of glycerol with the molecular structure ch2ocor I ch ocor' I ch2ocor" where r, r' and r" are derived from the fatty acids.

These tri-esters have high molecular weights, and high melting points and viscosities.

Typically, the transesterification process is catalysed by alkoxide ions, sodium methoxide being an example of a common catalyst. The vegetable oil must contain no free fatty acids that could react with the catalyst and may be washed with sodium hydroxide to remove such acids. The monohydric alcohol used must be in its anhydrous form. The transesterification process using ethanol C2H1-OH can be represented as follows:- 1 98995 3 ch2ocor C2H5ocor ch 2 OH \ ch ocor1 + 3c„hcoh 2 D C2H5ocor' + ch oh ch2ocor' 1 ^HgOCOR" ch 2 oh Triglyceride Mixture of esters Glycerol In a particular example the transesterification process is carried out using sunflower oil and ethanol as raw materials to produce a mixture of ethyl esters as follows:- Ethyl palmitate and ethyl stearate 10 - 12% Ethyl linoleate 45 - 52% Ethyl oleate 36 - 48% Ethyl linoleate 2-4% This mixture of esters had a viscosity of 4.46 cSt, specific gravity 0.88 at 60°F and a cetane value of 63 as measured using IP 41/a.

Blending this mixture with 20 per cent by volume ethanol or methanol reduces the cetane number to 50.

Typically, fuels suitable for diesel engines have a cetane number from 45 to 60 and a viscosity from 1.5 to 5.0 cSt at 100°F.

It will be appreciated that the transesterification process according to the invention can be applied to many different vegetable oils such as sunflower oil, safflower oil, soya oil, ground nut oil, rape seed oil, palm oil, cotton seed oil and coconut oil. It can equally well be applied to animal oils, such as whale oil, and vegetable and animal fats. t 198995 4 U.S. Patent No. 2654767 discloses a typical process for producing the methyl and ethyl esters of high molecular weight fatty acids of vegetable oils by alcoholysis with methanol or ethanol respectively, using an alkaline earth base as catalyst. Other processes are known and may also be suitable.

I 198995

Claims (8)

WHAT WE CLAIM IS:

1. A fuel suitable for a diesel engine comprising a fatty acid ester formed between a monohydric alcohol and a fatty acid.

2. A fuel as claimed in claim 1 in which the ester is a methyl or ethyl ester of an acid selected from lauric, rnyrist-ic, palmitic, stearic, oleic, linoleic and palmitoleic and mixtures thereof.

3. A fuel as claimed in claim 1 in which the ester is a methyl or ethyl ester produced by transesterification of a fatty oil of animal, vegetable or fish origin.

4. A fuel as claimed in claim 3 in which the ester is a methyl or ethyl ester produced by transesterification of sunflower oil, safflower oil, soya oil, ground nut oil, rape seed oil, palm oil, cotton seed oil or coconut oil.

5. A fuel as claimed in claim 1 in which the fatty acid has from 12 to 20 carbon atoms.

6. A fuel as claimed in any one of the preceding claims comprising a blend of said fatty acid ester with methanol or . ethanol.

7. A fuel as claimed in any one of the preceding claims having a cetane number from 45 to 60 and a viscosity from 1.5 to 5.0 cSt at 100°F.

8. A fuel as claimed in claim 1 substantially as herein described . MASSEY-FERGUSON PERKINS LIMITED By His/Their authorised Agents, A. J. PARK & SON