GB2147005A

GB2147005A - Improvements in or relating to fuel additives

Info

Publication number: GB2147005A
Application number: GB08423974A
Authority: GB
Inventors: Charles Voegtlin; Hans Stettler
Original assignee: Sandoz AG
Current assignee: Sandoz AG
Priority date: 1983-09-24
Filing date: 1984-09-21
Publication date: 1985-05-01
Also published as: ZA847507B; BE900593A; IT8448888A0; JPS6092394A; BR8404743A; GB8423974D0; FR2552444A1; IT1199192B; AU3345184A

Abstract

Alcohol-containing fuels are rendered non-corrosive by addition of a phosphoric acid diester or salt thereof preferably together with a further anticorrosive agent and further additives such as acid regulators, nonionic surfactants, mild oxidising agents and agents to prevent crust formation, the additive being of formula I <IMAGE> in which R is C1-20alkyl; R1 is C1-20alkyl; n is 2 or 3; x is 1 to 15; and M is hydrogen, an alkali metal cation, an ammonium or substituted ammonium ion or one equivalent of an alkaline earth metal or zinc cation.

Description

SPECIFICATION Improvements in or relating to organic compounds This invention relates to corrosion proofing of alcohol-containing fuels for internal combustion engines.

It is known that the normal hydrocarbon fuel for internal combustion engines, particularly Otto motors, may be replaced wholly or in part by alcohols, particularly methanol and ethanol. However, such fuels cause corrosion of metals with which they come in contact, e.g. storage tanks, pumps and automobile parts. The corrosion is believed to be due at least in part to traces of formic and acetic acids in technical grade methanol and ethanol.

It has now been found that this corrosion, particularly of steel, can be greatly reduced by the addition to the fuel of certain phosphoric acid esters. Surprisingly these esters do not adversely affect the combustion process nor give rise to toxic products in the exhaust gases.

Accordingly, the invention provides a fuel for internal combustion engines comprising an alcohol or a mixture of alcohol and hydrocarbons together with a phosphoric acid diester of formula I

in which R is C1 20alkyl; R1 is C1-20 alkyl; n is2or3; x is 1 to 15; and M is hydrogen, an alkali metal cation, an ammonium or substituted ammonium ion or one equivalent of an alkaline earth metal or zinc cation.

In formula I, R is preferably R' where R' is C8-18 alkyl, more preferably R" where R" is C12 16alkyl. R1 is preferably R; where R; is C1 5alkyl, most preferably R"1 where R1' is C2 4alkyl, particularly R'''1 where R'''1 is propyl or butyl. The alkyl groups of R and R1 are preferably linear.

n is preferably 2 and xis preferably x' where x' is 3 to 12, more preferably x" where x" is 6 to 9. The values for x, x' and x" represent average values when mixtures of compounds of formula I are present, and may be non-integral. Similarly where both ethyleneoxy and propyleneoxy groups are present n may represent an average value between 2 and 3.

M is preferably M' where M' is Na#, K#, Ca##, Zn#, ammonium substituted by up to 4(C1 4)alkyl or (C2.3)-hydroxyalkyl groups, or morpholinium; more preferably M" where M" is Na#, K#, Zn##, NH4# or HN#(C2H5OH)3.

Preferred compounds are those of formula la

especially those of formula Ib

particularly those of formula Ic

Compounds of formula I are known and are described for example in US Patent 4,389,259.

Preferred alcohols are methanol, ethanol and t-butanol, particularly methanol and ethanol. Preferred hydrocarbons are the saturated petroleum oil fractions normally used as fuel for Otto motors, e.g. pentane, heptane and octane fractions.

Mixtures of alcohols and hydrocarbons may be in any desired proportions, but of particular interest are those containing i) 90-99% vol. hydrocarbons and 10-1% vol. alcohol, preferably 10-2% voi. methanol or methanol/tert.

butanol or ii) 90-95% vol. methanol and 10-5% vol. hydrocarbons.

Other preferred fuels are technical methanol alone (95% methanol, approximately 5% water) and refined 98%-99.9%) methanol alone.

The quantity of compound of formula I when used as the sole anticorrosive agent in the fuel is preferably from 50-300 ppm by wt., more preferably from 60-120 by wt., based upon the alcohol content of the fuel.

However, the quantity used is not critical and may be increased above these preferred values.

The compounds of formula I (component a) are, however, preferably used together with other corrosion inhibitors (components b), e.g. mercaptobenzothiazoles, benzotriazoles, tolytriazoles and sodium boroheptonate. Such corrosion inhibitors are particularly effective in preventing corrosion of zinc, copper, and its alloys, and this anticorrosive effect is increased synergistically by the presence of compound of formula I.

Further additives (components c) include acid regulators to control pH, surfactants, mild oxidising agents, and agents to prevent crust from forming on metals coming in contact with the fuel.

Preferred components b) are selected from unsubstituted mercaptobenzthiazole, its alkali metal salts; unsubstituted benzotriazole; unsubstituted tolyltriazole; and sodium boroheptonate; more preferably benzotriazole and sodium boroheptonate.

Suitable acid regulators for use as component c) include sodium hydroxide, sodium carbonate, sodium bicarbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium acetate, monoethanoiamine, diethanolamine, and triethanolamine; preferably mono- or di-ethanolamine, particularly the former.

Suitable surfactants are conventional nonionic surfactants, and suitable mild oxidising agents are preferably nitrates, e.g. zinc nitrate. As agents to prevent crust formation may be used one or more compounds selected from hydroxycarboxylates (e.g. gluconates and heptonates); aminocarboxylates (e.g.

the sodium salts of nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminopentaacetic acid); and citrates. Preferred compounds are gluconic, mannonic and heptonic acids or their sodium salts.

It is preferred that component a) is used together with at least one compound of component b), more preferably with at least one compound of component b) and at least one compound of component c). In addition it is preferred that zinc ion should be present, and if the compound of formula I is not present in the form of its zinc salt, zinc ion may be added preferably in the form of zinc nitrate.

A preferred anti-corrosive concentrate for addition to an alcohol-containing fuel for internal combustion engines has the following composition, based on 100 parts bywt. of component a) (compound of formula I): Compound parts by weight component b): mercaptobenzothiazole 0-120, preferably 10-30 and/or benzotriazole componentc): i) acid regulator 0-30,preferably5-10 ii) nonionic surfactant 0-20, preferably 0-5 iii) zinc nitrate 0-1 preferably 0.05-0.2 iv) agent to prevent 0-50, preferably 0-30 crust formation water 0-200, preferably 40-100 Preferably some water is added in order to obtain a homogeneous liquid composition. The presence of water is not harmful to the fuel since the amount of concentrate which is added is small and the alcohol in the fuel will always contain some water.

The quantities of anti-corrosive concentrate used in the alcohol-containing fuel are preferably such that the total weight of concentrate added (ignoring the weight of water present as component d)) is from 50-300 ppm based on the weight of alcohol in the fuel, more preferably 60-120 ppm. That is, the weight of concentrate used is essentially the same as the weight of component a) when used alone. Alcohol-containing fuel protected against corrosion by compound of formula I or by the anti-corrosive concentrate described above may be used in contact with iron, steel, zinc, aluminium, copper and alloys thereof, without significant corrosion of the metals.

The following Examples, in which all parts are by weight illustrate the invention.

Examples 1 to 15 Table 1 sets out anticorrosive concentrates which may be used to add to alcohol-containing fuels. The weights are those of the water-free components. The formula of component a) is

or an amine salt of the same anion. TABLE 1 % by weight Example No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Compound a) Na salt 43,8 43,8 47,5 54,75 43,8 43,8 65,7 51,1 29,2 49,0 - - - 54 Compound a) TEA salt - - - - - - - - - - 30 - - - 30 Compound a) DEA salt - - - - - - - - - - - 30 - - Compound a) morpholine salt - - - - - - - - - - - - 30 - Mercaptobenzothiazole 10,0 - - - - - - - - - - - - - Tolyltriazole - 10,0 15,0 10,0 30,0 10,0 10,0 20,0 20,0 10,0 10 10 10 10 10 Zinc nitrate 0,006 - - - - - - - 0,03 0,006 - - - - 0,1 (citrate in Example 15) Triethanolamine 5,0 - 5,0 - - - - 5,0 - - - - - 1 Na heptonate 3,0 - - 3,0 - 7,5 - 0,9 - 3,5 - - - - Na boroheptonate - 18,7 9,4 - - - - - 18,7 - 7 7 7 - Na nitrilotriacetate - 0,8 0,8 1,0 - - - - - 0,8 0,8 - 0,8 - 0,8 Nonionic surfactant - - - - 3,0 5,0 - 2,0 10,0 - - - - 0,1 2,2-dichloro-5,5-dihydroxy diphenylmethane (biocide) 4,0 3,2 - - - - - - - - - - - - Water 34,2 23,5 22,3 31,25 23,2 33,7 24,3 23,0 22,1 36,7 52,2 53 52,2 34,9 59,1 TEA = triethanolamine DEA = diethanolamine Application Examples 16 to 19 100 ppm of the composition of Example 10 is added to refined (99.9%) methanol. The product shows substantially reduced corrosion on a number of metals when compared with methanol alone. Similar results are obtained with the compositions of Examples 11, 12 and 13.

Application Examples 20 to 23 5 ppm of the composition of Example 10 is added to a fuel consisting of 95% petroleum hydrocarbons and 5% technical grade methanol (= 100 ppm based on methanol content). Good anti-corrosion properties were obtained. Similar results are obtained with the compositions of Examples 11, 12 and 13.

Claims

1. A fuel for internal combustion engines comprising an alcohol or a mixture of alcohol and hydrocarbons together with a phosphoric acid diester of formula I

in which R is C1-20 alkyl; R1 is C1-20 alkyl; n is2or3; x is 1 to 15; and M is hydrogen, an alkali metal cation, an ammonium or substituted ammonium ion or one equivalent of an alkaline earth metal or zinc cation.

2. A fuel as claimed in Claim 1 in which the phosphoric acid diester is of formula la

in which R' is C8-18 alkyl, R1 is C1.5aIkyl, x' is3tol2,and M' is Na#, K#, Ca##, Zn##, NH4#, ammonium substituted by up to 4 (C1-4) alkyl or (C2-3) hydroxyalkyl groups, or morpholonium.

3. A fuel as claimed in Claim 2 in which the phosphoric acid diester is of formula Ib

in which R'' is C12-16 alkyl, R1' is C2 4alkyl, x" is 6 to 9 and M'' is Na#, K#, Zn##, NH4# or HN#(C2H5OH)3.

4. A fuel as claimed in Claim 3 in which the phosphoric acid diester is of formula Ic

where R," is propyl or butyl and R", x" and M" are as defined in Claim 3.

5. A fuel as claimed in any one of Claims 1 to 4 comprising 90-99% vol. hydrocarbons and 10-1% alcohol.

6. A fuel as claimed in any one of Claims 1 to 4 comprising 90-95% vol. methanol and 10-5% vol.

hydrocarbons.

7. A fuel as claimed in any one of Claims 1 to 4 consisting essentially of technical or refined methanol.

8. A fuel as claimed in any one of the preceding claims containing from 50-300 ppm bywt. of phosphoric acid diester, based on the alcohol content of the fuel.

9. Afuel as claimed in any one of the preceding claims containing in addition one or more corrosion inhibitors b) selected from mercaptobenzothiazoles, benzotriazoles, tolytriazoles and sodium boroheptonate.

10. Afuel as claimed in Claim 9 containing in addition one or more additives c) selected from acid regulators, nonionicsurfactants, mild oxidising agents, and agents to prevent crust formation, selected from hydroxycarboxylates, aminocarboxylates and citrates.

11. A fuel as described in any one of Application Examples 16 to 23.

12. An anticorrosive concentrate comprising a compound of formula I, stated in Claim 1, at least one corrosion inhibitor b) defined in Claim 9 and at least one further additive c) defined in Claim 10.

13. An anticorrosive concentrate as claimed in claim 12 having the following composition (parts by weight) a) compound of formula I, stated in Claim 1, 100 parts b) mercaptobenzothiazole 10-30 parts and/or benzotriazole c) i) acid regulator 5-10 parts ii) nonionic surfactant 0- 5 parts iii) zinc nitrate 0.05-0.2 parts iv) agent to prevent crust formation 0.30 parts d) water 40-100 parts

14. An anticorrosive concentrate as described in any one of Examples 1 to 15.

15. A method for reducing the corrosive properties of an alcohol-containing fuel comprising adding to the fuel an effective amount of a compound of formula I, stated in Claim 1.

16. A method for reducing the corrosive properties of an alcohol-containing fuel comprising adding to the fuel from 50-300 ppm of an anticorrosive concentrate as claimed in any one of Claims 12 to 14, said quantity being by weight, ignoring the weight of water present as component d), and based on the alcohol content of the fuel.