GB2193224A - Fuel oil additives - Google Patents

Abstract

A composition suitable for addition to an oil, especially a fuel oil, is described comprising at least one inorganic salt and a water soluble alkyl glycoside or oligosaccharide or both or one or more derivatives thereof. The use of such a composition enables the salt to be incorporated in the oil without difficulty; the resulting mixture is storage stable.

Description

SPECIFICATION Oil additives This invention relates to oil additives and, in particular, inorganic additives.

There is a need, for a variety of purposes, of incorporating inorganic materials, in particular metal salts, into oils. A typical example of this is the addition of metal salts to fuel oil as combustion catalysts. In order that the metal salt can blend homogeneously in the oil it is necessary to add it to the oil as a formulation. A variety of different types of vehicle have been used for such formulations, many of these contain surfactants. However, there is a general difficulty about the use of surfactants in that formulations containing metal salts and surfactants tend not to be stable on storage after a few days. Further the compositions tend not to remain dispersed in the oil. Iron salts which are particularly useful as additives are especially troublesome in this respect.In an attempt to overcome this difficulty a variety of mixtures of surfactants have been made up for this purpose but the use of mixtures adds to the complexity and cost of the formulations. So far as the applicants are aware, it has not so far been possible to formulate reliably a metal salt with a single surfactant product which produces a composition which is storage stable.

US-A-4512774 advocates the use of a nonionic or anionic surfactant having a hydrophilic-lipophilic balance (HLB) from 12 to 17. However we have established that the HLB value is no real guide for storage stability. Thus we have found that non ionic surfactants having an HLB from 12 to 17, said to be preferred in the patent, including polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan monolaurate, all containing 20 oxyethylene units, do not give rise to an iron salt-containing oil composition which is stable for more than a few days.

The present invention is based on the discovery that if a special class of surfactant product is employed it is possible to formulate metal salts, including iron salts, into compositions which are stable on storage without the need for an additional surfactant or other additive.

According to the present invention there is provided a composition suitable for addition to an oil which comprises at least one inorganic salt and a water-soluble alkyl glycoside or oligosaccharide or both or one or more derivatives thereof, as well as a method of introducing an inorganic salt into an oil which comprises adding the salt to the oil as a mixture with an alkyl glycoside or oligosaccharide or both or one or more derivatives thereof.

Typically the glycosides and oligosaccharides used in the present invention possess the formula: R~O~(CnH2n - 20n i)mH where R represents an alkyl group having 1 to 32 carbon atoms, m is 1 (in the case of a glycoside) or at least 2 but generally at least 3 (when the compound is an oligosaccharide), and n is from 5 to 7, especially 6 i.e. the product of formula: R-0-(C6H i005)mH.

In this formula one or at least one of the glycosyl units is connected via its number 1 carbon atom to the specified oxygen atom.

Specific alkyl radicals which can be mentioned include methyl, lauryl (C,2H25), C,4H29, C16H33, Ct8H37 and a mixture of C,2H25 and C,3H27 as well as a mixture of C,2H2s, C13H27, C'4H29 and C,5H3,. The glycoside units are generally glucoside units.

Typical derivatives of such compounds include polyoxyethylenated compounds containing, say, 1 to 30, typically 10 to 20, oxyethylene units and/or mono-, di- or tri- esters, or mixtures thereof, with acids such as lauric, oleic, palmitic and stearic acids such as polyoxyethylenated derivatives of methyl glucoside and of methyl glucoside sesquistearate; specific commercially available products include Glucam E-10, E-20 and Glucamate SSE-20, supplied by D.F. Anstead where "10" and "20" represent the number of oxyethylene units.

It will, of course, be appreciated that these surfactants are generally produced in the form of a mixture of compounds and frequently a mixture of oligosaccharide and glycoside will be present.

A particularly preferred product is such a mixture, it being known under the trade mark "TRITON BG10" of Rohm and Haas.

The present invention has a variety of different utilities. A preferred area is as a fuel oil additive where the additive acts as a combustion catalyst. Typical metal salts which may be employed for this purpose include salts of calcium, iron, copper, zinc, manganese, chromium and zirconium. If a calcium salt is employed it is typically the acetate, bromide, chloride, iodide or nitrate but the chloride is preferred. Typical iron salts which may be employed include ferric acetate, bromide, chloride, iodide, nitrate or sulphate with the chloride being particularly pre ferred. Similar anions can be employed with manganese while typical zirconium salts include the acetate, hydroxy chloride, oxychloride, nitrate and sulphate with the oxychloride being preferred.

In this connection, it has been found that the zirconium compounds when formulated with the specified surfactant are effective not only as combustion catalysts but also prevent fouling, slagging and corrosion by modifying the nature of the material depositing upon combustion.

As will be appreciated, the formulation of the composition, will depend on the particular purpose to which it is to be put but, in general, the composition will contain from 0.1 to 25% by weight of the surfactant and preferably 1 to 15%, especially 5 to 15%, by weight with one or more metal salts and water with it. Typically, though, the concentration of metal salt will vary from 2 to 50%, especially 5 to 40%, more especially 10 to 30%, by weight of the composition but the amount of metal salt present will also vary depending on the surfactant concentration.

Typical maximum metal contents are given below: Maximum Metal Contents 1% Surfactant 15% Surfactant (by weight) Calcium DAS (using the acetate bromide, chloride, iodide or nitrate but preferably the chloride 15.3% 13. 1% Iron DAS (using ferric acetate, bromide, chloride, iodide, nitrate or sulphate but preferably the chloride) 14.5% 12.5% Magnesium DAS (using the acetate, bromide, chloride, iodide, nitrate or sulphate but preferably the chloride) i 8.9% 7.5% Zirconium DAS (using the acetate, hydroxychloride, oxychloride, nitrate or sulphate but preferably the oxychloride) 14.6% 12.5% It will be appreciated that it is, in general, necessary to strike a balance between the metal and surfactant contents in a given product to ensure that, on the one hand, the product disperses adequately in the oil and, on the other hand, provides the correct metal dose.

Typical formulation ranges employing a mixture of metal salts are given below (by weight): Ferric chloride 0.3- 9% Magnesium chloride 20-32% Triton BG10 5-15% Make up with water to 100% Ferric chloride 3.0-30% Calcium chloride 3.0-30% Triton BG10 10-15% Make up with water to 100% Other typical formulations include: Copper sulphate 5-16% Triton BG10 5-15% Make up with water to 100% Ferric chloride 5-40% Triton BG10 5-15% Make up with water to 100% Magnesium chloride 10-30% Triton By 10 5-15% Make up with water to 100% Zinc sulphate 5-34% Triton BG10 5-15% Make up with water to 100% Of course, a considerable variation in properties can be obtained within these ranges; thus, with the second formulation type only 3% of each chloride might give insufficient metal. Typically 15% of each chloride will be employed.

While the metal salts may be added as combustion catalysts (and deposit modifiers) metal salts may also be employed as high or low temperature anti-corrosion and/or anti-fouling agents and, of course, a mixture of metal salts can be used to provide more than one of these functions. Thus apart from the metal salts already mentioned, it is, in general, possible to use water soluble salts, for example the acetates, halides, nitrates and sulphates, of aluminium, barium, cerium (and other lanthanides) chromium, cobalt, copper, lead, manganese, titanium and zinc.

It has been found that when the compositions are added to fuel oil which may be stored under static conditions i.e. in a storage tank, the fuel oil can remain stable for many weeks with the additive remaining dispersed in it. Accordingly, the use of the compositions of the present invention enables the metal salt to be dosed into the fuel storage tank or into the oil ring main prior to the burner without fear of the additive depositing out of the oil.

As previously indicated, the concentration of the ingredients in the oil will vary depending on the purpose of adding the metal salt and the nature of the fuel oil. In general, however, the concentration of surfactant will be from 0.05 to 500 ppm, preferably 0.5 to 300 ppm, while the concentration of metal will generally be from 1 to 200 ppm, preferably 5 to 150 ppm. Thus a product containing 5% by weight of iron would typically be dosed at 20 to 1,000 ppm and preferably 100 to 800 ppm. If, however, magnesium were the salt and it is added for low or high temperature anti-corrosion purposes, the amount of metal would typically be from 5 to 100 ppm and preferably 20 to 90 ppm. Thus a composition containing 7% by weight magnesium would be dosed at, say, 70 to 1,400 ppm and preferably 280 to 1290 ppm.

The present invention is also applicable to the addition of metal salts as corrosion inhibitors not only in fuel oils but also in, for instance, cutting oils and lubricating oils. For such purposes, the metal salts are typically salts of molybdenum, chromium and zinc. Metal salts can also be incorporated using the present invention for use as biocides in, for instance, fuel oils, cutting oils and oil based paints. Suitable metal salts which can be employed for this purpose include those of tin, gold, cobalt, aluminium, lead, nickel and zinc but, more particularly, copper, silver and mercury.

Again, various metals, particularly transition metals, can be employed as catalysts in organic reactions and petroleum refining where the process step is carried out in the organic phase. Here too the metal salts can be incorporated using the compositions of the present invention.

The following Examples further illustrate the present invention: EXAMPLE I A product with the following formulation Magnesium chloride 24% Water 66% Triton BG10 10% 100.0% was dispersed at 700 ppm into residual fuel oil (BS 2869, Class G). The treated fuel oil was stored at 40"C and samples were isolated periodically for metal analysis. The results obtained are tabulated below Time lapse/days Mg content of oil/ppm Middle of Sample Bottom of Sample 0 42 42 31 36 45 121 38 44 This Example demonstrates the stability of a dispersion of an aqueous solution of magnesium chloride and Triton BG10 under the static conditions which would prevail in fuel kept in a storage tank.

EXAMPLE 2 A combustion test rig fired with residual fuel oil (8S 2689, Class G) was used to compare the catalytic effects of an iron-containing aqueous solution with an oil-soluble iron organometallic.

The aqueous solution had the following formulation: Ferric chloride 14.5% Water 75.5% Triton BG10 10.0% The organometallic consisted of an iron-tall oil complex containing 15% metal. Both materials were dosed individually into the fuel oil upstream of the burner at dose rates which yielded 80 ppm iron in the fuel. Combustion efficiency was monitored by Bacharach smoke index, a reduction of which when dosing an additive indicates a combustion efficiency improvement. The aqueous iron solution and iron organometallic were found to reduce the smoke index to a similar degree when dosed individually.

The iron containing aqueous solution has also been found to reduce the smoke index of flue gas in a small package boiler.

This Example demonstrates the similarity in performance between aqueous metal solutions containing Triton BG10 and oil-soluble metal compounds used as fuel oil additives.

EXAMPLE 3 Example 1 was repeated with the following formulation: Ferric chloride 14.5% Water 75.5% Triton BG10 10.0% The iron content in the oil was determined after 71 days with the following results Time lapse/days Fe content of oil/ppm Middle -of Sample Bottom of Sample 0 43 43 71 41 55 This demonstrates the stability of compositions containing this type of surfactant even when an iron salt is present. Triton BG10 is believed to have an HLB of about 16t0.5. When the formulation was made using the following surfactant with similar HLB noticeable precipitation in the formulation occurred in 1-7 days: CRILLET 2 ~ polyoxyethylene (2) sorbitan mono palmitate (HLB 15.6) CRILLET 4 : polyoxyethylene (2) sorbitan mono oleate (HLB 15.0) CRILLET 1 polyoxyethylene (2) sorbitan mono laurate (HLB 16.7) Accordingly no tests were carried out on a dispersion of these formulations in oil.

Claims (22)

1. A composition suitable for addition to an oil which comprises at least one inorganic salt and a water soluble alkyl glycoside or oligosaccharide or both or one or more derivatives thereof.

2. A composition according to Claim 1 in which the glycoside or oligosaccharide possesses the formula: R#O#(CnH2n#2On t)mH where R represents an alkyl group having 1 to 32 carbon atoms, m is 1 or more and n is from 5 to 7.

3. A composition according to Claim 2 in which n is 6.

4. A composition according to Claim 1 in which the derivative is a polyoxyethylated compound containing 1 to 30 oxyethylene units and or a mono-, di- or tri-ester, or a mixture thereof, with lauric, oleic, palmitic or stearic acid.

5. A composition according to Claim 4 in which the derivative is a polyoxyethylenated derivative of methyl glucoside or of methyl glucoside sequiestearate.

6. A composition according to any one of the preceding claims in which the metal salt is a salt of calcium, iron, copper, zinc, managanese, chromium or zirconium.

7. A composition according to Claim 6 in which the salt is calcium chloride, ferric chloride, manganese chloride, or zirconium oxychloride.

8. A composition according to any one of the preceding claims which contains from 0.1 to 25% by weight of the surfactant and 2 to 50% by weight of the metal salt.

9. A composition according to Claim 8 which contains 1 to 25% by weight of the surfactant and 5 to 40% by weight of the metal salt.

10. A composition according to Claim 9 which contains 5 to 15% by weight of the surfactant and 10 to 30% by weight of the metal salt.

11. A composition according to Claim 1 substantially as described in any one of the Examples.

12. A method of introducing an inorganic salt into an oil which comprises adding the salt to the oil in the form of a composition as claimed in any one of the preceding claims.

13. A method according to Claim 12 in which the oil is a fuel oil.

14. A method according to Claim 12 or 13 in which the composition is added to provide a surfactant concentration in the oil from 0.05 to 500 ppm and a concentration of metal in the oil from 1 to 200 ppm.

15. A method according to Claim 14 in which the composition is added in an amount to provide 0.5 to 300 ppm of surfactant#in the oil and from 5 to 150 ppm of metal in the oil.

16. A method according to any one of Claims 12, 14 and 15 in which the oil is a cutting oil or lubricating oil.

17. A method according to any one of Claims 12, 14 and 15 in which the oil is an organic phase of an organic reaction or petroleum refinery mixture.

18. A method according to Claim 12 substantially as described in any one of the Examples.

19. An oil comprising an inorganic salt and a water soluble alkyl glycoside or oligosaccharide or both or one or more derivatives thereof.

20. An oil according to Claim 19 which is a fuel coil.

21. An oil according to Claim 19 or 20 in which the glycoside or oligosaccharide or derivative thereof is one defined in any one of Claims 2 to 7.

22. A composition according to any one of Claims 19 to 21 whenever prepared by a method as claimed in any one of Claims 12 to 18.