GB2249316A - Fuel oil composition treatment - Google Patents

Abstract

A fuel oil composition such as one containing cracked components is treated to stabilise it against forming sediment and becoming discoloured during storage. The treatment comprises contacting the composition either with one solid polymeric material containing either acidic (eg sulphonic acid) or basic groups (eg substituted guanidines or quaternary ammonium hydroxides) groups, or with more than one such solid polymeric material, the materials being for example resins and being insoluble in the composition.

Description

FUEL OIL COMPOSITION TREATMENT This invention relates to the treatment of fuel oil compositions to stabilise them against forming sediment and becoming discoloured during storage.

It is known that diesel and heating oils can become discoloured and precipitate sludge or sediment when they are stored at ambient or slightly elevated temperatures in air, and further that such problems are exacerbated by the presence in the fuel of cracked components, included to give higher yields of the oils. See, for example, the "Proceedings of the 2nd and 3rd International Conferences on the Long Term Stability of Liquid Fuels", published in October 1986 and 1988 respectively.

Proposals for meeting the above problems by use of additives are described in the art. See, for example, US Patent Nos 3,336,124; 3,640,692; 3,701,641; and 4,040,799, and French Patent No. 1,441,717. Also, International Patent Application Publication No. WO 88/00914 describes use of solid materials containing polar sites to enable polar condensation of the fuel constituents active in degradation, the fuel being stored with the solid materials. Examples of solid materials described are polyether or polyester polyurethane open cell foams and examples of polar sites described are urea and carbamate, ester or amide groups.

The present invention meets the above-mentioned problems by use of fuel insoluble solid materials containing acidic or basic groups. Thus, the invention provides a method of treating a fuel oil composition which comprises contacting the composition either with one solid polymeric material containing either acidic or basic groups, or with more than one such solid polymeric material, the solid polymeric material(s) being insoluble in the fuel composition.

The invention is found to be effective in stabilising fuel oil compositions against sediment formation as evidenced, for example, by the experimental data provided in this specification.

Each of the polymeric material may, for example, be a resin.

Specific examples of such polymeric materials, including resins, include: i) a phenol - formaldehyde condensation product ii) products based on acrylic acid iii) products based on methacrylic acid iv) products based on acrylic acid and methacrylic acid which have been cross-linked with divinyl benzene v) products based on styrene and alpha-methyl styrene vi) products based on styrene and alpha-methyl styrene which have been cross-linked with divinyl benzene The above exemplified polymeric materials and their synthesis are known. The acidic or basic groups may be incorporated therein during their synthesis by polymerisation or be grafted onto a synthesised polymeric material by methods known in the art.

Where an acidic group is provided, it may be any type of acidic group, preferably a strongly acidic group. Specific examples include: i) phenol ii) carboxylic acid iii) dicarboxylic acid iv) keto-acid i.e. polymers which may be considered for example as substituted pyruvic acids, acetoacetic acids, levulinic acids; v) hydroxy-acids i.e. polymers which may be considered for example as substituted glycolic acids, lactic acids, mandelic acids, glyceric acids malic acids, tartaric acids; vi) sulphonic acid.

Of the above, sulphonic acid is preferred.

Where a basic group is provided, it may be any type of basic group, preferably a strongly basic group. Specific examples include: i) primary amine ii) secondary amine iii) tertiary amine iv) substituted guanidine v) quaternary ammonium compound.

Of the above, substituted guanidines and quaternary ammonium compounds are preferred, quaternary ammonium hydroxides being particularly preferred.

The invention may be performed in a number of ways. For example, the solid polymeric material may be suspended in a porous container in the fuel composition to allow contact between the material and the fuel composition.

Alternatively, the material may form part of a filter through which the fuel composition is passed. Also, if desired, the polymeric material may be used to treat more than one batch of fuel composition. For example, batches of fuel compositions may be treated sequentially, or, alternatively, the polymeric material may be present in a container from which the fuel composition is removed and to which fresh fuel composition is added to maintain a constant volume. The weight of polymeric material may, for example, be at least 0.001%, preferably from 0.5 to 5.0%, of the weight of the fuel composition being treated.

In an embodiment of the invention that is preferred because it is found in the examples hereinafter to give rise to the largest improvement in stability of the fuel composition, the fuel is contacted simultaneously with two solid polymeric materials, one of which contains acidic groups and the other contains basic groups.

The cracked component in the fuel oil which gives rise to the undesirable discoloration and precipitation is generally obtained by cracking heavy oil and may be fuel oil in which the main constituent is a fraction obtained from residual oil. Cracking may, for example, be done thermally by methods such as visbreaking and delayed coking, or catalytically by methods such as moving-bed cracking and fluidised bed cracking. After cracking, the distillate oil is extracted by normal or vacuum distillation when the boiling point of the distillate obtained is usually 60iC to 500it. The invention may, for example, be applied to compositions composed entirely of this fuel or to fuels which are mixtures of the cracked fraction and normal distillates as main constituents.

The mechanism of the present invention is believed to be as follows: basic groups, if present, neutralise those strong acids formed as a result of oxidation to prevent them participating in sediment-forming reactions; acidic groups, if present, neutralise basic compounds in the fuel which would otherwise participate in sediment-forming reactions.

The invention will now be particularly described by way of example only as follows, where Examples 1 to 3 are examples of the invention and Example A is a comparative example.

EXAMPLES Materials used (A) Fuel oil composition : a combination of a stable almost water white distillate (80% by weight) and an unstable vis-broken gas oil (20% by weight).

(B) Resin containing acidic groups : AMBERLITE IR-120 (plus), which is a poly(styrenesulphonic acid)..

(C) Resin containing basic groups : AMBERLITE IRA-400 (OH), which is a functionalised polystyrene.

(AMBERLITE is a Registered Trade Mark) Fuel Treatment Method Samples of the resin (5g) were placed in soxhlet extraction thimbles, the ends of which were sealed. Fuel (500g) in which the above thimbles were suspended was stored in darkness at 40 degrees Celsius for 28 days. The thimbles were then removed, the fuel filtered and the weight of sediment determined. The colour of the filtrate was measured on the ASTM D1500 scale.

Results The above method was performed in the absence of resin as a comparative example (Example A), in the presence of only the resin containing acidic groups (Example 1), in the presence of only the resin containing basic groups (Example 2), and in the presence of both of the above resins (Example 3). Two results were obtained for each example. The results are summarised in the Table below.

SEDIMENT COLOUR EXAMPLE (ma/100m1 of fuel) HASTY D1500) A 5.06 5.5 3.76 6.0 1 2.34 5.0 2.66 5.0 2 1.12 4.0 1.44 4.0 3 0.56 4.0 0.80 4.5 The results show that each resin used above reduced sediment formation which reduction was further enhanced using the resins together when the reduction was about 85%. Also, the final colour of the fuel was reduced using the resins singly or together.

Claims (12)

1. A method of treating a fuel oil composition which comprises contacting the composition either with one solid polymeric material containing either acidic or basic groups, or with more than one such solid polymeric material, the solid polymeric material or materials being insoluble in the fuel composition.

2. A method according to claim 1 wherein the composition is contacted simultaneously with two solid polymeric materials, one containing acidic groups and the other containing basic groups.

3. A method according to claim 1 or claim 2 wherein the or at least one of the polymeric materials is a resin.

4. A method according to any of the preceding claims wherein the polymeric material is a phenol-formaldehyde condensation product; a polymer of acrylic or methacrylic acid; a cross-linked polyacrylic or polymethacrylic acid; a polymer of styrene or of a substituted styrene; or a cross-linked polystyrene.

5. A method according to any of the preceding claims wherein the acidic groups, where present, are carboxylic acids; di-carboxylic acids; keto-acids; hydroxy-acids; or unsubstituted or substituted sulphonic acids.

6. A method according to any of the preceding claims wherein the basic groups, where present, are primary, secondary or tertiary amines; substituted guanidines; or quaternary ammonium compounds.

7. A method according to claim 6 wherein the basic groups are quaternary ammonium hydroxides.

8. A method according to any of the preceding claims wherein the weight of the polymeric material is at least 0.001% by weight of the weight of the fuel oil composition being treated.

9. A method according to claim 8 wherein the weight is from 0.5 to 5.0% by weight.

10. A method according to any of the preceding claims wherein the fuel oil composition comprises a direct distillation fraction and a cracked fraction, the cracked fraction comprising 5 to 97% by weight of the composition.

11. A method of treating a fuel oil composition substantially as described herein with reference to any of Examples 1 to 3.

12. A fuel oil composition according to any of the preceding claims.