NO127710B - - Google Patents

Description

Hydrocarbon fuel or crude oil composition.

The present invention relates to hydrocarbon fuel oils and crude oil compositions containing polyesters for lowering the pour point.

According to the present invention, fuel or crude oil compositions are provided comprising a hydrocarbon fuel oil or a crude oil containing a polyester (hereinafter called polymer) obtained by reacting (1) a dicarboxylic acid, a dicarboxylic acid anhydride or a dicarboxylic acid ester, where the number of C atoms in the hydrocarbon chain which connecting the two carbonyl groups is between 1 and 12 inclusive, and 5) a polyol containing at least 4 hydroxyl groups where all the C atoms in the 3-position in relation to the hydroxyl group must be tertiary C atoms, and (3) a monocarboxylic acid, and provided that either reactant (1) or reactants (1) and (3) has a C- and H-containing group which also contains 8 - 44, preferably 18 - 44 carbon atoms which are either bonded to the ;'aV; C-atoméne' 1 the hydrocarbon chain that connects the two carbonyl groups in (1) or bound to the carboxyl group in the acid (3).

From British lit rir. 1,055,337, the use in hydrocarbon fuel oils of esters obtained by reaction of C^Q-substituted succinic acids with hydroxy compounds is known. When producing the esters, however, monocarboxylic acids are not used as in the present invention. The reaction with the monocarboxylic acid gives long-chain hydrocarbon side groups which interact with the surrounding waxes in the special petroleum fraction so that the pour point is lowered. The esters in said British patent no. 1 055 337 are stated to be cleaning lubricants which are used under other conditions to achieve completely different effects than that which is the case in the present invention, namely pouring point lowering.

Compared to the polymers produced according to the method described in British Patent No. 1,140,067, polymers of the present invention exhibit improved pour point lowering properties and generally have better temperature stability.

The dicarboxylic acids and anhydrides from which the polymers used are derived have the general formula:

where and R<£> are hydrogen atoms or hydrogen- and carbon-containing groups, and p and q are equal to zero or whole numbers, and such that p + q is equal to at least 1 but at most 12.

It is an advantage that p + q is rather low, i.e. 1-5, especially equal to 2, so that the acid or anhydride is a hydrocarbon-substituted succinic acid or anhydride.

If reactant (1) has a hydrocarbon substituent, this is preferably an alkenyl group, but can however be an alkyl group or an alkynyl group. Thus, suitable dibasic acid anhydrides where p+q=2 and R£ is an alkenyl group can be prepared by reacting a normal α-olefin with maleic anhydride. If desired, the C- and H-containing group can be a hydrocarbon group substituted with a small amount (e.g. below 10 SS) of other atoms or groups, e.g. halogen atoms.

Instead of an acid or an acid anhydride, the corresponding esters can be used, and particularly suitable esters are derived from low-boiling alcohols, e.g. C-^ - C^-aliphatic alcohols, such as methanol, ethanol or isopropanol.

Polyols in which all the fl-C atoms are tertiary C atoms include tetrols having the general formula:

where to Rg inclusive, which may be the same or different, are hydrogen atoms, halogenated or unsubstituted hydrocarbon groups or halogen atoms, and 0. denotes a carbon atom, a hydrocarbon group, a halogenated hydrocarbon group or an oxygen-containing hydrocarbon group, each bond "to the four C atoms bearing a hydroxyl group goes to a tertiary C atom in the group Q.

In preferred tetrols, the group Q is a C atom, e.g. pentaerythritol itself, or halogenated pentaerythritol. Other suitable tetrols are 1,2,4>5-tetramethylol-benzene.

Other suitable polyols, which contain more than 4 hydroxyl groups, include e.g. polypentaerythritols denoted by the formula:

where m = 0 or an integer.

The monocarboxylic acid (with formula RoC00H") is preferably an acid where Rg consists of an alkyl group, preferably containing from 12 to 30 C atoms, for example octadecyl. However, acids where Rn denotes alkenyl, alkaryl, aryl or aralkyl groups can be used. Examples suitable acids are dodecanoic acid, heptadecanoic acid, eicosanoic acid, tetracosanoic acid, triacontansyfe, benzoic acid and phenylacetic acid. You can also possibly use mixtures of monocarboxylic acids, for example a mixture of ^ 2Q~ °S C^ acids.

In order for the produced polymer to have good pour point-lowering properties, it is advantageous if the C- and H-containing group which is a substituent in reactants (1) and/or (3) is a straight-chain group. The chain length of this substituent is preferably between and especially between 18 and e.g. about. 25 C atoms, especially when the polymer is used as a pour point lowering additive in crude oils or heavy fuel oils, i.e. oils that have kinematic viscosities of more than 15 cS at 38°C and atmospheric pressure. If the polymer is used as a pour point depressant in distillate oils, however, the hydrocarbon group substituent may have less than 10 carbon atoms.

To produce the polymer, the three components (1), (2) and (3^) are reacted with each other. In a preferred embodiment where the polyplene is a tetrol, the amounts of the three components are two moles (3) to one mole (1 ) and a mol (2), but one can easily deviate from these quantity ratios, by, for example, using 0.5 - 1.5 m°l (1) reacted with 0.5 to 1.5 mol (2) and 1.0 to 3.0 moles (3).

The simplified equations below show the main reactions that take place when the polyol is a tetrol:

(A) Component (1) is an acid

Thus, when n mol (1) is reacted with n mol (2) and 2n mol

(3), a total of (4n - 1) mol H2O is removed.

(B). Component (1) is an ester.

Thus, when n mol (1) is reacted with n mol (2) and 2n mol (3)", a total of 2n mol of water and (2n - 1) mol of alcohol are removed.

(C) Component (1) is an anhydride.,

Thus, when n mol (1) is reacted with n mol (2) and 2n mol

(3), a total of (3n-l) moi of water is removed.

The polymer's molecular weight should preferably be above 1000, e.g. between 1,200 and 20,000. This means that for typical polymers where one of the above preferred compounds is used and one reacts (1), (2) and (3)", the number n will be between 2 dg 6, e.g. in medium 4-The polymer's molecular weight can be regulated by controlling the amount of water or alcohol that is removed during the polymerisation reaction. For a polymer with an average of 4 units, i.e. n = 4> and' if 4 m°l of dicarboxylic acid is reacted with 4 m°l (2) and 8 mol t3)> 15 mol, i.e. (4n-l) mol of water must be removed . If dicarboxylic anhydride is used instead of an acid or ester, under similar conditions only 11 mol, i.e. (3n-1) mol of water will be removed. For a polymer with an average of 6 units, i.e. n = 6, the amount of water removed with acid and anhydride will be 23 mol and 17 mol, respectively. Thus, the chain length of the polymer can be regulated by the amount of water that is drained off. For a polymer with a longer backbone length, more water or alcohol must be removed, i.e. the reaction must be carried out over a longer period of time and/or at a higher temperature.

The polymers can be produced by heating the three components (1), (2) and (3) together at a temperature between 100° and 300°C, e.g. around 200°C. The polymerization should preferably be carried out for between 2 and 20 hours, e.g. for about 6 hours.

Optionally, the three components (1), (2) and (3) can be heated together in an aqueous solvent, e.g. xylene, toluene, benzene or heptane, in the presence of a catalyst such as para-toluenesulfonic acid or sulfuric acid. The reaction time should also be between 2 and 20 hours. The water of reaction is removed by azeotropic distillation.

Another alternative is that the reaction is carried out as a two-stage process, with components (2) and (3) being reacted first and the reaction product being reacted with component (1). In this case, a solvent and catalyst can also be used in each reaction step, and the same examples of catalyst and solvent are valid.

After the reaction has been completed, the polymer from the reaction mixture is processed by e.g. evaporation of the solvent under reduced pressure.

The polymers used in the present invention are added to fuel oils or crude oils, and act as pour point lowering agents. The polymer is used in concentrations such as e.g. is between 0.001% and 10.0%, especially between 0.05% and •

5.0%, for example around 0.1% t calculated as a weight percentage of the oil. Optionally, the polymers can be used with advantage in the same quantity ratio.

in lighter hydrocarbons, i.e. in distilled fuels produced by distillation of crude oil at atmospheric pressure, such as e.g. distilled fuel oils that boil above 3&°C at atmospheric pressure, diesel base oil, heating oils or refined petroleum.

The polymers are particularly suitable for use in crude oils or relatively heavy oils. Preferred fuel oils according to the invention are of two types. Firstly, residual fuel oils which are defined as a fuel oil containing residues (residue) from distillation at atmospheric pressure of crude oil or shale oil or mixtures thereof. Secondly, flash-distilled oils which are defined as distillation oils produced by flash distillation at reduced pressure of the oil residues that come from the distillation of crude oil at atmospheric pressure.

Usually, the residual oils will contain from approx. 35$ to 100 wt% residual oils, and typically have kinematic viscosities between .10 and 350° CS at 38°C. However, the viscosity of some particularly waxy fuel oils can be difficult to measure accurately at 38°C, and it is well known in the art that the viscosity of such fuel oils is measured at a higher temperature. The viscosity at 38°C is then obtained by extrapolation with a R.E.F.U.T.A.S. viscosity/temperature table. The extrapolated kinematic viscosity will then fall within the desired range at 38°C. The R,E.F.U.T.A.S. viscosity/temperature table was introduced by CI. Kelly, M. Sc, TECH, F.I.C., M. Inst., A.M.I.A.E., P.T., Baird & Tatlock (London) Ltd., 14-17 Cross Street, Hatton Garden, London, E.C.l.

Fuel oils with kinematic viscosities between 15 and

1500 cS/38°C is preferred, and likewise fuel oils where at least 60% by weight boil above 260°C at atmospheric pressure.

The oils to which the present invention is directed thus include light, medium and heavy base oils or fuel oils with viscosities between 10 and 3500 cS at 38°C, but usually the maximum viscosity will be approx. 1500 cS at 38°^. Examples of suitable oils are described in "Pt 3 Industrial and Marine Fuels of BS 2689", 1957.

Crude oils from which the above fuel oils are derived3 can also be used.

The polymers are added and mixed into the crude oil or heavy oil preferably in an amount of between 0.001 and 10.0% by weight, especially between 0.01 and 1.0% by weight, e.g. 0.3% by weight, based on the oil weight.

The invention will now be described with reference to the following representations and examples.

Preparation 1.

Alkenyl succinic anhydride (ARA) was first prepared by heating 26~°-*-enes containing approx. 60% α-olefins and the remainder p- or f-olefins (32 kg) with maleic anhydride (96 kg) in a 100 liter flask equipped with Ng recirculation tubes, stirrers and reflux condenser: the α-olefin chain length distribution was as follows : ;;The procedure was as follows: ;The reactants were filled into the flask and heated to 90 - 1OCPc. The contents of the flask were thoroughly purged with nitrogen, the Ng-through bubbling was set to minimal speed and the reactants were heated to 230°C with continuous stirring under reflux of maleic anhydride. The temperature was kept at 230°C in this way for 6 hours and then reduced to 150 - 175°C, after which excess maleic anhydride was removed by evaporation under a Ng atmosphere at reduced pressure. ;This ARA-(alkenyl succinic anhydride) had a saponification number of 254 mg KOH/g, corresponding to an effective molecular weight of 442. ;The apparatus for the preparation of the polymer consisted of a 500 ml flanged flask fitted with Ng blow-through nozzles, anchor stirrups , air cooler and contact thermometer. The heating took place using a heating jacket regulated by the contact thermometer. ;The batch was as follows: ;;Reaction conditions ;The contents of the flask were heated and stirred under a nitrogen atmosphere, first for 1/2 hour at 175 - 177°C under reflux and then immediately for "6 hours at 195 - 206°C during evaporation of the formed water. The product was poured into a can and allowed to solidify. ;The properties of the polymer produced. ;Example 1. ;Preparation 1 was added in different concentrations to different oils and the solidification points were measured. The results were as follows: ;(a ) 0.05 wt-$ in light fuel oil A ;(b) 0.30 wt-#, at 342°C f "FVT Brega" residual oil (c) 0.15 wt-% at 342°C "FVT Brega" residual oil ;instead of 0.14°C/minute. ;Preparation 2. ;Alkenyl succinic anhydride was the same as in preparation 1. Apparatus: 500 ml flask with flange and fitted with Ng blow-in and blow-out system, anchor stirrers, thermometer, "Dean and Stark" -water trap and reflux cooler. Heated in a heating jacket. ;Input: ;;The xylene was boiled under reflux for 8.5 hours at about 155°C. One collected 10.3 ml of water. The product was evaporated, initially on a rotary vacuum evaporator and then at a vacuum of 0.1 mm Hg/90°C. Properties of the produced polymer. ;;Example 2. ;Preparation 2 was added in different concentrations to different oils and the solidification points were measured. The following results were obtained: (a) 0.0*5% by weight in light fuel oil A (b) 0.30% by weight in 342°C + "FVT Brega"-restol. ie. 2- ]

Preparation 3

During this preparation, the alkenyl succinic anhydride was produced on a laboratory scale (approx. 1 kg). The procedure was essentially the same as in preparation 1, and the product had a saponification number of 205 mg KOH/g, corresponding to an effective molecular weight of 547•

Bet:

Properties of the produced polymer.

Example 3.

Preparation 3 was added in different concentrations to the different oils and the solidification points were measured. The results were as follows:

(a) 0.05 wt-^ in light fuel oil A

(b) 0.15 wt-$ in 342°C "FVT Brega"-residual oil

Preparation 4.

Two types of ARA were used during this preparation:

(<a>) <C>22_2g-ARA prepared as above, saponification value 226 mg KOH/g, effective molecular weight 496. (b) " C^q+-ARA prepared from oc-olefins with a higher molecular weight distribution (25% under G ^ Q, 75% G^ Q and higher, iodine number 40.4 g. J2/100 g sample, corresponding to 628 in average molar weight). This C^g^ARA was prepared by reacting 1.2 mol of a-olefins with 1 .2 mol (+ 10% excess) of maleic anhydride, and the reaction conditions were as for preparation 1. The product had a saponification value of 145 mg KOH/g, effective molecular weight 774.

Apparatus:

As for preparation 1.

Bet:

React. ionic condition:

As for preparation 1.

Properties of the manufactured polymer:

Melting point, °C 53-54

Total acid value, mg KOH/g 14.30.

Example 4.

Preparation 4 was added in different concentrations to different fuel oils and the solidification points were measured. The results were as follows:

(a) 0.05 wt - fo in light fuel oil 3 ( LBO 3)

(b) 0.15% by weight in 342QC "FVT Brega" restol. ie (c) 0.10 wt -% at 342°C "FVT Brega"- restol. ie

Preparation 5.

The ARA that was used for the preparation of this preparation was in its entirety a C^Q^ compound (see preparation 4 for the preparation of this).

Apparatus:

As for preparation 1.

Bet:

React. ionic conditions:

As for preparation 1.

Properties of manufactured polymer:

Example 5.

Preparation 5 hie in different concentrations added to different fuel oils and the solidification points measured. The results were as follows:

(a) 0, <0>5 wt -% in light fuel oil. ie.

(b) 0.15% by weight of the 342°C "FVT Brega" residual oil

Example 6

An attempt was made to determine whether the polymer produced as preparation 4b is sufficiently temperature stable to withstand a distillation process so that improvements in the crude oil are transferred to residual oil after distillation. A mixture (0.1% by weight) of the polymer in Brega residual oil was prepared and the mixture was heated to 345° - 400°C and held at this temperature for 6 minutes. The properties of the mixture were then measured and compared with the properties of the untreated sample.

Base residual oil without additives has an upper pour point of 40°C and an IP-25 poise limit of 37°C

The flow properties or pour point properties in the cold state of this same polymer when added to waxy North African crude oil (upper pour point 2 4°C) were also measured, applying methods used for the determination of crude oils for major European pipelines, i.e. .for measuring the yield value (the ease with which the contents of a solidified pipeline are pushed forward) and the pump viscosity at certain temperatures.

To measure the yield point, a pipeline of 6 mm x 15 ra filled with crude oil was used, which was cooled to 10°C with a cooling rate of 0.14°G/minute, and which was kept at this temperature for 1 hour, after which air pressure was applied to one end of the pipeline, the pressure being steadily increased by 1 lb/in 2 (0.07 kg/cm 2 ) until the solidified crude began to move.

where Po = the pressure in dyne/cm 2 needed to start the movement,

D = pipeline diameter in cm,

L = the length of the pipeline in cm

the yield stress pressure T(dyn/em 2) is calculated.

The results were as follows:

The pump viscosity of this mixture of polymer and North African crude oil was also measured in a transportable Ferranti coaxial cylinder viscometer at various shear forces. The measurement was carried out by cooling the oil from about 60° to 10°C at a rate of about 0.14°C/minute while measuring the viscosity at decreasing shear stresses.

Results:

Claims (8)

1. Hydrocarbon fuel oil or crude oil composition, characterized by. that the oil contains a polymer obtained by reaction of (1) a dicarboxylic acid, a dicarboxylic acid anhydride or a dicarboxylic acid ester, where the number of carbon atoms in the hydrocarbon chain connecting the two carbonyl groups is 1 - 12, inclusive, with (2) a polyol containing at least 4 hydroxyl groups where all the C atoms in the 3-position in relation to a hydroxyl group must be tertiary C atoms, and (3) a monocarboxylic acid, and provided that either reactant (1) or reactants (1) and (3) have a C- and H-containing group which also contains 8-44, preferably 18-44 carbon atoms which are either bound to one of the C atoms in the hydrocarbon chain connecting the two carbonyl groups in (1), or are bound to the carboxyl group in the acid (3). 2. Composition as stated in claim 1, characterized in that the acid or acid anhydride (1) has the formula: or where R^ and R£ are H- and C-containing groups and p and q are whole numbers, and so that p + q lies between 1 and 5 and is preferably equal to 2. 3. Composition as stated in claim 1, characterized in that the ester (1) is an ester derived from a C, - Cr aliphatic alcohol. 4. Composition as stated in one or more of the above claims, characterized in that the polyol (2) is a tetrol with the general formula: where R^ - Rg inclusive, which may be the same or different, are hydrogen atoms, halogenated or unsubstituted hydrocarbon groups or halogen atoms, and Q is a carbon atom, a hydrocarbon group, a halogenated hydrocarbon group, or an oxygen-containing hydrocarbon group, and where each bond to the four carbon atoms bearing a hydroxyl group goes to a tertiary "carbon atom in group Q. 5. Composition as stated in claim 4, characterized in that the tetrole is pentaerythritol. 6.. Composition as stated in one or more of claims 1-3, characterized in that the polyol is a poly-pentaerythritol with formula: where m is equal to 0 or an integer. 7. Composition as stated in one or more of the above requirements, k a r; a c t e r i s e r t v e d . that: the monocarboxylic acid (3) has the formula R^COOH, where R^ is a C 1 -C 2 alkyl group. 8. Composition as stated in claims 1-7, characterized in that it has added 0.001% to 10.0% by weight of said polymer, based on the weight of crude oil or fuel oil. 9- Composition as specified in one or more of the above claims, characterized in that the molecular weight of the polymer is between 1,200 and 20,000.