EP0055355A1 - Petroleum distillates with improved low-temperature sensitivity - Google Patents

Abstract

1. A petroleum distillate exhibiting improved lowtemperature properties and consisting of hydrocarbons boiling in the range from 130 to 420 degrees C, which contains an oil-soluble acid amide alone or in combination with conventional agents for improving the flow behaviour and/or the pour point, which acid amide is prepared from a polyamine and a fatty acid mixture containing oleic acid and palmitic acid as main components.

Description

Petroleum distillates usually show large fluctuations in their composition. Gas oils, for example, which occur in a boiling range between 130 and 420 ° C, can contain 75 - 85% of saturated hydrocarbons, of which in turn 20 _- 35% can be present as n-alkanes (paraffins). The paraffins essentially determine the cold properties of a gas oil.

Paraffins crystallize when the oil, especially gas oil and diesel fuel, cool to low temperatures.

When handling, transporting and storing such petroleum distillates, the paraffins that precipitate below the cloud point and settle in storage tanks, transport vehicles and pipelines form a major problem: outlet devices on the tank bottom can become blocked and zones with very different product compositions form in the storage tank .

This can e.g. lead to the formation of "fractions" in the interior of the tank, which are composed differently and differ in their physical and application properties. When such fractions are filled, sensitive disruptions in pipelines, pre-filters, combustion units or fuel filters or fuel metering devices can occur even at higher outside temperatures.

The temperature at which this phenomenon is first observed is the Clöud Point. The temperature at which the sample is still flowing is called the pour point and the temperature at which it solidifies is the pour point.

The filterability is also used to assess the cold behavior of an oil. The filterability under standardized cooling conditions is measured in the so-called CFPP test ("Cold Filter Plugging Point", DIN). The shape and size of the precipitated paraffin crystals have a significant influence on the filterability of a middle distillate.

It is known that the cold properties of gas oils can be influenced. Above all, additives should achieve better filterability and pumpability. Such additives act as crystal nucleating agents and growth regulators for paraffin crystals. They keep the wax crystals small and thus lower the CFPP and pour point.

Flow and pour point improvers keep paraffins small in their crystal size, but they do not prevent settling.

Additives that delay the start of paraffin excretion are not yet known. The French (additional) patent 95 355 only describes that the addition of approx. 0.01 ppm of different fatty amine acetates reduces the proportion of paraffins precipitating in the cold from approx. 6% to 3 to 5%.

The object of the invention is to provide products which are capable of precipitating in the cold from petroleum distillates ^n-paraffin finkristalle _or evenly distributed to keep. to prevent their sedimentation. It does not come after so much important to improve the above-mentioned Kennzah- _len, but to form a homogeneous crystal dispersion.

entsprechen (wobei X einen Ethylen-, Propylen- oder Isopropylen-Rest bedeutet und m wie auch n zwischen 0 und 500, vorzugsweise zwischen 2 und 50 liegen) mit einer Fettsäure mit 8 oder mehr C-Atomen umsetzt, so enthält man mindestens partiell umgesetzte Säureamide, die öllöslich sind und im Sinne der Erfindung verwendbar sind.It has been found that oil-soluble acid amides of oligo- 11 and polyamines with long-chain fatty acids or fatty acid-like substances are able to disperse wax crystals in petroleum distillates and prevent them from sinking: if oligo- or polyamines, for example of the formula

correspond (where X is an ethylene, propylene or isopropylene radical and m as well as n are between 0 and 500, preferably between 2 and 50) are reacted with a fatty acid with 8 or more carbon atoms, at least partially converted Acid amides, which are oil-soluble and can be used for the purposes of the invention.

Such amides can also be obtained by condensing oligo- or polyamines with suitable fatty acid esters, such as e.g. (Saturated or unsaturated) half esters of saturated or unsaturated dicarboxylic acids with long-chain alcohols with elimination of water.

The condensation can be carried out without auxiliary agents, but also in solvents such as Toluene or xylene, which allow an azeotropic removal of the water formed in the reaction. The condensation proceeds. between 80 and 220 ° C, preferably between 120 and 190 ° C. Up to 1 mol of carboxylic acid can be reacted per reactive equivalent: the conversion ratio of the reactive amino groups is usually 0.2 to 1.

As is known per se, acid amides can also be prepared with the aid of carboxylic acid derivatives such as carboxylic acid esters, carboxylic acid anhydrides or carboxylic acid chlorides. The course of the reaction can be followed simply by determining the amine number and the acid number, but also by means of the amount of water which is distilled off. The reaction does not need to be driven to full implementation. This is advantageous, for example, in order to avoid thermal decomposition in the case of higher molecular weight polyamines.

Suitable polyamines which can be acylated are, for example, diethylenetriamine, triethylenetetramine, dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine and polyethyleneimines with an average degree of polymerization of e.g. 10, 35, 50 or 100 as well as polyamines which are obtained by reacting oligoamines with acrylonitrile and subsequent hydrogenation, i.e. Chain extension were obtained such as N, N'-bis (3-aminopropyl) ethylenediamine.

Suitable fatty acids are pure fatty acids and particularly technically customary fatty acid mixtures which contain stearic acid, palmitic acid, lauric acid, oleic acid, linoleic acid and / or linolenic acid. The natural fatty acid mixtures such as e.g. Tallow fatty acid, coconut oil fatty acid, trans fatty acid, coconut palm kernel oil fatty acid, soybean oil fatty acid, rapeseed oil fatty acid, peanut oil fatty acid, palm oil fatty acid, etc., which contain oleic acid and palmitic acid as main components.

Fatty acid-analogous compounds can also be used; Monoesters of long-chain alcohols of dicarboxylic acids, such as, for example, tallow fatty alcohol maleic acid semi-esters or tallow fatty alcohol succinic acid half-esters or corresponding Glutaric or adipic acid half esters are such technically common substances.

It can be seen from the above that the acid amides to be used according to the invention are generally technical mixtures. They can therefore best be described by the process for their preparation.

• - Art und Menge der im Erdöldestillat enthaltenen Paraffine
• - Siedelage des Erdöldestillates
• - der Provenienz des zugrunde liegenden Rohöls bzw. der Rohölgemische
• - Art und Menge der dem Erdöldestillat sonst noch zugesetzten Additive, insbesondere Additive zur Verbesserung der Kälteeigenschaften des Erdöldestillates
• - der Lagertemperatur bzw. Außentemperatur
• - der Abkühlungsgeschwindigkeit
• - der Form eines Lager- bzw. Transportbehälters für das Erdöldestillat

der Oberflächenbeschaffenheit der Lager- bzw. Transportbehälter.The polyaminamides described can largely prevent sedimentation of paraffin crystals at temperatures below the cloud point in amounts between 0.005 and 0.5% by weight, especially between 0.02 and 0.2% by weight, in the case of petroleum distillates. The effectiveness and dosage of the products of the invention as a dispersant is also influenced by, among others

• - The type and amount of paraffins contained in the petroleum distillate
• - Settlement of petroleum distillate
• - the provenance of the underlying crude oil or crude oil mixtures
• - Type and amount of the additives otherwise added to the petroleum distillate, in particular additives for improving the cold properties of the petroleum distillate
• - the storage temperature or outside temperature
• - the cooling rate
• - The shape of a storage or transport container for the petroleum distillate

the surface condition of the storage or transport container.

The products according to the invention can be added to the petroleum distillate as the sole additive. However, the addition is preferred together with commercially available flow improvers. These are mostly polymers or copolymers based on ethylene and unsaturated compounds or chlorinated polyethylene waxes. The known commercially available flow improvers based on ethylene / vinyl acetate or ethylene / alkyl acrylate may be mentioned as an example. The paraffin dispersants according to the invention can be used in pure form, but also as a solution in suitable solvents, e.g. Dimethylformamide, higher alcohols, ethyl acetate, butyl acetate, benzene, but preferably in toluene, xylene or other hydrocarbons.

This largely prevents paraffins from settling in petroleum distillates at low temperatures, clogging pipes and pipes, and maintaining the homogeneity of petroleum distillates in the storage tanks.

A examples General regulation A 1 - A 82

1 molar equivalent of carboxylic acid (in the case of acid mixtures calculated on average molecular weight in relation to acid number) are placed at 80 ° C. in a closed stirred vessel with a stirrer, thermometer and distillation bridge. Then add 1 to 5 mole equivalents of the polyamine to and condensed 5 to 50 hours at 150 to 180 ⁰ _C while distilling off the water of reaction. Finally, a water jet vacuum is applied for a few hours at 120 ^° C. The Table A contains key figures, yields, etc.: A degree of condensation suitable as a key figure can be determined from amine and acid equivalents of the amide formed.

General regulations A 83 - A 86

To 1 mole equivalent of maleic anhydride melted at 60 ° C, 1 mole equivalent of tallow fatty alcohol (of approx. 60 ° C) is gradually added and stirred until the mixture has reached an acid equivalent of 2.9 meq / g (approx. 1 hour). Then you add 1 to 5 molar equivalents of amine at 80 ° C and distilled in a nitrogen stream at 150 to 170 ° C then at 120 ° C in a water jet vacuum. The exact conditions can be found in Table 1.

• - durch visuelle Beurteilung der ausgefallenen Paraffine in einem in der Kälte gelagerten Mitteldestillat;
• - durch Erstellung eines Eigenschaftsprofils für ein gelagertes öl, in dem man an verschiedenen, jedoch definierten Stellen eines Lagergefäßes aus dem öl Proben entnimmt und diese Proben durch ihre physikalischen Eigenschaften (CFPP-Wert, Cloud Point, Pour Point) und ihre chemische Zusammensetzung (im wesentlichen Gehalt an n-Paraffinen) charakterisiert.

The paraffin-dispersing effect of the amides described can be determined and evaluated

• - by visual assessment of the precipitated paraffins in a middle distillate stored in the cold;
• - By creating a property profile for a stored oil, in which samples are taken from the oil at various, but defined points of a storage vessel and these samples are identified by their physical properties (CFPP value, cloud point, pour point) and their chemical composition (in essential content of n-paraffins).

Visual assessment of the paraffin-dispersing effect:

example

The product from synthesis example A 25 was used as a paraffin dispersant.

0.1% by weight of a petroleum distillate was added to a 70% by weight solution of product A-25 in xylene. A commercially available heating oil, extra light, from a West German refinery was used as the petroleum distillate. The heating oil having a boiling range of 182 ⁰ C to 359 ⁰ C was obtained from a crude oil mixture with 85% Dubai crude oil (residual unknown) and had the following physical data:

After adding a commercially available flow improver based on ethylene / vinyl acetate, the following were measured:

After addition of the inventive agent 1 liter of the fuel oil at -15 ⁰ C in a graduated cylinder was stored for 72 hours.

In the sample added for comparison only with the flow improver, the sediment of paraffin crystals was then 17% of the total liquid volume.

In the sample additionally provided with product A25 according to the invention, only 3% of the liquid volume was found as sediment. The protruding phase showed a uniformly cloudy distribution of the precipitated paraffin crystals in the heating oil.

• I. Prüfap^paratur mit seitlicher Probenahme

Assessment of the paraffin-dispersing effect by creating a property profile:

• I. Prüfap ^p Aratur with lateral sampling

The 3 liter measuring cylinder shown on the left in FIG. 1 served as the test apparatus.

Commercially available heating oils, extra light, West German refinery goods were tested in the measuring cylinders. For this purpose, 3 liters of heating oil were mixed with commercially available flow improvers or additionally with the paraffin dispersants according to the invention to be tested and stored in a refrigerator at temperatures above the pour point.

Before the start of the test, the following data were determined in the crude heating oil sample: cloud point (according to DIN 51597), CFPP (according to DIN 51428 or EN 116) and pour point (according to DIN 51597). After adding the flow improver on the one hand and the paraffin dispersant on the other hand, the same data were determined again in order to determine the influence of the paraffin dispersant on the other parameters for characterizing the cold properties of a heating oil.

During the test period of 24 to 72 hours or at the end of the test, samples of approx. 50 to 80 ml each were taken from 5 side taps at different heights.

After thawing or heating to room temperature or homogenization by shaking, the parameters for characterizing the cold properties of a heating oil were determined in these samples: cloud point, pour point and CFPP value (according to DIN). In addition, the content of n-paraffins was determined by gas chromatography. With the help of this data, it is possible to determine the relevant characteristic data for each lateral sampling valve and to set up a "property profile" over the entire sample volume of 3 liters.

In order to enable differentiated statements, the respective content of n-paraffins for the C numbers C ₈ to C _{26 as} a whole or for the range C ₁₉ to C critical for the low-temperature properties was added up.

Comparative Experiment I (not according to the invention)

An unimproved heating oil was used extra light - with the following key figures:

To improve the cold flow behavior, 250 ppm by weight of a commercially available flow improver were added to the heating oil. The flow improver contains as active substance e.g. an ethylene / vinyl acetate copolymer.

After adding the flow improver, the heating oil had the following key figures:

3 liters of this heating oil were stored for 72 hours in a refrigerator at -15 ° C. in the apparatus described under I..

After 72 hours, the wax crystals had settled in the lower part of the test cylinder, as shown in FIG.

After 72 hours, samples were taken from some of the side taps, starting from the bottom on

As can be seen from FIG. 1 a, this represents a sensible distribution of the sampling points over the entire liquid volume.

This distribution of the sampling points was kept constant in all tests.

The evaluation of the experiment is shown in the following FIG. 2. The 6 sample fractions are plotted on the abscissa and the content of n-paraffins (upper part) and the temperatures for the critical parameters CFPP, cloud point, and pour point are plotted on the ordinate.

It can be seen that due to the paraffin distribution in the test apparatus, fractions 1 and 2 contain the highest proportion of n-paraffins at approximately 11.5%. Correspondingly high in fractions 1 and 2 is Cloudpoint and CFPP with 10 and 11 ° C, respectively.

Fraction 3, in Figure 1, already outside the paraffin separation, has a significantly lower content of n-paraffins (5.2%) than Fraction-1 and 2 and accordingly good cold properties, namely Cloudpoint and CFPP (-14 ° C). The same behavior applies to fractions 4, 5 and 6.

The increase in the pour point from -27 ° C (fraction 1) to -18 ° C (fraction 6) is understandable. The heating oil added flow improvers also have a lowering effect on the pour point. However, since the flow improver forms mixed crystals with the paraffin and thus precipitates and settles together with the paraffins, depletion of effective flow improver or pour point improver also occurs in the upper "less paraffin" areas in the test cylinder. This becomes clear when the CFPP in fraction 6 rises to -12 ° C or the pour point to -18 ° C.

example 1

The procedure was as described in the comparative experiment, but 0.05% by weight of compound A 9 was additionally added to the oil. After that the heating oil showed

After standing for 72 hours at -15 ° C, the test was evaluated: the paraffin suspension was found to be uniformly cloudy, without sediment.

• Der Cloudpoint fällt von -1°C (Fraktion 1) auf -4°C (Fraktion 6), der CFPP ist mit -12°C praktisch über alle 6 Fraktionen konstant, ebenso der Pourpoint mit -18°C. Der Gehalt an n-Paraffinen ^C ₁₉ bis ^C ₂₇ liegt zwischen 6,8 % (Fraktion 1) und 5,4 % (Fraktion 6).

It can also be seen clearly in FIG. 3 from the uniform characteristic values for the 6 sampling points that the paraffin crystals were practically completely dispersed in the test cylinder:

• The cloud point drops from -1 ° C (fraction 1) to -4 ° C (fraction 6), the CFPP is practically constant at -12 ° C across all 6 fractions, as is the pour point at -18 ° C. The content of n-paraffins ^C ₁₉ to ^C ₂₇ is between 6.8% (fraction 1) and 5.4% (fraction 6).

Examples 2 and 3 are based on analogous experiments with a heating oil which, in addition to the flow improvers mentioned above, each contained 0.05% by weight of compound A 14; the storage temperature was -15 ° C in Example 2 and -10 ° C in Example 3. The key figures found are listed in Table 2 at the end of the description together with the comparative test example 1 and a further series of tests.

II. Test equipment with sampling via capillary tubes

The 3 liter measuring cylinders shown in FIG. 1b served as test equipment. 6 melted capillary tubes, which had been melted down and ended at different heights - each at the point where the test taps of the device according to FIG. 19 are located - were immersed in the heating oil. The capillaries were bent over at the upper end and closed with a hose that was put over them using a pinch valve. Sampling was carried out using 50 ml pipettes at the tube connections of the capillaries.

The test was carried out in principle as described under I.

Comparative experiment II

A heating oil - extra light - was used with the following key figures:

0.025% by weight of a commercial flow improver was added to the heating oil to improve its cold behavior. After adding the flow improver, the oil had the following key figures:

3 liters of this heating oil according to FIG. 1b were stored in the test apparatus at -15 ° C. in a refrigeration cabinet for 72 hours.

The property profile is shown in Fig. 6. It can be seen that due to the paraffin distribution in the test apparatus, fractions 1, 2 and 3 with 11.2 and 10.3 as well as 9.4% have the highest content of n-paraffins. The cloud point is correspondingly high at 5 or 3.5 ° C and the CFPP at 4, -1 or 0 ° C. Fractions 4 to 6 were drawn above the paraffin deposition and show significantly better, i.e. lower indicators for the cold behavior. The dependence of the pour point on the tapping point is similar to the method according to Fig. La. In the separated paraffin sediment (fractions 1 to 3), the pour point is the lowest at -27 to -30 ° C due to the failed flow improver. A higher pour point of -24 to -21 ° C. is measured in the "paraffin-poor" fractions 4 to 6, which contain fewer flow improvers.

Examples 4 to 6

The procedure was as in Comparative Experiment II. The heating oil and flow improver described were mixed with 0.05% of compound A 25 (example 4) A.27 (example 5; Storage temperature -15 ° C) A 27 (Example 6; storage temperature -10 ° C) added.

Example 7

The procedure was as described above, but initially no actual flow improver was added to the heating oil, but 0.025% by weight of a commercially available pour point improver: from commercially available flow improvers for middle distillates, e.g. Copolymers of ethylene and vinyl acetate, Pourpoint improvers usually differ by a higher proportion of vinyl acetate.

After adding the pour point improver, the oil had the following metrics:

0.025% of a commercially available flow improver of the paraffin dispersant A'27 according to the invention was then added to this oil. Afterwards the oil had the following characteristics:

The oil was stored for 72 hours at -15 ° C and then showed an even turbidity on the outside.

Claims (3)

1. Petroleum distillate with improved low-temperature behavior, consisting of hydrocarbons with a boiling range of about 130 to 420 ° C, characterized in that it, optionally in addition to conventional agents for improving the flow behavior and / or pour point, is an oil-soluble acid amide of a polyamine with an at least 8 C-containing fatty acid or a free carboxyl group-containing fatty acid analogue compound. 2. Petroleum distillate according to claim 1, characterized in that it contains an acid amide of an average of at least 2 units per molecule having polyalkyleneimine, the alkylene residues of which are ethylene and / or propylene with an acid residue which corresponds to a natural fatty acid mixture. 3. Petroleum distillate according to claim 1, characterized in that it contains an effective amount of 2 percent by weight or less of the acid amide.

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