JPH0473473B2 - - Google Patents

Description

[Detailed description of the invention]

Mineral oil containing paraffin wax has the characteristic that fluidity decreases as the temperature of the mineral oil decreases. This loss of fluidity is due to the wax crystallizing into platelets (ultimately forming a spongy mass with mineral oil entrapped therein). In the past, various additives have been known that act as wax crystal modifiers when mixed with waxy mineral oils. These compositions change the shape and size of wax crystals and reduce the adhesion between oils and crystals of wax so that the oil can maintain its fluidity at low temperatures. be. Various pour point depressants have been described in the literature;
Some of them are used commercially. For example, US Pat. No. 3,048,479 teaches the use of copolymers of ethylene and _C3 - _C5 vinyl esters, such as vinyl acetate, as flow depressants for fuels, particularly heating oils, diesel and jet fuels. Ethylene and higher α-olefins,
Hydrocarbon polymer flow depressants based on propylene, for example, are also known. US Patent No.
No. 3,961,916 teaches the use of copolymer mixtures in which one copolymer is a wax crystal nucleating agent and the other copolymer is a growth inhibitor to control wax crystal size. GB 1263152 suggests that wax crystal size could be controlled by the use of copolymers with a lower degree of side chain branching. As a co-additive for ethylene/vinyl acetate copolymers,
It has been demonstrated that copolymers of di-n-alkyl fumarate and vinyl acetate, previously used as flow depressants for lubricating oils, can be used to treat distillate fuels with high final boiling points for improved low temperature flow properties. For example, it is proposed in British Patent No. 1469016. According to GB 1469016, these polymers can be _C6 - _C18 alkyl esters of unsaturated _C4 - _C8 dicarboxylic acids, especially lauryl fumarate and lauryl-hexadecyl fumarate. The substances used typically average about 12
It is a mixed ester (polymer A) having carbon atoms of . It is noteworthy that this additive has been shown to be ineffective on "normal" fuels with lower final boiling points. With the increasing diversity of distillate fuels, fuel types have emerged that cannot be treated with existing additives or that require uneconomically high levels of additives. In order to make them commercially usable, it is necessary to reduce their pour points to the necessary extent and to control the wax crystal size to enable cryogenic filtration. One particular group of fuels for which such problems exist are those that have a relatively narrow and/or low boiling point region. The fuel is
They are often characterized by their initial boiling point, final boiling point, and temperature during which a certain volume percent of the initial distillate is distilled. 20%~90% distillation point is 70~
Fuels differing within a range of 100°C and/or whose 90% boiling point is between 10 and 25°C of the final boiling point and/or whose final boiling point is between 340 and 370°C may sometimes contain additives. They were found to be particularly difficult to process, requiring very high levels of additives. All distillations described herein are
According to ASTMD86. With the rise in oil prices, there is a need to increase the production of distillate fuels, and to reduce the number of distillate fuels that require processing levels that are unacceptably high from an economic point of view, or that cannot be treated with common additives in distillate fuels. It has become important for refiners to optimize their operations using what are known as difficult sharp cuts. A typical sharply fractionated fuel has a range of 10 to 25
Has a final boiling point range of 90% to 100°C, usually below 100°C,
Generally has a 20-90% boiling range of 50-100℃.
Both types of fuel have a final boiling point of over 340°C,
It generally has a final boiling point in the range 340°C to 370°C, especially 340°C to 365°C. In addition to this, it may be necessary to lower what is known as the cloud point of distillate fuel oils. Note that the cloud point here is the temperature at which wax crystals begin to precipitate from fuel oil when it is cooled.
This includes the fuel oils listed above and typical boiling points of 120~
It should be applied to the entire range of distilled fuel oils in the 500°C range and those that are difficult to process. Copolymers of ethylene and vinyl acetate, which have been widely available and widely used for improving the flow of distillate fuels, have the narrow boiling point and/or
It has not been found to be effective in treating sharp fraction fuels. Furthermore, it has not been found to be effective to use the mixture described in GB 1469016. However, the inventors have discovered that copolymers containing very specific alkyl groups, such as certain di-n-alkyl fumarate/vinyl acetate copolymers, can control wax crystal size to enable filtration. , and fuels that were difficult to treat as described above (including lower final boiling point fuels for which the additives of GB 1469016 were ineffective).
It has been found that it is effective in lowering the pour point of We have also found that the copolymers are effective in lowering the cloud point of many fuel oils across the entire range of distillate fuel oils. In particular, the inventors found that the average number of carbon atoms in the alkyl groups in the copolymer should be between 12 and 14;
And it has been found that there should be at most 10% by weight of copolymers with alkyl groups containing more than 14 carbon atoms, and preferably at most 20% by weight of copolymers with alkyl groups containing less than 12 carbon atoms. These copolymers are particularly effective when used in combination with other cold flow improvers that are not themselves effective for these types of fuels. Therefore, the present invention provides mono-ethylenically unsaturated
Improving the flow properties of distilled petroleum fuel oils in the boiling range 120-500°C using additives containing polymers or copolymers containing at least 25% by weight of n-alkyl esters of _C3 - _C8 mono- or dicarboxylic acids. It is. However, the above polymer or copolymer has an n-alkyl group having an average carbon number of 12 to 14, and the ester polymer or copolymer contains an ester monomer containing an alkyl group having more than 14 carbon atoms. It contains no more than 20% by weight of ester monomers having alkyl groups having less than 12 carbon atoms, preferably no more than 20% by weight. This additive is preferably used in an amount of 0.0001 to 0.5% by weight based on the weight of the distilled petroleum fuel oil, and the invention also encompasses such treated distillate fuels. The copolymers can also be di-n-alkyl esters of dicarboxylic acids containing _C12 / _C14 alkyl groups and can contain from 25 to 70% by weight of vinyl esters, alkyl acrylates, methacrylates or alpha-olefins. The polymer preferably used in the present invention has a number average molecular weight of 1,000 to 100,000, preferably 1,000 to 30,000, as measured by, for example, distillation pressure osmotic pressure method. The dicarboxylic acid esters useful in the production of the above polymers have the general formula (where R ₁ and R ₂ are hydrogen or C ₁ -C ₄ alkyl groups, e.g. methyl, and R ₃ is an average C ₁₂ -C ₁₄
Straight chain alkyl group, and R ₄ is COOR ₃ , hydrogen or C ₁
~ _C4 alkyl group, preferably _COOR3 ). These can be prepared by esterifying certain mono- or di-carboxylic acids with appropriate alcohols or mixtures of alcohols. Examples of other C ₁₂ -C ₁₄ unsaturated esters include C ₁₂ -C ₁₄ alkyl acrylates and methacrylates. The dicarboxylic acid mono- or di-ester monomers can be copolymerized with various amounts of other unsaturated esters or olefins, for example from 5 to 70 mole percent. Other such esters have the formula: (However, R′ is hydrogen or a C ₁ to C ₄ alkyl group,
R″ is −COOR′′′′ or −OOCR′′′′ (However, R′
''' is a branched or unbranched _C1 - _C5 alkyl group) and R is R'' or hydrogen. Examples of these short chain esters include methacrylates, acrylate,
fumarate, malate, vinyl ester,
Preferred are vinyl esters such as vinyl propionate and vinyl acetate. More specific examples include methyl methacrylate, isopropenyl acetate and butyl and isobutyl acrylate. Preferred copolymers of the invention have an average _C12 to _C14
It contains 40-60 mol% of dialkyl fumarate and 60-40 mol% of vinyl acetate. Preferred ester copolymers are prepared under an atmosphere of an inert gas such as nitrogen or carbon dioxide to remove oxygen, usually using a peroxide or azo type catalyst such as benzoyl peroxide or azodi-isobutyronitrile. Accelerates the reaction, generally from 20℃
It can be conventionally prepared by polymerizing ester monomers in solution in a hydrocarbon solvent such as heptane, benzene, cyclohexane, or white oil at temperatures in the range of 150°C. The additives of the present invention are particularly effective when used in combination with other additives commonly known for improving the cold flow properties of distillate fuels, but are one of the combinations for improving the cold flow behavior of fuels. It can also be used alone as one. The additives of the invention are polyoxyalkylene esters, ethers, esters/esters and mixtures thereof, in particular at least one, preferably at least two _C10 to _C30 linear saturated alkyl groups and a molecular weight of 100 to 5000, preferably 200 to 5000 polyoxyalkylene glycol groups, and the alkyl group in the polyoxyalkylene glycol is 1 to 4.
It is particularly effective when used with those containing carbon atoms. These substances are the subject of European Patent Publication No. 0061895A2. The esters, ethers, and esters/ethers used in the present invention preferably have the following structural formulas. R-O-(A)-O-R' where R and R' may be the same or different, () n-alkyl () () () is preferred. In the formula, the alkyl group has 10 to 10 carbon atoms.
30 linear saturated groups, and A is a substantially linear polyoxymethylene, polyoxyalkylene of a glycol having an alkylene group of 1 to 4 carbon atoms, such as a polyoxyethylene or polyoxytrimethylene moiety; Indicates the component. Although some degree of branching with short alkyl side chains, such as in polyoxypropylene glycols, is acceptable, it is preferred that the glycols be substantially linear. Generally suitable glycols have a molecular weight of about 100 to
5000, preferably about 200 to 2000, substantially linear polyethylene glycol (PEG) and polypropylene glycol (PPG). Esters are preferred, fatty acids having 10 to 30 carbon atoms are suitable for reacting with the glycols mentioned above to form ester additives, and fatty acids having 18 to 24 carbon atoms are preferably used, especially behenic acid. The esters can also be prepared by esterification of polyethoxylated fatty acids or polyethoxylated alcohols. Polyoxyalkylene diesters, diethers, ether/esters and mixtures thereof are
Preferred as additives, diesters are preferably used for narrow boiling range distillates, although small amounts of monoethers and monoesters may also be present or formed during production. . In short, it is important for the performance of the additive that the majority of the additive be present as a dialkyl compound. Among these, diesters of stearic acid or behenic acid of polyethylene glycol, polypropylene glycol or polyethylene/polypropylene glycol mixtures are particularly preferred. Ethylene-unsaturated ester copolymer flow improvers can be used as additives in the present invention. This unsaturated monomer copolymerizable with ethylene includes
Includes unsaturated mono- and diesters represented by the following general formula. formula, In the formula, R ₆ is hydrogen or a methyl group, R ₅ is -OOCR ₈
A group represented by (where R ₈ is hydrogen or a group having 1 to 1 carbon atoms)
28, more generally a linear or branched alkyl group having 1 to 17 carbon atoms, preferably 1 to 8 carbon atoms) or a group represented by -COOR ₈ (where R ₈ has the same meaning as above) (but not hydrogen), R ₇ is hydrogen or -COOR ₈ as above. In the case of a monomer in which R ₆ and R ₇ are hydrogen and R ₅ is -COOR ₈ , the number of carbon atoms is from 1 to 29, more generally from 1 to 29 carbon atoms.
Vinyl alcohol esters having 18 monocarboxylic acids, preferably monocarboxylic acids having 2 to 5 carbon atoms, are included. Examples of vinyl esters that copolymerize with ethylene include vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl isobutyrate, and among these, vinyl acetate is preferred. In addition, vinyl ester is used as a copolymer.
20-40% by weight. Preferably, it contains 25 to 35% by weight. This copolymer has been developed in U.S. Patent No.
It may also be a mixture of two copolymers as described in No. 3961916. These copolymers preferably have a number average molecular weight of 1000 to 6000, more preferably 1000 to 3000, as measured by vapor phase osmotic pressure method. The additives of the present invention can be used in distillate fuels in combination with ionic or nonionic polar compounds that act as wax crystal growth inhibitors in the fuel oil. It has been found that polar nitrogen-containing compounds are particularly effective when used in combination with glycol esters, ethers or esters/ethers, and therefore these ternary mixtures are included within the scope of this invention. These polar compounds are preferably amine salts and/or amides, and the amides include at least 1 mole of a hydrocarbon-substituted amine, 1 mole of a hydrocarbon acid having a carboxylic acid group having 1 to 4 carbon atoms, or an anhydride thereof. It was formed by the reaction of In addition, the total number of carbon atoms is generally 30 to 300,
Preferably 50 to 150 esters/amides can also be used. These nitrogen compounds are described in U.S. Patent No.
It is described in No. 4211534. As an amine,
Generally, primary, secondary, tertiary or quaternary amines having long chains with a carbon number of 12 to 40 are preferred, but amines with shorter chains than those mentioned above can also be used if the resulting nitrogen compound is oil-soluble. . Therefore, amines having a total carbon number of about 30 to 300 are usually used. The nitrogen compound preferably has at least one linear alkyl segment having 8 to 40 carbon atoms, more preferably 14 to 24 carbon atoms. Suitable amines include primary, secondary, tertiary or quaternary amines, with secondary amines being preferred. Tertiary amines and quaternary amines can only form amine salts. Examples of the amine include tetradecylamine, cocoaamine, and hydrogenated beef tallow amine. Further, examples of the secondary amine include dioctadecylamine and methyl-behenylamine. Mixtures of amines are also suitable, as are many amine mixtures derived from natural substances. Hydrogenated beef tallow secondary amines of the formula HNR ₁ R ₂ are preferred. In addition, in the formula, R ₁ and R ₂ are approximately C ₁₄
4%, C ₁₆ 31%, and C ₁₈ 59%. Examples of carboxylic acids suitable for producing the above nitrogen compounds and their anhydrides include cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, cyclopentanedicarboxylic acid, di-α-naphthyl acetate acid, and naphthalene dicarboxylic acid. Generally, these acids have 5 carbon atoms.
It has ~13 annular parts. Preferred acids in the present invention are benzenedicarboxylic acids such as o-phthalic acid, p-phthalic acid and m-phthalic acid. Among these, o-phthalic acid or its anhydride is particularly preferred. A particularly preferred amine compound is an amide-amine salt obtained by reacting 1 mole of phthalic anhydride with 2 moles of dihydrogenated beef tallow amine. Other preferred compounds are diamides obtained by dehydrating the above amide-amic acids. When used as a mixture, 0.5 to 20 of the polymers of the invention containing n-alkyl groups with an average carbon number of 12 to 14 are added to 1 part of polyoxyalkylene ester, ether or ester/ether.
The amount is preferably 1.5 to 9 parts by weight. The additive of the present invention can be used for any type of distilled petroleum in the boiling point range of 120-500°C, but especially for low-temperature filterability of fuel oils where the difference between the 20% and 90% distillation temperatures is less than 100°C. and/or the difference in distillation temperature from 90% of distillation to the final distillation is within the range of 10 to 25 °C, and/or the final distillation temperature is in the range of 340 to 370 °C. It is particularly useful for improving the flow properties of distillate fuels. The additive system of the present invention is preferably supplied as a concentrate for addition to the main distillate fuel. These concentrates can also contain other additives if necessary. These concentrates preferably contain 3
-75% by weight (hereinafter abbreviated as %), preferably 3-60%, most preferably 10-50% of additives, and is preferably a solution in oil. Such concentrates are also within the scope of this invention. The invention is illustrated by the following examples, in which the effectiveness of the additives of the invention as pour point depressants and filterability improvers was compared to other similar additives by the following tests. One method is to determine the response of mineral oils to additives using the Cold Filter Plugging Point Test.
“CFPP”). This method is
Jouranl of the institute of Petroleum, 52 volumes,
No. 510, June 1966 issue, pages 173-185. This test correlates with the cold flow properties of middle distillates in diesel vehicles. To simply demonstrate this method, the sample mineral oil is
The sample is placed in a bath maintained at 0.degree. C. and non-linearly cooled at a rate of about 1.degree. C./min. The cooled mineral oil was tested intermittently, starting at a temperature of at least 2°C above the cloud point and decreasing in 1°C increments, for flowability through a narrow screen within a preset period of time. This test was conducted using a test apparatus in which the lower end of a pipette was connected to an inverted funnel that was placed below the surface of the mineral oil sample. The mouth of the funnel extends over a 350 mesh screen with an area of 12 mm in diameter. This intermittent test is initiated by aspirating the top of the pipette, allowing the mineral oil to pass through the screen and into the pipette for 20 minutes.
It rises to the point where it shows the amount of ml. After rising,
Immediately return the mineral oil to the CFPP tube. This test is performed by decreasing the temperature in 1°C increments until the pipette can no longer be filled with mineral oil within 60 seconds.
Then, this temperature is defined as the CFPP temperature. and,
The difference between the CFPP of mineral oil without additives and the CFPP of the same mineral oil with additives was defined as the CFPP reduction due to additives. The most effective flow improvers yield greater CFPP drop at the same concentration of additive. Another method to examine the fluidity improvement effect is the distillate operability test “DOT”.
This test is carried out under the following conditions:
It is a slow cooling test and correlates to pumping of stored heated fuel oil. In this test, the cold fluidity of the fuel containing the additive was determined by the following DOT test.
300 ml of mineral oil were cooled linearly at a rate of 1° C./hour to the test temperature and maintained at this temperature. After two hours at the test temperature, a surface layer of about 20 ml of unusually large wax crystals, which tend to form at the mineral oil/air interface during cooling, is removed. Put the wax into the bolt, stir gently to disperse it, and then insert the CFPP assembly. Then open the stopper
Suction is performed at 500 mm of mercury pressure, and when 200 ml of fuel oil has passed through the filter and entered the calibrated receiver, the stopper is closed. If 200ml is collected within 10 seconds through a given mesh size, record a Pass; if the flow rate becomes too slow, indicating a clogged filter, record a FAIL. Record. 20, 30, 40, 60, 80, 100, 120, 150, 200,
Using a CFPP filter assembly with filter screens of 250 and 350 mesh numbers,
Determine the smallest mesh (largest mesh number) through which fuel oil passes. The larger the mesh number through which the wax containing fuel oil passes, the smaller the wax crystals become, and the greater the fluidity-improving effect of the additive. It should be noted that the same treatment level with the same flow improving additive will not give exactly the same results for the two fuel oils. The pour point is determined by placing the test additive and a 100 ml sample of fuel oil in an ASTMD97 or 150 ml narrow-neck bottle, and placing the test additive and a 100 ml sample of fuel oil at a temperature of 5 ml below the temperature at which the wax precipitates.
It is determined by two methods: a visual method of cooling at a rate of 1°C/hour from a temperature above 1°C. The fuel oil samples were tilted or inverted at 3°C intervals to check their flowability. A fluid sample (referred to as F) is one that flows easily when tilted, a semi-fluid sample (referred to as semi-F) is one that flows almost upside down, and a solid sample (referred to as S) is one that flows easily when tilted. However, it does not move at all. The following fuel oils were used in the experiment.

[Table] The following additives were used. ○ Additive 1: Polyethylene glycol with an average molecular weight of 400 is esterified with 2 moles of behenic acid. ○ Additive 2: 50% of linear _C12 and _C14 alcohols:
50 (weight ratio) mixture reacted with fumaric acid and mixed
A copolymer obtained by solution copolymerization of C ₁₂ /C ₁₄ alkyl fumarate and vinyl acetate in a ratio of 1:1 (molar ratio) and azodiisobutyronitrile as a catalyst. The results are shown below.

[Table] The additive of the present invention has a number average molecular weight of 2500,
13 parts by weight of ethylene/vinyl acetate copolymer with vinyl acetate content of 36% by weight and number average molecular weight of 3500
and was compared in the DOT test with Additive 3, an oil solution containing 63% by weight of a blend of polymers consisting of 1 part by weight of an ethylene/vinyl acetate copolymer with a vinyl acetate content of about 13% by weight.

Table: Various fumarate/vinyl acetate copolymers were tested in admixture (3 parts) with Additive 1 (2 parts) to determine the effect of chain length in the fumarate and the following results were obtained. Ta.

Table: Various fumarate/vinyl acetate copolymers obtained from 25 different alcohols (but having an average of 12 to 13.5 carbon atoms in the alkyl group) were tested for CFPP and visual pour point tests as in the example above. A similar mixture was tested and the results are as follows.

TABLE Fuels B and C were used in the following examples with Fuel F ASTM D-86 Distilled °C IBP 20% 50% 90% FBP 182 254 285 324 343. The results are shown in the table below. If the additive does not have a flow-reducing effect, the CFP value cannot be measured. This is because fuel cannot be used without flow drop.

【table】

【table】

[Table] The additive was also tested in combination with a partial amide obtained by reacting 2 moles of hydrogenated beef tallow amine with phthalic anhydride (Additive 4).
The CFPP drop is as follows. Additives CFPP lowering additive 4 (250ppm) 6 Additive 3 (100ppm) C ₁₂ /C ₁₄ F/VA (250ppm) Additive 4 (300ppm) Additive 1 (100ppm) 6 C ₁₂ /C ₁₄ F/VA ( 100ppm) Additive 4 (250ppm) 0 _C12 / _C14F /VA (250ppm) The fact that the additive of the present invention has the effect of lowering the cloud point of distilled fuel oil was confirmed by the standard cloud point test (IP-219).
or ASTM-D2500), and also estimated by differential scanning calorimetry using a Mettler TA2000B differential scanning calorimeter. In this test, a 25μ sample of fuel oil was cooled at a rate of 2°C/min from a temperature at least 10°C above the estimated point, and the cloud point of the fuel oil was adjusted to the temperature indicated by the differential scanning calorimeter + 6°C. Estimated to be the wax precipitation temperature. The following fuel was used.

[Table] The results of measurements using a differential scanning calorimeter on a fuel oil containing the same C ₁₄ fumarate/vinyl acetate copolymer used previously and 0.2% by weight of Additive 2 are shown below.

[Table] The cloud point of the fuel containing 0.2% by weight of C ₁₄ fumarate/vinyl acetate copolymer was also determined using the ASTM cloud point test. The results are shown below. ASTM D 2500 Fuel Cloud Point ℃ G -20 H -15.5 I -9 J -11 K -21 L -18 M -4

Claims (1)

[Claims] 1 Distilled petroleum fuel with a boiling point range of 120°C to 500°C, where the difference between the 20% distillation point and 90% distillation point is 100°C
and/or the difference between the distillation temperature of the 90% distillation point and the final boiling point is in the range of 10 to 25 °C, and/
Or to the fuel oil whose final boiling point is 340 to 370°C,
Mono- whose n-alkyl group has an average carbon number of 12 to 14
At least 25 n-alkyl esters of ethylenically unsaturated C ₄ -C ₈ mono- or dicarboxylic acids containing comonomers containing alkyl groups with more than 14 carbon atoms in an amount of not more than 10% by weight
An additive composition containing a copolymer containing wt%
Distilled petroleum fuel oil, characterized in that it contains 0.001-0.5% by weight.