NZ202674A

NZ202674A - Cloud point decreasing additives for middle distillates

Info

Publication number: NZ202674A
Application number: NZ202674A
Authority: NZ
Inventors: P Maldonado; R Leger; C Cohen; B Sillion
Original assignee: Inst Francais Du Petrole; Elf France
Priority date: 1982-06-10
Filing date: 1982-12-01
Publication date: 1986-05-09
Also published as: ZA828904B; AU1214588A; FR2528423B1; FR2528423A1; AU9134782A; AU609778B2

Description

New Zealand Paient Spedficaiion for Paient Number £02674 9Q2674 Priority Date(sV: 'fi. . )Q&$■ Complete Specification Filed: Ciass: | 33* • C0.7WQ > •> £PSC(a3 b9 MAf 1986 Ptihticaticn Date: P.O. Journal. No: ..

Patents form No.5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "NITROGEN - CONTAINING ADDITIVES USABLE AS AGENTS FOR DECREASING THE CLOUD POINT OF HYDROCARBON MIDDLE DISTILLATES AND COMPOSITIONS OF HYDROCARBON MIDDLE DISTILLATES CONTAINING THESE ADDITIVES" -f-,WE INSTITUT FRANCAIS DU PETROLE a body corporate of 4, Avenue de Bois-Preau, 92502 Rueil-Malmaison, France, and ELF FRANCE, a body corporate, of 137, rue de l'Universite 75007 Paris France, hereby declare the invention, for which-f/we pray that a patent may be granted to me-/us, and the method by which it is to be performed, to be particularly described in and by the following statement (folfowed by page I A.) 267 4 The invention relates to new nitrogen additives which can "be used as agents for decreasing the cloud point of hydrocarbon middle distillates (fues oils, gas oils), as well as to compositions of middle distillates containing said additives.

The oil distillates concerned by the invention are middle distillates (fuel oils, gas oils) whose distillation range (standard ASTK D 86-87) is between 150°C and 450°C. Gas oils which are more particularly concerned distill between an initial temperature from 160°C to t90°C and a final temperature from 350°C to 390°C» A great number of products sold on the market have the pur pose to improve the limit filtrability temperature and the pour point of oil cuts of high paraffin content, for example : - polymers based on long chain olefins, - copolymers based on alpha-olefins, - ethylene-vinyl acetate copolymers, - H-acylarainoethyleaters of acid-containing polymers, or - halocarbon compounds. of These products act on the kineticyiSrystallization phenomena and change the crystal size, thus .allowing the use of the suspension 20 at a lower temperature without plugging of the pipes and the filters. The above products do not modify the temperature at which the first paraffin crystals appear. As a matter of fact, it lias been considered, up to now, that this temperature was dependent on the molecular weight and the composition of the paraffins and on the nature of the solvent.

A decrease of the cloud point of middle distillates (particularly gas oils) by means of an additive would be highly beneficial to the refiners, since it would allow without changing the distillation diagram, to caaply with the standards which are presently subject to an increasing severity. - ifC It has now been discovered that contain chemicals, whose definition is given hereinafter, when added to middle distillates, have the property to make the first paraffin crystals appear at a lower temperature than that observed in the absence of these additives. This property is the more unobvious as it is still maintained after several cycles of heating and cooling and operates according to a mechanism which has not yet been explained.

This class of chemical compounds also has an action on other properties of middle distillates (particularly gas oils), by modi-10 fying the behavior of the medium which contains the precipitated paraffins.

Thus, the compounds proposed in this invention have a substantial effect on the limit filterability temperature and the pour point.

When paraffin crystals have formed by cooling, their normal tendency is to assenble by gravity at the bottom. This phenomenon, generally called settling, results in the plugging of ducts and filters and is detrimental to a safe use of middle distillates, particularly gas oils. The chemicals proposed in the invention can decrease substantially the settling rate of the paraffins formed by cooling of gas oils and other middle distillates.

Finally, the proposed products for having the above mentioned properties, also confer to the gas oils and middle distillates, to which they are added, anti-corrosion properties with respect to metal surfaces.

•As a general rule, the additives of the invention can be defined as products having an average molecular weight of about 300 to 10 000, obtained by condensation of at least one compound comprising a primary amine function, complying with one of the following 30 general formulae (I) and (II) : and E^O -C(c? ) HH- -H BO - OS, - R - NBj _ 2 - (I) (II) A,, V 202674 with at least one dicarboxylic compound as hereinafter defined.

In formula (I) , R^" is a monovalent saturated aliphatic radical comprising from 1 to 30 carbon atoms ; n is an integer from 2 to 4 and m is an integer from 1 to 4.

The compounds of formula (I) contemplated in this invention may consist of ether-amines, more particularly those complying with the formula : R1 - O- -(CH2'n" -NH- m the radical R^" comprises 1 to 24, preferably 8 to 22 carbon atoms, m is an integer from 1 to 4 and n an integer from 2 to 4, preferably 2 or 3.

Specific compounds of the ether-amine type are : 2-methoxy ethylamine, 3-methoxy propylamine, 4-methoxy butylamine, 3-ethoxy propylamine, 3-octyloxy propylamine, 3-decyloxy propylamine, 3-hexadecyloxy propylamine, 3-eicosyloxy propylamine, 3-docosyloxy propylamine, N-(3-octyloxy propyl) 1,3-diamino propane, N-(3-decyloxy propyl) 1,3-diamino propane, 3-(2,4,6-trimethyl decyl) oxy propylamine and N- 3-(2,4,6-trimethyl decyl) oxy propyl 1,3-diamino propane.

The compound with a primary amine function which is used for preparing additives conforming to the invent^OT^i^ty^ V also consist of an aminoalcohol of formula (II): HO - CH2 - R2 - NH2 (II) 2 wherein R is a divalent saturated aliphatic radical, linear or branched, preferably linear, comprising 1 to 18 and preferably 10 to 18 carbon atoms.

Specific examples are : monoethanolamine, 1-amino 3-propanol, 1-amino 4-butanol, 1-amino 5-pentanol, 1-amino 6-hexanol, 1-amino 7-heptanol, 1-amino B-octanol, 1-amino 10-decanol, 1-amino 11-undecanol, 1-amino 13-tridecanol, 1-amino 14-tetradecanol , 1-amino 16-hexadecanol, 2-amino 2-methyl 1-propanol, 2-amino 1-butanol and 2-amino 1-pentanol. It must be understood that, without departing from the invention, it is possible to operate with one or more compounds of formula (I) and one or more compounds of formula (II).

It is also possible to use proportions of less than 50% with respect to the total amount of compounds of formula (I), (II) and (III), of at least one compound obtained by condensation of at least one dicarboxylic compound as defined herein above with at least one compound comprising a primary amine function and complying with the formula: B — 2 -H (III) wherein R represents a monovalent saturated aliphatic radical as of 1 to 30 carbon atoms and n is /defined above 3 3. and Z is NH or NR , R being a saturated aliphatic monovalent radical and m is zero when Z is NH or an integer from 1 to 4 in all cases. 4 _ The compounds of the above formula (III) may cons^s^^?'^" primary amines of the formula R - NH2 (in that case, in formula (III), Z represents a - NH - group and the value of m is zero).

The radical R is preferably linear and comprises from 12 to 30, particularly from 16 to 25 carbon atoms.

Specific examples of these amines are : dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine and docosylamine, hexadecylamine and octadecylamine being preferred.

The compounds of the formula (III) may also consist of polyamines obtained from saturated aliphatic amines of the formula: _ R - NH- (CH-) NH- 2 n H m corresponding to the general formula (III) wherein Z is a - NH - group; m may have a value from 1 to 4 and n a value from 2 to 4, preferably 3.

Preferably, the radical R is linear and comprises from 12 to 30 and particularly from 16 to 25 carbon atoms.

Specific compounds are : N-dodecyl 1,3-diamino propane, N-tetradecyl 1,3-diamino propane, N-hexadecyl 1,3-diamino propane, N-octadecyl 1,3-diamino propane, N-eicosyl 1,3-diamino propane, N-docosyl 1,3-diamino propane, N-hexadecyldipropylene triamine, N-octadecyl dipropylene triamine, N-eicosyldipropylene triamine and N-docosyl dipropylene triamine. There are more advantageously used N-docosyl-, N-eicosyl-, N-octadecyl-, N-hexadecyl^ or N-dodecyl 1,3-diamino propane, as well as N-hexadecyl- and N-octadecyl- dipropylene - triamine.

The compounds of formula (III) may also consist of polyamines of the formula : R4 N- R5/ (CH2) NH - 5 - "'?«C!rq1936 , ■ 202,674 wherein R and R , identical or different/ are each an alkyl radical with 1 to 24 and preferably 8 to 22 carbon atoms, R4 and R^ preferably comprising together from 16 to 32 carbon atoms ; n has a value from 2 to 4 and m a value from 1 to 4.

Specific compounds are : N, N-diethyl 1,2-diamino ethane, N, N-diisopropyl 1,2-diamino ethane, N, N-dibutyl 1,2-diamino ethane, N, N-diethyl 1,4-diamino butane, N, N-dimethyl 1,3-diamino propane, N, N-diethyl 1,3-diamino propane, N, N-dioctyl 1,3-diamino propane, N, N-didecyl 1,3-diamino propane, N, N-didodecyl 1,3-diamino propane, N, N-ditetradecyl 1,3-diamino propane, N, N-dihexadecyl 1,3-diamino propane, N, N-dioctadecyl 1,3-diamino propane, N, N-didodecyldipropyle-netriamine, N, N-ditetradecyldipropylene triamine, N, N-dihexadecyldipropylene triamine and N, N-dioctadecyldipropylenetriamine.

The dicarboxylic compounds on which is effected the condensation of a compound of formula (I) or a compound of formula (II) such as described hereinbefore are more particularly selected from the anhydrides of aliphatic, preferably unsaturated, a, 6 - dicarboxylic acids, such as, for example, maleic anhydride, alkyl-maleic anhydrides, for example methylmaleic (or citra-conic) anhydride, or from the alkenyl-succinic anhydrides, for example those obtained by reacting at least one a -olefin, preferably linear, (having, for example, 10 to 30 carbon atoms) with maleic anhydride. Specific examples are n-octadecenyl succinic anhydride or dodecenyl succinic anhydride or dodecenyl succinic anhydride. It is obviously possible to use mixtures of two (or more) of these compounds. 202674 The above mentioned anhydrides may be replaced by the corresponding dicarboxylic acids, or by the C^-.c^alkyl diesters thereof { e.g. , methyl, ethyl, jtnojyl and butyl esters)* The compounds with a primary amine function of the formulas 10 (i) and (II) are comaonly used in a proportion of 1.02 to 1.2 mole, preferably 1.05 to 1.1 cole, per mole of the dicarboxylic compound. The compound with a primary aadne function (i) or (n) nay also be used in slight defect,down to 0.9 mole per mole of the dicarbosylic compound. The proportion is thus generally from 0.9 to 1.2 mole/ mole.

The condensation of the compounds of foraula (l) and/or (H) on the dicarboxylic compounds (for example dicarboxylic acids, esters or preferably anhydrides) may be effected without solvent ; but preferably with a solvent, consisting more particularly of an aromatic or naphteno-eromatic hydrocarbon having a boiling point of for example, from 70 to 250°C j toluene, xylenes, diisopropylbenzene,or an oil cut having the appropriate distillation range. j9PFB/986^ The additive compositions of the invention can be prepared, in practice, as follows : the compound of fornula (I) and/or (H) is introduced progressively into a reactor containing the dicarboxylic compound, while maintaining the temperature between 30 and 60°C. The temperature is then raised to 120-200°C while eliminating the resultant volatile products (water or alcohols), either stripping with a stream of inert, gas or by aseotropic distillation with the 50 selected solvent ; the content of dry substance is, for example, from 40 to 70 /5, more of tin about 60 jS, This leads predominantly to the formation of imide linkages. fThe reaction tine, after addition of the reactants, is, for example, from 1 to 6 hours, preferably 3 to 6 hours. 7 202674 The additives contemplated in this invention are particularly efficient for improving the cloud point of oil middle distillates (particularly gas oils), thus decreasing the temperature at which appear the first crystals of paraffin contained therein.

Although the action of these additives on the temperature at which the paraffin crystals appear in the middle distillates has not yet been clearly elucidated, a positive improvement of the cloud point of the middle distillates treated with these additives is observed, when the latter are added in a proportion of, for example, from 10 20 to 2000 g per ton of middle distillate. The preferred concentrations range from 100 to 2000 g/t. The decrease of the cloud point may reach, for example, 5°C, sometimes more.

It is also remarkable that the additives of the invention, which improve efficiently the cloud point of middle distillates, have also the properties of inhibiting the settling of n-paraffins contained in middle distillates, at rest, of improving the limit filterability temperature and the pour temperature and of inhibiting the corrosion of metal surfaces in contact with these distillates.

Thus, in the range of additive concentrations from 20 to 20 2000 g per ton, it is possible to observe a decrease the filterability te-perature of, for example, up to 12°C, a decrease of the pour point of up to 20°Ct a decrease of the proportion of settled paraffins and a clear anticorrosion effect particularly on ferrous metals.

The middle distillate compositions according to the invention may be prepared by dircctly admixing additives to the middle distillatei It is however often advantageous to introduce them in the fom of "mother-solutions" previously prepared in the above-mentioned solvents.

The "mother-solutions" can contain, for example, from 20 30 to 60 jS by weight of additive.

The following examples illustrate the invention and must not be considered as limitative thereof in any respect. ml S - EXAMPLE 1: 202674 294 g (3 moles) of maleic anhydride dissolved in 500 g of xylene are introduced into a stirred 3 1 reactor, and the temperature is decreased to 30°C. A solution of 797 g (3.1 moles) of 3-(2,4,6-trimethyl decyl) oxy propylamine in 324 g of xylene is added, while maintaining the temperature below 40°C. The addition lasts one hour, and heating is then performed for 3 hours at xylene reflux. The inner temperature is 144°C. 67 g of water are removed by distillation, corresponding to 54 g of reaction water and 13 g of water contained in the amine ; after completion of the reaction, 200 g of dilution xylene are added to obtain a 50 % b.w. solution of additive I in xylene.

Additive I has been analyzed after evaporation of the solvent. Its molecular weight by number, determined by tonometry, is 500, The thin layer infrared spectrum shows imide bands at 1700 and 1780 cm-^, secondary amide bands at 1635 and 1560 cm ^ and an ether band at 1100 cm"1. The secondary, amide bands are however very weak in intensity.

The additives II and VI, whose manufacture is described in the following examples, show the same I.R. absorption bands as those of additive I; their molecular weights are between 600 and 3000.

- EXAMPLES 2 and 3; The method of manufacture is the same as in example 1, with similar molar ratios, but the amine compounds differ.

- EXAMPLE 2; Additive II is obtained by condensing maleic anhydride on N- 3-(2,4,6-trimethyl decyl) oxy propyl 1,3-diaminopropane. 2021674 - EXAMPLE 3; Additive III is obtained from the condensation product of maleic anhydride on a mixture comprising, by mole, 55 % of ethanolamine and 45 % of a N-alkyl propylenediamine cut of the trade, whose alkyl chains consist of about 27 % of chain and 72 % of C^g chain (equivalent molecular weight : 370 per primary amine function).

- EXAMPLES 4 and 5: These examples are conducted according to the operating mode of example 1, the molar ratios of the reactants being the same as in example 1.

- EXAMPLE .4; 3-(2,4,6-trimethyl decyl) oxy propylamine is condensed on an alkenyl succinic anhydride obtained by reacting equimolecular proportions of maleic anhydride and of a cut of linear a-olefins containing approximately 49 % of C20 olefin, 42 % of C22 olefin and 9% of C2^ olefin.

The result of this condensation is additive IV.

- EXAMPLE 5: Ethanolamine is condensed on the alkenylsuccinic anhydride of example 4 , the molar ratio of the ethanolamine to the anhydride content of the alkenylsuccinic anhydride being 1/1. Additive V is obtained. n .202674 In the above examples, the additives are obtained as a solution in xylene whose concentration is adjusted, so as to obtain 50 % b.w. solutions of additive in xylene.

The activity of these additive compositions is tested by incorporating them, in a proportion of 0.1 % b.w. with respect to the gas oil, to the two gas oils cuts of ARAMCO origin, designed as and whose properties have been given above.

Three determinations have been performed on each of the so-formed compositions : - cloud point according to standard NF T 60 - 105 - limit filterability temperature (LFT) according to standard NF M 07 - 042 - pour point according to method NF T 60 - 105.

, E/\T *9fEB1986< v The results of these determinations are given in Table I below : TABLE I ADDITIVES CLOgD POINT TLF (6C) POUR POINT ( C) .

G2 G2 G1 G2 G1 .

G2 Without +2 +6 0 +3 -6 -3 0.1 % I -1 +3 -6 -2 -9 -6 0.1 % II -1 +3 -3 0 -12 -9 0.1 % III -2 +3 -7 -5. -12 -9 0 1- ft TV 1 1-> i D o 0 0.1 % iv -3 +2 -8 -4 -24 -21 0.1 % V -2 +2 -8 -5 -21 -18 II -x 202674 - EXAMPLE 6: The inhibiting effect of an additive according to the invention on the settling of n-paraffins crystallizing in a gas oil cut maintained at rest at low temperature is tested in this example.

Two 100 cc test tubes are filled with the previously used gas oil No.2 (distillation range IP = 186°C, FP = 385°C).

No additive is introduced into the first test tube. 0.1 % b.w. of additive I is introduced into the second test tube. The two test tubes are hermetically closed and left at rest in a cold room at -10°C for one week.

After one week, the settling rate of the settled paraffins, expressed as the volume of the limpid upper phase, is noted in the following Table : TABLE II TEST TUBE No.l ADDITIVE - FREE GAS OIL TEST TUBE No.2 GAS OIL + ADDITIVE XI 50 % vol. % vol.

All the precipitated paraffins are present in 50 % of the volume of the additive - free gas oil, which makes the lower portion thereof more difficult to use, as a result of the pumps, filters and pipes plugging.

There is only 15 % of limpid upper phase in the additive-containing gas oil. The paraffins are contained \ 85 % of the total volume. They are better dispersed and can be transported more easily.

I "2— - AT- 202674 - EXAMPLE 7; The anti-corrosion effect of additive I of example 1 is tested in this example.

Product I has been used in the two already described gas oils G^ and G2 at a concentration of 0.01 % b.w.

The corrosion test consists of examining the corrosion rate of cylindrical polished steel or iron test pieces, caused by synthetic sea water, according to standard A S T M D 665 modified as follows : the temperature is 32.2°c and the test time is 20 hours.

The two additive - free gas oils G^ and G2 give test pieces rusted on 100 % of their surface , and the two gas oils containing 0.01 % b.w. of additive give test pieces totally free of rust. 202674

Claims

WHAT WE CLAIM IS:

1. An additive, useful, in particular, to decrease the cloud point of middle distillates, characterized as having a molecular weight of 300 to 10,000 and resulting from the condensation of at least one aliphatic dicarboxylic compound selected from maleic and alkyl-maleic and alkenylsuccinic acids, anhydrides, and alkyl diesters, with at least one compound having a primary amine function, complying with general formulae : "(CH_) ^ n NH- m H (I) or with HO - CH2 - R - NH2 (II) wherein R represents a monovalent saturated aliphatic radical of 1 to 30 carbon atoms, n is an integer from 2 to 4, m is 2 an integer from 1 to 4; and R represents a divalent saturated aliphatic radical having 1 to 18 carbon atoms, said compound of formula (1) or (II) being used in a proportion of 0.9 to 1.2 mole per mole of said dicarboxylic compound, the reactants being brought in contact at 30-80°C, and then heated at 120-200°C.

2. An additive according to claim 1, characterized in that the compound having a primary amine function consists of at least one ether-amine of the formula : R1 - O- -(CH-) -2. n -NH m (I) T f f/VA\ c\ wherein R represents an alkyl radical of 8 to 22 carbon atoms, n is an integer from 2 to 4 and m is an integer from 1 to 4. -A -X- 202674

3. An additive according to claim 1, characterized in that the compound having a primary amine function consists of at least one amino-alcohol of the formula: HO - CH2 - R2 - NH2 (II) 2 where R represents a linear alkylene radical containing 1 to 18 carbon atoms^

4. An additive according to one of claims 1 to 3, characterized in that it comprises, in a proportion of less than 50%, at least one compound obtained by condensation of at least one dicarboxylic compound as defined in claim 1 with at least one compound having a primary amine function and the formula: R - Z (CH,) NH- 2 n m (in) wherein R represents a monovalent saturated aliphatic radical -as of 1 to 30 carbon atoms and n is/defined in the preceding claims 3 3 and Z is NH or NR , R being a saturated aliphatic monovalent radical and m is zero when Z is NH or an integer from 1 to 4 in all cases.

5. An additive according to one of claims 1 to 4, characterized in that said aliphatic dicarboxylic compound is selected from maleic anhydride, methylmaleic anhydride, and n-octadecenyl and dodecenyl succinic anhydrides.

6. An additive according to one of claims 1 to 5, characterized in that the reaction performed to prepare it comprises admixing, at a temperature of 30 to 80"C, (a) said at least one dicarboxylic compound with (b) at least one compound having a primary amine function comprised of more than 50% of at least and one compound of formulae (I) /(II), and less than 50% of at least one compound of formula (III), said compounds (a) and (b) being in substantially equimolecular proportions with respect to each other^ and heating the resultant mixture at a temperature of 120 to 200°C for 1 to 8 hours. -> . „ _ ] 5 1986 202674

7. A middle distillate composition, characterized in that it comprises a major proportion of middle distillate of distillation range from 150 to 450°C, and a minor proportion, sufficient to decrease the cloud point thereof, of at least one additive according to one of claims 1 to 6.

8. A middle distillate composition according to claim 7, characterized in that said middle distillate consists of a gas oil cut distilling between an initial temperature of 160 to 190°C and a final temperature of 350 to 390°C.

9. A middle distillate composition according to one of claims 7 and 8, characterized in that the proportion of said additive is from 20 to 2000 g/ton.

10. A middle distillate composition according to claim 9, characterized in that the proportion of said additive is about 1000 g/ton.

11. An additive useful in particular to decrease the cloud point of hydrocarbon middle distillates, as claimed in claim 1, substantially as specifically described herein in any one of the-Examples.

12. A middle distillate composition containing an additive as claimed in claim 1, substantially as specifically described herein in any one of the Examples.