FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)


TITLE OF THE INVENTION
A biodegradable, non-carcinogenic, crude oil pour point depressant and a process for the preparation thereof
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Prabhadevi, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Chaudhari Sushil Ekanath of Crompton Greaves Limited, CG House, Dr Annie Besant Road, Prabhadevi, Mumbai 400 030, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a biodegradable, non-carcinogenic, crude oil pour point depressant and a process for the preparation thereof.
BACKGROUND OF THE INVENTION
The pour point is the lowest temperature at which liquids can flow under standard conditions prescribed by ASTM D97. A pour point depressant (PPD) lowers that temperature. Pour point depressants are designed to control wax crystal formation in crude oil resulting in improved flow performance of the crude oil at lower temperatures, i.e, the PPDs lower the pour point of the crude oil.
Depending on the source, different crude oils have various types and concentrations of wax. At higher temperatures, the paraffin/wax in the crude oil is usually in the liquid state. The crude oil is transported to refineries by means of pipelines and tankers. In cold conditions, the paraffin/wax starts to crystallize in the form of thin plates, needles or mal-crystals. At low temperatures, the plate shaped wax crystals coil on their edges forming needle shaped wax crystals which compact into a 3-dimensional network to form cage like structures. Thus, in cold conditions, when the paraffin from the crude oil begins to precipitate out, it gets deposited on the wall of the pipelines or tankers. These deposits plug pipelines carrying the crude oil thereby blocking the crude oil's flow. As the effective diameter of the pipe keeps decreasing, the pressure at the two ends of the pipeline keeps increasing. The storage of crude oil is also adversely affected in cold conditions due to the wax crystal formation.
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3 0 MAR 2009

Many methods have been employed to prevent wax crystallization during the transportation and storage of crude oil. These methods include heating the pipelines, diluting the crude oil with solvents and treatment with additives. Additives like PPDs are known in the art for depressing the pour point of crude oils. Pour point depressants, when added to the crude oil, hinder the crystallization of the wax molecules by incorporation of the PPD molecules on the fastest growing edge of the wax crystals thereby forming an imperfection on the crystal face and sterically hindering further growth in that direction and thus preventing wax crystallization and deposition. This reduces the pour point of the crude oil.
Pour point depressants for crude oil currently being used include, ethylene vinyl acetate (EVA) copolymers, polymethacrylates, polyacrylates, alkyl esters of styrene-maleic anhydride copolymers, copolymers of olefins, acrylamides, polyacrylamides, copolymers of maleimide, maleic anhydrides, compounds of alkyl amines, alkyl ammonium salts, copolymers of mono, dicarboxylic acids with monohydric, dihydric or polyhydric alcohols, branched polyalkyl methacrylates with functional group containing nitrogen, sulfone copolymers or copolymers of alpha olefins and maleic anhydride. However, many of these pour point depressants like polymethacrylates, polyacrylates and polyalkyl methacrylates are known to be non-biodegradable, expensive and even carcinogenic.

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3 0 MAR 2009

OBJECTS OF THE INVENTION
An object of the invention is to provide a pour point depressant for crude oil, which is biodegradable and non- carcinogenic and which is effective in depressing the pour point of crude oil.
An object of the invention is to provide a pour point depressant for crude oil, which is inexpensive.
Another object of the invention is to provide a process for the preparation of a biodegradable, non-carcinogenic pour point depressant for crude oil.
Another object of the invention is to provide a process for the preparation of a biodegradable, non-carcinogenic pour point depressant for crude oil which is easy to carry out and is economical.
DETAILED DESCRIPTION OF THE INVENTION

According to the invention there is provided a biodegradable, non-carcinogenic, crude oil pour point depressant having the general formula (I):
(I) 4
13 0 MAR 2009

wherein, R stands for a C10 to C22 straight chain aliphatic alkyl group with the condition that all the three alkyl groups represented by R have the same alkyl chain length and n represents the number of repeating units.
According to the invention there is also provided a process for the preparation of a biodegradable, non-carcinogenic, crude oil pour point depressant having the general formula (I):

(I) wherein, R stands for a C10 to C22 straight chain aliphatic alkyl group with the condition
that all the three alkyl groups represented by R have the same alkyl chain length and n
represents the number of repeating units, the process comprising:
a) esterifying a straight chain aliphatic unsaturated ricinoleic acid with a fatty alcohol of the general formula R-OH, where R is as defined above, in the molar ratio of 1.5:1 in the presence of an organic solvent and a catalyst like sulphuric acid at 110°C to 140°C under azeotropic conditions to obtain an alkyl ester;
b) copolymerizing the alky! ester with double crystallized maleic anhydride in 1:1 molar ratio under inert atmosphere and in the presence an organic

solvent and a free radical initiator at 70°C to 75°C to obtain a high molecular weight copolymer; and c) diesterifying the copolymer with a straight chain fatty alcohol of the general formula R-OH, where R is as defined above, in a molar ratio of 1:2 at 110°C to 140°C in the presence of an organic solvent and a catalyst like para-toluene sulfonic acid (PTSA) or sulphuric acid or a combination thereof.
Preferably, the solvent is selected from toluene or dry benzene or xylene.
Preferably, the inert atmosphere is provided by dry nitrogen gas.
Preferably, the free radical initiator is benzoyl peroxide or azobisisobutyronitrile (AIBN).
The molecular weights of the pour point depressants of the invention are between 10,000 to 50,000.
The invention also provides a crude oil comprising lOOOppm to 3000ppm of the pour point depressant prepared by the above process. The invention also provides a crude oil comprising lOOOppm to 3000ppm of the pour point depressant poly(hexadecyl ricinoleate-co-maleic anhydride)dihexadecylate prepared by the above process wherein each R, as defined above, is a C16 straight chain aliphatic alkyl group. The invention also provides a crude oil comprising lOOOppm to 3000ppm of the pour point depressant poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate prepared by the above process wherein each R, as defined above, is a C14 straight chain aliphatic alkyl group.

Pour point depressants for crude oil prepared by the above process involve the use of raw materials such as fatty alcohols and ricinoleic acid which are easily obtainable from naturally occurring fats and oils. As the raw materials for the above process are obtained from natural sources, they are cheap and as a result, the process of the invention is economical. Also, as the raw materials for the above process are obtained from naturally occurring fats and oils which are non-carcinogenic and easily biodegradable, the pour point depressant for crude oil prepared from such raw materials is also non-carcinogenic and easily biodegradable. Also, as the process of the invention is simple, the pour point depressant for crude oil is easy to manufacture.
The following examples are illustrative of the invention:
Example No. 1
Excess ricinoleic acid was esterified with C10, C12, C14, C16, C18, and C22 straight chain aliphatic alcohols in a molar ratio of 1.5:1 at 110 ° C for 8 to 12 hours in presence of toluene as a solvent and 0.2ml of sulphuric acid as a catalyst to yield six different alkyl esters of ricinoleic acid. Water was eliminated by azeotropic ditillation. The resulting crude esters were neutralized with sodium bicarbonate. The organic layer was separated and washed with water to remove traces of sodium bicarbonate and finally dried over anhydrous sodium sulphate. Solvent recovery was achieved by vacuum distillation. Table 1.1 illustrates the quantities of reactants used for the preparation of each of these esters.

Table 1.1 Data related to preparation of n-alkyl ricinoleate

Sr. No. Reactants Toluene ml Alkyl ricinoleate

Ricinoleic acid mole Fatty Alcohol mole

1 0.052 M (15.519 gm) Decyl alcohol 0.026 M (4.115 gm) 50 Decyl ricinoleate
2 0.052 M (15.519 gm) Dodecyl alcohol 0.026 M (4.844 gm) 50 Dodecyl ricinoleate
3 0.052 M (15.519 gm) Tetradecyl alcohol 0.026 M (5.574 gm) 50 Tetradecyl ricinoleate
4 0.052 M (15.519 gm) Hexadecyl alcohol 0.026 M (6.303 gm) 50 Hexadecyl ricinoleate
5 0.064 M (19.101 gm) Octadecyl alcohol 0.032 M (8.655 gm) 50 Octadecyl ricinoleate
6 0.040 M (11.938 gm) Behenyl alcohol 0.020 M (6.532 gm) 50 Behenyl ricinoleate
The alkyl ricinoleic esters were then copolymerized with double recrystallized maleic
anhydride in 1:1 molar ratio in the presence of dry benzene under dry nitrogen atmosphere
with benzoyl peroxide as an initiator at 70 to 75°C with constant stirring for 8 hours to give
poly(n-alkyl ricinoleate-co-maleic anhydride). The resulting poly(n-alkyl ricinoleate-co-
maleic anhydride) were purified by repeated solvent non-solvent method (Benzene-
methanol). Traces of solvent were removed by drying under reduced pressure at 50°C /
25mm Hg for 5 hours. Table 1.2 illustrates the quantities of the reactants used in the
copolymerization reaction. _. .
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Tablel.2 Data related to preparation of poly(n-alkyl ricinoleate-co-maleic anhydride)

Reactants Benzene ml Copolymer
Alkyl ricinoleate
(mole) Maleic anhydride
(mole) Benzoyl peroxide gm (% on wt. of
total monomers)

Decyl ricinoleate 0.020 M
8.774 gm 0.020 M 1.961 gm 0.107 gm 22 poly(decyl ricinoleate-co-maleic anhydride)
Dodecyl ricinoleate
0.021 M
9.802 gm 0.021 M 2.059 gm 0.118 gm 25 poly(dodecyl
ricinoleate-co-maleic
anhydride)
Tetradecyl
ricinoleate 0.020 M
9.897 gm 0.020 M 1.961 gm 0.118 gm 22 poly (tetradecyl
ricinoleate-co-maleic
anhydride)
Hexadecyl
ricinoleate 0.019 M
9.935 gm 0.019 M 1.863 gm 0.117gm 24 poly(heaxdecyl
ricinoleate-co-maleic
anhydride)
Octadecyl
ricinoleate 0.018 M
9.917 gm 0.018 M 1.765 gm 0.116 gm 22 poly(octadecyl
ricinoleate-co-maleic
anhydride)
Behenyl
ricinoleate 0.013 M
7.891 gm 0.013 M 1.274 gm 0.091 gm 20 poly(behenyl
ricinoleate-co-maleic
anhydride)
The anhydride copolymers were esterified with the same straight chain aliphatic fatty alcohols used for the first esterification step in a molar ratio of 1:2 in the presence of xylene and a catalyst namely 0.1 gm of para-toluene sulfonic acid (PTSA) along with 0.2 ml of sulphuric acid at 140°C to produce diesters. These diesters were neutralized by sodium bicarbonate and separated and dried over anhydrous sodium sulfate. Solvent was recovered by vacuum distillation. Finally, the crude diesters were purified by repeated precipitation in excess acetone or methanol and dried under vacuum at 40°C/25mm Hg
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for 5 hours. Table 1.3 illustrates the quantities of the reactants used in the diesterifi cation reaction.
Table 1.3 Data related to preparation of poly (n-alkyl recinoleate-co-maleic anhydride)dialkylate

Reactants Xylene (ml) Pour Point Depressant
Copolymer (mole) Alcohol (mole)

poly(decyl ricinoleate-co-maleic anhydride) 0.013 M (6.978 gm) Decyl
alcohol
0.026 M
(4.115 gm) 60 poly(decyl ricinoleate-co-maleic
anhydride) didecylate
[Alkyl chain length=Cio]
poly(dodecyl ricinoleate-co-maleic anhydride) 0.011 M (6.213 gm) Dodecyl
alcohol
0.022 M
(4.099 gm) 60 poly(dodecyl ricinoleate-co-maleic anhydride) didodecylate [Alkyl chain length=C12]
poly(tetradecyl
ricinoleate-co-maleic
anhydride)
0.011 M
(6.522 gm) Tetradecyl alcohol 0.022 M
(4.716 gm) 60 poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate [Alkyl chain lengthen]
poly(heaxdecyl
ricinoleate-co-maleic
anhydride)
0.012 M
(7.451 gm) Hexadecyl alcohol 0.024 M
(3.394 gm) 60 poly(hexadecyl ricinoleate-co-maleic anhydride)dihexadecylate [Alkyl chain length=Ci6]
poly(octadecyl
ricinoleate-co-maleic
anhydride)
0.011 M
(7.139 gm) Octadecyl
alcohol
0.022 M
(5.950 gm) 60 poly(octaadecyl ricinoleate-co-maleic anhydride)dioctaadecylate [Alkyl chain length=Cig]
poly(behenyl ricinoleate-co-maleic anhydride) 0.0075 M (5.288 gm) Behenyl
alcohol
0.015 M
(4.899 gm) 50 poly(behenyl ricinoleate-co-
maleic anhydride) dibehenylate
[Alkyl chain length=C22]

Example No. 2
1000 ppm, 2000ppm and 3000ppm of the pour point depressants obtained in Example 1
were added to an Indian crude oil having a wax content of 26.85% by weight. The
standard method as prescribed by ASTM D97 was used for determining the different
pour points of the crude oil on addition of varying amounts of the PPDs obtained in
Example 1 to the crude oil and the results are compiled in Table 2.
Table 2 Pour point test data

Pour Point Depressant Pour
point
of
virgin
crude
oil
(°C) Pour point of PPD treated crude oil
(°C) Extent of depression in pour point
(°C)

1000 ppm 2000 ppm 3000 ppm 1000 ppm 2000 ppm 3000 ppm
poly(decyl ricinoleate-co-
maleic anhydride)
didecylate
[AlkyI chain length=C]0] 39 36 36 36 3 3 3
poly(dodecyl ricinoleate-co-maleic anhydride) didodecylate [Alkyl chain length-C^l 39 36 36 36 3 3 3
poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate [Alkyl chain length=C(4] 39 30 27 27 9 12 12
poly(hexadecyI ricinoleate-co-maleic anhydride)dihexadecylate [Alkyl chain length=C]6J 39 30 27 24 9 12 15
poly(octaadecyl ricinoleate-co-maleic anhydride)dioctaadecylate [Alkyl chain length=C!8] 39 33 33 33 6 6 6
poly(behenyl ricinoleate-co-maleic anhydride) dibehenylate [Alkyl chain length=C22l 39 33 33 33 6 6 6

Table 2 shows that of the PPDs prepared in Example 1, the PPDs which were most effective in reducing the pour point of the crude oil were those having C16 and C14 pendant alkyl chains i.e. poly(hexadecyl ricinoleate-co-maleic anhydride)dihexadecylate and poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate respectively.
It was observed that when 1000 ppm po!y(hexadecyl ricinoleate-co-maleic anhydride)dihexadecylate was added to the crude oil, the pour point of the crude oil was reduced by 9°C and when 2000 ppm of the same PPD was added, the pour point of the crude oil was reduced by 12°C. Finally, when concentration of PPD used was 3000 ppm, the pour point of the crude oil was reduced by 15°C.
Another effective PPD among those tested in Example No 2 was poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate. On addition of 2000ppm of the PPD to crude oil, the pour point of the crude oil was reduced by 12°C
Poly(octaadecyl ricinoleate-co-maleic anhydride)dioctaadecylate and poly(behenyl ricinoleate-co-maleic anhydride)dibehenylate reduced the pour point by 6°C at all the concentrations of the PPDs tested while poly(decyl ricinoleate-co-maleic anhydride) didecylate and poly(dodecyl ricinoleate-co-maleic anhydride) didodecylate reduced the pour point by 3°C at all the concentrations of the PPDs tested. Thus Table 2 shows that PPDs having higher alkyl pendant chains such as those of lengths C18 and C22 are more effective in depressing the pour point of crude oils than PPDs having lower alkyl pendant chains such as those of lengths C10andC12
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The above examples are non-limiting. The invention is defined by the claims that follow.

We claim:
1. A biodegradable, non-carcinogenic, crude oil pour point depressant having the general formula (I):

(I) wherein, R stands for a C10 to C22 straight chain aliphatic alkyl group with the
condition that all the three alkyl groups represented by R have the same alkyl
chain length and n represents the number of repeating units.
2. A process for the preparation of a biodegradable, non-carcinogenic, crude oil pour point depressant having the general formula (I):

(i)
wherein, R stands for a C10 to C22 straight chain aliphatic alkyl group with the condition that all the three alkyl groups represented by R have the same alkyl
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chain length and n represents the number of repeating units, the process comprising:
a) esterifying a straight chain aliphatic unsaturated ricinoleic acid with a fatty
alcohol of the general formula R-OH, where R is as defined above, in the
molar ratio of 1.5:1 in the presence of an organic solvent and a catalyst
like sulphuric acid at 110°C to 140°C under azeotropic conditions to
obtain an alkyl ester;
b) copolymerizing the alkyl ester with double recrystallized maleic anhydride
in 1:1 molar ratio under inert atmosphere and in the presence an organic
solvent and a free radical initiator at 70°C to 75°C to obtain a high
mofecufar weight copolymer; and
c) diesterifying the copolymer with a straight chain fatty alcohol of the
general formula R-OH, where R is as defined above, in a molar ratio of
1:2 at 110°C to 140°C in the presence of an organic solvent and a catalyst
like para-toluene sulfonic acid (PTSA) or sulphuric acid or a combination
thereof.
3. The process as claimed in claim 2, wherein the organic solvent is selected from
toluene or dry benzene or xylene.
4. The process as claimed in claim 2 or 3, wherein the inert atmosphere is provided
by dry nitrogen gas.
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5. The process as claimed in any one of claims 2 to 4, wherein the free radical initiator is benzoyl peroxide or azobisisobutyronitrile (AIBN).
6. A crude oil comprising l000ppm to 3000ppm of the pour point depressant as claimed in claim 1 and prepared by the process as claimed in any one of claims 2 to 5.
7. A crude oil comprising l000ppm to 3000ppm of poiy(hexadecyl ricinoleate-co-maleic anhydride)dihexadecylate as claimed in claim 6.
8. A crude oil comprising 1000ppm to 3000ppm poly(tetradecyl ricinoleate-co-maleic anhydride)ditetradecylate as claimed in claim 6.
Dated this 30th day of March 2009


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(Ivan Bernard Fuller)
Of Khaitan&Co
Agent for the Applicants